Patent ID: 7035725

Claim:
A sliding, integral, and proportional controller for providing anti-skid braking control for an aircraft having a plurality of tires and brakes, comprising: a reference velocity subsystem generating a reference velocity signal based upon an input wheel velocity signal; means for generating a velocity error signal based upon the reference velocity signal and the input wheel velocity signal; a velocity error ratio subsystem generating a modified slip ratio signal (S mod ) based upon a ratio of the difference between the reference velocity and the wheel velocity to the reference velocity; a main controller subsystem receiving the reference velocity signal and the S mod signal, the main controller subsystem generating a control command output signal indicative of a command braking pressure responsive to the reference velocity signal and the S mod signal, the main controller subsystem including: a) a one dimensional sliding mode controller subsystem to determine an estimated net wheel torque signal; b) an adaptive threshold subsystem for generating an adaptive threshold based upon the S mod signal and a clock signal; c) first summing means for summing an integral gain, a deep skid signal, and a modification of an initial braking command signal to avoid S mod signals that are too small or negative of an initial braking command signal to provide an output sum, said integral gain being based upon the estimated net wheel torque signal and the adaptive threshold, and said deep skid signal being based upon the S mod signal, the wheel velocity signal, the reference velocity signal, a tire rolling radius, a predetermined deep skid limitation of the S mod signal, and first and second function coefficients; and d) a proportional controller subsystem generating a proportional controller output signal to prevent sudden deep skids based upon said S mod signal and said velocity error signal; and e) second summing means for summing said output sum and said proportional controller output signal to provide said control command output signal.