Method of detecting absolute rotational position

Abstract

Before detecting a mechanical angular absolute position (theta abs) of a rotating shaft (4) within one turn using a two-pole absolute value encoder (2) and a multi-pole absolute value encoder (3) having Pp (Pp: an integer of 3 or more) pole pairs, the rotating shaft (4) is rotated to measure a temporary absolute value (theta elt) of the multi-pole absolute value encoder (3) in relation to each absolute value (theta t) of the two-pole absolute value encoder (2), and a temporary pole-pair number (Nx) for a multi-pole magnet is assigned to each absolute value (theta t). In actual ditecting, an absolute value (theta ti) of the two-pole absolute value encoder and an absolute value (theta elr) of the multi-pole absolute value encoder are measured, the temporary pole-pair number (Nx) assigned tothe absolute value (theta ti) is corrected on the basis of an absolute value (theta elti) of the multi-pole absolute value encoder assigned to the absolute value (theta ti) and the measured absolute value (theta elr), thus calculating a pole-pair number (Nr). The absolute position (theta abs) is calculated using an expression of (NrOEelp+theta elr) / Pp with a mechanical angle (theta elp) corresponding to an electrical angle of one period of an output signal of the multi-pole absolute value encoder.

Description

technical field [0001] The present invention relates to a magnetic absolute rotational position detection method and a magnetic absolute value encoder capable of detecting the absolute position within one revolution of a rotating shaft with high precision by using two sets of magnetic encoders. Background technique [0002] A system using two sets of magnetic encoders is known as a magnetic absolute encoder for detecting the absolute position of a rotary shaft with high precision. Patent Document 1 discloses a structure for obtaining a 12-bit absolute value output with a resolution of 4096 (64×64) using a two-pole magnetic encoder and a 64-pole magnetic encoder. In this magnetic encoder, the upper 6 bits are generated by a 2-pole magnetic encoder, and the lower 6 bits are generated by a 64-pole magnetic encoder. [0003] Patent Document 1: Japanese Patent Application Laid-Open No. 06-10813 [0004] However, in the magnetic encoder of this structure, it is necessary to make...

AI Technical Summary

Problems solved by technology

Therefore, in order to obtain higher-precision output, it is necessary to further improve the precision of the two-pole magnetic encoder, so it is difficult to achieve high precision.

In addition, it is also necessary to align the output signal of the two-pole magnetic encoder with the rising edge point of the output signal of the 64-pole magnetic encoder, and there is a problem that it takes time to adjust this

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