Waymo LLC v. Uber Technologies, Inc. et al

Filing 1

COMPLAINT for Violation of Defense of Trade Secret Act; Demand for Jury Trial against Otto Trucking LLC, Ottomotto LLC, Uber Technologies, Inc. (Filing Fee $ 400.00, receipt number 0971-11180330.). Filed by Waymo LLC. (Attachments: #1 Exhibit A, #2 Exhibit B, #3 Exhibit C, #4 Civil Cover Sheet)(Verhoeven, Charles) (Filed on 2/23/2017) Modified on 2/28/2017 (gbaS, COURT STAFF).

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 1 of 28

EXHIBIT B

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 2 of 28
US009368936B1

(12) United States Patent
Lenius et al.
(54)

LASER DIODE FIRING SYSTEM

(10) Patent No.:
(45) Date of Patent:
(56)

US 9,368,936 B1
Jun. 14, 2016

References Cited
|U.S. PATENT DOCUMENTS

(71) Applicant: Google Inc., Mountain View, CA (US)
(72) Inventors: Samuel William Lenius, Sunnyvale, CA
(US); Pierre-yves Droz, Mountain View,
CA (US)
(73) Assignee: Google Inc., Mountain View, CA (US)

3,790,277 A
4,700,301 A

2/1974 Hogan
10/1987 Dyke

4,709,195 A
5,202,742 A
6,882,409 B1

11/1987 Hellekson et al.
4/1993 Frank et al.
4/2005 Evans et al.

7,089,114 B1
7,248.342 B1

8/2006 Huang
7/2007 Degnan

(*) Notice:

7,255,275 B2
7,969,558 B2
8,188,794 B2

8/2007 Gurevich et al.
6/2011 Hall
5/2012 Lautzenhiser

Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 378 days.

(21) Appl. No.: 14/132,219
(22) Filed:

Dec. 18, 2013

Related U.S. Application Data
(60) Provisional application No. 61/884,762, filed on Sep.
30, 2013.

(51)

Int. Cl.

G0IC 3/08
H0 IS 5/06
G0IS 17/32
PHOIS 5/062

PH05B 33/08
G0IJ 1/46

(52)

(2006.01)
(2006.01)
(2006.01)
(2006.01)

(2006.01)
(2006.01)

U.S. CI.

CPC H01S 5/06 (2013.01); G0IS 17/32 (2013.01);
G0IJ 1/46 (2013.01), HOIS 5/062 (2013.01);
H05B 33/0842 (2013.01); H05B 33/0845
(2013.01)
(58)

Field of Classification Search

CPC ... G01J 1/46; H05B 33/0845, H05B 33/0842;
H01S 5/06; H01S 5/062; G01S 17/06

8,320,423 B2 11/2012 Stern
9,185,762 B2 * 1 1/2015 Mark ........................ G01J 1/46
2013/0106468 A1
5/2013 Aso
2013/0314711 A1 * 1 1/2013 Cantin .................... G01S 17/10
356/445
2014/0269799 A1* 9/2014 Ortiz ..................... H01S 5/0428
372/38.02
2014/0312233 A1 * 10/2014 Mark ........................ G01J 1/46
250/341.8

* cited by examiner
Primary Examiner – Mark Hellner
(74) Attorney, Agent, or Firm — McDonnell Boehnen
Hulbert & Berghoff LLP
(57)

ABSTRACT

A laser diode firing circuit for a light detection and ranging
device is disclosed. The firing circuit includes a laser diode
coupled in series to a transistor, such that current through the
laser diode is controlled by the transistor. The laser diode is
configured to emit a pulse of light in response to current
flowing through the laser diode. The firing circuit includes a
capacitor that is configured to charge via a charging path that
includes an inductorand to discharge via a discharge path that
includes the laser diode. The transistor controlling current
through the laser diode can be a Gallium nitride field effect
transistor.

USPC ..…. 359/4.01

See application file for complete search history.

20 Claims, 11 Drawing Sheets

y^T 500

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U.S. Patent

Sheet 1 of 11

Jun. 14, 2016

US 9,368,936 B1

Vehicle 100

Propulsion
System 102
Engine /

Sensor System

Control System

Peripherals

104

106

108

Motor

Global Positioning
System

Steering Unit

Wireless
Communicat

118

122

Energy
Source

Inertial Measure
ment Unit

119

124

Transmiss
ion

ion System 146

Throttle

Touch-screen

134

148

RADAR Unit

Brake Unit

Microphone

126

120

132

136

150

Speaker

Laser

Algorithm
138

Camera

121

Sensor Fusion

Rangefinder /
LIDAR Unit 128

Wheels/Tires

Computer Vision
System

130

152

140

Microphone

Navigation /
Pathing System
142
Obstacle

g

Avoidance System
Processor

|

113

144

Instructions
115

Data Storage

Power Supply

User Interface

110

116

Computer System
112

Figure 1

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U.S. Patent

Jun. 14, 2016

Sheet 2 of 11

Back View

US 9,368,936 B1

Top View

Figure 2

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U.S. Patent

Jun. 14, 2016

308

Sheet 3 of 11

US 9,368,936 B1

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U.S. Patent

US 9,368,936 B1

Z09)

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U.S. Patent

Jun. 14, 2016

Sheet 5 of 11

520d

530

4tow-> ! <st-º

520g

AT

Atcharge

T,

Figure 5B

US 9,368,936 B1

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U.S. Patent

US 9,368,936 B1

93G.InõÃH¡SOs

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U.S. Patent

Jun. 14, 2016

544

V,

542

Tº
CIRCUIT

546

GATE DRIVER

548

Sheet 7 of 11

US 9,368,936 B1

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U.S. Patent

Jun. 14, 2016

Sheet 8 of 11

US 9,368,936 B1

TURN OFF TRANSISTOR TO THEREBY CAUSE CAPACITOR
TO CHARGE AND INDUCTOR TO DECREASE STORED
ENERGY

!

602

TURN ON TRANSISTOR TO THEREBY CAUSE CAPACITOR

TO DISCHARGE, LASER DIODE TO EMIT A PULSE OF
LIGHT, AND INDUCTOR TO INCREASE STORED ENERGY

!

END

Figure 6A

604

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U.S. Patent

Jun. 14, 2016

Sheet 9 of 11

START

TURN OFF GaNFET TO THEREBY CAUSE CAPACITOR TO
CHARGE AND INDUCTOR TO DECREASE STORED ENERGY

US 9,368,936 B1

ay

TURN ON GaNFET TO THEREBY CAUSE CAPACITOR TO

DISCHARGE, LASER DIODE TO EMIT A PULSE OF LIGHT,
AND INDUCTOR TO INCREASE STORED ENERGY

24

DETERMINE TRANSMISSION TIME OF THE EMITTED
LIGHT PULSE

2 86

RECEIVE A REFLECTED LIGHT PULSE DUE TO THE
EMITTED LIGHT PULSE BEING REFLECTED BY AN
ENVIRONMENTAL OBJECT

DETERMINE A RECEPTION TIME OF THE REFLECTED
LIGHT PULSE

DETERMINE A DISTANCE TO THE OBJECT BASED ON THE
TRANSMISSION TIME AND RECEPTION TIME

TN630
Ts

–I- “.
NAVIGATE AN AUTONOMOUS VEHICLE BASED IN PART ON
THE DETERMINED DISTANCE TO THE OBJECT

!
END

Figure 6B

634

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U.S. Patent

Jun. 14, 2016

Sheet 10 of 11

US 9,368,936 B1

640

INCREASE ENERGY STORED IN INDUCTOR

TURN OFF GaNFET

RELEASE ENERGY STORED IN INDUCTOR

CHARGE CAPACITOR FROM ENERGY RELEASED BY
INDUCTOR

REVERSE BLAS DIODE TO HOLD CHARGE ON CAPACITOR
-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

656

END

Figure 6C

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U.S. Patent

US 9,368,936 B1

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US 9,368,936 B1
1

2

LASER DIODE FIRING SYSTEM

inductor. The increase in inductor current causes the inductor

CROSS-REFERENCE TO RELATED
APPLICATIONS

This application claims priority to U.S. Provisional Patent
Application No. 61/884,762, filed Sep. 30, 2013, which is
incorporated herein by reference in its entirety and for all
purposes.
10

BACKGROUND

Unless otherwise indicated herein, the materials described

in this section are not prior art to the claims in this application
and are not admitted to be prior art by inclusion in this section.
Vehicles can be configured to operate in an autonomous
mode in which the vehicle navigates through an environment
with little or no input from a driver. Such autonomous
vehicles can include one or more sensors that are configured
to detect information about the environment in which the

vehicle operates. The vehicle and its associated computer
implemented controller use the detected information to navi
gate through the environment. For example, if the sensor(s)
detect that the vehicle is approaching an obstacle, as deter
mined by the computer-implemented controller, the control
ler adjusts the vehicle’s directional controls to cause the
vehicle to navigate around the obstacle.
One such sensor is a light detection and ranging (LIDAR)
device. A LIDAR actively estimates distances to environmen
tal features while scanning through a scene to assemble a
cloud of point positions indicative of the three-dimensional
shape of the environmental scene. Individual points are mea
sured by generating a laser pulse and detecting a returning
pulse, if any, reflected from an environmental object, and
determining the distance to the reflective object according to
the time delay between the emitted pulse and the reception of
the reflected pulse. The laser, or set of lasers, can be rapidly
and repeatedly scanned across a scene to provide continuous
real-time information on distances to reflective objects in the
scene. Combining the measured distances and the orientation
of the laser(s) while measuring each distance allows for asso
ciating a three-dimensional position with each returning
pulse. A three-dimensional map of points of reflective fea
tures is generated based on the returning pulses for the entire
scanning zone. The three-dimensional point map thereby
indicates positions of reflective objects in the scanned scene.

15

20

25

30

35

40

45

SUMMARY

A laser diode firing circuit for a light detection and ranging
(LIDAR) device is disclosed. The firing circuit includes a
laser diode coupled in series with a transistor, such that cur
rent through the laser diode is controlled by the transistor. The
laser diode is configured to emit a pulse of light in response to
current flowing through the laser diode. A capacitor is con

50

55

nected across the laser diode and the transistor such that the

capacitor discharges through the laser diode when the tran
sistor is turned on. The capacitor is charged by a voltage
source via a charging path that includes a diode and an induc
tor. The inductor has one terminal coupled to the voltage
source and another terminal coupled to the anode of the diode,
and the cathode of the diode is coupled to the capacitor. As a
result, the capacitoris only charged while the diode is forward
biased. Upon turning on the transistor, the capacitor dis
charges through the laser diode and a pulse of light is emitted.
Once the capacitor discharges to a voltage level sufficient to
forward bias the diode, current begins flowing through the

