Electronic Interpolation Errors

Abstract

High-precision and resolution motion control relies critically on the precision and resolution of positional measurements achievable from the encoders. These factors are in turn limited by the technology behind the manufacturing of encoders. To-date, the scale grating on linear optical encoders can be manufactured to less than four micrometers in pitch, but clearly, further reduction in pitch is greatly constrained by physical considerations in the manufacturing processes. This implies an optical resolution of one micrometer is currently achievable after a for fold interpolation. Analog interpolation using soft techniques will provide an interesting possibility to further improve on the encoder resolution, by processing the analog encoder signals online to yield the small intermediate positions.