Vehicle automatic transmission control system

• US 5,079,704 A
• Filed: 11/20/1989
• Issued: 01/07/1992
• Est. Priority Date: 11/18/1988
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Matsui, Hiroki, Yamamoto, Masataka, Sakai, Ichiro, Arai, Yasuhisa
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/439,933
• Time in Patent Office: 778 Days
• Field of Search: 364/424.01, 364/424.1, 364/426.01, 364/426.04, 364/148, 364/164, 364/513, 74/866, 180/170
• US Class Current: 701/57
• CPC Class Codes: B60W 2050/0057 Frequency analysis, spectral techniques or transforms
• CPC Class Codes: F16H 2059/142 of driving resistance calculated from weight, slope, or the like
• CPC Class Codes: F16H 2061/0081 Fuzzy logic
• CPC Class Codes: F16H 61/0213 characterised by the method for generating shift signals
• CPC Class Codes: F16H 61/682 with interruption of drive
• CPC Class Codes: Y10S 706/90 Fuzzy logic

Abstract

A system for controlling automatic, multi-step or continuously variable, transmission equipped with a motor vehicle utilizing fuzzy logic. In the system, fuzzy production rules have been prepared based upon an expert driver'"'"'s judgments and operation made on a vehicle with a manually shifted transmission. Various operating conditions including opening degree of a throttle valve and road speed of the vehicle are detected and from the detected value, various predictions are made such as an appropriateness of vehicle response determined from the reserve motive force with respect to a gear ratio shift intended by the driver and engine output change that would occur should the transmission be shifted to the gear ratio. These measured or estimated value are put on a common scale named universe of discourse and membership values of the rules are sucessively calculated. Among the rules, one rule is finally selected and according to the gear ratio indicated in the selected rule, the current gear ratio is shifted up or down or is held at the present ratio. Similarly, the speed ratio in the continuously variable transmission is determined from the selected rule.

Claims

1. A system for controlling a continuously variable transmission of a vehicle, comprising:

control means for receiving outputs of a throttle position sensor, crankshaft angle sensor, and vehicle speed sensor as operating condition inputs to determine detected values for various operating conditions of the vehicle including engine speed, degree of throttle opening, vehicle speed, and current speed ratio, said control means further comprising a

means for calculating and obtaining calculated values for change in throttle opening degree, acceleration, driving resistance and motive force to be generated at full throttle opening at speed ratios to which it is possible to shift to from the current speed ratio, to obtain a calculated value for change in the reserve motive force which would occur upon shifting to each of said speed ratios,

means for establishing a membership function of a fuzzy set for each of a plurality of parameters from said detected values and calculated values in accordance with a plurality of predetermined fuzzy production rules defining a plurality of respective conclusions expressed in terms of speed ratio change, and

means for carrying out fuzzy reasoning based on the fuzzy production rules to determine said respective conclusions and to determine a command value for speed ratio change based on the conclusions; and

actuator means for actuating a speed ratio change mechanism in response to the determined command value to change said current speed ratio.

2. A system according to claim 1, wherein said speed ratio change is a coefficient which is to be multiplied to said speed ratio.

3. A system according to claim 1, wherein said driving resistance is calculated back from the law of motion such that the driving resistance is the difference between the force and the product of vehicle mass and the change in the vehicle speed.

4. A system according to claim 3, wherein said driving resistance is calculated based on a value expressed in terms of vehicle output torque exerted on a vehicle axle.

5. A system according to claim 4, wherein said vehicle output torque is calculated by averaging the torque generated for a predetermined period.

6. A system according to claim 4, wherein said vehicle output torque is adjusted by a slip factor existing between an input shaft rotation of the transmission and an output shaft rotation thereof.

7. A system according to claim 4, wherein said driving resistance calculation is interrupted when the vehicle is braking.

8. A system according to claim 7, wherein said driving resistance calculation is interrupted for a predetermined period after the vehicle braking has ceased

9. A system according to claim 8, wherein said driving resistance is set to be a predetermined value when the calculation is interrupted.

10. A system according to claims 7 or 8, wherein said reserve motive force is set to be a predetermined value when the calculation is interrupted.

