VEHICLE SELF-TRACKING SYSTEM

A system for permitting the operator of a motor vehicle to determine the location of his vehicle relative to a map includes an indicator movable beneath the map and having a concentrated light source which shines through the map to give the vehicle location. The drive and steering of the indicator are electrically slaved to the linear speed and turning movements of the vehicle. The indicator includes a steerable drive wheel which may engage a mode of the terrain shown by the map or a flat surface if any error which might be introduced by the latter is within the limits of tolerance desired. The electronic circuitry for the drive and steering of the indicator includes a main pulse generator having an output frequency related to the instantaneous speed of the vehicle and a further pulse generator having alternate pulse outputs whose pulse durations are variable in opposite sense with respect to each other in response to steering movements imparted to the vehicle. The indicator drive is controlled by the speed-related pulses whereas steering of the indicator is effected by ANDing signals derived from both circuits. The circuitry includes a novel pulse generator for producing the alternate pulses.