ABS is very simple and only needs to know the difference between the speed of the tire and the speed of the road. It is more complicated systems like ESC (which works with ABS) that need to know about steering inputs.
I thought the "speed of the road" was calculated by checking the speeds of the other types, which is trivial if you are going in a straight line, but needs correction if you are steering, hence needs steering angle?
Simple ABS only cares if the wheel is stationary/goes much slower vs other wheels. Like it wouldn't be perfect but still vast improvement over locking all 4 wheels. Hell, the older ABS systems controlled pair of wheels and activated on both regardless of which one was locking
I'd imagine once they are implementing ESC the ABS also gets the benefit of steering sensor but it is not strictly necessary.
To nitpick, simple ABS is an improvement over locking some of the wheels. It often struggles with preventing a lock of all 4 wheels, because it loses reference for the road speed. A dumb ABS system with just wheel speed sensors can't tell if [0,0,0,0] means all 4 are locked, or if you're stationary.
I don't know as much about the implementation details of modern ESC systems, but I'm guessing this problem is much easier to solve with accelerometer data.
> To nitpick, simple ABS is an improvement over locking some of the wheels
In direction control, sure, but you are getting less braking out of it. The earlier ones could be outbraked by skilled driver keeping brake just at the edge of wheel locking, but that isn't the case for the modern ones, precisely because it can brake each wheel separately
> A dumb ABS system with just wheel speed sensors can't tell if [0,0,0,0] means all 4 are locked, or if you're stationary.
I'm actually curious how they deal with ice, you might be breaking but still getting near zero decceleration from it. Then again if it is that slipper it doesn't matter all that much...
Or is there a simpler way in non-ESC systems?