60

65

to increase energy stored in its magnetic field, and drives the
voltage applied to the anode of the diode lower than the
voltage source. Once the transistor is turned off, the laser
diode ceases emission, and the current through the inductoris
directed to recharge the capacitor, which causes the inductor
current to begin decreasing. The sudden change in current
through the inductor causes an increase in the voltage applied
to the anode of the diode. The capacitor is charged until the
voltage of the capacitor approximately matches the voltage at
the diode anode, at which point the diode becomes reverse
biased. Upon reverse biasing the diode, the current through
the inductor goes to zero and the charging cycle is complete.
Both the emission and charging operations of the firing circuit
can thus be controlled by operation of the single transistor.
Some embodiments of the present disclosure provide an
apparatus. The apparatus includes a voltage source, an induc
tor, a diode, a transistor, a light emitting element, and a
capacitor. The inductor can be coupled to the voltage source.
The inductor can be configured to store energy in a magnetic
field. The diode can be coupled to the voltage source via the
inductor. The transistor can be configured to be turned on and
turned off by a control signal. The light emitting element can
be coupled to the transistor. The capacitor can be coupled to a
charging path and a discharge path. The charging path can
include the inductor and the diode. The discharge path can
include the transistor and the light emitting element. The
capacitor can be configured to charge via the charging path
such that a voltage across the capacitorincreases from a lower
voltage level to a higher voltage level responsive to the tran
sistor being turned off. The inductor can be configured to
release energy stored in the magnetic field such that a current
through the inductor decreases from a higher current level to
a lower current level responsive to the transistor being turned
off. The capacitor can be configured to discharge through the
discharge path such that the light emitting element emits a
pulse of light and the voltage across the capacitor decreases
from the higher voltage level to the lower voltage level
responsive to the transistor being turned on. The inductor can
be configured to store energy in the magnetic field such that
the current through the inductor increases from the lower
current level to the higher current level responsive to the
transistor being turned on.
Some embodiments of the present disclosure provide a
method. The method can include turning off a transistor and
turning on a transistor. The transistor can be coupled to a light
emitting element. Both the transistor and the light emitting
element can be included in a discharge path coupled to a
capacitor. The capacitor can also be coupled to a charging
path including a diode and an inductor. The inductor can be
configured to store energy in a magnetic field. The diode can
be coupled to a voltage source via the inductor. The capacitor
can be configured to charge via the charging path such that a
voltage across the capacitor increases from a lower voltage
level to a higher voltage level responsive to the transistor
being turned off. The inductor can be configured to release
energy stored in the magnetic field such that a current through
the inductor decreases from a higher current level to a lower
current level responsive to the transistor being turned off. The
capacitor can be configured to discharge through the dis
charge path such that the light emitting element emits a pulse
of light and the voltage across the capacitor decreases from
the higher voltage level to the lower voltage level responsive
to the transistor being turned on. The inductor can be config
ured to store energy in the magnetic field such that the current

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US 9,368,936 B1
4
by reading the following detailed description, with reference
where appropriate to the accompanying drawings.

3
through the inductor increases from the lower current level to
the higher current level responsive to the transistor being
turned on.

Some embodiments of the present disclosure provide a
light detection and ranging (LIDAR) device. The LIDAR
device can include a light source, a light sensor, and a con
troller. The light source can include a voltage source, an
inductor, a diode, a transistor, a light emitting element, and a
capacitor. The inductor can be coupled to the voltage source.
The inductor can be configured to store energy in a magnetic
field. The diode can be coupled to the voltage source via the
inductor. The transistor can be configured to be turned on and
turned off by a control signal. The light emitting element can
be coupled to the transistor. The capacitor can be coupled to a
charging path and a discharge path. The charging path
includes the inductor and the diode. The discharge path
includes the transistor and the light emitting element. The
capacitor can be configured to charge via the charging path
such that a voltage across the capacitorincreases from a lower
voltage level to a higher voltage level responsive to the tran
sistor being turned off. The inductor can be configured to
release energy stored in the magnetic field such that a current
through the inductor decreases from a higher current level to
a lower current level responsive to the transistor being turned
off. The capacitor can be configured to discharge through the
discharge path such that the light emitting element emits a
pulse of light and the voltage across the capacitor decreases
from the higher voltage level to the lower voltage level
responsive to the transistor being turned on. The inductor can
be configured to store energy in the magnetic field such that
the current through the inductor increases from the lower
current level to the higher current level responsive to the
transistor being turned on. The light sensor can be configured
to detect a reflected light signal comprising light from the
emitted light pulse reflected by a reflective object. The con
troller can be configured to determine a distance to the reflec
tive object based on the reflected light signal.
Some embodiments of the present disclosure provide a
means for controlling a laser diode firing circuit to operate in
an emission mode and a charging mode using a single tran
sistor. Embodiments may include means turning off a tran
sistor and turning on a transistor. The transistor can be
coupled to a light emitting element. Both the transistor and
the light emitting element can be included in a discharge path
coupled to a capacitor. The capacitor can also be coupled to a
charging path including a diode and an inductor. The inductor
can be configured to store energy in a magnetic field. The
diode can be coupled to a voltage source via the inductor. The
capacitor can be configured to charge via the charging path
such that a voltage across the capacitorincreases from a lower
voltage level to a higher voltage level responsive to the tran
sistor being turned off. The inductor can be configured to
release energy stored in the magnetic field such that a current
through the inductor decreases from a higher current level to
a lower current level responsive to the transistor being turned
off. The capacitor can be configured to discharge through the
discharge path such that the light emitting element emits a
pulse of light and the voltage across the capacitor decreases
from the higher voltage level to the lower voltage level
responsive to the transistor being turned on. The inductor can
be configured to store energy in the magnetic field such that
the current through the inductor increases from the lower
current level to the higher current level responsive to the
transistor being turned on.
These as well as other aspects, advantages, and alterna
tives, will become apparent to those of ordinary skill in the art

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a functional block diagram depicting aspects of an
example autonomous vehicle.
FIG. 2 depicts exterior views of an example autonomous
vehicle.
10

FIG. 3A provides an example depiction of a LIDAR device
including beam steering optics.
FIG. 3B symbolically illustrates an example in which a
LIDAR device scans across an obstacle-filled environmental
SCèIlê.

15

FIG. 3C symbolically illustrates an example point cloud
corresponding to the obstacle-filled environmental scene of
FIG. 3B.

20

25

30

35

FIG. 4A symbolically illustrates a LIDAR device scanning
across an example obstacle-filled environmental scene and
using reflected signals to generate a point cloud.
FIG. 4B is an example timing diagram of transmitted and
received pulses for the symbolic illustration of FIG. 4A.
FIG. 5A is an example laser diode firing circuit.
FIG. 5B is a timing diagram that shows operation of the
example laser diode firing circuit of FIG. 5A.
FIG. 5C shows a current path through the example laser
diode firing circuit of FIG. 5A during a charging mode.
FIG. 5D shows a current path through the example laser
diode firing circuit of FIG. 5A during an emission mode.
FIG. 5E illustrates an arrangement in which multiple laser
diode firing circuit are charged via a single inductor.
FIG. 6A is a flowchart of an example process for operating
a laser diode firing circuit.
FIG. 6B is a flowchart of an example process for operating
a LIDAR device.

FIG. 6G is a flowchart of another example process for
operating a laser diode firing circuit.
FIG.7 depicts a non-transitory computer-readable medium
configured according to an example embodiment.
40

DETAILED DESCRIPTION

I. Overview
45

50

55

Example embodiments relate to an autonomous vehicle,
such as a driverless automobile, that includes a light detection
and ranging (LIDAR) sensor for actively detecting reflective
features in the environment surrounding the vehicle. A con
troller analyzes information from the LIDAR sensor to iden
tify the surroundings of the vehicle. The LIDAR sensor
includes a light source that may include one or more laser
diodes configured to emit pulses of light that are then directed
to illuminate the environment surrounding the vehicle. Cir
cuits forfiring a laser diode and determining a pulse emission
time from the laser diode are disclosed herein.

According to some embodiments, a LIDAR device
includes one or more laser diode firing circuits in which a
laser diode is connected in series to a transistor such that
60

65

current through the laser diode is controlled by the transistor.
A capacitoris coupled to a charging path and a discharge path.
The discharge path includes the laser diode and the transistor
such that turning on the transistor causes the capacitor to
discharge through the laser diode, which causes the laser
diode to emit a pulse of light.
The capacitor’s charging path includes an inductor and a
diode. The inductor is configured to store energy in a mag
netic field, and is connected between a voltage source and the

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US 9,368,936 B1
5
diode. An increasing inductor current charges the inductor by
increasing the energy stored in the magnetic field of the
inductor. The increasing current induces a voltage across the
inductor, such that a voltage less than the voltage source is
applied to the diode. A decreasing inductor current discharges
the inductor by decreasing the energy stored in the magnetic
field. The decreasing current induces a voltage across the
inductor, such that the voltage applied to the diode exceeds
the voltage source. The diode is also connected to the capaci
tor and is configured to be forward biased when the voltage
across the capacitor does not exceed the voltage applied to the
diode by the inductor (to thereby charge the capacitor). The
diode is also configured to be reverse biased when the voltage
across the capacitor exceeds the voltage applied to the diode
by the inductor (to thereby prevent the capacitor from dis
charging).
In some embodiments, the firing circuit disclosed herein is
configured to switch between a charging mode and an emis
sion mode based on operation of a single transistor. In
response to turning the transistor off, current through the laser
diode ceases and emission of a pulse terminates. In response
to turning off the transistor, if the charging path diode is
forward biased, the capacitor begins recharging through the
charging path. As charge accumulates on the capacitor the
current through the charging path (and the inductor)

6
mode, and thus may be referred to as an “autonomous
vehicle.” For example, a computer system 112 can control the
vehicle 100 while in an autonomous mode via control instruc

10

15

20

munication. Thus, one or more of the functions of the vehicle
25

decreases, and the decrease in inductor current causes the

inductor to release energy stored in its magnetic field. The
released energy from the inductor causes the voltage applied
to the capacitor through the diode to exceed the voltage of the
voltage source, at least transiently. The transient voltage is
applied to the capacitor through the diode. The capacitor is
therefore charged according to the transient voltage and then
holds its charge level when the diode becomes reverse biased.
Following a charging interval, the voltage charged across the
capacitor can be greater than the voltage of the voltage source.
The laser diode can emit light in the visible spectrum,
ultraviolet spectrum, infrared spectrum, near infrared spec
trum, and/or infrared spectrum. In one example, the laser
diode emits pulses of infrared light with a wavelength of
about 905 nm. The transistor can be a Gallium nitride field

30

35

40

II. Example Autonomous Vehicle System
45

50

55

in or take the form of other vehicles, such as cars, trucks,

motorcycles, buses, boats, airplanes, helicopters, lawn mow

60

ers, earth movers, boats, snowmobiles, aircraft, recreational

vehicles, amusement park vehicles, farm equipment, con
struction equipment, trams, golf carts, trains, and trolleys.
Other vehicles are possible as well.
FIG. 1 is a functional block diagram illustrating a vehicle
100 according to an example embodiment. The vehicle 100 is
configured to operate fully or partially in an autonomous

100 described herein can optionally be divided between addi
tional functional or physical components, or combined into
fewer functional or physical components. In some further
examples, additional functional and/or physical components
may be added to the examples illustrated by FIG. 1.
The propulsion system 102 can include components oper
able to provide powered motion to the vehicle 100. In some
embodiments the propulsion system 102 includes an engine/
motor 118, an energy source 119, a transmission 120, and
wheels/tires 121. The engine/motor 118 converts energy
source 119 to mechanical energy. In some embodiments, the
propulsion system 102 can optionally include one or both of
engines and/or motors. For example, a gas-electric hybrid
vehicle can include both a gasoline/diesel engine and an
electric motor.

effect transistor (FET), for example.
Some aspects of the example methods described herein
may be carried out in whole or in part by an autonomous
vehicle or components thereof. However, some example
methods may also be carried out in whole or in part by a
system or systems that are remote from an autonomous
vehicle. For instance, an example method could be carried out
in part or in full by a server system, which receives informa
tion from sensors (e.g., raw sensor data and/or information
derived therefrom) of an autonomous vehicle. Other
examples are also possible.
Example systems within the scope of the present disclosure
will now be described in greater detail. An example system
may be implemented in, or may take the form of, an automo
bile. However, an example system may also be implemented

tions to a control system 106 for the vehicle 100. The com
puter system 112 can receive information from one or more
sensor systems 104, and base one or more control processes
(such as setting a heading so as to avoid a detected obstacle)
upon the received information in an automated fashion.
The autonomous vehicle 100 can be fully autonomous or
partially autonomous. In a partially autonomous vehiclesome
functions can optionally be manually controlled (e.g., by a
driver) some or all of the time. Further, a partially autono
mous vehicle can be configured to switch between a fully
manual operation mode and a partially-autonomous and/or a
fully-autonomous operation mode.
The vehicle 100 includes a propulsion system 102, a sensor
system 104, a control system 106, one or more peripherals
108, a power supply 110, a computer system 112, and a user
interface 116. The vehicle 100 may include more or fewer
subsystems and each subsystem can optionally include mul
tiple components. Further, each of the subsystems and com
ponents of vehicle 100 can be interconnected and/or in com

