Controlling sideways position of construction or agricultural machine - using pair of ultrasonic detectors to generate control input to e.g. tractor

摘要

The position of a machine, e.g. tractor, relative to a reference, is controlled based upon ultrasonic sensing from a system using a pair of detectors (5,6) within a tube (1). The detectors can be operated in dual mode as transmitters. The control circuit causes pulses to be generated alternately from the ultrasonic elements. Reflections occur from the edges of the surfaces (7,8) and the transmission time before signals are received by the sensors are dependent upon the guide element (9) which may be a tensioned wire. ADVANTAGE - Can compensate for propagation time vagaries arising e.g. from temp. variations. Avoids faulty steering if ultrasonic sensor fails.