G’day mitchnvic,
There is an optimum amount of ‘skid’ for maximum braking retardation on a dry surface, this of course differs for wet and contaminated surfaces. What the anti-skid system attempts to do is achieve and maintain this optimum skid under heavy braking conditions. The system does this by comparing actual wheel speed to the speed of the other wheels as well as to the inertial reference system speed and when it detects excessive skid the brake pressure is backed off a bit until the optimum is achieved. All this is re-calculated several times a second for each individual wheel, that’s right each wheel. You can have vastly different braking requirements over the width of the main undercarriage which on a B747 is over 30 feet wide so one side of the aeroplane can be braking harder than the other depending on the surface condition of the runway.
Incorporated into the ant-skid system on modern airliners is an autobrake system which, when selected, decelerates the aeroplane at a predetermined rate up to a maximum setting and the ant-skid function activates if required.
I hope this makes sense and explains it for you.
Regards,
BH.