Abstract: The invention is a conveyor control system having self-propelled vehicles having wheels, each driven by a motor (14) to move along rails. The system includes power rails (18) for supplying power to the vehicle (12) and at least one command rail (20, 21) which transmits a constant command signal indicative of requested speed. The command rail (20) is comprised of isolated sections of rail for carrying different command signals along each isolated section to enable the vehicle (12) to travel at different speeds dependent on which section of rail the vehicle is within. The command signal may be in the form of an analog signal on one rail (20) or a digital signal on two rails (20, 21). Each vehicle (12) includes a control circuit (22) which interprets the command signal to drive the vehicle (12) at the requested speed. An override circuit (28, FIG. 2b, FIGS. 3 and 4) senses external activity for proper control of the circuit.

Abstract: The assembly (10) is a self-propelled conveyor system including a vehicle (12) having wheels (18) and a motor (16) for moving the vehicle (12) along a track (20). The vehicle (12) includes a speed sensor (24) for sensing actual speed of the vehicle (12) and a location sensor (26) for sensing the absolute position of the vehicle (12) along the track (20). A control (22) receives the actual speed and absolute location signals and drives the vehicle (12) at a speed associated with the absolute position, this value being obtained from a memory (32). The control (22) drives the motor (16) at the selected speed with a feedback signal of actual speed wherein the control (22) may adjust the drive signal when actual speed differs from selected speed.