Patent GB-1137189-A (GB)
Title: Control system for vehicles
IPC: B61L3/00
Filed: 1966-10-24
Abstract: 1,137,189. Automatic train control. GENERAL SIGNAL CORP. 24 Oct., 1966 [23 Oct., 1965], No. 47653/66. Heading B7N. [Also in Division G3] In an automatic train control arrangement, apparatus for controlling the speed of a train can be switched to operate in one of three modes, a first mode, known as acceleration mode, which is switched in when the desired speed exceeds the actual speed and during which a desired rate of acceleration is compared with the actual rate to provide a propulsion control signal, a second, velocity mode in which the vehicle speed is controlled in accordance with a comparison between a desired and actual speed and a third, stopping mode in which the speed is controlled in accordance with a desired deceleration pattern. On closure of the train doors preparatory to moving off, contacts 48 are closed to apply a desired velocity signal VD of positive polarity, which is automatically selected in accordance with the traffic in advance, from a selector 107 via line 64 to an input of amplifier 63 which is also supplied with a second input of negative polarity and indicative of actual train speed from an axle driven generator 67. Since the difference between the signals exceeds a value equivalent to 4 miles/hr. relay DM picks up and switches the circuit to the acceleration mode. In this mode a relay DAP is energized to supply a selected acceleration signal aD 1  from selector 80 on line 82 to an input of amplifier 32 where it is compared with an actual acceleration signal aA on line 42. This latter signal is supplied by differentiator 37 to which the output of the axle driven generator 67 is connected. The result of the comparison is applied via integrator 33, converter 34 and lines 87, 88 to control the propulsion and braking controller 24. When the speed builds up to a value which is less than 4 m.p.h. below the desired speed, relay DM drops away and the apparatus is switched to the velocity mode. In this mode relays VM, Pcc and AABP are picked up to supply the desired speed signal VD on line 11 to amplifier 32 which is also supplied with the actual speed signal VA on line 114. The result of the comparison controls the propulsion and braking controller 24. In this mode a fraction of the actual acceleration signal aA is supplied to the input to the amplifier causing the acceleration rate to decrease as the actual velocity approaches the desired value and a dead band control 44 is provided across the amplifier 32 to prevent it supplying an output when the actual and desired speed values differ by only a small percentage of the actual speed value. When the train passes a trackside coil SZMf 1  in approach to a stopping point, relays SZMR (not shown) and SZP release to initiate the stopping mode of control. In this mode of control a braking pattern reference signal is obtained by integrating the actual velocity signal to give distance from which the distance to stop is determined, by finding the square root of this latter value and multiplying the result by a factor which is a function of the deceleration rate required. The reference signal value is corrected at members 500Mf 2  and 100Mf 3  when the train has 500 feet and 100 feet to go respectively. The reference signal when compared with the actual signal provides the stopping control.