SYSTEM AND METHOD FOR ACTUATOR CONTROL

• US 20130024013A1
• Filed: 06/26/2012
• Published: 01/24/2013
• Est. Priority Date: 07/21/2011
• Status: Active Grant

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: ABB Technology AG (ABB Limited)
• Inventors: Mullin, Francis P.
• Granted Patent: US 9,116,516 B2
• Time in Patent Office: Days
• US Class Current: 700/29
• CPC Class Codes: G05B 19/0428 Safety, monitoring G05B19/0423 takes precedence
• CPC Class Codes: G05B 2219/24033 Failure, fault detection and isolation

Abstract

Information from a real sensor and a virtual sensor are fused to form a hybrid sensor. Control signals (and/or the absolute value of the control signals) applied to an actuator are accumulated and converted to a position the actuator should be in based on the accumulated control signals to form the virtual sensor. The actuator position from the virtual sensor is fused with an actuator position from a real sensor to form the hybrid sensor. Small periodic corrections can be made to the accumulating control signals to maintain or achieve, if possible, correlation between the virtual sensor and the real sensor over time. The corrections slowly decrement errors in the actuator position indicated by the virtual sensor. Accumulating numerical errors in the accumulating control signals are reduced and the significance of long past events is de-emphasized by a forgetting factor (k_ff) used at defined periods of time (t_ff).

Claims

1. A system for actuator sensor fusion comprising:

at least one real sensor coupled to an actuator and generating real sensor signals;

at least one virtual sensor generating virtual sensor signals based on signals used to control the actuator; and

a processor for fusing said real sensor signals and said virtual sensor signals to detect failure of the actuator and/or said at least one real sensor.

2. A system for actuator sensor fusion as claimed in claim 1 wherein said processor is configured to revert to operation of the actuator using said at least one virtual sensor upon sensed failure of said at least one real sensor.

3. A system for actuator sensor fusion as claimed in claim 1 wherein said processor models said at least one virtual sensor and accumulates historical tracking data representative of control signals sent to the actuator.

4. A system for actuator sensor fusion as claimed in claim 1 wherein said processor is configured for fusing said real sensor signals and said virtual sensor signals by comparing a position of the actuator indicated by said real sensor signals and a position of the actuator indicated by said virtual sensor signals to determine a difference in indicated position of the actuator and to indicate a failure of the actuator and/or said at least one real sensor upon said difference in indicated position exceeding a difference limit.

5. A sensor for actuator sensor fusion as claimed in claim 1 wherein said processor is configured to accumulate periodic corrections made to said virtual sensor and compare said accumulated periodic corrections to a limit to determine deterioration of the actuator and/or said real sensor.

6. A sensor for actuator sensor fusion as claimed in claim 5 wherein said processor is configured to apply a forgetting factor (k_ff) at defined periods of time (t_ff) to said accumulating periodic corrections so that said accumulating periodic corrections are periodically reduced by a certain proportion of their current values.

7. A sensor for actuator sensor fusion as claimed in claim 5 wherein said processor is configured to accumulate absolute values of said periodic corrections made to said virtual sensor and compare said accumulated absolute values of said periodic corrections to a limit to determine deterioration of the actuator and/or said real sensor.

8. A sensor for actuator sensor fusion as claimed in claim 7 wherein said processor is configured to apply a forgetting factor (k_ff) at defined periods of time (t_ff) to said accumulating periodic corrections and to apply a forgetting factor (k_ff1) at defined periods of time (t_ff1) to said accumulating absolute values of said periodic corrections so that said accumulating periodic corrections and said accumulating absolute values of said periodic corrections are periodically reduced by certain proportions of their current values.

9. A sensor for actuator sensor fusion as claimed in claim 1 wherein said processor is configured to accumulate the absolute values of periodic corrections made to said virtual sensor and to compare said accumulated absolute values of said periodic corrections to a limit to determine deterioration of the actuator and/or said real sensor.

10. A sensor for actuator sensor fusion as claimed in claim 9 wherein said processor is configured to apply a forgetting factor (k_ff1) at defined periods of time (t_ff1) so that said accumulating absolute values of said periodic corrections are periodically reduced by a certain proportion of their current values.

20. A method for actuator sensor fusion as claimed in claim 9 further comprising applying, using a processor, a forgetting factor (k_ff1) at defined periods of time (t_ff1) so that said accumulating absolute values of said periodic corrections are periodically reduced by a certain proportion of their current values.

11. A method for actuator sensor fusion comprising:

monitoring, using a processor, at least one real sensor coupled to an actuator;

monitoring, using a processor, at least one virtual sensor; and

fusing, using a processor, real sensor signals generated by said real sensor and virtual sensor signals generated by said virtual sensor to detect failure of the actuator and/or said at least one real sensor.

12. A method for actuator sensor fusion as claimed in claim 11 further comprising reverting to operation of the actuator using said at least one virtual sensor upon sensed failure of said at least one real sensor.

13. A method for actuator sensor fusion as claimed in claim 11 further comprising:

modeling said at least one virtual sensor; and

accumulating historical tracking data representative of control signals sent to the actuator.

14. A method for actuator sensor fusion as claimed in claim 11 wherein fusing said real sensor signals and said virtual sensor signals comprises:

comparing a position of the actuator indicated by said real sensor signals and a position of the actuator indicated by said virtual sensor signals;

determining a difference in indicated position of the actuator; and

indicating a failure of the actuator and/or said at least one real sensor upon said difference in indicated position exceeding a difference limit.

15. A method for actuator sensor fusion as claimed in claim 11 further comprising:

accumulating periodic corrections made to the virtual sensor; and

comparing the accumulated periodic corrections to a limit to determine deterioration of the actuator and/or said at least one real sensor.

16. A method for actuator sensor fusion as claimed in claim 15 further comprising applying a forgetting factor (k_ff) at defined periods of time (t_ff) to said accumulating periodic corrections so that said accumulating periodic corrections are periodically reduced by a certain proportion of their current values.

17. A method for actuator sensor fusion as claimed in claim 15 further comprising:

accumulating the absolute magnitude of periodic corrections made to the virtual sensor; and

comparing the accumulated periodic corrections to a limit to determine deterioration of the actuator and/or said at least one real sensor.

18. A method for actuator sensor fusion as claimed in claim 17 further comprising:

applying, using a processor, a forgetting factor (k_ff) at defined periods of time (t_ff) to said accumulating periodic corrections; and

applying, using a processor, a forgetting factor (k_ff1) to said accumulating absolute values of said periodic corrections at defined periods of time (t_ff1) so that said accumulating periodic corrections and said accumulating absolute values of said periodic corrections are periodically reduced by certain proportions of their current values.

19. A method for actuator sensor fusion as claimed in claim 11 further comprising:

accumulating, using a processor, the absolute values of periodic corrections made to said virtual sensor; and

comparing said accumulated absolute values of said periodic corrections to a limit to determine deterioration of the actuator and/or said real sensor.