[mikeleslie]

Not to want to carry on the ABS thing too long, but the article is a bit misleading. (and this part is actually valueable in a FIRST situation)
The wheel sensors look at rotational speed at each axle (i.e. an encoder at each wheel) The system then can look at the realtive speed of each wheel. When you mash on the brakes, it monitors each wheel to see that they are moving (more or less) at the same speed. When one stops turning, (no changes at the wheel sensor), the system sees the difference and dumps the pressure to that brake line until it starts turning again, whn it's turning again, the dump valve is closed and pressure returns. now since the systems lost pressure, the pump pushes some extra back in so your foot does not hit the floor. (this is a very generic description here, so some license is taken with when the valve closes etc)

Now looking at vehicle stability systems is where you find the big use of the acceleramoters. They know what is supposed to be happening (accel, brake, turn etc,) and look at the body response. If it's out of bounds (accel a direction not intended), they use the ability of the ABS to apply and release the brakes in combination with changes in engine timing to reduce power to try and get things back within a safe zone. (again, this doesn't describe everything and there's much variation in the specific systems)

So how can you use this on a robot?....well, if you can look at each of your wheels independently (one channel per independently rotational wheel ) to see what they are doing, and you can look at the operator input to see wht you want to be happening, and you can look at the net affect on the body (2d acceleramoter) then you can use this info to do things like pulse the motors (to change from the dynamic friction during wheel rotation) or stop the wheels from turning, or trun away......of course, a really good driver just does this without even thinking about it. sort of a hardware vs software trade