Adaptive linear resonance actuator controller

Patent metadata

Field	Value
Publication number	US-9800191-B2
Application number	US-201414502493-A
Country	US
Kind code	B2
Filing date	Sep 30, 2014
Priority date	Nov 19, 2013
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A system includes a controller to control movement of a linear resonant actuator (LRA). The system includes a monitor in the controller to monitor a back electromotive force (BEMF) signal from the LRA representing the movement of the LRA. The monitor generates an indicator that indicates whether or not movement of the LRA has occurred. A primary loop module in the controller controls acceleration and braking of the LRA based on the monitored BEMF signal if the indicator from the monitor indicates that LRA movement has occurred. An alternate cycle module in the controller pushes the LRA at a predetermined frequency if the indicator from the monitor indicates that LRA movement has not occurred. The push is employed to move the LRA when the BEMF signal is undetectable by the monitor with respect to a predetermined threshold.

First claim

What is claimed is:

1. A system comprising:
a monitor coupled to detect a back electromotive force (BEMF) signal from a linear resonant actuator (LRA), the BEMF signal representing movement of the LRA, wherein the monitor is coupled to generate an indicator to: indicate that LRA movement has occurred, in response to the BEMF signal being detectable by the monitor with respect to a predetermined threshold; and indicate that LRA movement has not occurred, in response to the BEMF signal being undetectable by the monitor with respect to the predetermined threshold;
a primary loop module coupled to control acceleration and braking of the LRA in a closed loop based on the detected BEMF signal, in response to the indicator from the monitor indicating that LRA movement has occurred; and
an alternate cycle module coupled to push the LRA in an open loop at a predetermined frequency, in response to the indicator from the monitor indicating that LRA movement has not occurred, wherein the push includes both: a first push to push the LRA in a first direction; and, after the first push, a second push to push the LRA in a second direction opposite the first direction.

2. The system of claim 1 , wherein the monitor is coupled to determine a direction and movement of the LRA based on zero crossings of the BEMF signal.

3. The system of claim 2 , wherein the monitor is coupled to analyze a low limit threshold and a high limit threshold with respect to the BEMF signal to provide a noise margin for detecting the zero crossings of the BEMF signal.

4. The system of claim 1 , wherein the monitor includes a counter to determine that LRA movement has not occurred, in response to the counter reaching a predetermined threshold number of missed zero crossing events.

5. The system of claim 1 , wherein the first push is to push the LRA in the first direction during a drive time, and the second push is to push the LRA in the second direction immediately after the drive time.

6. The system of claim 1 , wherein the first push is to push the LRA in the first direction during a drive time, and the second push is to push the LRA in the second direction following a predetermined waiting period after the drive time.

7. The system of claim 1 , wherein the predetermined frequency is a resonant frequency of the LRA.

8. The system of claim 1 , wherein the BEMF signal is undetectable by the monitor with respect to the predetermined threshold, in response to at least one of: the LRA being frozen due to temperature; and high noise conditions negating zero crossing detection of the LRA.

9. A method comprising:
detecting, by a monitor, a back electromotive force (BEMF) signal from a linear resonant actuator (LRA), the BEMF signal representing movement of the LRA;
determining that LRA movement has occurred, in response to the BEMF signal being detectable by the monitor with respect to a predetermined threshold;
determining that LRA movement has not occurred, in response to the BEMF signal being undetectable by the monitor with respect to the predetermined threshold;
controlling acceleration and braking of the LRA in a closed loop based on the detected BEMF signal, in response to determining that LRA movement has occurred; and
pushing the LRA in an open loop at a predetermined frequency, in response to determining that LRA movement has not occurred, wherein the pushing includes both: a first push to push the LRA in a first direction; and, after the first push, a second push to push the LRA in a second direction opposite the first direction.

10. The method of claim 9 , further comprising:
determining a direction and movement of the LRA based on zero crossings of the BEMF signal.

11. The method of claim 10 , further comprising:
analyzing a low limit threshold and a high limit threshold with respect to the BEMF signal to provide a noise margin for detecting the zero crossings of the BEMF signal.

12. The method of claim 9 , wherein the first push is to push the LRA in the first direction during a drive time, and the second push is to push the LRA in the second direction immediately after the drive time.

13. The method of claim 9 , wherein the first push is to push the LRA in the first direction during a drive time, and the second push is to push the LRA in the second direction following a predetermined waiting period after the drive time.

14. The method of claim 9 , wherein determining that LRA movement has not occurred comprises:
determining that LRA movement has not occurred, in response to counting a predetermined threshold number of missed zero crossing events.

15. The method of claim 9 , wherein the first push and the second push have different drive times.

16. The method of claim 9 , further comprising initiating a resonant push command or a resonant brake command to the LRA based on an error signal.

17. The method of claim 9 , wherein the predetermined frequency is a resonant frequency of the LRA.

18. An integrated circuit, comprising:
a monitor coupled to detect a back electromotive force (BEMF) signal from a linear resonant actuator (LRA), the BEMF signal representing movement of the LRA, wherein the monitor is coupled to generate an indicator to: indicate that LRA movement has occurred, in response to the BEMF signal being detectable by the monitor with respect to a predetermined threshold; and indicate that LRA movement has not occurred, in response to the BEMF signal being undetectable by the monitor with respect to the predetermined threshold;
a controller to generate an output signal to accelerate or brake the LRA;
a primary loop module coupled to command the controller to control acceleration and braking of the LRA in a closed loop based on the detected BEMF signal, in response to the indicator from the monitor indicating that LRA movement has occurred; and
an alternate cycle module coupled to command the controller to push the LRA in an open loop at a predetermined frequency, in response to the indicator from the monitor indicating that LRA movement has not occurred, wherein the push includes both: a first push to push the LRA in a first direction; and, after the first push, a second push to push the LRA in a second direction opposite the first direction.

19. The integrated circuit of claim 18 , wherein the controller includes at least one of: the primary loop module; and the alternate cycle module.

20. The integrated circuit of claim 18 , wherein the monitor includes a counter to determine that LRA movement has not occurred, in response to the counter reaching a predetermined threshold number of missed zero crossing events.

Assignees

• Texas Instruments Inc

Inventors

• Barsilai Mandy
• Hernandez David

Classifications

• H02P25/06

  Linear motors · CPC title

• H02P25/032 Primary

  Reciprocating, oscillating or vibrating motors · CPC title

• H02P6/182

  using back-emf in windings · CPC title

• H02P25/027 Primary

  Electricity · mapped topic