Patent GB-1080800-A (GB)
Title: Automatic electrical control system for vehicles
IPC: B60L15/20
Filed: 1965-11-23
Abstract: 1,080,800. Automatic train control. GENERAL ELECTRIC CO. Nov. 23, 1965 [Dec. 14, 1964], No. 49758/65. Heading B7N. [Also in Division G3] An automatic control system for rail vehicles comprises vehicle-carried apparatus for operating the vehicle in accordance with each of a number of command signals transmitted from the wayside. When an approach speed signal is received through pick-ups 10, 11, selector 18 energizes relays ASR, RSR. A speed reference signal is supplied to comparator 90 and an open loop speed signal to translator 97. Actual speed is measured by a tachometer circuit, the signal on line 73 being proportional to speed. The open loop signal from potentiometer 101 establishes the reference speed under normal loading conditions, the error signal being superimposed as a corrective signal on the open loop signal. A clear speed signal establishes a higher speed command reference and open loop reference. Receipt of a positioned stop signal by selector 17 causes integrating amplifier (108) to subtract the distance travelled from the reference distance represented by the charge on capacitor (115). The signal at line (116) represents the computed actual distance to the stopping-point. Square function generator (107) produces a signal which represents the programmed distance to the stop point based on the square of the velocity of the train at any given instant. The error signal at line (122) controls the braking effort so that the deceleration rate conforms with a desired programme. The error signal on line (122) is translated with respect to earth due to the difference in potential between lines 63 and 21, so providing fail-safe operation. An open loop brake rate is imposed by translator (123) and has its value fixed by a signal from a station programmed pick-up 13. The overall braking rate signal, which is a combination of the open loop brake rate and distance error signal, is derived on line (130) which is connected to the braking and propulsion control line (131). The distance error signal modulates the brake rate above and below the open loop rate to maintain the programmed velocitydistance relationship. When a train enters a station stop approach area at a low speed, braking is not applied immediately but is held off until the velocity-distance programme calls for the application of the brake. At a number of points along the wayside, between the point of initiation of a positioned stop and the stoppoint, signals are derived to reset the target distance computer and remove accumulated errors. Receipt of a location reference A signal by pick-up 12 actuates selector 28 to energize relay LRAR. The voltage across capacitor (115) is reset, after which the positioned stop programme is resumed. Similar operation takes place at location B. As the train comes to a stop, a relay is de-energized to permit station programme functions such as door-actuation, these functions being under the control of signals from pick-up 13. Actuation of a high performance request relay opens contacts (HPRR1) to insert maximum resistance and reduce the programmed distance signal on line (114), a higher open loop brake rate being called for by actuation of contacts (HPRR2). Reception of a zero-positioned stop command signal through pick-ups 10, 11, actuates selector 16 to remove the speed reference voltage and open loop speed signals from amplifiers 91 and 98 respectively. The speed signal on line (105) is applied to the square function generator (107) to initiate the stop programme. The speed signal on line (106) is supplied to integrating amplifier (108) and the signal on line (104) is applied to the propulsion and braking controls.