System and method for automatically controlling a vehicle speed to a

Abstract

A system and method for automatically controlling a vehicle speed to a desired vehicle speed in which, when a set switch is operated, a vehicle speed V.sub.1 at the time of the predetermined set storage unit of microcomputer and a limit vehicle speed switch operation is stored in a vehicle speed V.sub.alpha is set which is lower than the stored vehicle speed by a predetermined value alpha (V.sub.alpha =V.sub.1 -alpha, alpha>0). The limit vehicle speed v.sub.alpha is a criterion of determining if a second initialize control should be executed. The second initialize control is such that an acceleration command signal is intermittently outputted to a throttle actuator until the deceleration of the vehicle becomes below a constant rate upon detection of a change rate of the vehicle speed after a first initialize control in which the acceleration command signal is outputted for a predetermined period of time upon receipt of a cruise command signal from a command switch. The limit speed is set to a value considerably close to the stored vehicle speed. When the actual vehicle speed V.sub.0 immediately after the first initialize control has a value larger than the limit speed V.sub.alpha, the following inequalities are established: V.sub.alpha <V.sub.0 <V.sub.1 . . . (1) or V.sub.1 V.sub.0 . . . (2) In either case (1) or (2), the second initialize control is inhibited. Thereafter a cruise speed control is carried out.