WARNING: crash risk ACC radar cruise control

[Suncoaster]

I have had my T-Cross stop dead at a drainage grate in the middle of a shopping centre car park. No big deal, but I thought that I had hit something at the time. Cheers-John

[Odin]

The radar that ACC uses is based on Doppler chirping radar. A characteristic of all Doppler radars is that they can only 'see' other objects when it has relative motion. Stationary objects are effectively invisible to Doppler. So it wouldn't have mattered if lanes were changed into the path of a stopped car, a brick wall, or a fallen roadside sign - they'd all be 'invisible' to the ACC's radar.

For a radar to detect a stopped car, and further discriminate against other harmless stationary roadside fixtures like armco barriers etc. would take some serious computing horsepower and a considerably more advanced radar to reliably achieve.

[Hillbilly]

The radar that ACC uses is based on Doppler chirping radar. A characteristic of all Doppler radars is that they can only 'see' other objects when it has relative motion. Stationary objects are effectively invisible to Doppler. So it wouldn't have mattered if lanes were changed into the path of a stopped car, a brick wall, or a fallen roadside sign - they'd all be 'invisible' to the ACC's radar.

For a radar to detect a stopped car, and further discriminate against other harmless stationary roadside fixtures like armco barriers etc. would take some serious computing horsepower and a considerably more advanced radar to reliably achieve.

Yeah those of us who have read and found that out know but most arent aware and therefore think its a fault The guy whose car stops because driveway probably slopes and it sees the perceived upslope of the road is stopping because the rear traffic alert is activated

[fatjoez]

The radar that ACC uses is based on Doppler chirping radar. A characteristic of all Doppler radars is that they can only 'see' other objects when it has relative motion. Stationary objects are effectively invisible to Doppler. So it wouldn't have mattered if lanes were changed into the path of a stopped car, a brick wall, or a fallen roadside sign - they'd all be 'invisible' to the ACC's radar.

For a radar to detect a stopped car, and further discriminate against other harmless stationary roadside fixtures like armco barriers etc. would take some serious computing horsepower and a considerably more advanced radar to reliably achieve.

Excellent contribution thanks Odin for clarifying.

Interesting that Tesla has switched to Camera based system rather than radar which will heavily increase the computing power required.

I expect mainstream radar tech and computing will accommodate stationary vehicles by 2025-30 since industry guidance is we will have full autonomous by then.

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[Nauend]

Yeah those of us who have read and found that out know but most arent aware and therefore think its a fault The guy whose car stops because driveway probably slopes and it sees the perceived upslope of the road is stopping because the rear traffic alert is activated

Nah it’s not my driveway - that’s flat. Am thinking the front assist has been picking up the side of the garage as I reverse out and turn slightly as I'm reversing.

Just read about chip Intel is developing that can do 176 trillion transactions per second to support the sort of decision making autonomous driving needs:intel's mobileye autonomous driving chip. there is also a good video on how the Waymo autonomous car operates and uses radar and cameras to self drive.