65

The energy source 119 represents a source of energy, such
as electrical and/or chemical energy, that may, in full or in
part, power the engine/motor 118. That is, the engine/motor
118 can be configured to convert the energy source 119 to
mechanical energy to operate the transmission. In some
embodiments, the energy source 119 can include gasoline,
diesel, other petroleum-based fuels, propane, other com
pressed gas-based fuels, ethanol, solar panels, batteries,
capacitors, flywheels, regenerative braking systems, and/or
other sources of electrical power, etc. The energy source 119
can also provide energy for other systems of the vehicle 100.
The transmission 120 includes appropriate gears and/or
mechanical elements suitable to convey the mechanical
power from the engine/motor 118 to the wheels/tires 121. In
some embodiments, the transmission 120 includes a gearbox,
a clutch, a differential, a drive shaft, and/or axle(s), etc.
The wheels/tires 121 are arranged to stably support the
vehicle 100 while providing frictional traction with a surface,
such as a road, upon which the vehicle 100 moves. Accord
ingly, the wheels/tires 121 are configured and arranged
according to the nature of the vehicle 100. For example, the
wheels/tires can be arranged as a unicycle, bicycle, motor
cycle, tricycle, or car/truck four-wheel format. Other wheel/
tire geometries are possible, such as those including six or
more wheels. Any combination of the wheels/tires 121 of
vehicle 100 may be operable to rotate differentially with
respect to other wheels/tires 121. The wheels/tires 121 can
optionally include at least one wheel that is rigidly attached to
the transmission 120 and at least one tire coupled to a rim of

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US 9,368,936 B1
8

7
a corresponding wheel that makes contact with a driving
surface. The wheels/tires 121 may include any combination

tion to slow the wheels/tires 121. In some embodiments, the

of metal and rubber, and/or other materials or combination of

brake unit 136 inductively decelerates the wheels/tires 121 by
a regenerative braking process to convert kinetic energy of the

materials.

wheels/tires 121 to electric current.

The sensor system 104 generally includes one or more
sensors configured to detect information about the environ
ment surrounding the vehicle 100. For example, the sensor
system 104 can include a Global Positioning System (GPS)
122, an inertial measurement unit (IMU) 124, a RADAR unit
126, a laser rangefinder/LIDAR unit 128, a camera 130, and/
or a microphone 131. The sensor system 104 could also
include sensors configured to monitor internal systems of the
vehicle 100 (e.g., O2 monitor, fuel gauge, engine oil tempera
ture, wheel speed sensors, etc.). One or more of the sensors
included in sensor system 104 could be configured to be
actuated separately and/or collectively in order to modify a
position and/or an orientation of the one or more sensors.
The GPS 122 is a sensor configured to estimate a geo
graphic location of the vehicle 100. To this end, GPS 122 can
include a transceiver operable to provide information regard
ing the position of the vehicle 100 with respect to the Earth.
The IMU 124 can include any combination of sensors (e.g.,
accelerometers and gyroscopes) configured to sense position
and orientation changes of the vehicle 100 based on inertial

The sensor fusion algorithm 138 is an algorithm (or a
computer program product storing an algorithm) configured
to accept data from the sensor system 104 as an input. The
data may include, for example, data representing information
sensed at the sensors of the sensor system 104. The sensor
fusion algorithm 138 can include, for example, a Kalman
filter, Bayesian network, etc. The sensor fusion algorithm 138
provides assessments regarding the environment surrounding
the vehicle based on the data from sensorsystem 104. In some

acceleration.

The RADAR unit 126 can represent a system that utilizes
radio signals to sense objects within the local environment of
the vehicle 100. In some embodiments, in addition to sensing
the objects, the RADAR unit 126 and/or the computer system
112 can additionally be configured to sense the speed and/or
heading of the objects.
Similarly, the laser rangefinder or LIDAR unit 128 can be
any sensor configured to sense objects in the environment in
which the vehicle 100 is located using lasers. The laser
rangefinder/LIDAR unit 128 can include one or more laser
sources, a laser scanner, and one or more detectors, among
other system components. The laser rangefinder/LIDAR unit
128 can be configured to operate in a coherent (e.g., using
heterodyne detection) or an incoherent detection mode.
The camera 130 can include one or more devices config
ured to capture a plurality of images of the environment
surrounding the vehicle 100. The camera 130 can be a still

10

embodiments, the assessments can include evaluations of
15

individual objects and/or features in the environment sur
rounding vehicle 100, evaluations of particular situations,
and/or evaluations of possible interference between the
vehicle 100 and features in the environment (e.g., such as
predicting collisions and/or impacts) based on the particular

20

situations.

25

30

35

40

camera or a video camera. In some embodiments, the camera

130 can be mechanically movable such as by rotating and/or
tilting a platform to which the camera is mounted. As such, a
control process of vehicle 100 may be implemented to control

45

the movement of camera 130.

The sensor system 104 can also include a microphone 131.
The microphone 131 can be configured to capture sound from
the environment surrounding vehicle 100. In some cases,
multiple microphones can be arranged as a microphone array,
or possibly as multiple microphone arrays.
The control system 106 is configured to control operation
(s) regulating acceleration of the vehicle 100 and its compo
ments. To effect acceleration, the control system 106 includes
a steering unit 132, throttle 134, brake unit 136, a sensor
fusion algorithm 138, a computer vision system 140, a navi
gation/pathing system 142, and/or an obstacle avoidance sys

50

55

tem 144, etc.

The steering unit 132 is operable to adjust the heading of
vehicle 100. For example, the steering unit can adjust the axis
(or axes) of one or more of the wheels/tires 121 so as to effect
turning of the vehicle. The throttle 134 is configured to con
trol, for instance, the operating speed of the engine/motor 118
and, in turn, adjust forward acceleration of the vehicle 100 via
the transmission 120 and wheels/tires 121. The brake unit 136
decelerates the vehicle 100. The brake unit 136 can use fric

60

65

The computer vision system 140 can process and analyze
images captured by camera 130 to identify objects and/or
features in the environment surrounding vehicle 100. The
detected features/objects can include traffic signals, roadway
boundaries, other vehicles, pedestrians, and/or obstacles, etc.
The computer vision system 140 can optionally employ an
object recognition algorithm, a Structure From Motion
(SFM) algorithm, video tracking, and/or available computer
vision techniques to effect categorization and/or identifica
tion of detected features/objects. In some embodiments, the
computer vision system 140 can be additionally configured to
map the environment, track perceived objects, estimate the
speed of objects, etc.
The navigation and pathing system 142 is configured to
determine a driving path for the vehicle 100. For example, the
navigation and pathing system 142 can determine a series of
speeds and directional headings to effect movement of the
vehicle along a path that substantially avoids perceived
obstacles while generally advancing the vehicle along a road
way-based path leading to an ultimate destination, which can
be set according to user inputs via the user interface 116, for
example. The navigation and pathing system 142 can addi
tionally be configured to update the driving path dynamically
while the vehicle 100 is in operation on the basis of perceived
obstacles, traffic patterns, weather/road conditions, etc. In
some embodiments, the navigation and pathing system 142
can be configured to incorporate data from the sensor fusion
algorithm 138, the GPS 122, and one or more predetermined
maps so as to determine the driving path for vehicle 100.
The obstacle avoidance system 144 can represent a control
system configured to identify, evaluate, and avoid or other
wise negotiate potential obstacles in the environment sur
rounding the vehicle 100. For example, the obstacle avoid
ance system 144 can effect changes in the navigation of the
vehicle by operating one or more subsystems in the control
system 106 to undertake swerving maneuvers, turning
maneuvers, braking maneuvers, etc. In some embodiments,
the obstacle avoidance system 144 is configured to automati
cally determine feasible (“available”) obstacle avoidance
maneuvers on the basis of surrounding traffic patterns, road
conditions, etc. For example, the obstacle avoidance system
144 can be configured such that a swerving maneuver is not
undertaken when other sensor systems detect vehicles, con
struction barriers, other obstacles, etc. in the region adjacent
the vehicle that would be swerved into. In some embodi

ments, the obstacle avoidance system 144 can automatically
select the maneuver that is both available and maximizes

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 18 of 28

US 9,368,936 B1
9
safety of occupants of the vehicle. For example, the obstacle
avoidance system 144 can select an avoidance maneuver pre
dicted to cause the least amount of acceleration in a passenger
cabin of the vehicle 100.

The vehicle 100 also includes peripherals 108 configured
to allow interaction between the vehicle 100 and external

sensors, other vehicles, other computer systems, and/or a
user, such as an occupant of the vehicle 100. For example, the
peripherals 108 for receiving information from occupants,
external systems, etc. can include a wireless communication
system 146, a touchscreen 148, a microphone 150, and/or a
speaker 152.
In some embodiments, the peripherals 108 function to
receive inputs for a user of the vehicle 100 to interact with the
user interface 116. To this end, the touchscreen 148 can both

10

vehicle 100 in a distributed fashion.
15

provide information to a user of vehicle 100, and convey
information from the user indicated via the touchscreen 148

to the user interface 116. The touchscreen 148 can be config
ured to sense both touch positions and touch gestures from a
user’s finger(or stylus, etc.) via capacitive sensing, resistance
sensing, optical sensing, a surface acoustic wave process, etc.
The touchscreen 148 can be capable of sensing finger move
ment in a direction parallel or planar to the touchscreen sur

25

vehicle 100 in the autonomous, semi-autonomous, and/or
30

35

40

CDMA, EVDO, GSM/GPRS, and/or 4G cellular communi

cation, such as WiMAX or LTE. Additionally or alternatively,
wireless communication system 146 can communicate with a
wireless local area network (WLAN), for example, using
WiFi. In some embodiments, wireless communication sys
tem 146 could communicate directly with a device, for
example, using an infrared link, Bluetooth, and/or ZigBee.
The wireless communication system 146 can include one or
more dedicated short range communication (DSRC) devices
that can include public and/or private data communications

45

50

between vehicles and/or roadside stations. Other wireless

protocols for sending and receiving information embedded in
signals, such as various vehicular communication systems,
can also be employed by the wireless communication system
146 within the context of the present disclosure.
As noted above, the power supply 110 can provide power to
components of vehicle 100, such as electronics in the periph
erals 108, computer system 112, sensor system 104, etc. The
power supply 110 can include a rechargeable lithium-ion or
lead-acid battery for storing and discharging electrical energy
to the various powered components, for example. In some
embodiments, one or more banks of batteries can be config
ured to provide electrical power. In some embodiments, the
power supply 110 and energy source 119 can be implemented
together, as in some all-electric cars.

with, and/or control one or more of the propulsion system
102, the sensor system 104, the control system 106, and the
peripherals 108.
In addition to the instructions 115, the data storage 114
may store data such as roadway maps, path information,
among other information. Such information may be used by
vehicle 100 and computer system 112 during operation of the
manual modes to select available roadways to an ultimate
destination, interpret information from the sensor system

allow communication between the vehicle 100 and external

systems, such as devices, sensors, other vehicles, etc. within
its surrounding environment and/or controllers, servers, etc.,
physically located far from the vehicle that provide useful
information regarding the vehicle’s surroundings, such as
traffic information, weather information, etc. For example,
the wireless communication system 146 can wirelessly com
municate with one or more devices directly or via a commu
nication network. The wireless communication system 146
can optionally use 3G cellular communication, such as

In some embodiments, data storage 114 contains instruc
tions 115 (e.g., program logic) executable by the processor
113 to execute various functions of vehicle 100, including
those described above in connection with FIG.1. Data storage
114 may contain additional instructions as well, including
instructions to transmit data to, receive data from, interact

20

face, in a direction normal to the touchscreen surface, or both,

and may also be capable of sensing a level of pressure applied
to the touchscreen surface. An occupant of the vehicle 100 can
also utilize a voice command interface. For example, the
microphone 150 can be configured to receive audio (e.g., a
voice command or other audio input) from a user of the
vehicle 100. Similarly, the speakers 152 can be configured to
output audio to the user of the vehicle 100.
In some embodiments, the peripherals 108 function to

10
Many or all of the functions of vehicle 100 can be con
trolled via computer system 112 that receives inputs from the
sensor system 104, peripherals 108, etc., and communicates
appropriate control signals to the propulsion system 102,
control system 106, peripherals, etc. to effect automatic
operation of the vehicle 100 based on its surroundings. Com
puter system 112 includes at least one processor 113 (which
can include at least one microprocessor) that executes instruc
tions 115 stored in a non-transitory computer readable
medium, such as the data storage 114. The computer system
112 may also represent a plurality of computing devices that
serve to control individual components or subsystems of the

104, etc.

