Steering practice
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Yes - definitely something wrong with this behavior ...Steering practice
This is because new paths are being calculated, and Beta is aligning the wheels along the new direction in preparation for when the car starts to move.Steering practice
Yes, that is very clear and I don’t think anyone really disputes that. It’s really very odd! You might call it sub-human.This is because new paths are being calculated, and Beta is aligning the wheels along the new direction in preparation for when the car starts to move.
Scrubbing the tires at zero speed isn’t good for the tires or the steering system. I’ve designed autosteer systems and I explicitly freeze the steering when almost stopped, and wait until the wheels are rolling again to begin steering again. Doesn’t take much distance to do it this way and is much smoother.This is because new paths are being calculated, and Beta is aligning the wheels along the new direction in preparation for when the car starts to move.
Don't they let you use the steering wheel for arcade games input?Scrubbing the tires at zero speed isn’t good for the tires or the steering system. I’ve designed autosteer systems and I explicitly freeze the steering when almost stopped, and wait until the wheels are rolling again to begin steering again. Doesn’t take much distance to do it this way and is much smoother.
Oh, a comedian! Must explain why your comments in this thread are mostly sillyDon't they let you use the steering wheel for arcade games input?
Oh, a comedian! Must explain why your comments in this thread are mostly silly
I have actually designed the algorithms and implemented the software for autosteer systems for multiple large production vehicles. Details about what vehicles are proprietary. But in general, behavior at very low speeds is a bugaboo of an autosteer system, because the path following control law is typically outputting a yaw rate command, and the steering angle control law gain that relates yaw rate command to steering angle is inversely proportional to speed, so that gain goes to infinity as speed goes to zero; obviously, you don‘t actually let the gain go to infinity, but how to limit that gain, and how to smoothly reduce steering commands to a steady state value as the vehicle comes to a stop (and do the opposite when starting from a stop), are nontrivial problems. Whether that’s what’s going on with FSD steering wheel jerkiness, or something else, I have no opinion; I don’t have FSD (and have no interest is being a beta tester for it), and have no direct insight into its steering control law, other than having done autosteer for other vehicles, knowing the physics of turning motion, and having successfully eliminated the steering jerkiness at low speeds (and high speeds too, but that’s another tale for another day…).
Doesn't dTheta / dt = steering deflection * speed / (distance between front and rear wheels); So the gain of steering input to yaw rate goes to zero when the speed is zero. This would require an infinite steering deflection for any requested yaw rate. But I was going to try and avoid things like yaw, yaw rates, gains, etc.he steering angle control law gain that relates yaw rate command to steering angle is inversely proportional to speed
That is odd because control laws and control theory definitely seem simpler conceptually (and much more theoretically grounded!) than path planning and perception, which seem to be where the difficulty lies.The class wasn't ready to move on yet.
I agree that perception and path planning have issues, but the exaggerated steering movements at low speed is a consequence of the path following control problem.That is odd because control laws and control theory definitely seem simpler conceptually (and much more theoretically grounded!) than path planning and perception, which seem to be where the difficulty lies.
But, it is understandable to stick with what is easier to capture in a closed-form solution.
I feel like we are going in circles. I think it was pretty obvious to everyone why the steering wheel jerks (and it seems like it could be addressed relatively easily). But why does the path move so much? Even if you fix the jerking steering, that would remain a problem. Seems like a lot of work left to be done. It will be interesting to see how different it is in 12-24 months.I agree that perception and path planning have issues, but the exaggerated steering movements at low speed is a consequence of the path following control problem.
Now that's funny. That's all I was ever trying to get across.I think it was pretty obvious to everyone why the steering wheel jerks (and it seems like it could be addressed relatively easily)
My experience as wellYeah, I find that FSD Beta jerks the wheel a lot during turns like it is kind of feeling its way through the turn. Also, sometimes, coming to a complete stop a red light but where the car will need to make a turn, it turns the wheel before stopping instead of keeping the wheel straight and only turning when it starts the turn.
Its just a bug they need to fix.Yeah, I find that FSD Beta jerks the wheel a lot during turns like it is kind of feeling its way through the turn. Also, sometimes, coming to a complete stop a red light but where the car will need to make a turn, it turns the wheel before stopping instead of keeping the wheel straight and only turning when it starts the turn.
Its just a bug they need to fix.
Essentially - they try a lot of simulations and come up with an optimized path they take. I guess there is a threshold "ok to go" probability they want to exceed before starting to apply any acceleration. Until then they should not apply any torque to the steering wheel. As simple as that.
There's nothing fundamentally different happening when you are stopped. One of the control parameters, speed, is just set to zero. The control loops continue to operate. It's best to keep them running continuously to avoid transients and instability caused by starting and stopping the digital control algorithms.
Let's say you've come to a stop, and while you were travelling at a slow speed FSD had to turn the wheel sharply to the right to follow the path. Now someone in the lane to your right pulls a yoohoo and edges over close to or into your lane because they are in wrong lane. If the control loop hasn't been tracking the required changes in steering continuously, now there is a big step change which might produce an exponentially decaying sinusoidal response in steering. Not to mention there probably won't be enough room to move forward while you align the steering for the new direction.
Now FSD has to decide whether to screw the other driver(which is what seems to happen), or wait for them to move forward and into your lane.
There are untold, unforseen possibilities.