Device for detecting multi-turn absolute rotation angle and method for detecting the same

Abstract

There is provided a method for calculating with high accuracy a multi-turn absolute rotation angle of a motor rotating shaft coupled to a motor output shaft. In a rotation angle detection device according to this invention, a rotation angle θof an n-th rotating shaft satisfies the relationship with a rotation angle θof the motor rotating shaft: θ=(−(m±1)/m)×θ. The rotation angle detection device as an embodiment of a mechanism satisfying the relationship includes a gear mechanism in which a gear having (m±1) teeth meshes with a gear having m teeth between each adjacent two of first to n-th rotating shafts. A multi-turn rotation angle of the first rotating shaft is expanded to a detected value pof the first rotating shaft which is a rotation angle of the first rotating shaft and R×m+R×m+ . . . R×mcorresponding to the number of revolutions of the first rotating shaft, coefficients Rto Rare obtained on the basis of detected values from angle detectors of the respective shafts, and the multi-turn rotation angle of the first rotating shaft is calculated. Detection errors generated in the angle detectors of the second and subsequent rotating shafts can be effectively reduced, and a high-accuracy multi-turn rotation angle can be calculated.