The vehicle 100, and associated computer system 112,
provides information to and/or receives input from, a user of
vehicle 100, such as an occupant in a passenger cabin of the
vehicle 100. The user interface 116 can accordingly include
one or more input/output devices within the set of peripherals
108, such as the wireless communication system 146, the
touchscreen 148, the microphone 150, and/or the speaker 152
to allow communication between the computer system 112
and a vehicle occupant.
The computer system 112 controls the operation of the
vehicle 100 based on inputs received from various sub
systems indicating vehicle and/or environmental conditions
(e.g., propulsion system 102, sensor system 104, and/or con
trol system 106), as well as inputs from the user interface 116,
indicating user preferences. For example, the computer sys
tem 112 can utilize input from the control system 106 to
control the steering unit 132 to avoid an obstacle detected by
the sensorsystem 104 and the obstacle avoidance system 144.
The computer system 112 can be configured to control many
aspects of the vehicle 100 and its subsystems. Generally,
however, provisions are made for manually overriding auto
mated controller-driven operation, such as in the event of an
emergency, or merely in response to a user-activated override,
etc.

55

60

65

The components of vehicle 100 described herein can be
configured to work in an interconnected fashion with other
components within or outside their respective systems. For
example, the camera 130 can capture a plurality of images
that represent information about an environment of the
vehicle 100 while operating in an autonomous mode. The
environment may include other vehicles, traffic lights, traffic
signs, road markers, pedestrians, etc. The computer vision
system 140 can categorize and/or recognize various aspects in
the environment in concert with the sensor fusion algorithm
138, the computer system 112, etc. based on object recogni
tion models pre-stored in data storage 114, and/or by other
techniques.

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 19 of 28

US 9,368,936 B1
11
Although the vehicle 100 is described and shown in FIG. 1
as having various components of vehicle 100, e.g., wireless
communication system 146, computer system 112, data stor
age 114, and user interface 116, integrated into the vehicle
100, one or more of these components can optionally be
mounted or associated separately from the vehicle 100. For
example, data storage 114 can exist, in part or in full, separate
from the vehicle 100, such as in a cloud-based server, for

example. Thus, one or more of the functional elements of the
vehicle 100 can be implemented in the form of device ele
ments located separately or together. The functional device
elements that make up vehicle 100 can generally be commu
nicatively coupled together in a wired and/or wireless fash

10

1011.

FIG.2 shows an example vehicle 200 that can include some

15

or all of the functions described in connection with vehicle

100 in reference to FIG.1. Although vehicle 200 is illustrated
in FIG. 2 as a four-wheel sedan-type car for illustrative pur
poses, the present disclosure is not so limited. For instance,
the vehicle 200 can represent a truck, a van, a semi-trailer
truck, a motorcycle, a golf cart, an off-road vehicle, or a farm

20

vehicle, etc.

The example vehicle 200 includes a sensor unit 202, a
wireless communication system 204, a RADAR unit 206, a
laser rangefinder unit 208, and a camera 210. Furthermore,
the example vehicle 200 can include any of the components

25

described in connection with vehicle 100 of FIG. 1. The

RADAR unit 206 and/or laser rangefinder unit 208 can
actively scan the surrounding environment for the presence of
potential obstacles and can be similar to the RADAR unit 126
and/or laser rangefinder/LIDAR unit 128 in the vehicle 100.
The sensor unit 202 is mounted atop the vehicle 200 and
includes one or more sensors configured to detect information
about an environment surrounding the vehicle 200, and out
put indications of the information. For example, sensor unit
202 can include any combination of cameras, RADARs,
LIDARs, range finders, and acoustic sensors. The sensor unit

30

35

202 can include one or more movable mounts that could be

operable to adjust the orientation of one or more sensors in the
sensor unit 202. In one embodiment, the movable mount

40

could include a rotating platform that could scan sensors so as
to obtain information from each direction around the vehicle

12
including such devices in or near the rear bumper, side panels,
rocker panels, and/or undercarriage, etc.
The wireless communication system 204 could be located
on a roof of the vehicle 200 as depicted in FIG. 2. Alterna
tively, the wireless communication system 204 could be
located, fully or in part, elsewhere. The wireless communi
cation system 204 may include wireless transmitters and
receivers that could be configured to communicate with
devices external or internal to the vehicle 200. Specifically,
the wireless communication system 204 could include trans
ceivers configured to communicate with other vehicles and/or
computing devices, for instance, in a vehicular communica
tion system or a roadway station. Examples of such vehicular
communication systems include dedicated short range com
munications (DSRC), radio frequency identification (RFID),
and other proposed communication standards directed
towards intelligent transport systems.
The camera 210 can be a photo-sensitive instrument, such
as a still camera, a video camera, etc., that is configured to
capture a plurality of images of the environment of the vehicle
200. To this end, the camera 210 can be configured to detect
visible light, and can additionally or alternatively be config
ured to detect light from other portions of the spectrum, such
as infrared or ultraviolet light. The camera 210 can be a
two-dimensional detector, and can optionally have a three
dimensional spatial range of sensitivity. In some embodi
ments, the camera 210 can include, for example, a range
detector configured to generate a two-dimensional image
indicating distance from the camera 210 to a number of points
in the environment. To this end, the camera 210 may use one
or more range detecting techniques.
For example, the camera 210 can provide range informa
tion by using a structured light technique in which the vehicle
200 illuminates an object in the environment with a predeter
mined light pattern, such as a grid or checkerboard pattern
and uses the camera 210 to detect a reflection of the prede
termined light pattern from environmental surroundings.
Based on distortions in the reflected light pattern, the vehicle
200 can determine the distance to the points on the object. The
predetermined light pattern may comprise infrared light, or
radiation at other suitable wavelengths for such measure
mentS.

200. In anotherembodiment, the movable mount of the sensor

The camera 210 can be mounted inside a front windshield

unit 202 could be moveable in a scanning fashion within a
particular range of angles and/or azimuths. The sensor unit
202 could be mounted atop the roof of a car, for instance,
however other mounting locations are possible. Additionally,

of the vehicle 200. Specifically, the camera 210 can be situ
ated to capture images from a forward-looking view with
respect to the orientation of the vehicle 200. Other mounting
locations and viewing angles of camera 210 can also be used,

45

the sensors of sensor unit 202 could be distributed in different

locations and need not be collocated in a single location.
Some possible sensor types and mounting locations include
RADAR unit 206 and laser rangefinder unit 208. Further
more, each sensor of sensor unit 202 can be configured to be
moved or scanned independently of other sensors of sensor

either inside or outside the vehicle 200.
50

The camera 210 can have associated optics operable to
provide an adjustable field of view. Further, the camera 210
can be mounted to vehicle 200 with a movable mount to vary
a pointing angle of the camera 210, such as via a pan/tilt
mechanism.

unit 202.

In an example configuration, one or more RADAR scan
ners (e.g., the RADAR unit 206) can be located near the front
of the vehicle 200, to actively scan the region in front of the
car 200 for the presence of radio-reflective objects. A
RADAR scanner can be situated, for example, in a location
suitable to illuminate a region including a forward-moving
path of the vehicle 200 without occlusion by other features of
the vehicle 200. For example, a RADAR scanner can be

55

60

situated to be embedded and/or mounted in or near the front

bumper, front headlights, cowl, and/or hood, etc. Further
more, one or more additional RADAR scanning devices can
be located to actively scan the side and/or rear of the vehicle
200 for the presence of radio-reflective objects, such as by

65

III. Example LIDAR Device
An example light detection and ranging (LIDAR) device
operates to estimate positions of reflective objects surround
ing the device by illuminating its surrounding environment
with pulses of light and measuring the reflected signals. An
example LIDAR device may include a light source, beam
steering optics, a light sensor, and a controller. The light
source may emit pulses of light toward the beam-steering
optics, which directs the pulses of light across a scanning
zone. Reflective features in the scanning zone reflect the
emitted pulses of light and the reflected light signals can be
detected by the light sensor. The controller can regulate the

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 20 of 28

US 9,368,936 B1
13
operation of the light source and beam-steering optics to scan
pulses of light across the scanning zone. The controller can
also be configured to estimate positions of reflective features
in the scanning zone based on the reflected signals detected by
the light sensor. For example, the controller can measure the
time delay between emission of a pulse of light and reception
of a reflected light signal and determine the distance to the
reflective feature based on the time of flight of a round trip to
the reflective feature. In addition, the controller may use the
orientation of the beam-steering optics at the time the pulse of
light is emitted to estimate a direction toward the reflective

5

10

feature. The estimated direction and estimated distance can

then be combined to estimate a three-dimensional position of
the reflective object relative to the LIDAR device.
FIG. 3A provides an example depiction of a LIDAR device
302 including beam steering optics 304. A laser beam 306 is
directed to the beam steering optics 304. In the example
illustrated in FIG. 3A, the beam steering optics 304 is a
rotating angled mirror that directs the laser beam 306 to
sweep across a scanning zone. The beam steering optics 304
may include a combination of lenses, mirrors, and/or aper
tures configured to direct the laser beam to sweep across a
scanning zone, and are interchangeably described as the rotat
ing angled mirror 304. The rotating angled mirror 304 rotates
about an axis substantially parallel, and roughly in line with,
the initial downward path of the laser beam 306. The rotating
angled mirror 304 rotates in the direction indicated by the

15

20

25

reference arrow 308 in FIG. 3A.

