Method of measuring position and orientation with improved signal to noise ratio
First Claim
1. A method of measuring position and orientation of an object in a prescribed three-dimensional space, including the steps of:
- a) providing a multi-axis transmitter located adjacent said space;
b) providing a multi-axis receiver attached to said object;
c) providing driver means for driving each transmitter axis to emit a square DC-based waveform into said space upon command from a computer having an integrator;
d) driving said transmitter such that a waveform emitted into said space by one axis thereof does not overlap with a waveform emitted by another axis thereof into said space;
e) providing each waveform with the following configurations;
i) beginning a rising edge at time T1;
ii) beginning a steady state at maximum amplitude at time T2;
iii) beginning a falling edge at time T3;
iv) beginning a steady state at minimum amplitude at time T4; and
v) beginning a next rising edge at time T5;
vi) wherein a time period T1 to T3 equals a time period T3 to T5;
f) activating a first axis of said transmitter to emit a waveform into said space;
g) receiving signals at said receiver and conveying said signals to said computer;
h) integrating said signals using said integrator from time T1 to T3 to obtain integration A;
i) integrating said signals using said integrator from time T3 to T5 to obtain integration B;
j) subtracting integration B from integration A to obtain final result C;
k) repeating steps f)-j) for each axis of said transmitter.
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Accused Products
Abstract
A method of measuring position and orientation of an object in a space in six-degrees of freedom includes a three axis transmitter transmitting a magnetic field to be received by a three axis receiver. The transmitter transmits a pulsed DC transmit waveform. The waveform is preferably a symmetrical square wave with distinct non-overlapping axes and signal processing is accomplished such that the integrator is reset at the start of the rising edge transient period, the coil output signal is integrated throughout the rising edge transient and steady state periods, and the integration result is measured at the end of the steady state period, for each axis. The result is dramatically enhanced signal to noise ratio. The timing of measurements is chosen to reduce eddy current distortion while providing improved compensation for drift of the sensor with respect to the Earth'"'"'s stationary magnetic field.
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Citations
19 Claims
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1. A method of measuring position and orientation of an object in a prescribed three-dimensional space, including the steps of:
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a) providing a multi-axis transmitter located adjacent said space;
b) providing a multi-axis receiver attached to said object;
c) providing driver means for driving each transmitter axis to emit a square DC-based waveform into said space upon command from a computer having an integrator;
d) driving said transmitter such that a waveform emitted into said space by one axis thereof does not overlap with a waveform emitted by another axis thereof into said space;
e) providing each waveform with the following configurations;
i) beginning a rising edge at time T1;
ii) beginning a steady state at maximum amplitude at time T2;
iii) beginning a falling edge at time T3;
iv) beginning a steady state at minimum amplitude at time T4; and
v) beginning a next rising edge at time T5;
vi) wherein a time period T1 to T3 equals a time period T3 to T5;
f) activating a first axis of said transmitter to emit a waveform into said space;
g) receiving signals at said receiver and conveying said signals to said computer;
h) integrating said signals using said integrator from time T1 to T3 to obtain integration A;
i) integrating said signals using said integrator from time T3 to T5 to obtain integration B;
j) subtracting integration B from integration A to obtain final result C;
k) repeating steps f)-j) for each axis of said transmitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of measuring position and orientation of an object in a prescribed three-dimensional space, including the steps of:
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a) providing a three axis transmitter located adjacent said space;
b) providing a three axis receiver attached to said object;
c) providing driver means for driving each transmitter axis to emit a square DC-based waveform into said space upon command from a computer having an integrator;
d) driving said transmitter such that a waveform emitted into said space by one axis thereof does not overlap with a waveform emitted by another axis thereof into said space;
e) providing each waveform with the following configurations;
i) beginning a rising edge at time T1;
ii) beginning a steady state at maximum amplitude at time T2;
iii) beginning a falling edge at time T3;
iv) beginning a steady state at minimum amplitude at time T4; and
v) beginning a next rising edge at time T5;
vi) wherein a time period T1 to T3 equals a time period T3 to T5;
f) activating a first axis of said transmitter to emit a waveform into said space;
g) receiving signals at said receiver and conveying said signals to said computer;
h) resetting said integrators and integrating said signals using said integrator from time T1 to T3 to obtain integration A;
i) resetting said integrator and integrating said signals using said integrator from time T3 to T5 to obtain integration B;
j) subtracting integration B from integration A to obtain final result C;
k) repeating steps f)-j) for each axis of said transmitter. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification