Duty cycle translator with solenoid modeling circuit for adaptive

Abstract

An adaptive braking system for a vehicle having fluid pressure operated brakes includes a skid detecting circuit for generating a skid detecting signal when an incipient skidding condition is detected, a pressure command generator which is responsive to the skid detecting signal for generating a pressure command signal, and a duty cycle translator responsive to the pressure command signal to actuate the brake pressure modulator. The duty cycle translator includes a circuit which generates a signal modeling the actual pressure level in the vehicle brake actuators. Since the modulator is actuated by a solenoid which is powered by the vehicle electrical supply, the opening and closing times of the solenoid will vary as a function of the power output of the vehicle power supply, which can vary over a substantial range depending upon ambient temperature and upon the strength of the vehicle battery. Accordingly, the duty cycle translator includes a circuit which models the opening and closing times of the solenoid actuators and the reaction time of the mechanical valve components to thereby more closely model the actual pressure level in the vehicle brake actuators.