4 ms·

Lidar kind of works the same way, but is a lot faster (speed of light vs speed of sound) I could also see sonar taking a lot more energy to use all the time as

by screye 9y ago

Lidar kind of works the same way, but is a lot faster (speed of light vs speed of sound) I could also see sonar taking a lot more energy to use all the time as compared to Lidar.

cr0sh 9y ago
No, it probably has more to do with your first point: speed. During the time it could take for a sonar (ultrasonic) sensor to send out a pulse and for it to return, the car may have travelled many feet depending on speed and road conditions. This would impact how long it would take to perform an evasive action and return to a safe state. That is just a guess, though - I haven't run the numbers to know if it is factual. Lidar, though, is much quicker, as you noted.
mandevil 9y ago
LIDAR has severe range limitations, such that it's basically unusable for highway speed driving (or at least did, <mumble> years ago when I worked on autonomous driving), which is why Tesla doesn't use LIDAR. Looking at Thrun et al.'s paper on Stanley (https://www-cs.stanford.edu/people/dstavens/jfr06/thrun_etal_jfr06.pdf https://www-cs.stanford.edu/people/dstavens/jfr06/thrun_etal...): "The effective maximum range at which obstacles can be detected with the laser mapper is approximately 22 m. This range is sufficient for Stanley to reliably avoid obstacles at speeds up to 25 mph. Based on the 2004 Race Course, the development team estimated that Stanley would need to reach speeds of 35 mph in order to successfully complete the challenge. To extend the sensor range enough to allow safe driving at 35 mph, Stanley uses a color camera to find drivable surfaces at ranges exceeding that of the laser analysis." They built a neural network to analyze terrain and find safe paths- and trained it driving at 25 mph across the environment with the LIDAR providing the control- and then let it work at higher speeds where the LIDAR would be able to panic stop but not much more.
- giobox 9y ago
  I may be way off base here, but hasn't the LIDAR field evolved enormously since 2006 (date of that paper)? Last I read prototype solid state LIDAR systems have ranges in the ~150m range, although I don't follow this field all that closely. Given that the major players like Waymo/Uber/Apple etc seem to be betting very heavily on LIDAR, one would assume these challenges are being resolved. I suspect the traditionally very high cost of LIDAR was likely a much bigger factor in Tesla's decision not to use, rather than any technical reason. Cameras plus radar is vastly cheaper to ship for now.

by screye 9y ago

Lidar kind of works the same way, but is a lot faster (speed of light vs speed of sound) I could also see sonar taking a lot more energy to use all the time as compared to Lidar.

cr0sh 9y ago

No, it probably has more to do with your first point: speed. During the time it could take for a sonar (ultrasonic) sensor to send out a pulse and for it to return, the car may have travelled many feet depending on speed and road conditions. This would impact how long it would take to perform an evasive action and return to a safe state. That is just a guess, though - I haven't run the numbers to know if it is factual. Lidar, though, is much quicker, as you noted.

mandevil 9y ago

LIDAR has severe range limitations, such that it's basically unusable for highway speed driving (or at least did, <mumble> years ago when I worked on autonomous driving), which is why Tesla doesn't use LIDAR. Looking at Thrun et al.'s paper on Stanley (https://www-cs.stanford.edu/people/dstavens/jfr06/thrun_etal_jfr06.pdf https://www-cs.stanford.edu/people/dstavens/jfr06/thrun_etal...): "The effective maximum range at which obstacles can be detected with the laser mapper is approximately 22 m. This range is sufficient for Stanley to reliably avoid obstacles at speeds up to 25 mph. Based on the 2004 Race Course, the development team estimated that Stanley would need to reach speeds of 35 mph in order to successfully complete the challenge. To extend the sensor range enough to allow safe driving at 35 mph, Stanley uses a color camera to find drivable surfaces at ranges exceeding that of the laser analysis." They built a neural network to analyze terrain and find safe paths- and trained it driving at 25 mph across the environment with the LIDAR providing the control- and then let it work at higher speeds where the LIDAR would be able to panic stop but not much more.

giobox 9y ago
I may be way off base here, but hasn't the LIDAR field evolved enormously since 2006 (date of that paper)? Last I read prototype solid state LIDAR systems have ranges in the ~150m range, although I don't follow this field all that closely. Given that the major players like Waymo/Uber/Apple etc seem to be betting very heavily on LIDAR, one would assume these challenges are being resolved. I suspect the traditionally very high cost of LIDAR was likely a much bigger factor in Tesla's decision not to use, rather than any technical reason. Cameras plus radar is vastly cheaper to ship for now.