Presently, most high performance motion servo systems rely onoptical encoders for position and velocity feedback. Optical encoderswith higher resolutions will increase the performance and accuracy ofthese motion systems. One method to increase the resolution of opticalencoders without the need to increase their optical resolution is to usesine-cosine interpolation. There are a few existing methods toaccomplish this task. However, all of them have limitations ordisadvantages. This paper provides a general overview of these existingmethods, highlights their features and limitations. Then, a novel andsimple method to realise sine-cosine interpolation of optical encodersis proposed. The proposed method can be implemented by using very fewlogic gates and comparators. Construction of a 16 times interpolationcircuit show that the proposed interpolation circuit can be built withvery few components, and its accuracy will not decrease when thetravelling speed of the encoder is increased
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