Automatic self-calibration of an incremental motion encoder

Our recently developed patented instrument, the Incremental Motion Encoder (IME) is able to monitor the rotation of mechanical systems. Using the disc from an Incremental Shaft Encoder, but with three or more read heads instead of one, the IME is able to resolve small transverse movements of the shaft as well as angular position. However, the accuracy of the measurements is limited by small distortions in the grating lines of the disc, due either to damage or to manufacturing errors. This paper presents algorithms which use data from the IME to compensate for such errors in the disc, thus enabling automatic self-calibration of the IME.