BRAKE CONTROL SYSTEM

• US 3,768,873 A
• Filed: 06/23/1971
• Issued: 10/30/1973
• Est. Priority Date: 06/23/1971
• Status: Expired due to Term

• Current Assignee: Edgar A. Hirzel
• Original Assignee: Edgar A. Hirzel
• Inventors: Hirzel, Edgar A.
• Primary Examiner(s): Buchler, Milton
• Assistant Examiner(s): Kunin, Stephen G.
• Application Number:
  US05/155,903
• Time in Patent Office: 860 Days
• Field of Search: 188/181C 244/111 303/20,21 317/5 318/52 340/263 324/160-161
• US Class Current: 303/126
• CPC Class Codes: B60T 8/1703 for aircrafts
• CPC Class Codes: B60T 8/17613 based on analogue circuits or digital circuits comprised of discrete electronic elements
• CPC Class Codes: B60T 8/885 using electrical circuitry

Abstract

A brake control system for a vehicle having a number of wheels with brake application device is provided with a slip error signal that is used to modify brake application means. The slip error signal is produced by comparing an instantaneous wheel speed signal to a simulated vehicle variable reference signal. The simulated vehicle variable reference signal is produced by a simulator supplied with wheel speed information obtained solely from one wheel to avoid error inducing introduction of wheel speed information from other wheels. An initial simulated vehicle variable reference signal is derived from maximum wheel speed attained during wheel acceleration. The simulated vehicle variable reference signal representing the speed of the vehicle during deceleration is produced by modifying the variable reference signal with a value including a force-analog signal representing the drag forces on the vehicle.

Claims

1. In a braking control system for a vehicle having a plurality of wheels having controlled brake application means, the combination for each one of said wheels comprising:

analog means responsive to rotation of said one wheel for producing a wheel-speed signal that is a function of the rotational speed of said one wheel;

simulator means supplied with information from said wheel-speed signal for producing a variable reference signal simulating vehicle speed without direct vehicle accelerative measurement, said simulator means utilizing wheel-speed information obtained solely from said one wheel so as to avoid error-inducing introduction of wheel-speed information from other wheels;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal wiTh said variable reference signal to provide a slip error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said slip error signal for producing a brake control signal for modifying the action of said brake application means.

2. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum speed attained during wheel acceleration;

means for producing a force-analog signal indicative of the drag forces acting on said vehicle; and

means for reducing said variable reference signal as a function of said force-analog signal.

3. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for effecting decay of said variable reference signal at a predetermined rate; and

means responsive to said brake control signal for modifying the rate of decay of said variable reference signal.

4. The invention defined in claim 1 wherein said simulator means comprises:

means responsive to said wheel-speed signal to establish an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means responsive to said wheel-speed signal to produce a reference deceleration signal representative of average vehicle deceleration; and

means for reducing said variable reference signal as a function of said reference deceleration signal.

5. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of said wheel speed signal; and

means for reducing said variable reference signal as a function of said force-analog signal.

6. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of said wheel speed signal as indicative of the drag forces acting on said vehicle; and

means responsive to said force-analog signal for forming a time integral function of said force-analog signal and reducing said variable reference signal in accordance therewith.

7. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to the difference between said wheel-speed signal and said variable reference signal; and

means for reducing said variable reference signal as a function of said force-analog signal.

8. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the difference between said wheel-speed signal and said variable reference signal; and

means responsive to said force-analog signal for forming a time integral function of said force-analog signal and reducing said variable reference signal in accordance therewith.

9. The invention defined in claim 1 wherein said simulator means comprises:

means for estabLishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of the difference between said wheel-speed signal and said variable reference signal; and

means for reducing said variable reference signal as a function of said force-analog signal.

10. The invention defined in claim 1 wherein said simulator means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of the difference between said wheel-speed signal and said variable reference signal; and

mass-analog means responsive to said force-analog signal for forming a time integral function of said force-analog signal in analog relation to vehicle mass and reducing said variable reference signal in accordance therewith.

11. The invention defined in claim 1 wherein said control means comprises:

means responsive to said error signal for producing a first brake control signal which is a time integral function of said slip error signal and for producing a second brake control signal which is a non-integral function of said slip error signal; and

means responsive to said first and second brake control signals for effecting said modification of the action of said brake application means.

12. The invention defined in claim 1 wherein said control means includes means for producing a brake control signal when said slip error signal exceeds a predetermined threshold level, said brake control signal being a time integral function of both positive and negative variation of said slip error signal from said threshold level.

13. In a braking control system for a vehicle having a plurality of wheels having controlled brake application means, the combination for each one of said wheels comprising:

analog means responsive to rotation of said one wheel for producing a wheel-speed signal that is a function of the rotational speed of said one wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal without direct vehicle accelerative measurement, said reference generating means utilizing wheel-speed information obtained solely from said one wheel so as to avoid error-inducing introduction of wheel-speed information from other wheels;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means.

14. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a first derivative function of said wheel speed signal; and

means for reducing said variable reference signal as a function of said reference control signal.

15. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a low frequency first derivative function of said wheel speed signal; and

means for reducing said variable reference signal as a function of said reference control signal.

16. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a first derivative function of said wheel speed signal; and

means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

17. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a low frequency first derivative function of the said wheel speed signal; and

means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

18. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a first derivative function of the difference between said wheel-speed signal and said variable reference signal; and

means for reducing said variable reference signal as a function of said reference control signal.

19. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a first derivative function of the difference between said wheel-speed signal and said variable reference signal; and

means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

20. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a low frequency first derivative function of the difference between said wheel-speed signal and said variable reference signal; and

means for reducing said variable reference signal as a function of said reference control signal.

21. The invention defined in claim 13 wherein said reference generating means comprises:

means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration;

means for producing a reference control signal which varies as a low frequency first derivative function of the difference between said wheel-speed signal and said variable reference signal; and

means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

22. The invention defined in claim 13 wherein said control means comprises:

means responsive to said error signal for producing a first brake control signal which is a time integral function of said error signal and for producing a second brake control signal which is a non-integral function of said error signal; and

means responsive to said first and second brake control signals for effecting said modification of the action of said brake application means.

23. The invention defined in claim 13 wherein said control means includes means for producing a brake control signal when said error siGnal exceeds a predetermined threshold level, said brake control signal being a time integral function of both positive and negative variation of said error signal from said threshold level.

24. A system for modifying the action of the brake application means for a wheel of a vehicle, comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of said wheel;

simulator means supplied with information from said wheel-speed signal for producing a variable reference signal simulating vehicle speed without direct vehicle accelerative measurement, said simulator means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of said wheel speed signal, and means for reducing said variable reference signal as a function of said force-analog signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide a slip error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said slip error signal for producing a brake control signal for modifying the action of said brake application means.

25. The invention defined in claim 24 wherein said means for reducing said variable reference signal as a function of said force analog signal comprises means responsive to said force analog signal for forming a time integral function of said force-analog signal and reducing said variable reference signal in accordance therewith.

26. A braking system for modifying the action of the brake application means for a wheel of a vehicle comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of one wheel;

simulator means supplied with information from said wheel-speed signal for producing a variable reference signal simulating vehicle speed without direct vehicle accelerative measurement, said simulator means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the difference between said wheel-speed signal and said variable reference signal, and means for reducing said variable reference signal as a function of said force-analog signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide a slip error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said slip error signal for producing a brake control signal for modifying the action of said brake application means.

27. The invention defined in claim 26 wherein said means for reducing said variable reference signal as a function of said force analog signal comprises means responsive to said force analog signal for forming a time integral function of said force-analog signal and reducing said force analog signal in accordance therewith.

28. A system for modifying the action of the brake application means for a wheel of a vehicle comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of said wheel;

simulator means supplied with information from said wheel-speed signal for producing a variable reference signal simulating vehicle speed, said simulator means comprising means for establishing an Initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of the difference between said wheel-speed signal and said variable reference signal, and means for reducing said variable reference signal as a function of said force-analog signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide a slip error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said slip error signal for producing a brake control signal for modifying the action of said brake application means.

29. The invention defined in claim 28 wherein said means for reducing said variable reference signal as a function of said force analog signal comprises mass-analog means responsive to said force analog signal for forming a time integral function of said force-analog signal in analog relation to vehicle means and reducing said variable reference signal in accordance therewith.

30. The invention defined in claim 29 wherein said control means comprises:

means responsive to said error signal for producing a first brake control signal which is a time integral function of said slip error signal and for producing a second brake control signal which is a non-integral function of said slip error signal; and

means responsive to said first and second brake control signals for effecting said modification of the action of said brake application means.

31. The invention defined in claim 29 wherein said control means includes means for producing a brake control signal when said slip error signal exceeds a predetermined threshold level, said brake control signal being a time integral function of both positive and negative variation of said slip error signal from said threshold level.

32. A system for modifying the action of the brake application means for a wheel of a vehicle, comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the instantaneous rotational speed of said wheel;

simulator means supplied with information from said wheel-speed signal for producing a variable reference signal simulating vehicle speed, said simulator means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a force-analog signal which varies as a function of the first derivative with respect to time of the low frequency content of the difference between said variable reference signal and said wheel-speed signal, and mass-analog means responsive to said force-analog signal for forming a time integral function of said force-analog signal in analog relation to vehicle mass and reducing said variable reference signal in accordance therewith;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide a slip error signal that is a function of the difference between said wheel-speed signal and said variable reference signal;

means responsive to said slip error signal for producing a first brake control signal when said slip error signal exceeds a first predetermined threshold level, said first brake control signal being a time integral function of both positive and negative variation of said slip error signal from said first threshold level;

means responsive to said error signal for producing a second brake control signal when said slip error signal exceeds a second predetermined threshold level, said second brake control signal being a non-integral function of said slip error signal; and

Means for summing said first and second brake control signals to produce a composite brake control signal for modifying the action of said brake application means.

