Abstract

An automatic guidance device for an electrically driven vehicle inductively coupled by a power receiver core to a roadway core connected to power source. The device which is attached to the power receiver core or to a ferrous bar connected to the underside of the vehicle comprises at least two sensor coils equally spaced from the midpoint of the power receiver core which is on the vehicle centerline. End portions of the vehicle core or bar which extend beyond the coils comprises magnetic poles which receive flux from the roadway inductor. Flux through the coils produces voltages which vary in proportion to their distance from the roadway inductor centerline and are compared to produce error signals used to control a steering servo on the vehicle. In event of roadway power failure a circuit is provided to enable the utilization of battery power to produce sufficient flux to maintain the production of error signals and thus steering control.