Abstract: Some embodiments include an absolute displacement detection device configured to calculate, from a plurality of displacement detection signals provided by a plurality of displacement detection mechanisms that detect displacement amounts, an absolute periodic signal having an absolute periodic signal period larger than displacement detection signal periods of the plurality of the displacement detection signals. Other embodiments of related devices and methods are also disclosed.

Abstract: Some embodiments address a problem of detecting the absolute amount of displacement of a moving body. In various embodiments, the multi-turn absolute angle of rotation of a main shaft is calculated from a rotation angle detected by an angle sensor joined to the main shaft and a countershaft. The rotation of a main shaft (12) joined to a rotary drive source (11) is transmitted to countershafts (13, 14) at a predetermined gear ratio. The rotation angles (Ss, Sp, Sq) of the main shaft (12) and the countershafts (13, 14) are detected by angle sensors (15a, 15b, 15c), each of the rotation angles is sent to a synchronizing/integer-obtaining processor (17) by an AD-conversion-angle calculator (16) as angle detection values (?s, ?p, ?q), and period signals (p, q) obtained as integers are calculated. The period signals (p, q) are sent to a period computer (18), and the period signal (r) of the main shaft is calculated.