| CPC G01B 7/30 (2013.01) [G01B 7/003 (2013.01)] | 9 Claims |
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1. A method for determining an angular position of a shaft of a motor vehicle by a target fixed to a free end of said shaft and comprising a magnetic element, and of a magnetoresistive position sensor mounted facing said target, said method comprising: at each instant: rotating the shaft, generating a sine signal, storing the values of the sine signal in a first memory zone, generating a cosine signal, storing the values of the cosine signal in a different memory zone, calculating a real-time “measured” angle from the sine and cosine signals representing the angular position of the shaft, storing the calculated measured angle in a memory zone different from the preceding zones, over one period of the sine and cosine signals: determining the measured angle as the sine signal passes through zero, determining the time at which the sine signal passes through zero, calculating the mean angular resolution, said mean angular resolution corresponding to the derivative, with respect to time, of the determined measured angle, calculating the time at which the cosine signal passes through zero, using the time at which the sine signal passes through zero and the mean angular resolution, determining the measured angle at the calculated time at which the cosine signal passes through zero, calculating the amplitude of the second harmonic of the measured angle signal from the measured angle determined at the time at which the sine signal passes through zero, and from the measured angle determined at the calculated time at which the cosine signal passes through zero, calculating a second-harmonic error from the calculated amplitude of the second harmonic, and calculating a compensated angle representing the corrected angular position of the shaft from the real-time measured angle and from the calculated second-harmonic error.
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8. A system for determining an angular position of a shaft of a motor vehicle by a target fixed to a free end of said shaft and comprising a magnetic element, and of a magnetoresistive position sensor mounted facing said target, said system comprising said sensor, said sensor being configured to generate a sine signal and a cosine signal representative of the angular position of the shaft, the system being configured to:
at each instant, generate a sine signal, store the values of the sine signal in a first memory zone, generate a cosine signal, store the values of the cosine signal in a second memory zone, calculate a real-time “measured” angle from the sine and cosine signals representing the angular position of the shaft, and store the calculated measured angle in a third memory zone, over one period of the sine and cosine signals: determine the measured angle as the sine signal passes through zero, determine the time at which the sine signal passes through zero, calculate the mean angular resolution, said mean angular resolution corresponding to the derivative, with respect to time, of the determined measured angle, calculate the time at which the cosine signal passes through zero, using the time at which the sine signal passes through zero and the mean angular resolution, determine the measured angle at the calculated time at which the cosine signal passes through zero, calculate the amplitude of the second harmonic of the measured angle signal from the measured angle determined at the time at which the sine signal passes through zero, and from the measured angle determined at the calculated time at which the cosine signal passes through zero, calculate a second-harmonic error from the calculated amplitude of the second harmonic, and calculate a compensated angle representing the corrected angular position of the shaft from the real-time measured angle and from the calculated second-harmonic error.
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