Duty cycle controller for anti-lock braking-pressure regulating valve,

Abstract

An anti-lock braking-pressure control apparatus for a vehicle having a plurality of wheels, including at least one wheel speed sensor which detects respective actual speeds of the wheels of the vehicle, at least one solenoid-operated valve which regulates respective braking pressures applied to the wheels, a ground-speed sensor which detects a ground-speed of the vehicle as a running speed thereof relative to a road surface, and a controller which electrically operates, for preventing locking of each of the wheels, a corresponding one of the one or more solenoid-operated valves at a controlled duty cycle, the controller selecting one of a plurality of duty-cycle determining rules, and determining the duty cycle of the corresponding one solenoid-operated valve according to the selected one duty-cycle determining rule, the plurality of duty-cycle determining rules comprising (A) a first determining rule wherein the duty cycle is determined based on both (a) a wheel speed error that is a deviation of the actual speed of the each wheel from a target wheel speed obtained based on the ground-speed of the vehicle, and (b) a time derivative of the wheel speed error, and (B) a second determining rule wherein the duty cycle is determined based on one of (a) the wheel speed error and (b) the time derivative of the wheel speed error.