Electronic clutch control system

An electronic control system for a friction clutch in an engine driven vehicle for starting the vehicle from rest comprising an engine speed sensor operatively connected to said engine for deriving an engine speed signal, a reference signal generator for generating a reference signal equivalent to the engine speed signal at a reference engine speed appropriate for starting from rest, means for comparing the engine speed signal with the reference signal to derive an error signal, a switchable integrator connected to receive said error signal and arranged to derive a clutch actuation command signal from the error signal, the switchable integrator being such that the command signal is equivalent to the error signal at engine speeds below the reference speed and equivalent to the integral of the error signal at engine speeds above the reference speed, a clutch position sensor operatively connected to said clutch for deriving a clutch position signal, means for comparing the command signal with the clutch position signal and deriving therefrom a comparison signal, a clutch actuation system responsive to said comparison signal and operatively connected to said clutch to move the clutch towards an engaged state when said command signal indicates that the engine speed exceeds the reference speed and thereby load the engine to hold down the engine speed to the reference speed, means for deriving and storing a clutch condition compensation signal from values of said engine speed signal and command signal during one clutch engagement and a gain control disposed operatively between said clutch position sensor and said means for comparing the command signal with the clutch position signal to provide gain in the clutch position signal, the gain control being responsive to the compensation signal to adjust the gain of the clutch position signal and thereby provide an adjusted clutch position signal for comparison with the command signal.