IMPROVEMENTS IN AND RELATING TO SPEED RESPONSIVE SYSTEMS

摘要

A system for controlling the speed of a motor vehicle has a speed detector which produces a first electrical signal having a mean level relating to the actual speed of the vehicle and an alternating component whose amplitude is also related to the actual speed of the vehicle. A memory is provided for storing a second electrical signal which has a mean level related to the required vehicle speed and which is substantially free of any alternating component. A comparator compares the first and second electrical signals and therefore produces an error signal which has a mean level corresponding to the difference (if any) between the actual and required vehicle speed and an alternating component related to the actual vehicle speed. A servo responds to the amplitude of the error signal to adjust the actual speed of the vehicle towards the required value. A relationship-varying circuit varies the relationship between the amplitude of the alternating component of the error signal and vehicle speed and thus increases the overall gain of the system at higher speeds. A tuning circuit tunes the system so as to provide increased gain at a frequency at which the system tends to hunt.