Although rangefinder 302 is depicted as having an approxi
mately 180 degree range of rotation for the scanning zone of
the laser beam 306 via the rotating angled mirror 304, this is
for purposes of example and explanation only. LIDAR 302
can be configured to have viewing angles (e.g., angular range
of available orientations during each sweep), including view
ing angles up to and including 360 degrees. Further, although
LIDAR 302 is depicted with the single laser beam 306 and a
single mirror 304, this is for purposes of example and expla
nation only, LIDAR 302 can include multiple laser beams
operating simultaneously or sequentially to provide greater
sampling coverage of the surrounding environment. The

30

35

40

LIDAR 302 also includes, or works in concert with, addi

tional optical sensors (e.g., a photo-detector, not shown) con
figured to detect the reflection of laser beam 306 from fea
tures/objects in the surrounding environment with sufficient
temporal sensitivity to determine distances to the reflective
features. For example, with reference to the vehicle 200 in
FIG. 2, such optical sensors can optionally be co-located with
the top-mounted sensors 204 on the autonomous vehicle 200.
FIG. 3B symbolically illustrates the LIDAR device 302
scanning across an obstacle-filled environmental scene. The
example vehicular environment depicted in FIG. 3B includes
a car 310 and a tree 312. In operation, LIDAR 302 rotates
according to motion reference arrow 308. While rotating, the
LIDAR 302 regularly (e.g., periodically) emits laser pulses,
such as the laser pulse 306. Objects in the surrounding envi

45

50

312 visible from the LIDAR device 302. The absence of

points between the car spatial data 314 and the tree spatial
data 316 indicates an absence of reflective features along the
sampled line of sight paths in the plane illustrated.
Each point in the example point cloud illustrated symboli
cally in FIG. 3C can be referenced by an azimuth angle p (e.g.
orientation of the LIDAR device 302 while emitting the pulse
corresponding to the point, which is determined by the ori
entation of the rotating angled mirror 304) and a line-of-sight
(LOS) distance (e.g., the distance indicated by the time delay
between pulse emission and reflected light reception). For
emitted pulses that do not receive a reflected signal, the LOS
distance can optionally be set to the maximum distance sen
sitivity of the LIDAR device 302. The maximum distance
sensitivity can be determined according to the maximum time
delay the associated optical sensors wait for a return reflected
signal following each pulse emission, which can itself be set
according to the anticipated signal strength of a reflected
signal at a particular distance given ambient lighting condi
tions, intensity of the emitted pulse, predicted reflectivity of
environmental features, etc. In some examples, the maximum
distance can be approximately 60 meters, 80 meters, 100
meters, or 150 meters, but other examples are possible for
particular configurations of the LIDAR device 302 and asso
ciated optical sensors.
In some embodiments, the sensor fusion algorithm 138,
computer vision system 140, and/or computer system 112,
can interpret the car spatial data 314 alone and/or in combi
nation with additional sensor-indicated information and/or

55

ronment, such as vehicle 310 and tree 312, reflect the emitted

pulses and the resulting reflected signals are then received by
suitable sensors. Precisely time-stamping the receipt of the
reflected signals allows for associating each reflected signal
(if any is received at all) with the most recently emitted laser
pulse, and measuring the time delay between emission of the
laser pulse and reception of the reflected light. The time delay
provides an estimate of the distance to the reflective feature by
scaling according to the speed of light in the intervening
atmosphere. Combining the distance information for each
reflected signal with the orientation of the LIDAR device 302
for the respective pulse emission allows for determining a

14
position of the reflective feature in three-dimensions. For
illustrative purposes, the environmental scene in FIG. 3B is
described in the two-dimensional x-y plane in connection
with a single sweep of the LIDAR device 302 that estimates
positions to a series of points located in the x-y plane. How
ever, it is noted that a more complete three-dimensional sam
pling is provided by either adjusting the beam steering optics
304 to direct the laserbeam 306 up or down from the x-y plane
on its next sweep of the scene or by providing additional
lasers and associated beam steering optics dedicated to sam
pling point locations in planes above and below the x-y plane
shown in FIG. 3B, or combinations of these techniques.
FIG. 3C symbolically illustrates a point cloud correspond
ing to the obstacle-filled environmental scene of FIG. 3B.
Spatial-point data (represented by stars) are shown from a
ground-plane (or aerial) perspective. Even though the indi
vidual points are not equally spatially distributed throughout
the sampled environment, adjacent sampled points are
roughly equally angularly spaced with respect to the LIDAR
device 302. A cluster of points referred to herein as car spatial
data 314 corresponds to measured points on the surface of the
car 310 with a line of sight to the LIDAR device 302. Simi
larly, a cluster of points referred to herein as tree spatial data
316 corresponds to measured points on the surface of the tree

60

65

memory-based pattern-matching point clouds and/or base
line maps of the environment to categorize or identify the
group of points 314 as corresponding to the car 310. Simi
larly, the tree spatial data 316 can identified as corresponding
to the tree 310 in accordance with a suitable object-detection
technique. As described further herein, some embodiments of
the present disclosure provide for identifying a region of the
point cloud for study with enhanced resolution scanning tech
nique on the basis of the already-sampled spatial-points.
FIG. 4A symbolically illustrates a LIDAR device 302 scan
ning across an example obstacle-filled environmental scene.
The LIDAR device 302 scans the laser beam 306 across the

environmental scene via its beam steering optics 304 while its
laser light source pulses, such that successive pulses are emit

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 21 of 28

US 9,368,936 B1
15
ted with an angular separation 01. Successive pulses are emit
ted periodically with a temporal separation tº. For illustrative
purposes, the angular separation 01 between adjacent, succes
sively emitted pulses is exaggerated in FIG. 4A to allow
individual pulses to be represented in the drawing. As a result
of the rotation of the beam steering optics in the LIDAR
device 302, temporally separated pulses (e.g., pulses emitted
at times separated by the time ti) are directed in respective
angular orientations separated by the amount of rotation of
the beam steering optics during the interval tº, (e.g., the angle
01). A controller 430 is arranged to receive signals from the
LIDAR device 302 and/or associated optical sensors to gen
erate point cloud data 440 indicative of the 3-D positions of
reflective features in the environmental scene surrounding the
LIDAR device 302.

FIG. 4B is a timing diagram of the transmitted and received
pulses for the exaggerated symbolic illustration of FIG. 4A.
The timing diagram symbolically illustrates the transmitted
pulses (labeled on FIG. 4B as “Tx”) and the corresponding
received pulses (labeled on FIG. 4B as “Rx”).
An example operation of the LIDAR device 302 is

10

15

20

described in connection with FIGS. 4A and 4B. At time Ta, a

first pulse 410a is emitted from the LIDAR device 302 and
directed along laser beam path 306a via the beam steering
optics. As shown in FIG. 4A, the beam path 306a is reflected
from near the front passenger-side region of the car 310, and
a first reflected signal 420a is detected at optical signals
associated with the LIDAR device 302 (e.g., via optical sen
sors included in the sensorsystem 202 mounted on the vehicle
200 in FIG. 2). The time delay between the emission of pulse
410a and reception of the reflected signal 420a is indicated by
time delay ATa. The time delay ATa and the orientation of the

25

30

LIDAR device 302 at time Ta, i.e., the direction of laser beam

306a, are combined in the controller 430 to map the 3-D
position of the reflective point on the front passenger-side
region of the car 310.
Next, at time Tb, a second pulse 410b is emitted from the
LIDAR device 302 and directed along laser beam path 306b.
Time Tb is temporally separated from time Ta by the interval
time t1, and the direction of the laser beam path 306b is
angularly separated from the direction of laser beam path
306a by angular separation 01, due to the change in orienta
tion of the beam steering optics in the LIDAR device during
the interval tº. The laser pulse 310b is reflected from near the
rear passenger-side region of the car 310, and a second
reflected signal 420b is detected with a relative time delay
ATb from the emission of the second pulse 410b. As illus
trated in FIG. 4B, the LIDAR device 302 is generally situated
behind the car 310, and so the reflective point near the rear
passenger-side region of the car 310 (responsible for the
reflected signal 420b) is closer to the LIDAR device 302 than
the reflective point near the front passenger-side region of the
car 310 (responsible for the reflected signal 420a). As a result,
the relative time delay ATb is shorter than the relative time
delay ATa, corresponding to the difference in roundtrip travel
time at the speed of light between the LIDAR device 302, and
the respective reflective points at the front and rear of the car.
Further, the sensors detecting the reflected signals can
optionally be sensitive to the intensity of the reflected signals.
For example, the intensity of the reflected signal 420b can be
perceptibly greater than the intensity of the reflected signal
420a, as shown symbolically in FIG. 4B. The controller 430
maps the 3-D position of the reflective point near the rear
passenger-side of the car 310 according to the time delay
value ATb and the orientation of the LIDAR device 310 at

time Tb, i.e., the direction of laser beam 306b. The intensity of
the reflected signal can also indicate the reflectance of the

16
reflective point, in combination with the distance to the point
as indicated by the measured time delay. The reflectance of
the reflective point can be employed by software and/or hard
ware implemented modules in the controller 430 to charac
terize the reflective features in the environment. For example,
traffic indicators such as lane markers, traffic signs, traffic
signals, navigational signage, etc., can be indicated in part
based on having a relatively high reflectance value, such as
associated with a reflective coating applied to traffic and/or
navigational signage. In some embodiments, identifying a
relatively high reflectance feature can provide a prompt to
undertake a further scan of the high reflectance feature with
one or more sensors, such as those in the sensing system 104.
Thus, in one example, a reflected signal indicating a high
reflectance feature can provide a prompt to image the high
reflectance feature with a camera to allow for identifying the
high reflectance feature. In some embodiments where the
high reflectance feature is a traffic sign, the camera image can
allow for reading the sign via character recognition and/or
pattern matching, etc. and then optionally adjusting naviga
tional instructions based on the sign (e.g., a sign indicating a
construction zone, pedestrian crosswalk, school zone, etc.
can prompt the autonomous vehicle to reduce speed).
At time Tc, following the time Tb by the interval t!, a third
pulse 410c is emitted from the LIDAR device 302. The third
pulse 410c is directed along a laser beam path 306c, which is
approximately angularly separated from the beam path 306b
by the angle 01. The pulse 410c is reflected from a point near
the middle of the rear bumper region of the car 310, and a
resulting reflected signal 420c is detected at the LIDAR
device 302 (or its associated optical sensors). The controller
430 combines the relative time delay ATc between the emis
sion of pulse 410c and reception of reflected signal 420c and
the orientation of the LIDAR device 302 at time Tc, i.e., the

35

40

direction of beam path 306c, to map the 3-D position of the
reflective point.
At time Td, following time Tc by the interval ti, a fourth
pulse 410disemitted from the LIDAR device 302. The fourth
pulse 410d is directed along a laser beam path 306d, which is
approximately angularly separated from the beam path 306c
by the angle 01. The beam path 306d entirely avoids the car
310, and all other reflective environmental features within a

45

50

55

maximum distance sensitivity of the LIDAR device 302. As
discussed above, the maximum distance sensitivity of the
LIDAR device 302 is determined by the sensitivity of the
associated optical sensors for detecting reflected signals. The
maximum relative time delay ATmax corresponds to the
maximum distance sensitivity of the LIDAR device (i.e., the
time for light signals to make a round trip of the maximum
distance). Thus, when the optical sensor associated with the
LIDAR device 302 does not receive a reflected signal in the
period ATmax following time Td, the controller 430 deter
mines that no reflective features are present in the surround
ing environment along the laser beam path 306d.
The reflective points on the car 310 corresponding to the
reflected signals 420a-c form a subset of points included in a
3-D point cloud map 440 of the environment surrounding the
LIDAR device 302. In addition, the direction of the laser

60

65

beam 310d is noted in the 3-D point cloud map 440 as being
absent of reflective features along the line of sight within the
maximum distance sensitivity of the LIDAR device 302,
because no reflected signal was received after the duration
ATmax following the emission of pulse 410d at time Td. The
points corresponding to laser beam directions 306a-d are
combined with points spaced throughout the scanning zone
(e.g., the region scanned by the LIDAR device 302), to create
a complete 3-D point cloud map, and the results are output as

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 22 of 28

US 9,368,936 B1
17
fixed resolution point cloud data 440 for further analysis by
object detection systems, pattern recognition systems, com
puter vision systems, etc.

