MOTOR CONTROLLER PROVIDING POSITION FEEDBACK CORRECTION
First Claim
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1. A motor controller system for the control of an electric motor comprising:
- a first input for receiving an incremental encoder signal from an incremental encoder driven by the electric motor;
a second input for receiving an absolute encoder signal from an absolute encoder driven by the electric motor;
a feedback circuit receiving a command signal for the control of a position of the electric motor and for receiving a position feedback signal indicating a position of the electric motor and derived from the incremental encoder signal, the feedback circuit producing an error signal used to drive and the electric motor; and
a correction circuit receiving the incremental encoder signal and the absolute encoder signal to compare the two to derive a feedback error signal on a regular basis for a detection of errors in the position feedback signal derived from the incremental encoder signal.
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Abstract
A motor controller employs absolute encoder signals to periodically assess the existence of cumulative error in a position signal derived from an incremental encoder signal. In one embodiment the absolute encoder signals are extracted from commutation switches of the motor eliminating the need for a separate absolute encoder.
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Citations
20 Claims
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1. A motor controller system for the control of an electric motor comprising:
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a first input for receiving an incremental encoder signal from an incremental encoder driven by the electric motor; a second input for receiving an absolute encoder signal from an absolute encoder driven by the electric motor; a feedback circuit receiving a command signal for the control of a position of the electric motor and for receiving a position feedback signal indicating a position of the electric motor and derived from the incremental encoder signal, the feedback circuit producing an error signal used to drive and the electric motor; and a correction circuit receiving the incremental encoder signal and the absolute encoder signal to compare the two to derive a feedback error signal on a regular basis for a detection of errors in the position feedback signal derived from the incremental encoder signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of controlling an electric motor comprising the steps of:
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(a) receiving an incremental encoder signal from an incremental encoder driven by the electric motor; (b) receiving an absolute encoder signal from an absolute encoder driven by the electric motor; (c) receiving a command signal for the control of a position of the electric motor and a position feedback signal indicating a position of the electric motor and derived from the incremental encoder signal, the feedback circuit producing an error signal used to drive and the electric motor; and (d) receiving the incremental encoder signal and the absolute encoder signal to compare the two to derive a feedback error signal on a regular basis for a detection of errors in the position feedback signal derived from the incremental encoder signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification