High-precision stages are industrial equipment used in micro-fabrications. Fast and precise positioning control is a very important technology for improving the throughput and the product quality. In particular, a large-scale stage has a low resonance mode which disturbs fast and precise positioning because of the structures of the stage. In this paper, a novel feedback system is proposed in a SIMO system using multiple position sensors which are located at an actuator side and a load side. The proposed feedback system has two remarkable features. One is that the effect of the vibration suppression and the phase stabilization of the resonance mode can be tuned simultaneously with only two parameters. The other is that the tuning of the resonance mode does not affect the rigid mode at all. Finally, simulations and experiments with an XY-gantry-stage are performed to demonstrate the advantages of the proposed feedback control system.
Ball-screw-driven stages are used for industrial equipments such as machine tools and exposure systems. Fast and precise positioning is necessary to enhance productivity and microfabrication technology of the system. Authors' research group has improved the positioning performance of the stage by using perfect tracking control (PTC). However, when modeling error occurs, the positioning performance of the stage is greatly degraded. Most of the modeling errors are rolling friction of the stage. Therefore, the control system based on the friction model is necessary. In this paper, we propose variable natural length spring model (VNLS-model) as the friction model. VNLS-model is simple and easy to implement as friction controller. Moreover, the control system based on VNLS-model is proposed. Finally, the simulations and experiments show that the advantages of the proposed method.
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