Servo Controller and control method using the same

• US 20070185594A1
• Filed: 06/26/2006
• Published: 08/09/2007
• Est. Priority Date: 06/27/2005
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Kataoka, Hiroaki, Iwazaki, Katsuhiko, Rattapon, Chumsamutr, Kawakami, Seiji
• Granted Patent: US 7,477,951 B2
• Time in Patent Office: Days
• US Class Current: 700/42
• CPC Class Codes: B62D 1/28 non-mechanical , e.g. following a line or other known markers
• CPC Class Codes: B62D 15/025 Active steering aids, e.g. helping the driver by actively influencing the steering system after environment evaluation B62D1/28 takes precedence
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.

Abstract

When an integral calculation of a physical quantity representing a state of a controlled system is performed, two integral calculations, that is, a positive-integral calculation and a negative-integral calculation are performed. In this way, differentiated information can be obtained, depending on the control conditions. A selection of which one of the integral value obtained by the positive-integral calculation and the integral value obtained by the negative-integral calculation is used, is made on the basis of an actual control value and a desired control value when control is performed so that a value representing the state of the controlled system becomes equal to the desired control value. In this way, a control parameter which has been judged to include a phase delay is removed. Thus, the phase delay in the overall control can be suppressed, and an appropriate steering assist control can be performed, for example.

Claims

1. A servo controller which repeatedly performs a predetermined control process, and controls a state of a controlled system on the basis of a result of performing the control process, comprising:

a detector for detecting the state of the controlled system; and

a control unit which performs

a positive-integral calculation in which an integral calculation of a physical quantity representing the state of the controlled system detected by the detector is performed, and in which, when a resulting integral value is positive, the integral calculation is continued, and

a negative-integral calculation in which an integral calculation of the physical quantity representing the state of the controlled system detected by the detector is performed, and in which, when a resulting integral value is negative, the integral calculation is continued, and

a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that a value representing the state of the controlled system becomes equal to a desired control value, wherein

the control unit performs control so that the value representing the state of the controlled system becomes equal to the desired control value, using one of the positive-integral calculation and the negative-integral calculation, which has been selected.

2. The servo controller according to claim 1, wherein

the control unit makes a selection of which one of the positive-integral calculation and the negative-integral calculation is used, on the basis of an actual control value and the desired control value.

3. The servo controller according to claim 2, wherein

the control unit selects the positive-integral calculation when a difference between the actual control value and the desired control value is larger than a predetermined positive threshold value, or selects the negative-integral calculation when the difference is less than a predetermined negative threshold value.

4. The servo controller according to claim 3, wherein

the control unit resets the integral value calculated by the positive-integral calculation to zero when the sign of the integral value calculated by the positive-integral calculation is negative, and resets the integral value calculated by the negative-integral calculation to zero when the sign of the integral value calculated by the negative-integral calculation is positive.

5. The servo controller according to claim 4, wherein

the control unit resets integral value calculated by the negative-integral calculation to zero when the difference is larger than the positive threshold value, and resets the integral value calculated by the positive-integral calculation to zero when the difference is less than the negative threshold value.

6. A servo controller for assisting steering operation of a vehicle so that the vehicle travels keeping a predetermined position in a travel lane, comprising:

a detector for detecting an offset, which is a deviation of a position of the vehicle from a desired position in a travel lane; and

a control unit which performs

a positive-integral calculation in which an integral calculation of the offset detected by the detector is performed, and in which, when a resulting offset integral value is positive, the integral calculation is continued, and

a negative-integral calculation in which an integral calculation of the offset detected by the detector is performed, and in which, when a resulting offset integral value is negative, the integral calculation is continued, and

a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that the position of the vehicle in the travel lane coincides with the desired position, wherein

the control unit performs control so that the position of the vehicle in the travel lane coincides with the desired position, using one of the positive-integral calculation and the negative-integral calculation, which has been selected.

7. The servo controller according to claim 6, wherein

the control unit makes a selection of which one of the positive-integral calculation and the negative-integral calculation is used, on the basis of the position of the vehicle in the travel lane and the desired position.

8. The servo controller according to claim 7, wherein

the control unit selects the positive-integral calculation when a difference between the position of the vehicle in the travel lane and the desired position is larger than a predetermined positive threshold value, or selects the negative-integral calculation when the difference is less than a predetermined negative threshold value.

