A second generation automotive speed control system using electronic circuits to perform the necessary logic and memory functions is described. Important considerations, such as performance and environmental factors, are discussed in relation to their design implications. Component function and system operation are covered using generalized circuit concepts. The unique Philco-Ford electronic speed control system is decribed in detail.
IT IS THE INTENT of this paper to describe the design factors, functional elements, and general operation of an automatic electronic speed control system for motor vehicle use.
Automatic electronic speed control is a feedback control system that has the ability to hold the vehicle speed constant for varying load conditions. This system relieves the driver of the boring task of maintaining the vehicle speed and allows him to concentrate on more significant aspects of his driving. To accomplish this function, the system monitors vehicle speed and compares it to a reference or set speed. Any deviation in vehicle speed causes a servo system to open or close the engine throttle as required to eliminate the speed error. The reference speed is set by a driver's instruction to the system to remember or hold the existing speed. In this electronic speed control system, the memory and logic functions are performed entirely with electronic circuits. Sensors are needed to get vehicle speed and driver commands into the system. Actuators are needed to convert electrical signals into the mechanical actions necessary to modulate the vehicle engine torque.