Method and system for determining position of a body
AssigneeHewlett-Packard Development Company, L.P.
InventorsDonald J. Fasen, Charles David Smith
Life of this patent
Estimating the term…
Abstract
A method for determining the position of a rotor with respect to a stator. The method includes generating offset N and Q signals when the rotor moves with respect to the stator and sampling the N and Q signals at a predetermined time interval. A section of a polar plot in which the N and Q signal sample lies is determined and compared to the section of a polar plot in which a previous N and Q signal sample lies. A long range rotor position is calculated by maintaining a count of the change of sections from previous N and Q signal samples. A sub-section rotor position for the N and Q signal sample is calculated and combined with the long range rotor position to create a linear position signal.
Claims31
A method for determining the position of a rotor with respect to a stator, comprising:
- generating offset Normal (N) and Quadrature (Q) signals when the rotor moves with respect to the stator;
- sampling the N and Q signals at a predetermined time interval;
- calculating a section of a polar plot in which the N and Q signal sample lies;
- counting the change of sections from prior N and Q signal samples to determine a long range rotor position;
- calculating a sub-section rotor position for the N and Q signal sample;
- and
- combining the long range rotor position with the sub-section rotor position to create a linear position signal indicative of the position of the rotor.
A method for measuring the distance traveled by a rotor from time t0 through tn, comprising:
- generating offset N and Q signals that vary cyclically with the rotor position;
- sampling the N and Q signals at successive predetermined time intervals t0 through tn to obtain signal samples NQt0 through NQtn;
- converting signal samples NQt0 through NQtn to a polar coordinate system;
- determining in which section of the polar coordinate system each of signal samples NQt0 through NQtn lies;
- counting the change of sections from signal samples NQt0 through NQtn;
- calculating a long range distance traveled by the rotor using the change of sections count;
- calculating a sub-section rotor distance for signal sample NQtn;
- and
- combining the long range rotor distance with the sub-section rotor distance to measure the distance traveled by the rotor from time t0 through tn.
A capacitive position sensor system comprising:
- an encoder for generating offset N and Q signals as a rotor moves with respect to a stator;
- means for converting signal samples NQt0 through NQtn to a polar coordinate system and determining in which section of the polar coordinate system each of samples NQt0 through NQtn lies;
- means for counting the change of polar coordinate sections from sample NQt0 through sample NQtn and calculating a long range distance traveled by the rotor;
- means for calculating a sub-section rotor distance for sample NQtn;
- and
- means for combining the long range rotor distance and the sub-section rotor distance to measure the distance traveled by the rotor from time t0 through tn.
Dependencies are inferred from the claim text.