Frequency-Modulated Automotive Lidar .•Pulsed lidar systems do not simultaneously measure range

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Copyright 2018 Xilinx

Frequency-Modulated Automotive Lidar

Jim Curry

VP of Product

Blackmore Sensors and Analytics, Inc.

curry@blackmoreinc.com

Copyright 2018 Xilinx

FMCW Measurement Theory

Pulse BWDetector BWDigitizer BWPeak Power

Limiters to rep rate, resolution, and range

Optical Bandwidth

Electronic Bandwidth

Peak Power

FMCW Uncouples Traditional System LimitationsMost 3D lidar systems are pulsed, direct detect based.

Flexible and adaptive technique which provides compelling advantages

trep

Pow

er

Time

Direct Detection

trep

Pow

er

Time

Heterodyne Detection = FMCW

Op

t.

Fre

q.

Time

Up Chirps

Constant Power / Frequency Modulated

Superior Resolution, Dynamic Range,

Single-Photon Sensitivity

Doppler MeasurementMulti-Return Resolution

Eye SafetyLow Cost

Copyright 2018 Xilinx

FMCW Measurement Theory

LO RX

Op

tica

l Fre

qu

en

cy

Time

=

The properties of light are leveraged to make a physically superior measurement

FFT to getrange profile

Po

we

r (d

B)

Range

=

2

The optical bandwidth, B, can be increased electronically to meet nearly any resolution

requirement

Result is a beat note with frequency that is digitized and processed.

Splits closelyspaced targets

The LO/RX mixing process is optical.

The beat note is measured, not the RX signal directly.

Shot-noise floor of the LO(very stable!)

Copyright 2018 Xilinx

No Compensationw/ Doppler Compensation

Doppler ChallengesStatic Imaging of Trees, Slight Breeze

In the infrared band, Doppler shifts are ~1MHz per m/s. This is very challenging to deal with compared to radar (~1kHz per m/s).

Copyright 2018 Xilinx

Simultaneous Range and Velocity

StationaryApproaching Receding

Pulsed lidar systems do not simultaneously measure range and velocity

Radar systems measure velocity but have poor spatial resolution

Coherent (FM) lidar combines high-resolution spatial and velocity measurements

For perception, instantaneous velocity is very valuable Faster and more accurate scene segmentation

Velocity content of tracked objects helps classify them (micro-doppler signatures)

5

+3.5m/s -3.5m/s

Illumination Direction

Copyright 2018 Xilinx

Simultaneous Range and Velocity

6

StationaryApproaching Receding

+3.5m/s -3.5m/s

Illumination Direction

6

150m

Copyright 2018 Xilinx

Interference Rejection

AM lidar pulses look exactly the same Lidar-to-lidar interference cited as a

pain point

Sunlight elevates noise floor of AM measurements, reducing lidar sensitivity in the daytime

Blackmores FM lidar operates interference-free No issues with sunlight

No issues with other cars sensors

No issues with self-interference

Copyright 2018 Xilinx

Long-Range Performance

Sensor Location

In-N-Out Burger Sign

Structure @ 400m

Gives autonomous systems plenty of range for smooth braking

Copyright 2018 Xilinx

A Scalable SolutionTechnology leverages semiconductor foundries

+

Low-power continuous-wave laser compatible with integrated photonics, including optical phased arrays

Non-Mechanical

Beam Scanning

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E

Example FM automotive lidar data

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Single-pass mappingHeight (Altitude) ColorationOne pass in one direction

One pass in each direction

Moving points stripped out using velocity field

Copyright 2018 Xilinx

High-Speed Performance

Performance Maintained at Highway Speeds

Height (Altitude) ColorationMoving Points Removed

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Point-by-Point Velocity

Direct velocity measurement enables segmentation and tracking

of moving objects

Foot trafficVelocity Coloration

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Motion-compensation of velocity dataMicro-doppler data reveals wheel-spin

Precise, high-dynamic range velocity data

Copyright 2018 Xilinx

Questions?

Height (Altitude) ColorationReflectivity Shading

No saturation or blooming artifacts from bright reflectors

Extremely high damage threshold Easily measures reflectivity differences from

pavement markings

High-Dynamic-Range Reflectivity Data

Copyright 2018 Xilinx

High Spatial Precision

Enables detection of even minor pavement defects

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See through, detect, and identify obscurants

Velocity coloring. Grey points=water surface, colored points=mist

Thin layer of suface mist over pool

Copyright 2018 Xilinx

Wing-Walk in Doppler FieldQuestions?Jim CurryVP of ProductBlackmore Sensors and Analytics, Inc.curry@blackmoreinc.com