Patent ID: 8169404
Filing Date: 2012-05-01
Classification: G06F

Abstract:
1. A method for determining a presence of an object comprising: detecting a movement and location of an object within a sensory space by tracking ultrasonic signals directed to and reflected off the object; estimating a phase angle of received waveforms for each of three transmit and receive pair transducers generating the sensory space; saving a history of received ultrasonic waveforms reflected off the object to within a predetermined time range according to the phase angle; creating a three-dimensional volumetric surface from the phase angles for each of the transmit and receive pair transducers calculating therefrom a broad intersection region of the three-dimensional volumetric surfaces; in addition to the phase angle, estimating a phase difference between successively received ultrasonic waveforms in the history of the movement; evaluating the phase difference to less than a wavelength of the received ultrasonic signals where the phase angle of the ultrasonic waveforms is within the predetermined range, and constraining the location of the object to a particular point within the intersection of the three-dimensional volumetric surfaces from the phase difference; and, resolving the location of the object with approximately a positional accuracy of one millimeter in the sensory space.