18
transistor 520 is turned off. For example, the discharge diode
522 may have an anode and a cathode; the anode can be

IV. Example Laser Diode Firing Circuit

charge remaining on an internal capacitance of the laser diode
518 following a firing operation causes the discharge diode
522 to be forward biased, and the internal capacitance is
allowed to discharge through the discharge diode 522. Fol
lowing such discharge, the discharge diode 522 is no longer

In order to illuminate a scanning zone with pulses of light,
a LIDAR device includes one or more light sources that are
triggered to emit pulses of light. The light sources may
include light emitting elements such as a laser diode or
another emissive light source. A laser diode is a semiconduc
tor device including a p-n junction with an active region in
which oppositely polarized, energized charge carriers (e.g.,
free electrons and/or holes) recombine while current flows
through the device across the p-n junction. The recombina
tion results in emission of light due to a change in energy state
of the charge carriers. When the active region is heavily
populated by such energized pairs (e.g., the active region may
have a population inversion of energized states), stimulated
emission across the active region may produce a substantially
coherent wavefront of light that is then emitted from the laser
diode. Recombination events, and the resulting light emis
sion, occur in response to current flowing through the device,
and so applying a pulse of current to the laser diode results in
emission of a pulse of light from the laser diode.
A light pulse with the desired temporal profile can be
generated by applying a rapidly switched current to a laser
diode (e.g., a current source that rapidly transitions from near

connected to the cathode of the laser diode 518; the cathode
can be connected to the anode of the laser diode 518. As such,

10

15

20

The inductor 510 is connected between the voltage source
502 and the anode of the diode 514. For convenience in the
25

30

35

be controlled by operating the transistor. An example circuit
may switch from near zero current through the laser diode, to
about 30 amperes, and back to near zero all in a span of about
1-2 nanoseconds.

40

The firing circuits disclosed herein may include a laser
diode configured to emit a pulse of light with a wavelength in
the visible spectrum, ultraviolet spectrum, near infrared spec
trum, and/or infrared spectrum. In one example, the laser
diode is configured to emit a pulse of light in the infrared
spectrum with a wavelength of about 905 nanometers.
FIG. 5A is an example laser diode firing circuit 500. The
firing circuit 500 includes a capacitor 516 connected to a laser
diode 518 and a transistor 520. In some examples, the capaci

45

tor 516, laser diode 518, and transistor 520 can be connected

50

cathode of the diode 514 is connected to the capacitor 516 and
also to the anode of the laser diode 518. The capacitor’s 516
charging path, which couples the capacitor 516 and the volt
age source 502, includes the inductor 510 and the diode 514.
During charging, the voltage across the inductor 510 varies in
accordance with changes in the inductor current, and the
diode 514 regulates the voltage applied to the capacitor 516
depending on whether the diode 514 is forward biased or
reverse biased. The diode 514 is forward biased (and thus
allows the capacitor 516 to charge) when the voltage at node
A 512 is greater than the voltage on the capacitor 516. The
diode 514 is reverse based (and thus prevents the capacitor
516 from charging) when the voltage at node A 512 is less
than the voltage on the capacitor 516. Voltage variations at
node A512 due to changes in current through the inductor 510
may result in a voltage being applied to the capacitor 516 that
exceeds the voltage of the voltage source 502.
For example, the voltage source 502 connected to one side
of the inductor 510 may have a voltage V1. The voltage on the
other side of the inductor 510, at node A 512, varies due to

55

the laser diode 518 is connected to one terminal of the tran

sistor 520, which has another terminal connected to ground
(which may also connect to the capacitor 516). The transistor
520 acts as a switch to selectively allow current to flow
through the laser diode 518 according to a control signal from
a gate driver 530.
A discharge diode 522 is coupled across the laser diode
518. The discharge diode 522 is configured to allow an inter
nal capacitance of the laser diode 518 to discharge when the

description and the drawings a point connecting the inductor
510 and the anode of the diode 514 is labeled node A512. The

laser diode, and thus emission from the laser diode, can then

in series. The capacitor 516 is connected to both a charging
path (e.g., FIG. 5C) and a discharge path (e.g., FIG. 5D). The
capacitor 516 has one terminal coupled to a voltage source
502 (e.g., through inductor 510 and diode 514) and an anode
of the laser diode 518. The other terminal of the capacitor 516
can be connected to ground, or to another reference voltage
sufficient to allow the capacitor 516 to be charged by the
voltage source 502, through the charging path. The cathode of

To initiate firing, the gate driver 530 causes the transistor
520 to turn on by adjusting the voltage applied to the gate
terminal 520g, which allows current to flow to the drain
terminal 520d through the laser diode 518. The capacitor 516
discharges through a discharge path that includes the laser
diode 518 and the transistor 520. The discharge current from
the capacitor 516 causes the laser diode 518 to emit a pulse of
light. The transistor 520 is turned back off by adjusting the
voltage applied to the gate terminal 520g via the gate driver
530. Upon turning off the transistor 520, the laser diode 518
ceases emission.

zero current to a current sufficient to cause the laser diode to

emit light). Circuits configured to convey such currents to
laser diodes to cause the laser diodes to fire (e.g., emit a pulse
of light) are referred to herein as laser diode firing circuits.
One example laser diode firing circuit includes a laser diode
connected in series with a transistor capable of switching
large currents over brief transition times. Current through the

forward biased.

60

65

induced voltage across the inductor 510 as the inductor cur
rent changes. In particular, during a charging operation to
recharge the capacitor 516, the current through the inductor
510 briefly increases and then decreases. As the inductor
current increases, the voltage at node A512 may decrease to
a voltage less than V1. As the inductor current changes from
increasing to decreasing, the voltage at node A 512 may
increase to a higher level voltage (e.g., a voltage greater than
V1), before decreasing. The transient higher level voltage at
node A512 (e.g., -VI) is applied to the capacitor 516, which
charges as the voltage at node A 512 decreases due to the
inductor current continuing to decrease. The capacitor 516
charges until the voltage on the capacitor 516 approximately
equal the voltage at node A 512. Upon the voltage at node A
512 approximately equaling the voltage on the capacitor 516,
the diode 512 is reverse biased. Upon the diode 514 being
reverse biased, the current through the inductor 510 goes to
zero and the voltage across the inductor 510 settles at zero,
which sets node A to the voltage of the voltage source 502
(e.g., the voltage VI), but the capacitor 516 may hold a higher
voltage (e.g., about 2 V1).

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 23 of 28

US 9,368,936 B1
19
The transistor 520 may be a field effect transistor (FET)
with a channel region including Gallium nitride (i.e., the
transistor 520 may be a GaNFET). However, alternative FETs
may be employed, such as FETs configured to rapidly switch
large current values, such as transistors with carrier mobility
(e.g., high electron mobility transistors (HEMTs)). In FIG.

20
Va., to a level sufficient to turn off the transistor 520, which
terminates current flowing through the laser diode 518.
The charging cycle is initiated in response to the transistor
520 firing, which discharges the capacitor 516. Upon the

capacitor voltage Vc, discharging to a voltage level suffi

5A, the transistor 520 is illustrated as a field effect transistor

(FET); although it is understood the firing circuit 500 may be
implemented with alternative transistors to selectively switch
current through the laser diode, such as a bipolar junction

10

transistor, etc. Further, while the transistor 520 is illustrated

as an n-type transistor, a complementary circuit may be
formed using a p-type transistor.
FIG. 5B is a timing diagram of a pulse emission operation
of the example laser diode firing circuit 500 of FIG. 5A.
Shown in FIG.5B is the gate voltage V., ofthe FET520, the
drain current Ioran, of the FET 520, the luminosity Loº?e of

15

the laser diode 518, the voltage V., of the capacitor 516, the

voltage.V., at node A512, the current Inly through the inductor
510, and the light signal received Rx from a reflected portion
of the emitted pulse. For convenience in the description, the
time at which an initiating signal is applied to the transistor
520 and a pulse is emitted is referred to herein and in the
drawings as the turn on time Toy.
Initially, the capacitor 516 is charged to a voltage set in part
by the voltage source 502. The charge on the capacitor 516
may exceed the voltage VI of the voltage source 502 due to
transient variations at node A 512 caused by changes in cur
rent through the inductor 510. A voltage that exceeds Vi may
be held on the capacitor 516 after the diode 514 is reverse
biased to terminate a charging operation. For example, the
capacitor 516 may be initially charged to a voltage level of
about 2 V1. At the turn on time Toy, an initiating signal is
applied to the transistor 520 from the gate driver 530. The
initiating signal can be a gate voltage Vaan, that transitions
from a low level to a high level so as turn on the transistor 520.
The transistor 520 turns on and the drain current Ioran, tran

20

the laser diode 518, and the diode 514 connects the inductor
25

with the sinusoidal oscillation, current continues to flow to

35

the capacitor 516, until the mid-point of the oscillation cycle,
at time T2, at which point the current reaches zero and the
capacitor 516 stores substantially all of the energy that had
been divided between the inductor 510 and the capacitor 516.
Before the energy stored on the capacitor 516 can transfer

40

biased, which causes the capacitor 516 to remain charged
with approximately twice the supply voltage VI. For
example, the supply voltage VI may be about 20 volts and the
voltage stored on the capacitor 516 following charging may

back to the inductor 510, the diode 514 becomes reverse

be about 40 volts.

45

50

diode 518.

In practice then, the energy stored on the capacitor 516 may
be consumed, and the laser diode 518 may turn off (at time
Torp), following a single half-cycle of the resonant LC cir
cuit formed by the capacitor 516 and the parasitic inductance
of the inductor 518. The pulse duration Atoy may be about 20
nanoseconds in some examples. In some cases (and as shown
in FIG. 5B), the laser diode 518 may cease emitting light prior
to turning off the transistor 520 (e.g., by adjusting the gate
voltage Vaale). Although, in some examples, and depending
on the values of the capacitor 516 and the parasitic inductance
of the laser diode 518, the pulse duration Atoy may continue
until the transistor 520 turns off. Thus, in some examples, the
transistor 520 can be turned off by adjusting the gate voltage

510 and the capacitor 516, which form a resonant LC tank
circuit. The current from the inductor 510 charges the capaci
tor 516, in a sinusoidal oscillatory fashion. At one quarter of
the oscillation period, the inductor current Inº, reaches a
maximum, and begins to decrease. At that point, the resonant
LC circuit divides its stored energy with about half in the
capacitor 516 and about half in the inductor 510. Continuing

30

sitions from a current near zero to a current sufficient to drive

the laser diode 518. The laser diode 518 emits a pulse of light,
as indicated by the luminosity Loºe. As the drain current
I,2,…, flows through the laser diode 518, the capacitor 516
discharges to source current to the laser diode 518. In some
examples, during pulse emission, the capacitor 516 and the
parasitic capacitance of the laser diode 518 can combine to
form a resonant LC tank circuit, which is heavily damped.
Discharging the capacitor 516 thus transfers the electrical
energy charged on the capacitor 516 to the laser diode 518,
where energy is consumed by current flowing in the laser
diode to produce light. Upon completion of a single half
cycle of the damped LC oscillation, there may be almost no
energy left to continue to drive current through the laser diode
518, and remaining voltage, if any, can return to the capacitor
516 via the diode 522 connected in parallel across the laser

cient to forward bias the diode 514, at time T1, current begins
flowing through the inductor 510 (as indicated by In, in FIG.
5B). In FIG. 5B, time T is shown during the interval Atoy
(i.e., before Torp), although in some implementations the
diode 514 may not begin conducting current until the transis
tor 520 has turned off (i.e., after Torp). The increase in
inductor current Inly causes the voltage at node A 512 to
decrease in proportion to the time derivative of the inductor
current Inº, because changes in the inductor current In,
induce a voltage in the inductor 510 that opposes the direction
of any current change. The voltage at node A512, and thus the
increasing inductor current Inº, are prevented from changing
so rapidly as to reverse bias the diode 514.
For example, starting at time T1, the voltage at node A512
may decrease to a voltage level less than VI (as indicated by
V., in FIG. 5B). At time Torp, current ceases flowing through

