Patent GB-1181419-A (GB)
Title: Improvements relating to Automatic Control Systems for Vehicles
Inventor: HARTLEY FREDERICK WALTER
IPC: G05D1/02
Filed: 1967-11-16
Abstract: 1,181,419. Block control system. ELECTRIC & MUSICAL INDUSTRIES Ltd. 12 Nov., 1968 [16 Nov., 1967], No. 52137/67. Heading B7N. [Also in Division H4] An automatic control system for vehicles includes conductors arranged in sections along a path, means for selectively energizing sections by a steering signal to effect steering control of a vehicle on the path, means for selectively energizing sections by a run signal to control the movement of a vehicle along the path, and control means such that a vehicle can be stopped in a section without loss of the steering signal whilst inhibiting the run signal in response to the presence of a steering signal in another section. As .described the invention relates to a conveyer system in which driverless vehicles are controlled and steered in response to alternating signals received from a guide conductor. The arrangement enables vehicles to queue in the stopped condition in adjacent sections. General arrangement. Fig. 1.-S n-2,  S n-1 , S n  and S n+1  represent four sections of the guide conductor, S n+1  being one of two. converging sections, the other section not shown. Block units B n-1,  B n  and B n+1  are provided for transition from one section to another, each guide conductor section being connected from its block unit to a common conductor 1 and being arranged so that the conductors of adjacent sections do not overlap with the exception of the converging sections S n+1  which overlap with S n . Block units.-Block units B n-1  and B n , Fig. 2, include a pick-up coil 2 which is energized by a signal from the vehicle to set a bi-stable 3 to operate a switch 5 and allow steering signal oscillations, e.g. 2 KHz. to be applied to the next guide conductor section. This switch is associated with a switch 6 which causes the steering signal to be amplitude modulated at a frequency of say 50 Hz. to form the run signal. The signal from bi-stable 3 also via lead 8 inhibits one or more other block units, a similar signal from an adjacent unit when operated being supplied to gate 7 which also receives an output when the bi-stable 3 is in the reset position. The output of gate 7 is inverted at 9 and supplied via a gate 10 to the modulator switch 6, the gate 10 being inhibited via lead 11 from another block unit under certain circumstances. The end of any output from inverter 9 produces a signal via circuit 12 to reset the bi-stable 3. Block unit B n+1 , Fig. 3, is arranged so that when bi-stable 3 is set it merely produces on lead 11 an inhibiting signal for gate 10 of block unit B n . The gate 7 is responsive to an inhibiting signal on lead 8, or 8 2  from the section which converges on S +n1  or the next following section respectively. An output from the inverter 9 is applied as an inhibiting signal via lead 8 to block unit B n  and operates both the modulator and oscillator switches 5, 6, so that the steering and run signals are applied simultaneously to the section S n+1  This arrangement prevents the two converging sections from inhibiting each other. Vehicle, Fig. 6.-The steerable front wheel 42 carries sensing coils 43, 44, responsive to the 2 KHz. signal applied to the guide conductor, the signal being amplified at 45, 46 to control the steering via circuit 56 so that the output of the two sensing coils is maintained equal. The outputs of coils 43, 44 are added at 47 and applied to a detector 48 for the 50 Hz. modulation which when present operates a relay 49 to connect the battery 50 to the driving motor. 5 KHz. oscillations are generated at 51 and applied selectively via a trigger 52, under the control of a programme device which determines which branch the vehicle is to follow at junctions, to one of two coils 53, 54 which co-operate with coils 2 of the block units positioned one on each side of the guide conductor. Operation.-When a vehicle reaches point P, Fig. 1, the signal from oscillator 51 is picked up via coil 2 and applied to set the trigger circuit 3, Fig. 2, so that the steering signal is applied to section S n-1  This applies an inhibiting signal to section S n-2  and switches of the steering and run signals in that section but there is sufficient delay to enable the vehicle to travel until its steering coils 43, 44 are in the control range of section S n-1 . If an inhibiting signal is present at gate 7 the run signal is not applied to section S n-1  and the vehicle remains stationary just inside section S n-1  When the inhibiting signal is removed the run signal is applied and the vehicle moves to point Q and the process is repeated, the inhibiting signal applied via lead 8 to gate 7 in B n-1  causing the bi-stable 3 to be reset. At point R the vehicle comes under the control of the block unit shown in Fig. 3 and the signal on lead 11 disables the modulator of unit B n  but the steering signal remains, so that the vehicle will stop on the overlap between sections S n  and S n+1  and will remain there if there is an inhibiting signal on one or both of leads 8 1 , 8 2 . When these inhibiting signals are removed the inverter 9 produces an output which operates switches 5, 6 so that the vehicle is able to proceed. Modified block unit.-A circuit is described, Fig. 5 (not shown), in which the 5 KHz. signal from a vehicle is induced into the guide conductor thus enabling a continuous search to be made for a vehicle in a particular block.