Vehicle speed control arrangement

• US 3,921,946 A
• Filed: 07/23/1974
• Issued: 11/25/1975
• Est. Priority Date: 08/18/1973
• Status: Expired due to Term

• Current Assignee: David John Norton, John Douglas Corrie
• Original Assignee: David John Norton, John Douglas Corrie
• Inventors: Norton, David John, Corrie, John Douglas
• Primary Examiner(s): Halvosa, George E. A.
• Assistant Examiner(s): Eisenzopf, Reinhard
• Application Number:
  US05/491,531
• Time in Patent Office: 490 Days
• Field of Search: 246/182B,182A,182C,187B 187/29R 235/150.2,150.24 180/105 105/61 317/5 104/149,152 340/248A
• US Class Current: 246/182.00A
• CPC Class Codes: B61L 15/0062 On-board target speed calculation or supervision
• CPC Class Codes: B61L 15/0094 Recorders on the vehicle

Abstract

A vehicle speed control arrangement with particular but not exclusive utility for bringing railway vehicles to a stop, e.g. at a station platform. A speed/distance retardation profile is contained in vehicle-mounted '"'"''"'"''"'"''"'"'look-up'"'"''"'"''"'"''"'"' read-only memories which are initiated into controlling the vehicle brakes by passing a fixed trackside marker. Profile deviation limits are initiated or inhibited to idealise the stopping procedure in respect of limitation of the number of braking level changes, minimising braking time to save total journey time, maximising passenger comfort, and repeatable accuracy of stopping.

Claims

1. A vehicle speed control arrangement comprising a distance/speed inter-relationship profile storage means containing signals representing desired vehicle reference speed values at particular reference distance values for a predetermined vehicle position at which the distance/speed profile is to be applied to the control of the vehicle, vehicle speed determining means coupled to the vehicle for determining the actual speed thereof, vehicle travel distance determining means coupled to the vehicle for determining the distance which the vehicle has travelled past said predetermined position, comparison means coupled to said speed determining means and to said travel distance determining means for comparing the actual speed/travel distance ratio with the desired value stored in said storage means to produce a resulting comparison, and vehicle speed control means coupled to said vehicle for controlling the vehicle speed in accordance with said resulting comparison to maintain the vehicle speed in relation to distance travelled past said predetermined position to within predetermined variations from said profile.

2. An arrangement according to claim 1, wherein said profile is a braking profile and said speed control means comprises at least one braking system of the vehicle coupled to the vehicle to reduce the vehicle speed upon receipt of braking signals from the comparison means.

3. An arrangement according to claim 2 wherein the distance for the measured distance value is the distance to a required stopping point for the vehicle.

4. An arrangement according to claim 3 including a distance counter and wherein said distance is measured by counting down the known distance from a marker positioned before the stopping point.

5. An arrangement according to claim 3 wherein the measured distance to the stopping point is derived from an approximate value stored on the vehicle, said value being corrected with information derived from trackside markers.

6. An arrangement according to claim 5 comprising a correction applying circuit including marker responsive means responsive to a first marker to insert said approximate value, which is of the distance of the first marker from the stopping point, into an up/down counter, means responsive to pulses representing unit distance travelled to reduce the value in the counter until the second marker, at a known fraction 1/N of the distance of the first marker from the stopping point is detected and means to derive (N-1) times the difference between the reduced value and the approximate value as the measured distance from the second marker.

7. An arrangement according to claim 5 wherein the measured distance is also derived by a circuit responsive to identifiable trackside markers to supply a value of measured distance appropriate to an identified marker as said smaller limit distance.

8. An arrangement according to claim 1 wherein said predetermined variations are predetermined upper and lower limits of deviation from said profile, the speed control means including means for bringing the vehicle speed in relation to distance travelled past said position back within said limits should they be exceeded.

9. An arrangemenT according to claim 8 wherein the limit deviations are each separated from the profile by a respective percentage of the speed set at the appropriate distance for the respective part of the profile.

10. An arrangement according to claim 9 wherein the resulting comparison represents one of these four conditions:

(a) the reference value is beyond one limit value;

(b and c) between a limit and centre value;

or (d) beyond the other limit value.

