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Comment by jeffbee | Hacker News Reader

My car with its drive-by-wire brakes has a brake feedback simulator that gives the driver the kind of feeling associated with power-boosted hydraulic brakes. This is by far the most expensive single component in the car. Arguably these are just expensive accommodations for human flaws. A self-driving car wouldn't need them. Can't the self-driving system act directly on data like pressure, flow, and displacement?

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Maybe it doesn't matter for a car because feeling the car's motion tells you most of what you need to know. A car is not meant to touch anything but the road, in normal conditions. I think steering is the only case where force feedback is very important for a car - In the winters up here, I can feel the steering go loose when I hit a patch of ice.

I imagine an excavator, meant to touch and dig through things, and lift things, benefits from force feedback for the same reason VR would.

Have you played those VR sword games? BeatSaber works great because you're cutting through abstract blobs that offer no resistance. But the medieval sword-slashing games feel weird because your sword can't impact your opponent.

I saw a video recently of a quadcopter lifting heavy objects. When it's overloaded, it can't maneuver because all its spare power is spent generating lift to maintain altitude. If the controls had force feedback, the copter's computer could tell you "I'm overloaded, I can't move" by putting maximum resistance on the sticks.

Interestingly, we had some people try out VR teleop: https://x.com/Scobleizer/status/1970245161306464667

https://x.com/jash_mota/status/1969091992140304703

I think force feedback is key for small excavators, but not really true for 25+ tons excavators. Hence how easy it is for operators to accidentally kill someone with it.

That's indeed what we're trying to test to the extreme - to see how far we could go with just vision. We haven't done heavy excavation workflows yet, but we have some early success with some excavation workflows with just vision input and joystick action output (even without joint angle feedback!). We're betting on having really huge data with compact observation input and experiment to see if it holds water. If not we can always dial it down and add more sensors/feedback.

There are no drive-by-wire brakes in the US or Europe for regular cars. Your car's actuator moves the piston that is mechanically linked to your pedal.

So even if the electric system fails completely, you can still actuate the brakes.

Toyota's hybrids, at least, have valves in the hydraulic system. If everything is working, the driver's pedal is isolated from the physical pistons. Pressing the pedal instead moves a 'stroke simulator' (a cylinder with a spring in it), and the pressure is measured with a transducer. The Brake ECU tries to satisfy as much braking demand through regenerative braking as possible, applying the rear brakes to keep balance and front brakes if you brake too hard, requesting more braking than can be generated or the battery can absorb.

If there's a failure of the electrical supply to the brake ECU, or another fault condition occurs, various valves then revert to their normally-open or normally-closed positions to allow hydraulic pressure from the pedal through to the brake cylinders, and isolate the stroke simulator.

Because the engine isn't constantly running and providing a vacuum that can be used to assist with brake force, the system also includes a 'brake accumulator' and pump to boost the brake pressure.

Reference: https://pmmonline.co.uk/technical/blue-prints-insight-into-t...

I don't know for certain, but I would assume that other hybrids and EVs have similar systems to maximise regenerative braking.

It depends on how you define brake by wire, but the one I'm referencing is the C8 Corvette and it's "eBoost" system. This isn't a purely electronic system like throttle by wire is, but it does mean there is no longer a linear relationship between pedal pressure and brake pad pressure. And my point about isolating the driver from feedback still holds true.

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