Haptic effects from focused acoustic fields
To resolve an issue related to the calibration of optical cameras in transducer-based mid-air haptic systems, the magnification of the motion induced on an optical camera by an acoustic field modulated at specific frequencies reveals very small temporal variations in video frames. This quantized distortion is used to compare different acoustic fields and to solve the calibration problem in an automatized manner. Further, mechanical resonators may be excited by ultrasound when it is modulated at the resonant frequency. When enough energy is transferred and when operating at the correct frequency, a user in contact with the device can feel vibration near areas of largest displacement. This effect can be exploited to create devices which can produce haptic feedback while not carrying a battery or exciter when in the presence of an ultrasonic source.
1. A method comprising:
scanning a focused acoustic field through space from an acoustic source until the focused acoustic field impinges upon an element of a camera with sufficient amplitude to cause vibration of the camera to a detectable level; and
estimating a relative location of the camera to the acoustic source based on the vibration of the camera.
2. The method as in claim 1 , further comprising:
detecting a camera imager blur via a contrast detection algorithm.
3. The method as in claim 2 , wherein the contrast detection algorithm compares a standard camera image contrast with a vibrating camera image contrast.
4. The method as in claim 3 , wherein the contrast detection algorithm further comprises excluding regions with possible changes.
5. The method as in claim 3 , further comprising:
determining a focus produced by the acoustic source that maximizes camera displacement.
6. The method as in claim 3 , wherein the contrast detection algorithm further comprises spatial and temporal processing to amplify the camera imager blur.
7. The method as in claim 2 , wherein the focused acoustic field includes a modulated carrier wave.
8. The method as in claim 7 , wherein the modulated carrier wave is calibrated to obtain a desired frequency of camera vibration.
9. The method as in claim 1 , further comprising:
detecting camera motion via a motion magnification algorithm.
10. The method as in claim 9 , further comprising:
detecting a camera imager blur via a contrast detection algorithm.
11. The method as in claim 10 , wherein the contrast detection algorithm compares a standard camera image contrast with a vibrating camera image contrast.
12. The method as in claim 11 , wherein the contrast detection algorithm further comprises excluding regions with possible changes.
13. The method as in claim 11 , further comprising:
determining a focus produced by e acoustic source that maximizes camera displacement.
14. The method as in claim 11 , wherein the contrast detection algorithm further comprises spatial and temporal processing to amplify the camera imager blur.
15. The method as in claim 10 , wherein the focused acoustic field includes a modulated carrier wave.
16. The method as in claim 15 , wherein the modulated carrier wave is calibrated to obtain a desired frequency of camera vibration.