Eccentric rotating mass actuator optimization for haptic effects

1. A method of generating a haptic effect using an Eccentric Rotating Mass (ERM) actuator, the method comprising:

determining a back electromotive force (EMF) of the ERM actuator;

receiving a haptic effect signal comprising one or more parameters, wherein one of the parameters is a voltage amplitude level as a function of time;

varying the voltage amplitude level based at least on the back EMF; and

applying the varied haptic effect signal to the ERM actuator.

2. The method of claim 1 , further comprising:

determining a rise time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the rise time.

3. The method of claim 1 , further comprising:

determining a brake time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the brake time.

4. The method of claim 1 , wherein the voltage amplitude level comprises an overdrive voltage.

5. The method of claim 1 , wherein the varied haptic effect signal is applied to the ERM actuator when the ERM actuator is operated in a haptically enabled device, and the back EMF is determined before the ERM actuator is placed in the haptically enabled device.

6. The method of claim 1 , wherein the varied haptic effect signal is applied to the ERM actuator when the ERM actuator is operated in a haptically enabled device, and the back EMF is determined while the ERM actuator is operated in the haptically enabled device.

7. The method of claim 1 , further comprising:

determining a relationship of an angular speed and the back EMF for the ERM actuator; and

varying the voltage amplitude level based at least on the relationship.

8. The method of claim 1 , further comprising:

using the back EMF to determine if the actuator is spinning.

9. A computer readable medium having instructions stored thereon that, when executed by a processor, cause the processor to generate a haptic effect using an Eccentric Rotating Mass (ERM) actuator, the generating comprising:

determining a back electromotive force (EMF) of the ERM actuator;

receiving a haptic effect signal comprising one or more parameters, wherein one of the parameters is a voltage amplitude level as a function of time;

varying the voltage amplitude level based at least on the back EMF; and

applying the varied haptic effect signal to the ERM actuator.

10. The computer readable medium of claim 9 , the generating further comprising:

determining a rise time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the rise time.

11. The computer readable medium of claim 9 , the generating further comprising:

determining a brake time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the brake time.

12. The computer readable medium of claim 9 , wherein the voltage amplitude level comprises an overdrive voltage.

13. The computer readable medium of claim 9 , wherein the varied haptic effect signal is applied to the ERM actuator when the ERM actuator is operated in a haptically enabled device, and the back EMF is determined before the ERM actuator is placed in the haptically enabled device.

14. The computer readable medium of claim 9 , wherein the varied haptic effect signal is applied to the ERM actuator when the ERM actuator is operated in a haptically enabled device, and the back EMF is determined while the ERM actuator is operated in the haptically enabled device.

15. The computer readable medium of claim 9 , the generating further comprising:

determining a relationship of an angular speed and the back EMF for the ERM actuator; and

varying the voltage amplitude level based at least on the relationship.

16. The computer readable medium of claim 9 , the generating further comprising:

using the back EMF to determine if the actuator is spinning.

17. A haptically enabled system comprising:

an Eccentric Rotating Mass (ERM) actuator; and

a controller coupled to the ERM actuator, wherein the controller receives a back electromotive force (EMF) of the ERM actuator, and receives a haptic effect signal comprising one or more parameters, wherein one of the parameters is a voltage amplitude level as a function of time;

the controller varying the voltage amplitude level based at least on the back EMF; and

the controller applying the varied haptic effect signal to the ERM actuator.

18. The haptically enabled system of claim 17 , the controller further:

determining a rise time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the rise time.

19. The haptically enabled system of claim 17 , the controller further comprising:

determining a brake time of the ERM actuator using the back EMF; and

varying the voltage amplitude level based at least on the brake time.

20. The haptically enabled system of claim 17 , wherein the voltage amplitude level comprises an overdrive voltage.

21. The haptically enabled system of claim 17 , wherein the varied haptic effect signal is applied to the ERM actuator, and the back EMF is determined before the ERM actuator is placed in the haptically enabled system.

22. The haptically enabled system of claim 17 , wherein the varied haptic effect signal is applied to the ERM actuator, and the back EMF is determined while the ERM actuator is operated in the haptically enabled system.

23. The haptically enabled system of claim 17 , the controller further:

determining a relationship of an angular speed and the back EMF for the ERM actuator; and

varying the voltage amplitude level based at least on the relationship.

24. The haptically enabled system of claim 17 , the controller further:

using the back EMF to determine if the actuator is spinning.