Vehicle speed automatic control device

摘要

An automatic vehicle speed control device for controlling a running speed of a vehicle at a certain set speed includes a microcomputer having a vehicle speed memory for storing a vehicle speed upon operation of a command switch, a control circuit for adjusting a throttle valve through an actuator by calculating the difference between the stored vehicle speed of the vehicle speed memory and an actual vehicle speed, and a signal oscillating circuit for generating a watch dog pulse signal having a constant period under normal operation conditions. A monitor circuit having an exclusive NOR element for detecting watch dog pulses generated from the microcomputer senses whether or not the microcomputer has an abnormal operation and renders the actuator in a non-operated condition during the abnormal operation of the microcomputer.