Patent GB-1391359-A (GB)
Title: Method of and apparatus for controlling the movement of a plurality of vehicles travelling on one track in a closed circuit
IPC: B61L3/22
Filed: 1972-07-03
Abstract: 1391359 Automatic vehicle control ANVAR (AGENCE NATIONALE DE VALORISATION DE LA RECHERCHE) 3 July 1972 [2 July 1971] 31076/72 Heading B7H In an arrangement for controlling the movement of vehicles, e.g. trains moving on a single closed circuit line, an imaginary train having a position defined by clock pulses derived from a signal received from a line side conductor is associated with and leads each actual train and the actual train is controlled by its position relative to its imaginary train and to the position of the imaginary train associated with the actual train to its rear. Pulses from a lineside conductor spaced by a constant interval of time are applied via a changeover switch 3 to a counter 1, which provides an output N which is a function of the imaginary train position. Pick up 7 co-operates with reference mark track elements 6 to provide input pulses to a counter 5 which provides an output n which is a function of actual train position. The difference (N-n) is representative of required speed and is compared in comparator 10 by a representation m of actual train speed from speedometer 8. The comparator provides an output to a decision maker 11 which controls the train drive motor and brakes. The value m is modified by a factor which ensures that the value (N-n) is always greater than the braking distance of the train to ensure the actual train does not overtake its associated imaginary train. Assume a train has to be stopped at a station between reference mark elements n i  and (n i  + 1) the position counter 1 of the imaginary train is stopped when it reaches a count of n i  as determined by a coincidence device 12 which acts via OR gate 13 to change over switch 3 whereby the clock pulses are switched from counter 1 to counter 16. With the stop in the valve of N the control system described in the previous para. acts to bring theactual train to a halt at the required position. For speed decrease in a linear manner the distance between the reference mark elements in advance of a station are arranged to decrease in arithmetic progression. On operation of the changeover switch 3 the clock pulses are supplied to a stop counter 16 which counts up to a time specified for the imaginary train to stop at the station. When the count is achieved a coincidence device Si operates and via OR gate 18 switches the changeover switch 3 whereby pulses are again applied to the imaginary train position counter N. At this instance with the associated actual train stopped at the station, the actual train speed m = 0, and counts N and n are equal to n i ; thus when N commences to increase N - n becomes greater than m so that if decision motor 11 receives an input 20 authorizing its departure and indicating that the train doors are closed, the unit 11 issues a command which actuates the train motors. To ensure that an actual train, when late, stops at a station and for sufficient time for passengers to leave and join, the output N from the imaginary train position counter is applied to the comparator 9 via a memory 22 which is blocked by the output from OR gate 13 when the imaginary train is stopped at the station. Thus the value of N remains constant even though the imaginary train leaves the station, until the train has stopped at the station for a period determined by a delay device 27 which is triggered when the actual train stops at a station via a coincidence device 26 associated with counter 5. The devices 26 are similar to those 12 associated with counter 1 and the output from the relevant device triggers a door opening mechanism in addition to the delay device. The output from the device 27 which has a delay less than the normal station stopping time is used to unblock the memory which then provides the output N from the counter 1. The total number of clock pulses issued less the number occurring during theoretical train stoppage at stations (N+ S<SP>1</SP>) is applied to a subtractor unit 34 with the total number n of track elements 6 passed and the difference is compared in unit 36 with a fixed number from unit 37 representing the number of elements between imaginary trains plus a safety factor. When the difference equals the number, indicating that the actual train is being caught by the imaginary train associated with the following actual train, an alarm is issued to a central station which acts to stop all the imaginary trains and hence the actual trains in the network. A signal at frequency 100 KHZ is applied to the lineside conductor at a central control station. In addition to being used to derive half second clock pulses this signal is also applied at each train to a divide by 2 circuit and also to a counter. Assume the vehicle is the pth vehicle in the system the counter issues an output at count 1000p and cuts it off at count 1000 (p+1). During this time slot if there is no alarm signal the vehicle transmits to the central office a signal at 50 KHZ., and these signals when received are compared with signals generated at the central office defining the time slots. Should an alarm signal occur on a vehicle the transmission of the signal at 50 KHZ during its time slot is blocked and the omission is detected at the central office whereby the 100 KHZ signal is square wave modulated each "on" period being insufficient to provide the count required to generate a clock pulse on the vehicles so that the imaginary trains are halted. Means are also provided for allowing the train to operate at greater than normal speed up to a fixed maximum to allow the train to catch up after a delay and trackside markers are provided to slow the train at bends and at positions where work is being carried out on the track.