Papers by Author: Chen Hsieh

Abstract: Current motion tables can hardly exhibit the capabilities of positioning with nanometer precision and carrying heavy loads simultaneously. This is mainly because that the driver used to drive the table cannot fulfill the requirements needed for driving an ultra precision system without sacrificing the power it can offer. In this research, the concept of a hybrid driver is introduced and tested. This driver is basically a combination of a linear amplifier and an on-off large power supply. Although there are still some defects need to be overcome, preliminary experimental tests have shown that this kind of driver does have potential to carry heavy loads to do fast and long distance positioning with nanometer precision and in-position vibration.

Abstract: For multiple-axis stages, it is required to operate the axes simultaneously, such that the resulting trajectory of platform follows a given contour. For most stage systems, friction acts as the major disturbance which degrades the precision of system motion and its effect should be compensated. In this paper, contouring control of a two-dimensional stage system subjected to friction is investigated. A systematic contour controller design based on task coordinate frame is proposed and its effectiveness is studied through theoretical analysis and numerical simulations.

Abstract: 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.