55

60

65

The oscillatory LC circuit described herein efficiently
transfers energy between the inductor 510 and the capacitor
516 during the recharge interval Atcº, lºgº of the circuit 500,
but the present disclosure is not limited to the use of resonant
LC circuits. Generally, the capacitor 516 may be charged to a
greater value than the supply voltage V1 based on transient
voltages on the inductor 510 caused by changes in current
following firing of the circuit 500. Current through the induc
tor 510 may change from increasing (e.g., between times T1
and Torº) to decreasing (e.g., following time Torº), and the
sudden change in current through the inductor 510 can induce
a rapid increase in voltage at node A512. For example, at time
Torp, the voltage at node A 512 can go to a voltage greater
than V1, and may be several times V1. The precise voltage
applied to node A 512 depends on the time derivative of the
inductor current when transitioning from an increasing cur
rent to a decreasing current, but may be several times the
voltage of the voltage source 502(e.g., just after Torr, V.1-X
V1, with X->2).
Following the increase in the voltage at node A 512, the
current through the inductor 510 can continue to decrease as
the capacitor 516 becomes charged, and the voltage at node A
512 can therefore decrease. The capacitor 516 may continue
charging until the diode 514 becomes reverse biased, at time
T2 in FIG. 5B. While charging, between times Torr, and T2,

the voltage Vox, across the capacitor 516 increases and the

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Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 25 of 28

US 9,368,936 B1
23
The current paths shown in FIGS. 5C and 5D illustrate two
operation modes of the firing circuit 500: a charging mode
(FIG. 5C) and an emission mode (FIG. 5D). In some
examples, the firing circuit 500 switches between the charg—
ing mode and the emission mode based solely on whether the
transistor 520 is turned on or turned off. In the charging mode,
the transistor 520 is turned off and current flows from the

voltage source 502 to the capacitor 516 via the charging path
(e.g., the current path including the inductor 510 and diode
514) until the diode 514 is reverse biased. In the emission

10

mode, the transistor 520 is turned on and current flows from

the charged capacitor 516 through the laser diode 518 and the
transistor 520 until the transistor 520 is turned off again.
FIG. 5E illustrates an arrangement 540 in which multiple
laser diode firing circuits 550a-n are connected to be charged
via a single inductor 544. The inductor 544 has one terminal
connected to a voltage source 542 (labeled V1), and a second
terminal that connects to the firing circuits 550a-n so as to be
included in a charging path of the respective firing circuits
550a-n. Each of the firing circuits 550a-n can be similar to the
firing circuit 500 described above in connection with FIGS.
5A-5D. For example, the first firing circuit 550a includes a
capacitor 558a connected to a laser diode 554a and a transis
tor 556a. The capacitor 558a, laser diode 554a, and transistor
556a can be connected in series such that turning on the
transistor 556a causes the capacitor 558a to discharge
through the laser diode 554a, which causes the laser diode to
emit a pulse of light. A discharge diode 560a can be connected
across the laser diode 554a to discharge the internal capaci
tance of the laser diode 554a. The first firing circuit 550a also
includes a diode 552a that connects the firing circuit 550a to
the inductor 544 and the voltage source 542. The diode 552a
can function similarly to the diode 514 described above in
connection with FIGS. 5A-5D. For example, the diode 552a
can become forward biased and draw current through the
inductor 544 to charge the capacitor 558a following a firing
event (and associated discharge of the capacitor 558a). Upon
the capacitor 558a being recharged, the diode 552a can then
become reverse biased and thereby cause the capacitor 558a
to maintain its stored charge.
The second firing circuit 550b is similarly connected to the
inductor 544 via a diode 552b and includes a capacitor 558b,
laser diode 554b, transistor 556b, discharge diode 560b. One
or more additional firing circuits can also be similarly con
nected in parallel with the inductor 544 to the “nth” firing
circuit 550m. In some cases, the arrangement 540 includes 16
individual laser diode firing circuits 550a-n connected to the
single inductor 544.
Similar to the operation of the firing circuit described
above in connection with FIGS. 5A-5D, the firing circuits
550a-n are turned on and off by operation of their respective
transistors 556a-n, which are controlled by the respective
gate voltages applied by the gate driver 548. For example, the
gate driver 548 can be used to turn on all of the firing circuits
550a-n at substantially the same time by setting the gate
voltage high (or otherwise manipulating the gate voltage to
turn the respective transistors on). The discharging capacitors
558a-n cause current to begin flowing through the inductor
544. Upon the transistors 556a-n in the firing circuits 550a-n
being turned back off (by the gate driver 548), the voltage
across the inductor rises to begin recharging the capacitors
558a-n in the firing circuits 550a-n until the respective diodes
552a-n are reverse biased, at which point recharging termi

15

20

ment described above in connection with FIG. 5A-5D.

V. Example Operations
25

FIGS. 6A through 6C present flowcharts describing pro
cesses employed separately or in combination in some
embodiments of the present disclosure. The methods and
processes described herein are generally described by way of
example as being carried out by an autonomous vehicle, such
as the autonomous vehicles 100, 200 described above in

30

connection with FIGS. 1 and 2. For example, the processes
described herein can be carried out by the LIDAR sensor 128
mounted to an autonomous vehicle in communication with

35

40

45

50

the computer system 112, sensor fusion algorithm module
138, and/or computer vision system 140.
Furthermore, it is noted that the functionality described in
connection with the flowcharts described hereincan be imple
mented as special-function and/or configured general-func
tion hardware modules, portions of program code executed
by a processor (e.g., the processor 113 in the computer system
112) for achieving specific logical functions, determinations,
and/or steps described in connection with the flowcharts.
Where used, program code can be stored on any type of
computer readable medium (e.g., computer readable storage
medium or non-transitory media, such as data storage 114
described above with respect to computer system 112), for
example, such as a storage device including a disk or hard
drive. In addition, each block of the flowcharts can represent
circuitry that is wired to perform the specific logical functions
in the process. Unless specifically indicated, functions in the
flowcharts can be executed out of order from that shown or

discussed, including substantially concurrent execution of
separately described functions, or even in reverse order in
some examples, depending on the functionality involved, so
long as the overall functionality of the described method is
55

60

nateS.

Additionally, the firing circuit arrangement 540 shown in

24
alternative current path during rapid current switching
through the inductor 544 to regulate and/or smooth the result
ing variations across the inductor 544. The snubber circuit
546 may include a resistor and/or capacitor connected in
parallel across the inductor 544, for example. The snubber
circuit 546 may additionally or alternatively include one or
more diodes and/or solid state components configured to limit
and/or regulate the maximum voltage and/or maximum volt
age rate across the inductor 544. Thus, the snubber circuit 546
may operate actively and/or passively to modify transient
voltage variations across the inductor 544. In some cases, the
snubber circuit 544 may be used to prevent transient voltage
variations from exceeding a predetermined threshold and
thereby prevent damage to circuit components. While illus
trated in FIG. 5E, the snubber circuit 544 may (or may not) be
included in particular implementations of the arrangement
540 shown in FIG. 5E. Moreover, a snubber circuit may (or
may not) be included across the charging path inductor in a
particular implementation of the single firing circuit arrange

65

maintained. Furthermore, similar combinations of hardware

and/or software elements can be employed to implement the
methods described in connection with other flowcharts pro
vided in the present disclosure.
FIG. 6A is a flowchart of an example process 600 for
operating a laser diode firing circuit. The laser diode firing
circuit may be the laser diode firing circuit 500 described
above in connection with FIG. 5. The laser diode firing circuit
may therefore include a capacitor connected to a charging
path and a discharge path. The discharge path can include a
laser diode and a transistor, and the charging path can include

FIG. 5E also illustrates a snubber circuit 546 connected

an inductor and a diode. At block 602, the transistor is turned

across the inductor 544. The snubber circuit 546 provides an

off, which causes the capacitor to charge via the charging

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 26 of 28

US 9,368,936 B1
25
path. The current through the charging path can flow through
the inductor and the diode. As charge builds on the capacitor,
the current through charging path (and the inductor)
decreases. The decrease in current through the inductor
causes the inductor to discharge energy stored in its magnetic
field. For example, the energy stored in the magnetic field of
the inductor may transition from a higher energy level to a
lower energy level in response to the transistor being turned

5

off. At block 604, the transistor can be turned on, which

causes the capacitor to discharge via the discharge path. The
current through the discharge path can flow through the laser

10

diode and the transistor, which causes the laser diode to emit

a pulse of light. The voltage stored on the capacitor can
discharge until the diode is forward biased, which causes the
current through the charging path (and the inductor) to
increase. The increase in current through the inductor causes
the inductor to charge energy stored in its magnetic field. For
example, the energy stored in the magnetic field of the induc
tormay transition from a lowerenergy level to a higher energy
level in response to the transistor being turned on.
In some embodiments, the operation of the transistor in
blocks 602 and 604 provides for operation of a laser diode
firing circuit to emit pulses of light and recharge by manipu
lating only a single transistor. In particular, turning the tran
sistor on (block 604) can cause the circuit to both emit a pulse
of light (by discharging the capacitor through the laser diode)
and initiate a recharge cycle (by the voltage on the capacitor
discharging to a level sufficient to forward bias the diode in
the charging path). The recharge cycle is then terminated in
response to turning off the transistor (block 602), which
directs the current conveyed via the charging path to the
capacitor (rather than through the laser diode).
FIG. 6B is a flowchart of an example process 620 for
operating a light detection and ranging (LIDAR) device. The
LIDAR device includes a light source having a laser diode
firing circuit similar to the firing circuit 500 described above
in connection with FIG. 5. For example, the laser diode firing
circuit may include a laser diode activated by current through
a discharge path of a capacitor. A transistor in the discharge
pathis configured to control such discharge events by turning
on and turning off. The capacitoris also connected to a charg
ing path that includes an inductor and a diode. The transistor
may be, for example, a Gallium nitride field effect transistor
(GaNFET). At block 622, the GaNFET is turned off to
thereby cause the capacitor to charge (via the charging path)
and the inductor (in the charging path) to decrease its stored
energy. The inductor can release stored energy as current
through the inductor decreases. At block 624, the GaNFET is
turned on to thereby cause the capacitor to discharge (via the
discharge path), which causes the laser diode to emit a pulse
of light. The inductor charges to an increased stored energy
level due to increasing current through the inductor, which

15

20

25

30

FIG. 6G is a flowchart of another example process 640 for
operating a laser diode firing circuit. The laser diode firing
circuit may be similar to the firing circuit 500 described above
in connection with FIG. 5. For example, the laser diode firing
circuit may include a laser diode activated by current through
a discharge path of a capacitor. A transistor in the discharge
pathis configured to control such discharge events by turning
on and turning off. The capacitoris also connected to a charg
ing path that includes an inductor and a diode. The transistor
may be, for example, a Gallium nitride field effect transistor
(GaNFET). At block 642, the GaNFET is turned on. At block
644, the capacitor discharges through the discharge path. At
block 646, a pulse of light is emitted from the laser diode due
to the discharge current. At block 648, energy stored in the
inductor included in the charging path is increased. For
example, upon the diode in the charging path becoming for
ward biased, the current through the inductor can be
increased, which causes energy to be stored in the magnetic
field of the inductor. At block 650, the GaNFET is turned off.