33. The invention defined in claim 32 wherein said second brake control signal is substantially a linear function of said slip error signal.

34. The invention defined in claim 32 further comprising capacitor means for providing a system lag compensating signal for summation with said first and second brake control signals to form said composite brake control signal.

35. A system for modifying the action of the brake application means for a wheel of a vehicle, comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the instantaneous rotational speed of said wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal without direct vehicle accelerative measurement, said reference generating means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a reference control signal which varies as a first derivative function of said wheel speed signal, and means for reducing said variable reference signal as a function of said reference control signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means.

36. The invention defined in claim 35 wherein said means for reducing said variable reference signal as a function of said reference control signal comprises means responsive to said reference control signal for forming a time integral function of said reference control signal in accordance therewith.

37. A system for modifying the action of the brake application means for a wheel of a vehicle comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of said wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal without direct vehicle accelerative measurement, said reference generating means comprising means for establishing an initial variable reference value derived from maximum wheel speed attained during wheel acceleration, means for producing a reference control signal which varies as a low frequency first derivative function of said wheel speed signal, and means for reducing said variable reference signal as a function of said reference control signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means.

38. The invention defined in claim 37 wherein said means for reducing said variable reference signal as a function of said reference control signal comprises means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

39. A system for modifying the action of the brake application means for a wheel of a vehicle comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of said whEel;

reference generative means supplied with information from said wheel-speed signal for producing a variable reference signal without direct vehicle accelerative measurement, said reference generating means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a reference control signal which varies as a first derivative function of the difference between said wheel-speed signal and said variable reference signal, and means for reducing said variable reference signal as a function of said reference control signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means.

40. The invention defined in claim 39 wherein said means for reducing said variable reference signal as a function of said reference control signal comprises means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

41. A system for modifying the action of the brake application means for a wheel of a vehicle, comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the rotational speed of said wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal, said reference generating means comprising means for establishing an initial variable reference signal without direct vehicle accelerative measurement value derived from maximum wheel speed attained during wheel acceleration, means for producing a reference control signal which varies as a low frequency first derivative function of the difference between said wheel-speed signal and said variable reference signal, and means for reducing said variable reference signal as a function of said reference control signal;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal; and

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means.

42. The invention defined in claim 41 wherein said means for reducing said variable reference signal as a function of said reference control signal comprises means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith.

43. The invention defined in claim 41 wherein said control means comprises:

means responsive to said error signal for producing a first brake control signal which is a time integral function of said error signal and for producing a second brake control signal which is a non-integral function of said error signal; and

means responsive to said first and second brake control signals for effecting said modification of the action of said brake application means.

44. The invention defined in claim 41 wherein said control means includes means for producing a brake control signal when said error signal exceeds a predetermined threshold level, said brake control signal being a time integral function of both positive and negative variation of said error signal from said threshold level.

45. A system for modifying the action of the brake application means for a wheel of a vehicle, comprising:

analog means responsive to rotation of said wheel for producing a wheel-speed signal that is a function of the instantaneous rotational speed of said wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal, said reference generating means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for producing a reference control signal which varies as a low frequency first derivative function of the difference between said wheel-speed signal and said variable reference signal, means responsive to said reference control signal for forming a time integral function of said reference control signal and reducing said variable reference signal in accordance therewith;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal;

means responsive to said error signal for producing a first brake control signal when said error signal exceeds a first predetermined threshold level, said first brake control signal being a time integral function of both positive and negative variation of said error signal from said first threshold level;

means responsive to said error signal for producing a second brake control signal when said error signal exceeds a second predetermined threshold level, said second brake control signal being a non-integral function of said error signal; and

means for summing said first and second brake control signals to produce a composite brake control signal for modifying the action of said brake application means.

46. The invention defined in claim 45 wherein said second brake control signal is substantially a linear function of said error signal.

47. The invention defined in claim 45 further comprising capacitor means for providing a system lag compensating signal for summation with said first and second brake control signals to form said composite brake control signal.

48. In a braking control system for a vehicle having a plurality of wheels having controlled brake application means, the combination for each one of said wheels comprising:

analog means responsive to rotation of said one wheel for producing a wheel-speed signal that is a function of the instantaneous rotational speed of said one wheel;

reference generating means supplied with information from said wheel-speed signal for producing a variable reference signal without direct vehicle accelerative measurement, said reference generating means utilizing wheel-speed information obtained solely from said one wheel so as to avoid error-inducing introduction of wheel-speed information from other wheels;

comparator means supplied with said wheel-speed signal and with said variable reference signal for comparing said wheel-speed signal with said variable reference signal to provide an error signal that is a function of the difference between said wheel-speed signal and said variable reference signal;

control means responsive to said error signal for producing a brake control signal for modifying the action of said brake application means; and

said reference generating means comprising means for establishing an initial variable reference signal value derived from maximum wheel speed attained during wheel acceleration, means for effecting decay of said variable reference signal at a predetermined rate, and means responsive to the brake control signals for all of said braked wheels for modifying the rate of decay of said variable reference signal.