Tracking in haptic systems
Described herein are techniques for tracking objects (including human body parts such as a hand), namely: 1) two-state transducer interpolation in acoustic phased-arrays; 2) modulation techniques in acoustic phased-arrays; 3) fast acoustic full matrix capture during haptic effects; 4) time-of-flight depth sensor fusion system; 5) phase modulated spherical wave-fronts in acoustic phased-arrays; 6) long wavelength phase modulation of acoustic field for location and tracking; and 7) camera calibration through ultrasonic range sensing.
1. A method comprising:
using an acoustic transducer to track an object by repeated switching between a control point activation state and a plane wave activation state;
wherein the acoustic transducer contributes to formation of a control point during the control point activation state;
wherein the acoustic transducer projects in-phase pulsed signals during the plane wave activation state; and
wherein the control point activation state substantially complies with U f (t)=Asin( 2 πf c t+0+ϕ). wherein A is amplitude of the in-phased pulsed signals, f c is a center frequency, θ is a phase delay added to the in-phased pulsed signal to activate a control point, and ϕ is a phase shift modulation applied to the in-phased pulsed signal to achieve tracking.
2. The method of claim 1 , further comprising:
modulating the in-phased pulsed signals by interpolating arbitrary waveforms between the control point activation state and the plane wave activation state so as to substantially maximize amplitude at the control point.
3. The method of claim 2 , wherein the modulating is dynamically tailored to match a sensing objective and environment.
4. The method as in claim 3 , wherein the modulating assists detection distance of an object from the acoustic transducer and the control point.
5. The method as in claim 4 , wherein the modulating is phase modulation, and further comprising demodulation of the in-phased pulsed signal via determining frequency and phase of the interpolating arbitrary waveforms.
6. The method as in claim 4 , wherein the modulating is frequency modulation, and further comprising estimating time-of-flight via cross-correlation algorithms.
7. The method of claim 1 , wherein the plane wave activation state substantially complies with Up(t)=Asin( 2 πf c +ϕ), wherein A is an amplitude of the in-phased pulsed, f c is a center frequency, and ϕ is a phase shift modulation applied to the in-phased pulsed signal to achieve tracking.