9. The servo controller according to claim 8, wherein

the control unit resets the offset integral value calculated by the positive-integral calculation to zero when the sign of the offset integral value calculated by the positive-integral calculation is negative, and resets the offset integral value calculated by the negative-integral calculation to zero when the sign of the offset integral value calculated by the negative-integral calculation is positive.

10. The servo controller according to claim 9, wherein

the control unit resets the offset integral value calculated by the negative-integral calculation to zero when the difference is larger than the positive threshold value, and resets the offset integral value calculated by the positive-integral calculation to zero when the difference is less than the negative threshold value.

11. A control method using a servo controller which repeatedly performs a predetermined control process, and controls a state of a controlled system on the basis of a result of performing the control process, comprising the steps of:

detecting the state of the controlled system;

performing a positive-integral calculation in which performed is an integral calculation of a physical quantity representing the state of the controlled system detected, and, when a resulting integral value is positive, the integral calculation is continued;

performing a negative-integral calculation in which performed is an integral calculation of the physical quantity representing the state of the controlled system detected, and, when a resulting integral value is negative, the integral calculation is continued;

making a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that a value representing the state of the controlled system becomes equal to a desired control value; and

performing control so that the value representing the state of the controlled system becomes equal to the desired control value, using one of the integral calculations, which has been selected.

12. The control method according to claim 11, further comprising the step of:

making a selection of which one of the positive-integral calculation and the negative-integral calculation is used, on the basis of an actual control value and the desired control value.

13. The control method according to claim 12, further comprising the steps of:

selecting the positive-integral calculation when a difference between the actual control value and the desired control value is larger than a predetermined positive threshold value; and

selecting the negative-integral calculation when the difference is less than a predetermined negative threshold value.

14. The control method according to claim 13, further comprising the steps of:

resetting the integral value calculated by the positive-integral calculation to zero when the sign of the integral value calculated by the positive-integral calculation is negative; and

resetting the integral value calculated by the negative-integral calculation to zero when the sign of the integral value calculated by the negative-integral calculation is positive.

15. The control method according to claim 14, further comprising the steps of:

resetting the integral value calculated by the negative-integral calculation to zero when the difference is larger than the positive threshold value; and

resetting the integral value calculated by the positive-integral calculation to zero when the difference is less than the negative threshold value.

16. A control method using a servo controller for assisting steering operation of a vehicle so that the vehicle travels keeping a predetermined position in a travel lane, comprising the steps of:

detecting an offset, which is a deviation of a position of the vehicle from a desired position in the travel lane;

performing a positive-integral calculation in which an integral calculation of the offset detected is performed, and in which, when a resulting offset integral value is positive, the integral calculation is continued;

performing a negative-integral calculation in which an integral calculation of the offset detected is performed, and in which, when a resulting offset integral value is negative, the integral calculation is continued;

making a selection of which one of the positive-integral calculation and the negative-integral calculation is used when control is performed so that the position of the vehicle in the travel lane coincides with the desired position; and

performing control so that the position of the vehicle in the travel lane coincides with the desired position, using one of the positive-integral calculation and the negative-integral calculation, which has been selected.

17. The control method according to claim 16, further comprising the step of:

making a selection of which one of the positive-integral calculation and the negative-integral calculation is used, on the basis of the position of the vehicle in the travel lane and the desired position.

18. The control method according to claim 17, further comprising the steps of:

selecting the positive-integral calculation when a difference between the position of the vehicle in the travel lane and the desired position is larger than a predetermined positive threshold value; and

selecting the negative-integral calculation when the difference is less than a predetermined negative threshold value.

19. The control method according to claim 18, further comprising the steps of:

resetting the offset integral value calculated by the positive-integral calculation to zero when the sign of the offset integral value calculated by the positive-integral calculation is negative; and

resetting the offset integral value calculated by the negative-integral calculation to zero when the sign of the offset integral value calculated by the negative-integral calculation is positive.

20. The control method according to claim 19, further comprising the steps of:

resetting the offset integral value calculated by the negative-integral calculation to zero when the difference is larger than the positive threshold value; and

resetting the offset integral value calculated by the positive-integral calculation to zero when the difference is less than the negative threshold value.