Precision-Limit Positioning of a Linear Motor Nano Drive System

Ultra high precision positioning is an important issue in modern manufacturing industries. As it comes to positioning it is widely believed that friction is detrimental to high precision. As a result, people usually use special mechanical systems such as air-bearing guides and/or hybrid drives in a high precision positioning system to avoid the influence of friction. These strategies, however, increase the operational cost and system complexity. In this paper, it describes how to apply the Precision-Limit Positioning (PLP) technique introduced in [1] to a standard linear motor system with the existence of friction. The position resolution is designed to equal to the resolution of the position sensor used in the feedback loop, which is 2nm/count. It is further requested that the repeatability and steady state vibration of the system are stable enough so that the table is capable of doing count-by-count operation.