Methods and systems for in-system estimation of actuator parameters

1. A method for estimating, in-situ and in real-time, actuator parameters for an actuator, the method comprising:

driving the actuator with a test signal imperceptible to a user of a device comprising the actuator during real-time operation of the device;

measuring a voltage and a current associated with the actuator and caused by the test signal;

determining one or more parameters of the actuator based on the voltage and the current;

determining an actuator type of the actuator based on the one or more parameters; and

controlling a playback signal to the actuator based on the actuator type.

2. The method of claim 1 , wherein the one or more parameters comprise mechanical impedance parameters of the actuator.

3. The method of claim 1 , wherein the one or more parameters comprise electrical impedance parameters of the actuator.

4. The method of claim 1 , wherein the test signal has a non-perceptible duration.

5. The method of claim 4 , wherein the non-perceptible duration is less than approximately 5 milliseconds.

6. The method of claim 1 , wherein the test signal has a non-perceptible amplitude.

7. The method of claim 6 , wherein the non-perceptible amplitude is between approximately 170 millivolts and approximately 130 millivolts.

8. The method of claim 1 , wherein the test signal has a frequency significantly different than a resonant frequency of the actuator.

9. The method of claim 1 , wherein measuring the current comprises measuring a sense voltage across terminals of a sense resistor in series with the actuator.

10. The method of claim 9 , further comprising operating the device in a plurality of modes comprising:

a characterization mode in which the sense resistor has a first resistance and in which the current is measured; and

an activation mode in which the sense resistor has a second resistance significantly smaller than the first resistance.

11. A system for estimating, in-situ and in real-time, actuator parameters for an actuator, the system comprising:

a test signal generator configured to generate a test signal imperceptible to a user of a device comprising the actuator in order to drive the actuator during real-time operation of the device; and

a measurement subsystem configured to:

measure a voltage and a current associated with the actuator and caused by the test signal;

determine one or more parameters of the actuator based on the voltage and the current;

determine an actuator type of the actuator based on the one or more parameters; and

control a playback signal to the actuator based on the actuator type.

12. The system of claim 11 , wherein the one or more parameters comprise mechanical impedance parameters of the actuator.

13. The system of claim 11 , wherein the one or more parameters comprise electrical impedance parameters of the actuator.

14. The system of claim 11 , wherein the test signal has a non-perceptible duration.

15. The system of claim 14 , wherein the non-perceptible duration is less than approximately 5 milliseconds.

16. The system of claim 11 , wherein the test signal has a non-perceptible amplitude.

17. The system of claim 16 , wherein the non-perceptible amplitude is between approximately 170 millivolts and approximately 130 millivolts.

18. The system of claim 11 , wherein the test signal has a frequency significantly different than a resonant frequency of the actuator.

19. The system of claim 11 , wherein measuring the current comprises measuring a sense voltage across terminals of a sense resistor in series with the actuator.

20. The system of claim 19 , the measurement system further configured to operate the device in a plurality of modes comprising:

a characterization mode in which the sense resistor has a first resistance and in which the current is measured; and

an activation mode in which the sense resistor has a second resistance significantly smaller than the first resistance.