GB873690A - Road vehicle steering control system - Google Patents

Abstract

873,690. Automatic steering control systems for road vehicles. GENERAL MOTORS CORPORATION. Oct. 16, 1959 [Nov. 3, 1958], No. 35077/59. Class 38 (4). In an automatic steering control system for a road vehicle, a steering arrangement is controlled in dependence on a signal representative of the displacement of the vehicle from a desired course and the sensitivity of the steering arrangement is varied in proportion to the road speed. As shown, an alternating flux around a leader-cable, not shown, induces alternating voltages in coils 22 carried on a road vehicle. The induced voltages are rectified and applied across capacitors 30 connected in series. The resultant voltage at point 34, representing the position of the coils 22 with respect to the leadercable, is applied to a potentiometer 40, 42. The voltage at a tapping 44 is fed to a ring modulator 56 energized via transformers 62, 154 from a power supply 66. An A.C. error signal is derived from a ring-modulator transformer 48 and fed to the input of a summing amplifier 104. An A.C. rate-of-displacement signal is derived from point 34 through a differentiating circuit 68, 70, a ring-modulator 80 and a transformer 78 and fed to the input of the summing amplifier 104. The amplified sum of the A.C. error signal and A.C. rate signal is fed through an amplifier 110 to a ring demodulator 118 the D.C. output of which energizes the coils 134 of an electro-hydraulic steering servo positioning guiding wheels so as to maintain the road vehicle in a predetermined position with respect to the leader cable. Feedback is applied to the amplifier 110 from a potentiometer 148 having a slider 150 positioned by the guiding wheels. The gain of the amplifier 104 is controlled in dependence on the road speed of the vehicle by feedback from a potentiometer 162 having a slider 106 positioned by a servomotor 160 controlled by a tachometer 158.