Frequency-domain haptic waveform compensation for haptic transducers

Patent metadata

Field	Value
Publication number	US-11641546-B2
Application number	US-201916715261-A
Country	US
Kind code	B2
Filing date	Dec 16, 2019
Priority date	Jun 17, 2019
Publication date	May 2, 2023
Grant date	May 2, 2023

Abstract

A method for minimizing post-playback oscillation during playback of a haptic playback waveform to a haptic transducer may include determining whether a frequency response of the haptic playback waveform has a notch with a notch frequency at approximately a resonant frequency of the haptic transducer and, responsive to the notch frequency differing from the resonant frequency, modifying the haptic playback waveform for playback to the haptic transducer by shifting the notch frequency to approximately the resonant frequency.

First claim

What is claimed is:

1. A method for minimizing post-playback oscillation during playback of a haptic playback waveform to a haptic transducer, comprising:
determining whether a frequency response of the haptic playback waveform has a notch with a notch frequency at approximately a resonant frequency of the haptic transducer; and
responsive to the notch frequency differing from the resonant frequency, modifying the haptic playback waveform for playback to the haptic transducer by shifting the notch frequency to approximately the resonant frequency.

2. The method of claim 1 , further comprising, responsive to an absence of a notch in the frequency response of the haptic playback waveform, modifying the haptic playback waveform for playback to the haptic transducer by applying a notch filter at approximately the resonant frequency to the haptic playback waveform.

3. The method of claim 1 , further comprising responsive to the notch frequency being approximately equal to the resonant frequency, playing back the haptic playback waveform without modification to the haptic transducer.

4. The method of claim 1 , wherein the shifting of the notch frequency to approximately the resonant frequency comprises:
determining a time scaling factor as a ratio between the notch frequency and the resonant frequency; and
time scaling the haptic playback waveform by the time scaling factor, such that the haptic playback waveform as modified v T (t)=v R (ct), where v R (t) defines the haptic playback waveform without modification as a function of time, and c is the time scaling factor.

5. The method of claim 1 , wherein the shifting of the notch frequency to approximately the resonant frequency further comprises applying an amplitude compensation factor to compensate the haptic playback waveform as modified such that a depth of the resulting notch in the frequency response of the haptic playback waveform as modified is approximately equal to the depth of the notch in the frequency response of the haptic playback waveform prior to modification.

6. A system for minimizing post-playback oscillation during playback of a haptic playback waveform to a haptic transducer, comprising:
one or more inputs for receiving information regarding a resonant frequency of the haptic transducer; and
a processing subsystem configured to:
determine whether a frequency response of the haptic playback waveform has a notch with a notch frequency at approximately the resonant frequency of the haptic transducer; and
responsive to the notch frequency differing from the resonant frequency, modify the haptic playback waveform for playback to the haptic transducer by shifting the notch frequency to approximately the resonant frequency.

7. The system of claim 6 , the processing subsystem further configured to, responsive to an absence of a notch in the frequency response of the haptic playback waveform, modify the haptic playback waveform for playback to the haptic transducer by applying a notch filter at approximately the resonant frequency to the haptic playback waveform.

8. The system of claim 6 , the processing subsystem further configured to, responsive to the notch frequency being approximately equal to the resonant frequency, play back the haptic playback waveform without modification to the haptic transducer.

9. The system of claim 6 , wherein the shifting of the notch frequency to approximately the resonant frequency comprises:
determining a time scaling factor as a ratio between the notch frequency and the resonant frequency; and
time scaling the haptic playback waveform by the time scaling factor, such that the haptic playback waveform as modified v T (t)=v R (ct), where v R (t) defines the haptic playback waveform without modification as a function of time, and c is the time scaling factor.

10. The system of claim 9 , wherein the shifting of the notch frequency to approximately the resonant frequency further comprises applying an amplitude compensation factor to compensate the haptic playback waveform as modified such that a depth of the resulting notch in the frequency response of the haptic playback waveform as modified is approximately equal to the depth of the notch in the frequency response of the haptic playback waveform prior to modification.

11. A mobile device, comprising:
a haptic transducer; and
a haptic control subsystem configured to:
determine whether a frequency response of a haptic playback waveform has a notch with a notch frequency at approximately the resonant frequency of the haptic transducer; and
responsive to the notch frequency differing from the resonant frequency, modify the haptic playback waveform for playback to the haptic transducer by shifting the notch frequency to approximately the resonant frequency.

12. The mobile device of claim 11 , the haptic control subsystem further configured to, responsive to an absence of a notch in the frequency response of the haptic playback waveform, modify the haptic playback waveform for playback to the haptic transducer by applying a notch filter at approximately the resonant frequency to the haptic playback waveform.

13. The mobile device of claim 11 , the haptic control subsystem further configured to, responsive to the notch frequency being approximately equal to the resonant frequency, play back the haptic playback waveform without modification to the haptic transducer.

14. The mobile device of claim 11 , wherein the shifting of the notch frequency to approximately the resonant frequency comprises:
determining a time scaling factor as a ratio between the notch frequency and the resonant frequency; and
time scaling the haptic playback waveform by the time scaling factor, such that the haptic playback waveform as modified v T (t)=v R (ct), where v R (t) defines the haptic playback waveform without modification as a function of time, and c is the time scaling factor.

15. The mobile device of claim 14 , wherein the shifting of the notch frequency to approximately the resonant frequency further comprises applying an amplitude compensation factor to compensate the haptic playback waveform as modified such that a depth of the resulting notch in the frequency response of the haptic playback waveform as modified is approximately equal to the depth of the notch in the frequency response of the haptic playback waveform prior to modification.

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Chang Kok Chin
• Janko Marco
• Wilkinson Kyle

Classifications

• G06F3/016 Primary

  Input arrangements with force or tactile feedback as computer generated output to the user · CPC title

• H04R3/04 Primary

  for correcting frequency response · CPC title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title