GB1097141A - Improvements relating to automatic control systems for vehicles - Google Patents

Abstract

1,097,141. Inductive signalling. ELECTRIC & MUSICAL INDUSTRIES Ltd. Aug. 24, 1964 [Aug. 22, 1963; Oct. 18, 1963], Nos. 33253/63 and 41167/63. Heading H4U. An automatic control system, whereby a vehicle is caused to follow a route defined by an energized leader cable, comprises two sensing devices 1 and 2 responsible to energization of the leader cable in dependance on the disposition of the devices relative to the cable, means 13 responsive to the output of the sensing devices to produce a pulse train, having a mark to space ratio representing said disposition, and means responsive to the pulse train to effect steering of the vehicle. The alternating signals, induced in the sensing devices, which should be positioned symmetrically on either side of the leader cable, are in phase and are fed to an analyzing circuit 3, which supplies the sum of the two signals on line 17, and the difference of the two signals on line 18. The phase of the difference signal is either equal to that of the sum signal or in antiphase thereto, depending on which sensing device produces the greater signal, and has an amplitude representing said disposition. The difference signal is fed to a pulse generator 13, which generates a pulse train having a mark to space ratio corresponding to the amplitude of the signal. The difference signal is also fed to phase comparator 6, together with the sum signal to give an output on lines 22 or 23 depending on the relative phase of the two signals. The vehicle is steered by a " steer left " motor 9 or a " steer right " motor 10, the appropriate one of which is energized by the pulse train via amplifier 8 and switching circuit 7. The switching circuit 7 determines which motor shall be so energized and is controlled by the output of the phase comparator 6. The amplifier 8 provides a negative feedback signal which is fed to the pulse generator, as a stabilizing signal. The same signal is also fed via terminal 9 to a threshold and braking system, whereby the drive motors of the vehicle are stopped should the amplitude of the same signal fall below a certain level. An all transistor embodiment of the circuit of Fig. 3 is shown in detail in Fig. 1 (not shown). Velocity feedback may be added to the system, Fig. 2 (not shown), using a tachogenerator coupled to the steering mechanism of the vehicle.