This paper discusses the issue of precision-limit positioning of a direct drive system with the existence of friction. By precision-limit positioning we mean that, in addition to the common sense of sub-micro, nano, or pico precision, the precision error equals to the resolution of the position sensor used in the feedback loop. This means a zero-count precision error when a digital type position
... [Show full abstract] sensor is used. Precision-limit positioning also enforces 100% repeatability as precision is concerned. Of course, this is the limit of the precision that a real control system can achieve. Traditionally, this kind of performance was not considered possible mainly for lacking accurate and enough information about friction, especially the static friction. However, as more and more knowledge of the pre-sliding motion has been revealed, it is shown in this research that such kind of performance can be achieved.