Large-sized gantry-type linear motor sliders are widely used in industry (e.g. in liquid crystal panel production equipment). An appropriate control model is important for deriving control methods to improve control performance. Although various control models of large-sized gantry-type linear motor sliders have been developed in previous studies, no results are yet reported regarding control models which precisely reproduce characteristics of a large-sized gantry-type linear motor slider. In general, a method to derive a transfer function by using frequency responses can be employed to obtain an accurate control model, however, large sized gantry-type linear motor sliders have unique characteristics, namely “distortion” and “coupling”, thus the transfer function derived using only the frequency response cannot reproduce the experimental results with high accuracy. In this paper we report on a method to obtain a highly precise control model of a large sized gantry-type linear motor slider.

Many transport units for large production devices now incorporate large-sized gantry type linear motor sliders comprising two parallel linear sliders linked by a joint table. This type of linear motor slider develops a unique mechanical distortion, generating a repulsive force between the two axes that can raise the motor output forces higher than their rated limit. A previous study proposed a method to suppress the repulsive force. However, as feedback gains are set high, force references oscillate and the control system becomes unstable. In past study, yawing vibration suppression methods have been proposed. But, we consider that this vibration is not yawing vibration because the force references include same phase vibration with high gains. Therefore, the modal analysis is performed to analyze this vibration. As a result, it was found that the pitching vibration of the slider was greatly affected. This paper considers this vibration phenomenon, and suppression of the vibration by control method which is similar to impedance control is presented. Hence, it is shown that considering multi-degree of freedom vibration which means yawing vibration and pitching vibration included is important in order to control the large-sized gantry type linear motor sliders.

This study treats the dyna皿 ic stabi 瓧 y of medhanical systems subjected to 皿 Ulti − directional exci 七ations ， such as dynamic buckling behav1or ， etc ． Asteel cylindrica ！ pier is treated and modeled analytically as a thin cyhndrica ユstructure wi も h an a も tached mass on its tip． The analysis is carried out by numerical simulations ， where the hor三zo 且 鳳 皿 d the vertic 組 seismic loads are apphed simu ユ taneously． The effects of the horizontal and vertical input 丘 equencies on the dynamic stability are studied ．工七 is known that the seismic responses of the thin cylindrica ユ shell struc 七 ure tend to increase due to the coupling effects between the horizontal and ver 七 ical excitations ， and that flattening phenomena make the cylindrical shell struc 七 ures Inore uns 七 able ．

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This study treats the dynamic stability of echanical systems subjected to multi −directional excitations ， sudh as dynamic buckling behavior ， etc ．A steel Cylindrical pier is treated a皿 d modeled analytically as a thin cylindrical structure wi 七 h an attached mass on its t玉 p ． The analysis is carried out by numerical simulations ， where the horizontal and the vertical seismic Ioads are applied simultaneously ． The effects of the horizontal and vertical input frequencies on the dynarnic stability are studied ． It is known that the seismic responses of the thin cylindric 田 shell structure tend to increase due to the coupling effects between the hodzontal and vertical excitations ， and that 且attening phenomena make the cylindrical shell structures more unstable