11. An arrangement according to claim 10, wherein each of the four conditons is represented by a combination of the comparator outputs of a one-bit binary signal and a validity signal, the state of the binary signal indicating which value is the greater and the validity signal indicating whether or not the comparison is valid.

12. An arrangement according to claim 4, wherein the degree of speed regulation is determined by said percentages setting, the limit values being chosen as less than the variation of speed obtained by a stop-change in the selected braking level.

13. An arrangement according to claim 8 wherein the comparison means includes two comparator circuit elements, one responsive to one or both of the reference values and the respective measured value or values, the other to a selected one of the limit values and the reference values.

14. An arrangement according to claim 13 wherein the limit value is selected by a switch responsive to the one comparator giving an indication on which side of the reference value the measured value lies.

15. An arrangement according to claim 13 wherein the degree of speed regulation is by selecting one level at a time from several levels of braking effort.

16. An arrangement according to claim 15, wherein the selected one level is derived from the outputs of the comparators in accordance with the condition indicated.

17. An arrangement according to claim 16 including a logic circuit responsive to the binary and validity signals to select the level required relative to the level chosen for the profile.

18. An arrangement according to claim 17 wherein the relative level is converted to an actual level by a further logic circuit in response to the relative level and the measured speed.

19. An arrangement according to claim 18 wherein the actual level is put into effect or delayed by a calculating circuit.

20. An arrangement according to claim 19 wherein the delay is to prevent an initial brake application below the profile level and subsequently to prevent a change in brake level until a certain deceleration from a previous change in level occurs.

21. An arrangement according to claim 18 wherein the actual level is put into effect via a latch set to the level.

22. An arrangement according to claim 8 wherein the plurality of distance values are produced by adding in appropriate binary adders respective percentages of a binary value representing whichever is the smaller limit distance.

23. An arrangement according to claim 22 wherein the smaller limit distance value is supplied from a memory on at least one occasion and corrected in a counter holding the value for movement of the vehicle by pulses representing units of distance travelled generated by a vehicle motivated tachometer.

24. An arrangement according to claim 23, wherein the reference value is contained in a further memory.

25. An arrangement according to claim 24 wherein the value is in digital form and the value appropriate to an instant in time or a position of the vehicle selected from values stored in the memory.

26. An arrangement according to claim 25, wherein the selection is caused by a signal representing the instantaneous measured value of another parameter, the value selected being in accordance with a desired relation between the one parameter and the another parameter.

27. An arrangement according to claim 1 wherein the distance is represented by a coded binary signal having two components, an exponent and a mantissa representing the suffIcient number of significant figures in the binary value of the distance and the exponent the order of the most significant figure of the mantissa.

28. An arrangement according to claim 1 wherein the vehicle speed determining means comprises a pulse-producing tachometer and the distance represented by the distance-travelled pulses is corrected for mechanical errors in the accuracy of their generation by a calibration means responsive to the number of pulses in a known externally indicated distance travelled to adjust the distance assigned to each pulse.

29. An arrangement according to claim 28 wherein the calibrator is a binary rate multiplier whose multiplication ratio is that ratio required to adjust the distance assigned.

30. An arrangement according to claim 29 wherein the ratio is derived from a store in response to an input of the number of pulses recorded in the known distance.

31. An arrangement according to claim 1 wherein the profile storage means has alternative parts each appropriate to a different type of vehicle path.

32. An arrangement according to claim 31 said different types of path are paths of different gradients.

33. An arrangement according to claim 32 wherein the path includes a plurality of differing gradients, and selection means are provided for selecting those parts of the profile storage means instantaneously appropriate to the gradient being traversed.

34. An arrangement according to claim 33 wherein said selection means is vehicle-mounted.

35. An arrangement according to claim 33 wherein said selection means is trackside-mounted.

36. An arrangement according to claim 1 wherein said predetermined vehicle position is marked by a track-bed marker to which said vehicle travel distance determining means is responsive in use.

37. An arrangement according to claim 36 wherein said marker is a single loop.

38. An arrangement according to claim 36 wherein said marker is a double loop, and said vehicle travel distance determining means responds in use to passage of the loop centre.

39. An arrangement according to claim 1 wherein said vehicle is a railway vehicle travelling on a pair of spaced-apart rails.