11. A system according to claim 4, wherein said driving resistance calculation is interrupted when said change in the throttle degree exceeds a reference value.

12. A system according to claim 11, wherein said driving resistance calculation is interrupted for a predetermined period after an excess in the change in throttle opening degree has ceased.

13. A system according to claim 11 or 12, wherein said driving resistance is set to be a predetermined value when the calculation is interrupted.

14. A system according to claim 13, wherein said predetermined value is the driving resistance calculated at a time prior to when said change in the throttle opening degree has exceeded said reference value.

15. A system according to claim 14, wherein said driving resistance is adjusted by a factor corresponding to the inertia resistance.

16. A system according to claim 15, wherein said driving resistance is adjusted by the factor which is determined with respect to a magnitude of the change in the vehicle speed.

17. A system according to claim 1, wherein said reserve motive force is used for determining upshifting.

18. A system according to claim 1, wherein said control means further obtains calculated values, with respect to speed ratios to which is possible to shift to from the current speed ratio, a ratio between change in engine output power estimated to be desired by a drive and that estimated to be actually generated, which would occur upon shifting to each of said speed ratios.

19. A system according to claim 17, wherein said calculated ratios are used for determining downshifting.

20. A system according to claim 1, wherein said control means further calculates, with respect to speed ratios to which it is possible to shift to from the current speed ratio, change in said engine speed which would occur upon shifting to each of said speed ratios.

21. A system according to claim 20, wherein said calculated values are used for determining upshifting and downshifting.

22. A system according to claim 1, wherein said control means determines the speed ratio to be shifted to by selecting one of a plurality of speed ratio shift rules based on at least one among the detected and calculated values.

23. A system according to claim 22, wherein said rule selection is carried out by calculating a membership value of the detected or calculated values.

24. A system according to claim 22, wherein said rules are established on the basis of an analysis of judgments and feelings of a driver of a vehicle with a manually shifted transmission.

25. A system according to claim 23, wherein said membership value is compared with a prescribed value and if the membership value is found to be not larger than the prescribed value, the selection of the rule is canceled.

26. A system according to claim 22, wherein said rules include a rule whose membership function complements that of another.

27. A method for controlling a continuously variable transmission of a vehicle, comprising the steps of:

determining detected values for vehicle operating conditions including degree of throttle opening, engine speed, vehicle speed, and current speed ratio;

determining whether braking is in progress;

calculating calculated values for vehicle acceleration, change in degree of throttle opening, driving resistance, motive force to be generated at speed ratios to which it is possible to shift to from the current speed ratio, and change in the reserve motive force which would occur upon shifting to each of said speed ratios;

substituting a predetermined value for said driving resistance when braking is in progress;

establishing a membership function of a fuzzy set for each of a plurality of parameters from said detected and calculated values in accordance with a plurality of predetermined fuzzy production rules defining a plurality of respective conclusions expressed in terms of speed ratio change;

carrying out fuzzy reasoning based on the fuzzy production rules to determine said respective conclusions and to determine a command value for speed ratio change based on the conclusions; and

changing said current speed ratio in response to the determined command value to change said current speed ratio.

28. A system for controlling a continuously variable transmission of a vehicle, comprising:

control means for receiving outputs of a throttle position sensor, crankshaft angle sensor, brake switch and vehicle speed sensor as operating condition inputs, to determine when braking is in progress and detected values for various operating conditions of the vehicle including engine speed, degree of throttle opening, vehicle speed, and current speed ration, said control means further comprising

means for calculating and obtaining calculated values for change in throttle opening degree, acceleration, driving resistance and motive force to be generated at speed ratios to which it is possible to shift to from the current speed ration, to obtain a calculated value for change in the reserve motive force which would occur upon shifting to each of said speed ratios,

means for establishing a membership function of a fuzzy set for each of a plurality of parameters from said detected values and calculated values in accordance with a plurality of predetermined fuzzy production rules defining a plurality of respective conclusions expressed in terms of speed ratio change, and

means for carrying out fuzzy reasoning based on the fuzzy production rules to determine said respective conclusions and to determine a command value for speed ratio change based on the conclusions; and

actuator means for actuating a speed ratio change mechanism in response to the determined command value to change said current speed ratio.