Inertial orientation tracker having automatic drift compensation for tracking human head and other similarly sized body
First Claim
1. An apparatus to be attached to a body having a size between the sizes of a human finger and a human torso, said body having an orientation relative to an external reference frame, said apparatus generating an orientation signal that corresponds to at least two degrees of freedom of said orientation of said body said apparatus comprising:
- a. three self contained angular rate sensors arranged to span three space that generate first sensor signals that correspond to rotational rates of said body with respect to at least two degrees of freedom of said body, said first sensor signals being impervious to any interference from electromagnetic, acoustic, optical and mechanical sources;
b. a mechanism for mounting said sensor to said body; and
c. coupled to said sensor, a signal processor that comprises an integrator that integrates said rotational rate signals with respect to time and generates an orientation signal that corresponds to said at least two degrees of freedom and;
d. a drift compensator, coupled to said angular rate sensor and said integrator, that compensates for any drift with respect to time in said rotational orientation signal, said drift compensator comprising at least one sensor being selected from the group consisting of;
an optical sensor, a radio frequency (RF) sensor and an acoustic sensor.
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Accused Products
Abstract
A self contained sensor apparatus generates a signal that corresponds to at least two of the three orientational aspects of yaw, pitch and roll of a human-scale body, relative to an external reference frame. A sensor generates first sensor signals that correspond to rotational accelerations or rates of the body about certain body axes. The sensor may be mounted to the body. Coupled to the sensor is a signal processor for generating orientation signals relative to the external reference frame that correspond to the angular rate or acceleration signals. The first sensor signals are impervious to interference from electromagnetic, acoustic, optical and mechanical sources. The sensors may be rate sensors. An integrator may integrate the rate signal over time. A drift compensator is coupled to the rate sensors and the integrator. The drift compensator may include a gravitational tilt sensor or a magnetic field sensor or both. A verifier periodically measures the orientation of the body by a means different from the drift sensitive rate sensors. The verifier may take into account characteristic features of human motion, such as stillness periods. The drift compensator may be, in part, a Kalman filter, which may utilize statistical data about human head motion.
242 Citations
4 Claims
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1. An apparatus to be attached to a body having a size between the sizes of a human finger and a human torso, said body having an orientation relative to an external reference frame, said apparatus generating an orientation signal that corresponds to at least two degrees of freedom of said orientation of said body said apparatus comprising:
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a. three self contained angular rate sensors arranged to span three space that generate first sensor signals that correspond to rotational rates of said body with respect to at least two degrees of freedom of said body, said first sensor signals being impervious to any interference from electromagnetic, acoustic, optical and mechanical sources; b. a mechanism for mounting said sensor to said body; and c. coupled to said sensor, a signal processor that comprises an integrator that integrates said rotational rate signals with respect to time and generates an orientation signal that corresponds to said at least two degrees of freedom and; d. a drift compensator, coupled to said angular rate sensor and said integrator, that compensates for any drift with respect to time in said rotational orientation signal, said drift compensator comprising at least one sensor being selected from the group consisting of;
an optical sensor, a radio frequency (RF) sensor and an acoustic sensor. - View Dependent Claims (2, 3, 4)
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Specification