Frequency-Modulated Automotive Lidar

Transcription

1 Frequency-Modulated Automotive Lidar Jim Curry VP of Product Blackmore Sensors and Analytics, Inc.

2 Opt. Freq. Power Power FMCW Measurement Theory Most 3D lidar systems are pulsed, direct detect based. FMCW Uncouples Traditional System Limitations Electronic Bandwidth Optical Bandwidth Peak Power t rep Direct Detection Time Pulse BW Detector BW Digitizer BW Peak Power Limiters to rep rate, resolution, and range Constant Power / Frequency Modulated t rep Heterodyne Detection = FMCW Time Up Chirps Time Flexible and adaptive technique which provides compelling advantages Superior Resolution, Dynamic Range, Single-Photon Sensitivity Doppler Measurement Multi-Return Resolution Eye Safety Low Cost

3 Optical Frequency Power (db) FMCW Measurement Theory The properties of light are leveraged to make a physically superior measurement LO RX The optical bandwidth, B, can be increased electronically to meet nearly any resolution requirement Splits closely spaced targets ΔR = c 2B f b B f b = κτ D FFT to get range profile τ D Time Range Result is a beat note with frequency f b that is digitized and processed. 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!)

4 Doppler Challenges Static Imaging of Trees, Slight Breeze No Compensation w/ Doppler Compensation 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).

5 Simultaneous Range and Velocity +3.5m/s Approaching Stationary Receding -3.5m/s Illumination Direction 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

6 Simultaneous Range and Velocity +3.5m/s Approaching Stationary Receding -3.5m/s Illumination Direction 150m 6 6

7 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 Blackmore s FM lidar operates interference-free No issues with sunlight No issues with other cars sensors No issues with self-interference

8 Long-Range Performance 400m In-N-Out Burger Sign Sensor Location Gives autonomous systems plenty of range for smooth braking

9 A Scalable Solution Technology leverages semiconductor foundries + Non-Mechanical Beam Scanning Low-power continuous-wave laser compatible with integrated photonics, including optical phased arrays

10 Example FM automotive lidar data E

11 Single-pass mapping Height (Altitude) Coloration One pass in one direction One pass in each direction Copyright 2018 Xilinx Moving points stripped out using velocity field

12 High-Speed Performance Performance Maintained at Highway Speeds Height (Altitude) Coloration Moving Points Removed

13 Point-by-Point Velocity Direct velocity measurement enables segmentation and tracking of moving objects Velocity Coloration Foot traffic

14 Precise, high-dynamic range velocity data Motion-compensation of velocity data Micro-doppler data reveals wheel-spin

15 Questions? High-Dynamic-Range Reflectivity Data No saturation or blooming artifacts from bright reflectors Extremely high damage threshold Easily measures reflectivity differences from pavement markings Height (Altitude) Coloration Reflectivity Shading

16 High Spatial Precision Enables detection of even minor pavement defects

17 See through, detect, and identify obscurants Thin layer of suface mist over pool Velocity coloring. Grey points=water surface, colored points=mist

18 Wing-Walk in Doppler Field Questions? Jim Curry VP of Product Blackmore Sensors and Analytics, Inc.