Motor based condition monitoring
First Claim
1. A method of analyzing operating characteristics of a motor actuated system comprising the steps of:
- sensing a current drawn by a motor for driving the system to obtain a current waveform in the time domain;
identifying a predetermined number of brush-switching peaks in the current waveform corresponding to a predetermined rotational travel of the motor; and
setting a width of the current waveform, defined by the predetermined number of brush-switching peaks, equal to a predetermined number of equally spaced increments to normalize the current waveform from the time domain to a set of data points defining a waveform in the spatial domain corresponding to the predetermined rotational travel of the motor.
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Abstract
A method of analyzing the condition of a motor driven rotating system using a current waveform produced by the motor. The motor position is initially identified from the current waveform produced by the motor and more particularly, a step of identifying the segment switching of the motor is performed to identify the system position with reference to individual rotations of the motor. The current waveform is then normalized to a preselected number of data points, each rotation being described by the preselected number of data points, such that the current waveform is converted from the time domain to a spatial domain corresponding to positions of the system. Subsequently, a frequency analysis is performed to identify frequencies corresponding to characteristics of the system, including calculating a frequency dependent distribution of the normalized current waveform to determine the energy content of the waveform at particular frequencies.
33 Citations
20 Claims
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1. A method of analyzing operating characteristics of a motor actuated system comprising the steps of:
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sensing a current drawn by a motor for driving the system to obtain a current waveform in the time domain; identifying a predetermined number of brush-switching peaks in the current waveform corresponding to a predetermined rotational travel of the motor; and setting a width of the current waveform, defined by the predetermined number of brush-switching peaks, equal to a predetermined number of equally spaced increments to normalize the current waveform from the time domain to a set of data points defining a waveform in the spatial domain corresponding to the predetermined rotational travel of the motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of analyzing operating characteristics of a motor actuated system comprising the steps of:
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sensing a current drawn by a motor for driving the system to obtain a current waveform in the time domain; filtering the current waveform about a band corresponding to a rotational frequency of the motor; identifying a predetermined number of peaks in the filtered current waveform corresponding to a predetermined rotational travel of the motor; defining a width of the unfiltered current waveform using the predetermined number of peaks of the filtered current waveform; and setting the defined width of the unfiltered current waveform equal to a predetermined number of equally spaced increments to normalize the unfiltered current waveform from the time domain to a set of data points defining a waveform in the spatial domain corresponding to the predetermined rotational travel of the motor. - View Dependent Claims (14, 15, 16)
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17. A method of analyzing operating characteristics of a motor actuated system comprising the steps of:
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sensing a current drawn by a motor for driving the system to obtain a current waveform in the time domain; analyzing the current waveform to determine a dominant frequency band corresponding to a rotational frequency of the motor; filtering the current waveform about the band corresponding to the rotational frequency of the motor; identifying a predetermined number of peaks in the filtered current waveform corresponding to a predetermined rotational travel of the motor; defining a width of the unfiltered current waveform using the predetermined number of peaks of the filtered current waveform; and setting the defined width of the unfiltered current waveform equal to a predetermined number of equally spaced increments to normalize the unfiltered current waveform from the time domain to a set of data points defining a waveform in the spatial domain corresponding to the predetermined rotational travel of the motor. - View Dependent Claims (18, 19, 20)
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Specification