Patent GB-1249465-A (GB)
Title: Improvements relating to automatic vehicle guidance systems
Inventor: HARTLEY FREDERICK WALTER
IPC: G05D1/02
Filed: 1967-11-30
Abstract: 1,249,465. Train control. E.M.I. Ltd. 25 Nov., 1968 [30 Nov., 1967], No. 54450/67. Heading B7N. [Also in Division H4] An automatic vehicle guidance system includes a plurality of vehicles each having identifying means, a plurality of decision elements which when actuated can exercise selective control on a vehicle arriving at respective decision points (e.g. turn off or stopping points) means for deriving a signal representing the identity of the vehicle arriving at a decision point, means for storing decisions for each of a plurality of vehicles, and means for utilizing an identity signal to actuate the decision element for the respective decision point in such a way as to render effective the decision stored for that particular vehicle. General arrangement, Fig. 1.-In the system, which is similar to that described in Specification 1,181,419, driverless tugs move along a route defined by a leader cable, a tug 30 being shown as travelling along a section Sn of the leader cable. Movement of the tug depends on the presence of both a steering signal and a run signal in that section of the cable, the steering signal being sensed by a pair of coils 35 to centre the front wheel bogey over the leader cable. The run signal is a modulation of the steering signal and the driving motor is energized only when this modulation is detected in the output of coils 35. Further sections of the route are shown as Sn+1 to Sn+4 with branch points Pn and Pn+1. Each tug 30 carries means 31 rendered operative by a switch 32 controlled by an actuator 33 at each decision point to transmit a digitally coded identification signal for a short period. This signal is received by a receiver such as In at the decision point and supplied to a control unit 34 where it is used to make operative a decision which has been stored previously for that tug. Block control units Bn+1, Bn+2 are provided for sections Sn+1, Sn+2 respectively and each tug transmits via coil 36 cooperating with stationary coil 37 a signal causing a block control unit to switch on the steering and run signals for the next section Sn + 1 or Sn+2 and remove it from section Sn, provided there are no inhibiting signals from other block units. At decision point Pn the stored decision will determine which of block control units Bn+1, Bn+ 2 is to be made operative. Control unit 34, Fig. 2.-A counter 3 is controlled by clock pulses on lead 24 and is arranged to register the count in each step in the same code as used for the tug identity signals. The identity signals received at In etc. are stored temporarily at 2n etc. and compared at 4n etc. with the count registered at each step by the counter 3, an ouput being provided on lead 5n etc. when the two inputs to a gate 4 agree. Sets of programme switches 6 1  for tug 1 to 6 m  for tug m are selectively operated according to the required decisions for each tug, the switch sets being energized in succession by a decoder 8 controlled by the counter 3. Each switch controls via diodes 10, 11 the energization of a " decision " line 9n etc. and as the counter scans the different tug identity signals a different set of decision lines is energized at each step. The output of each " decision " line is supplied via an AND gate 12 to a bi-stable device 15 and the output inverted at 13 is supplied via an AND gate 14 to the bi-stable, the bi-stable controlling the initiation of either one of two control operations. Gates 12, 14 are controlled by the output of the corresponding gate 4. The identification code may be an error detecting code using an " m out of n " code for each bit.