Abstract: In a motor driven automotive cruise control system, the engine throttle is progressively released upon actuation of the vehicle service brakes to avoid objectionable pedal slap noise. The release is initiated by the electric motor, which drives the engine throttle toward its closed (rest) position while maintaining engagement of a clutch connected therebetween. If the duration of the brake actuation exceeds a reference interval sufficiently long as to indicate potentially significant braking effort, the clutch is immediately disengaged to return the throttle to its closed position without further delay. If the duration of the brake actuation is less than the reference interval, engagement of the clutch is maintained until the motor has returned the throttle to its closed position.

Abstract: The phase winding energization frequency of a stepper motor throttle operator is adjusted in relation to a comparison between the actual neutral voltage crossing of back-EMF in the phase windings and a previously determined optimum point of crossing. The energization frequency is increased to increase motor speed when the actual crossing occurs prior to the optimum point, and decreased to decrease motor speed when the actual crossing occurs after the optimum point.

Abstract: A digital speed control system including a processor performing arithmetical and logic operations in response to command inputs from the operator to maintain the present vehicle speed, to accelerate at a substantially constant rate to a new cruising speed or to a previously established cruising speed is disclosed. Certain processor operations are phased to speed sensor pulses to permit rate of change of speed computations to be performed with minimum hardware.