| 摘要 |
A position detector is provided to increase interpolation accuracy even if a position sensor, which outputs a signal having a long pitch corresponding to a measurement displacement, is used. A high speed Fourier calculator(19) calculates a radial value(RD) outputted by a radial calculator(18) whenever a rotary position of the high speed Fourier calculator is changed by lambda, using an interpolation value(IP) outputted by an interpolation calculator(17). C1 and S1 are numerical values of cosine and sine components of lambda. C2 and S2 are numerical values of cosine and sine components of lambda/2. C3 and S3 are numerical values of cosine and sine components of lambda/3. The high speed Fourier calculator outputs a numerical value(RDA). The high speed Fourier calculator outputs a storage command signal(SET) to storages(30,31,32,33). A calculator(36) adds numerical values(C0,C1). A calculator(37) adds numerical values(S0,S1). A calculator(35) outputs a numerical value(DP). A subtractor(38) subtracts the numerical value(DP) from a numerical value(PJ). A calculator(34) outputs a numerical value(DB). A multiplier(39) multiplies a numerical value(BJ) by the numerical value(DB).
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