35

40

At block 652, energy stored in the inductor is released as the
inductor current decreases. At block 654, the capacitor is
charged from energy released by the inductor. For example,
following turning off the GaNFET, current through the induc
tor is conveyed to the capacitor via the charging path. The
inductor current can transition from increasing (while the
transistor is on) to decreasing (once the transistor is off and
current no longer flows through the laser diode). The decrease
in inductor current causes the inductor to release its stored

45

50

55

determined based on the time at which the transistor is turned

on to initiate the discharge current and/or based on the time an
induced voltage is detected in a conductive feedback loop
configured to react to changes in the discharge current path.
At block 628, a reflected light pulse is received. The reflected
light pulse can include at least a portion of the light pulse
emitted in block 624 that is reflected from a reflective object
in an environment surrounding the LIDAR device. At block
630, a reception time of the reflected light pulse is deter
mined. At block 632, a distance to the reflective object is
determined based on both the time of reception determined in
block 630 of the reflected light signal and the transmission

autonomous vehicle 100 described in connection with FIG. 1

may control the autonomous vehicle to avoid obstacles (e.g.,
the reflective object), navigate toward a predetermined desti
nation, etc.

occurs once the diode is forward biased. At block 626, the

transmission time of the emitted pulse (e.g., the pulse emis
sion time) is determined. The pulse emission time may be

26
time determined in block 624. For example, the distance can
be determined based on computing the round trip travel time
to the reflective object from the difference of the reception
time and emission time, multiplying by the speed of light in
the surrounding environment and dividing by 2. At block 634,
the autonomous vehicle is navigated based at least in part on
the determined distance to the reflective object. In some
examples, one or more of the control systems 106 of the

60

65

energy, and that released energy can be transferred, at least in
part, to the capacitor. At block 656, the charging path diode
can become reverse biased, which causes the capacitor to hold
charge due to the released energy from the inductor. For
example, while the inductor releases its stored energy, the
voltage conveyed to the capacitor via the diode can transiently
exceed the voltage of the voltage source connected to the
inductor. The capacitor charges until the capacitor voltage
approximately equals the voltage applied to the diode, at
which point the diode is reverse biased. The capacitor holds a
voltage due in part to the transient voltage while the voltage
applied to the diode settles to the voltage of the voltage source
(e.g., upon the inductor current reaching zero).
As indicated by the dashed arrow in FIG. 6G, the process
640 can be repeated to cause the firing circuit to repeatedly
emit pulses of light, and be recharged immediately following
each firing event. Moreover, the firing circuit may be operated
such that the voltage charged on the capacitor following a
given firing event is not sufficient to forward bias the diode in
the charging path. In such an example, the firing circuit is not
recharged and the firing circuit is re-activated by discharging
the charge remaining on the capacitor to generate current
through the laser diode and transistor. If the voltage on the
capacitor discharges to a level sufficient to forward bias the
diode in the charging current path following such a second

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 27 of 28

US 9,368,936 B1
27
firing (or third firing, etc.), the firing circuit can then undergo
the charging mode with the capacitor recharging via the
charging path.
FIG. 7 depicts a computer-readable medium configured
according to an example embodiment. In example embodi
ments, the example system can include one or more proces
sors, one or more forms of memory, one or more input
devices/interfaces, one or more output devices/interfaces, and
machine-readable instructions that when executed by the one
or more processors cause the system to carry out the various
functions, tasks, capabilities, etc., described above, such as
the processes discussed in connection with FIGS. 6A through

28
are for purposes of illustration and are not intended to be
limiting, with the true scope and spirit being indicated by the
following claims.
What is claimed is:

10

6C above.

As noted above, in some embodiments, the disclosed tech

niques can be implemented by computer program instruc
tions encoded on a non-transitory computer-readable storage

15

media in a machine-readable format, or on other non-transi

tory media or articles of manufacture (e.g., the instructions
115 stored on the data storage 114 of the computer system 112
of vehicle 100). FIG. 7 is a schematic illustrating a conceptual
partial view of an example computer program product 700
that includes a computer program for executing a computer
process on a computing device, arranged according to at least
some embodiments presented herein.
In one embodiment, the example computer program prod
uct 700 is provided using a signal bearing medium 702. The
signal bearing medium 702 may include one or more pro
gramming instructions 704 that, when executed by one or
more processors may provide functionality or portions of the
functionality described above with respect to FIGS. 1-6. In
some examples, the signal bearing medium 702 can be a
non-transitory computer-readable medium 706, such as, but
not limited to, a hard disk drive, a Compact Disc (CD), a
Digital Video Disk (DVD), a digital tape, memory, etc. In
some implementations, the signal bearing medium 702 can be
a computer recordable medium 708, such as, but not limited
to, memory, read/write (R/W) CDs, R/W DVDs, etc. In some
implementations, the signal bearing medium 702 can be a

20

level; and
25

30

35

40

45

form of the communications medium 710.

The one or more programming instructions 704 can be, for
example, computer executable and/or logic implemented
instructions. In some examples, a computing device such as
the computer system 112 of FIG. 1 is configured to provide
various operations, functions, or actions in response to the
programming instructions 704 conveyed to the computer sys
tem 112 by one or more of the computer readable medium
706, the computer recordable medium 708, and/or the com
munications medium 710.

50

7. The apparatus of claim 1, wherein the light emitting
element is a laser diode.
55

device that executes some or all of the stored instructions
60

2. Alternatively, the computing device that executes some or
all of the stored instructions could be another computing
device, such as a server.

While various example aspects and example embodiments
have been disclosed herein, other aspects and embodiments
will be apparent to those skilled in the art. The various
example aspects and example embodiments disclosed herein

higher current level.
2. The apparatus of claim 1, wherein the lower current level
is approximately zero.
3. The apparatus of claim 1, wherein the capacitor is
charged immediately following emission of a pulse of light
from the light emitting element.
4. The apparatus of claim 1, wherein the higher voltage
level is greater than a voltage of the voltage source, and
wherein the diode has an anode coupled to the voltage source
via the inductor and a cathode coupled to the capacitor, such
that the diode is forward biased when the voltage across the
capacitor is at the lower voltage level and the diode is reverse
biased when the voltage across the capacitor is at the higher
voltage level.
5. The apparatus of claim 1, wherein the transistor is a
Gallium nitride field effect transistor (GaNFET).
6. The apparatus of claim 5, wherein the control signal
applies voltage to a gate of the GaNFET to selectively turn the
GaNFET on and off.

The non-transitory computer readable medium could also
be distributed among multiple data storage elements, which
could be remotely located from each other. The computing
could be a vehicle, such as the vehicle 200 illustrated in FIG.

wherein, responsive to the transistor being turned on, the
capacitor is configured to discharge through the dis
charge path such that the light emitting element emits a
pulse of light and the voltage across the capacitor
decreases from the higher voltage level to the lower
voltage level and the inductor is configured to store
energy in the magnetic field such that the current through
the inductor increases from the lower current level to the

communications medium 710, such as, but not limited to, a

digital and/or an analog communication medium (e.g., a fiber
optic cable, a waveguide, a wired communications link, a
wireless communication link, etc.). Thus, for example, the
signal bearing medium 702 can be conveyed by a wireless

1. An apparatus, comprising:
a voltage source;
an inductor coupled to the voltage source, wherein the
inductoris configured to store energy in a magnetic field;
a diode coupled to the voltage source via the inductor;
a transistor configured to be turned on and turned off by a
control signal;
a light emitting element coupled to the transistor;
a capacitor coupled to a charging path and a discharge path,
wherein the charging path includes the inductor and the
diode, and wherein the discharge path includes the tran
sistor and the light emitting element;
wherein, responsive to the transistor being turned off, the
capacitor is configured to charge via the charging path
such that a voltage across the capacitor increases from a
lower voltage level to a higher voltage level and the
inductor is configured to release energy stored in the
magnetic field such that a current through the inductor
decreases from a higher current level to a lower current

65

8. The apparatus of claim 7, further comprising a drain
diode coupled across the laser diode, wherein the drain diode
is configured to discharge an internal capacitance of the laser
diode through the drain diode when the transistor is off.
9. A method, comprising:
turning off a transistor, wherein the transistor is coupled to
a light emitting element, wherein both the transistor and
the light emitting element are included in a discharge
path coupled to a capacitor, wherein the capacitoris also
coupled to a charging path including a diode and an
inductor, wherein the inductor is configured to store
energy in a magnetic field, wherein the diode is coupled
to a voltage source via the inductor, and wherein,
responsive to the transistor being turned off, the capaci

Case 3:17-cv-00939 Document 1-2 Filed 02/23/17 Page 28 of 28

US 9,368,936 B1
29
toris configured to charge via the charging path such that
a voltage across the capacitor increases from a lower
voltage level to a higher voltage level and the inductoris
configured to release energy stored in the magnetic field
such that a current through the inductor decreases from
a higher current level to a lower current level; and
turning on the transistor, wherein responsive to the transis
tor being turned on, the capacitor is configured to dis
charge through the discharge path such that the light
emitting element emits a pulse of light and the voltage
across the capacitor decreases from the higher voltage
level to the lower voltage level and the inductor is con
figured to store energy in the magnetic field such that the
current through the inductor increases from the lower
current level to the higher current level.

30
a voltage source;
an inductor coupled to the voltage source, wherein the
inductor is configured to store energy in a magnetic
field;
5

10

15

10. The method of claim 9, wherein the lower current level

is approximately zero.
11. The method of claim 9, wherein the capacitor is
charged immediately following emission of a pulse of light
from the light emitting element.
12. The method of claim 9, wherein the higher voltage level
is greater than a voltage of the voltage source, and wherein the
diode has an anode coupled to the voltage source via the
inductor and a cathode coupled to the capacitor, such that the
diode is forward biased when the voltage across the capacitor
is at the lower voltage level and the diode is reverse biased
when the voltage across the capacitor is at the higher voltage

20

25

level.

13. The method of claim 9, wherein the charging of the

capacitor is carried out in about 500 nanoseconds.

30

14. The method of claim 9, wherein the light emitting
element is a laser diode.

15. The method of claim 14, further comprising:
when the transistor is off, discharging an internal capaci
tance of the laser diode via a drain diode coupled across

35

the laser diode.

16. The method of claim 9, wherein the transistor com

prises a Gallium nitride field effect transistor (GaNFET),
wherein the GaNFET is turned on and turned off by applying
a control signal to a gate of the GaNFET.
17. A light detection and ranging (LIDAR) device compris
1ng:
a light source including:

40

a diode coupled to the voltage source via the inductor;
a transistor configured to be turned on and turned off by
a control signal;
a light emitting element coupled to the transistor;
a capacitor coupled to a charging path and a discharge
path, wherein the charging path includes the inductor
and the diode, and wherein the discharge path
includes the transistor and the light emitting element;
wherein, responsive to the transistor being turned off,
the capacitor is configured to charge via the charging
path such that a voltage across the capacitor increases
from a lower voltage level to a higher voltage level
and the inductor is configured to release energy stored
in the magnetic field such that a current through the
inductor decreases from a higher current level to a
lower current level; and

wherein, responsive to the transistor being turned on, the
capacitor is configured to discharge through the dis
charge path such that the light emitting element emits
a pulse of light and the voltage across the capacitor
decreases from the higher voltage level to the lower
voltage level and the inductor is configured to store
energy in the magnetic field such that the current
through the inductor increases from the lower current
level to the higher current level;
a light sensor configured to detect a reflected light signal
comprising light from the emitted light pulse reflected
by a reflective object; and
a controller configured to determine a distance to the
reflective object based on the reflected light signal.
18. The LIDAR device of claim 17, wherein the lower
current level is approximately zero.
19. The LIDAR device of claim 17, wherein the capacitor
is charged immediately following emission of a pulse of light
from the light emitting element.
20. The LIDAR device of claim 17, wherein the transistor
is a Gallium nitride field effect transistor (GaNFET).