Detection and prevention of non-linear excursion in a haptic actuator

Patent metadata

Field	Value
Publication number	US-12159528-B2
Application number	US-202218080900-A
Country	US
Kind code	B2
Filing date	Dec 14, 2022
Priority date	Jan 25, 2022
Publication date	Dec 3, 2024
Grant date	Dec 3, 2024

Abstract

A method for determining and mitigating over-excursion of an internal mass of an electromechanical transducer may include measuring a sensed signal associated with the electromechanical transducer in response to a driving signal driven to the electromechanical transducer, determining a non-linearity value based on the sensed signal, mapping the non-linearity value to a probability of over-excursion of the internal mass, and applying a gain to a signal path configured to generate the driving signal based on the probability.

First claim

What is claimed is:

1. A method for determining and mitigating over-excursion of an internal mass of an electromechanical transducer, the method comprising:
measuring a sensed signal associated with the electromechanical transducer in response to a driving signal driven to the electromechanical transducer;
determining a non-linearity value based on the sensed signal;
mapping the non-linearity value to a probability of over-excursion of the internal mass; and
applying a gain to a signal path configured to generate the driving signal based on the probability.

2. The method of claim 1 , wherein determining the non-linearity value based on the sensed signal comprises determining a back-electromotive force associated with the electromechanical transducer based on the sensed signal.

3. The method of claim 1 , wherein determining the non-linearity value comprises:
determining a first content ratio equal to a ratio of content present in the driving signal in a first frequency band to content present in the driving signal in a second frequency band;
determining a second content ratio equal to a ratio of content present in the sensed signal in the first frequency band to content present in the second frequency band; and
determining the non-linearity value based on a comparison of the first content ratio and the second content ratio.

4. The method of claim 1 , wherein determining the non-linearity value comprises:
determining a first content ratio equal to a ratio of high-frequency content present in the driving signal above a particular frequency to low-frequency content present in the driving signal below the particular frequency;
determining a second content ratio equal to a ratio of high-frequency content present in the sensed signal above the particular frequency to low-frequency content present in the sensed signal below the particular frequency; and
determining the non-linearity value based on a comparison of the first content ratio and the second content ratio.

5. The method of claim 1 , wherein determining the non-linearity value comprises determining the non-linearity value based on noise gating of a magnitude of the driving signal compared to noise gating of a magnitude of the sensed signal.

6. The method of claim 1 , wherein determining the non-linearity value comprises:
generating the driving signal as a pilot tone at a frequency greater than a resonance frequency of electromechanical transducer;
measuring total harmonic distortion present in the sensed signal in response to the pilot tone; and
determining the non-linearity value based on the total harmonic distortion.

7. The method of claim 1 , further comprising attenuating the driving signal based on the gain.

8. The method of claim 1 , wherein:
determining the non-linearity value based on the sensed signal comprises measuring harmonic components of the sensed signal; and
the method further comprises determining an orientation of the electromagnetic transducer based on amplitude and phase of harmonic components of the sensed signal.

9. The method of claim 1 , wherein:
the driving signal is a voltage signal; and
the sensed signal is a current signal.

10. The method of claim 1 , wherein the electromagnetic transducer is one of a haptic transducer, a voice coil, and a loudspeaker.

11. A system for determining and mitigating over-excursion of an internal mass of an electromechanical transducer, the system comprising:
an input configured to measure a sensed signal associated with the electromechanical transducer in response to a driving signal driven to the electromechanical transducer; and
a non-linear excursion detector configured to:
determine a non-linearity value based on the sensed signal;
map the non-linearity value to a probability of over-excursion of the internal mass; and
apply a gain to a signal path configured to generate the driving signal based on the probability.

12. The system of claim 11 , wherein determining the non-linearity value based on the sensed signal comprises determining a back-electromotive force associated with the electromechanical transducer based on the sensed signal.

13. The system of claim 11 , wherein determining the non-linearity value comprises:
determining a first content ratio equal to a ratio of content present in the driving signal in a first frequency band to content present in the driving signal in a second frequency band;
determining a second content ratio equal to a ratio of content present in the sensed signal in the first frequency band to content present in the second frequency band; and
determining the non-linearity value based on a comparison of the first content ratio and the second content ratio.

14. The system of claim 11 , wherein determining the non-linearity value comprises:
determining a first content ratio equal to a ratio of high-frequency content present in the driving signal above a particular frequency to low-frequency content present in the driving signal below the particular frequency;
determining a second content ratio equal to a ratio of high-frequency content present in the sensed signal above the particular frequency to low-frequency content present in the sensed signal below the particular frequency; and
determining the non-linearity value based on a comparison of the first content ratio and the second content ratio.

15. The system of claim 11 , wherein determining the non-linearity value comprises determining the non-linearity value based on noise gating of a magnitude of the driving signal compared to noise gating of a magnitude of the sensed signal.

16. The system of claim 11 , wherein determining the non-linearity value comprises:
generating the driving signal as a pilot tone at a frequency greater than a resonance frequency of electromechanical transducer;
measuring total harmonic distortion present in the sensed signal in response to the pilot tone; and
determining the non-linearity value based on the total harmonic distortion.

17. The system of claim 11 , wherein the non-linear excursion detector is further configured to attenuate the driving signal based on the gain.

18. The system of claim 11 , wherein:
determining the non-linearity value based on the sensed signal comprises measuring harmonic components of the sensed signal; and
the method further comprises determining an orientation of the electromagnetic transducer based on amplitude and phase of harmonic components of the sensed signal.

19. The system of claim 11 , wherein:
the driving signal is a voltage signal; and
the sensed signal is a current signal.

20. The system of claim 11 , wherein the electromagnetic transducer is one of a haptic transducer, a voice coil, and a loudspeaker.

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Janko Marco A
• Rossi Filippo
• Sepehr Hamid
• Wilkinson Kyle
• Marchais Emmanuel A
• Konradi Vadim
• Lal Anil
• Khenkin Aleksey S
• Yong Chin Huang

Classifications

• B06B2201/53

  with vibrating magnet or coil · CPC title

• G08B6/00 Primary

  Tactile signalling systems, e.g. tactile personal calling systems · CPC title

• B06B1/045 Primary

  using vibrating magnet, armature or coil system · CPC title