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Comment by Retric | Hacker News Reader

Radar has serious issues detecting stationary objects. Which is why early automatic cruse control systems had minimum speeds, they simply don’t work in stop and go traffic.

Lidar on the other hand has no problem with stationary objects, but cars can’t depend on it in all weather conditions. Which means full self driving cars need to be able to operate based on vision like we do. I would expect all level 5 systems to use Lidar especially if costs continue to drop, but it’s not as clear cut as you might think.

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The advantage of computer integration is that self-driving vehicle can use all three technologies to make the best use of everything and compensate for any technology's failures.

Unless they remove them and rely on only one type of sensor, which is exactly what Tesla has done. It's like complaining that each sense has issues, then removing all but one. Multimodal integration is literally how we use our senses normally.

I am not convinced any self driving system is going to be dependent on RADAR in 20 years. Tesla was using RADAR and stopped because it just don’t really solve any specific problems well.

RADAR is great for collision detection and early breaking systems because drivers don’t depend on them. If they fail in an early breaking system noting worse happens. But self driving systems can’t accept failures like that. These systems would need to stop if their camera/Lidar system failed so what’s it actually useful for?

Radar detects stationary objects just fine.

From my understanding, the problem is the software doesn't know if that radar object is a car or a sign or an overpass. So it assumes that moving objects are cars, and makes a good guess at stationary objects. Occasionally when it is wrong, there would be unusual braking for signs, or just plowing into stationary cars.

Detection is overstating things, current RADAR systems don’t have much in the way of resolution. So a manhole and an object in the road can be effectively indistinguishable in the raw sensor data.

RADAR systems are rapidly improving, but there’s a reason everyone shows Lidar data over RADAR.

Not every radar out there is a Doppler radar.

But you are right on the point of there being no silver bullet sensing technology. All of them have their own very glaring weaknesses.

Radars are superior for simple collision avoidance for them being able to directly sense the velocity, but they are obviously useless for lane keeping.

Lidars are super unreliable from both internal factors, and the environment. Basically, a splat of dirt, and a collision.

Cameras are subject to all uncertainties of a CV system, and smog, smoke, and weather as well.

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