Method and apparatus to monitor position of a rotatable shaft
First Claim
Patent Images
1. Method for monitoring rotational position of a rotatable shaft, comprising:
- generating output signals corresponding to a plurality of discrete rotational angles of the shaft;
monitoring the output signals and elapsed times corresponding to the discrete rotational angles of the shaft for a complete rotation during which rotational speed of the shaft is substantially constant;
determining a true angular velocity of the shaft for the complete rotation during which the rotational speed of the shaft is substantially constant;
calculating angular velocities between contiguous pairs of the discrete rotational angles;
determining a velocity correction based upon the calculated angular velocities and the true angular velocity;
determining an error in measurement of the rotational angle of the shaft based upon the velocity correction; and
determining a rotational angle error term combinable with the discrete rotational angles of the shaft.
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Abstract
A rotatable shaft is equipped with a measurement device that generates output signals corresponding to discrete angular positions of the shaft. Rotational angles of the shaft are measured for a complete rotational period. A true angular velocity of the shaft is determined. Angular velocity is calculated between contiguous pairs of the discrete angular positions. A velocity correction is determined, and a rotational angle error term is determined based upon the velocity correction.
228 Citations
15 Claims
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1. Method for monitoring rotational position of a rotatable shaft, comprising:
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generating output signals corresponding to a plurality of discrete rotational angles of the shaft; monitoring the output signals and elapsed times corresponding to the discrete rotational angles of the shaft for a complete rotation during which rotational speed of the shaft is substantially constant; determining a true angular velocity of the shaft for the complete rotation during which the rotational speed of the shaft is substantially constant; calculating angular velocities between contiguous pairs of the discrete rotational angles; determining a velocity correction based upon the calculated angular velocities and the true angular velocity; determining an error in measurement of the rotational angle of the shaft based upon the velocity correction; and determining a rotational angle error term combinable with the discrete rotational angles of the shaft. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Method for measuring a true rotational angle of a rotatable shaft, comprising:
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fixedly attaching a resolver rotor to the shaft; providing a resolver stator to generate a resolver stator signal corresponding to rotational angles at discrete angular positions of the rotor; rotating the shaft and monitoring the resolver stator signal; measuring the rotational angles and elapsed times therebetween for a complete rotation of the shaft during which rotational speed of the shaft is substantially constant; determining a true angular velocity of the shaft for the complete rotation during which the rotational speed of the shaft is substantially constant; calculating an angular velocity between contiguous pairs of the discrete angular positions for the complete rotation of the shaft; determining a velocity correction between the calculated angular velocity and the true angular velocity; determining a rotational angle error term based upon the velocity correction; and correcting the measured rotational angle with the rotational angle error term. - View Dependent Claims (9, 10, 11, 12)
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13. Method to determine an error in measurement of an angular position of a rotatable shaft, comprising:
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determining rotational angles corresponding to discrete angular positions of the shaft; rotating the shaft and measuring the rotational angles corresponding to the discrete angular positions for a complete rotation of the shaft during which rotational speed of the shaft is substantially constant; determining a true angular velocity of the shaft for the complete rotation during which rotational speed of the shaft is substantially constant; calculating angular velocities between contiguous pairs of the discrete angular positions for the complete rotation of the shaft; determining a velocity correction between the calculated angular velocity and the true angular velocity for each of the contiguous pairs of discrete angular positions; and determining a rotational angle error term based upon the velocity correction for each of the contiguous pairs of discrete angular positions. - View Dependent Claims (14, 15)
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Specification