Dynamic clipper for use in a vehicle guidance system

摘要

A dynamic clipper is used in the guidance control circuits of a wire guided vehicle, such as a lift truck, that is guided by a wire laid in floors between storage racks into which an alternating electrical signal is provided to remove the effects of noise pulses. The wire signal is detected by sensor coils carried by the vehicle, and the amplitude of this signal is used as an indication of the distance of the vehicle to the wire. The dynamic clipper includes a first comparator having one input from the sensor coil and the other input from a reference source. All noise signals greater than the reference voltage are removed. The output is then passed to an inverter and then to a second comparator which performs the same function. Thus both the positive and negative going noise pulses greater than the reference are removed from the sensor output signal. The resulting output is then rectified with a full wave rectifier and integrated to provide a direct current reference signal, the magnitude of which is therefore related directly to the proximity of the sensor coil to the buried wire.