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Absolute position detection apparatus and error compensation methods therefor

  • US 5,677,686 A
  • Filed: 01/27/1995
  • Issued: 10/14/1997
  • Est. Priority Date: 01/28/1994
  • Status: Expired due to Term
First Claim
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1. In an absolute position detection method wherein one or more sets of sine and cosine waves are generated within a cycle of a rotating device, the generated sine and cosine waves are analog-to-digital converted into digital values, and error compensation is performed using an arithmetic process to compensate for errors including offset, amplitude and phase errors on the digital values, the error compensation method comprises the steps of:

  • determining maximum and minimum values of the digital values, said maximum and minimum values representing peak values of the sine and cosine waves;

    calculating an amplitude value for each of said sine and cosine waves using a difference between said maximum and minimum values;

    determining an amplitude damping factor which varies as a function of an angular speed of said rotating device;

    calculating an amplitude compensation factor for each of said sine and cosine waves as a function of said amplitude value, said amplitude damping factor and a reference amplitude value;

    amplitude compensating each of said sine and cosine waves by multiplying each of said digital values by said amplitude compensation factor, thereby adjusting the amplitude of each of said sine and cosine waves to a reference amplitude.

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