Accurate and steady control on trajectory tracking for the wafer transfer robot

Purpose - The purpose of this paper is to focus on the accurate and steady control on trajectory tracking for wafer transfer robot, suppress the vibration and reduce the contour error. Design/methodology/approach - The wafer transfer robot dynamic model is modeled. Through analyzing the characteristics of wafer transfer robot, cross-coupled synchronized control is proposed based on the contour error model in task space to improve synchronization of the joints; the shaping for the joints by input shaper in task space is applied to suppress the vibration of the end effector during trajectory tracking. Then combining the cross-coupled synchronized control with input shaping is proposed to improve accuracy and suppress the vibration. Findings - The combination of cross-coupled synchronized control and input shaping control method can improve the contour accuracy and reduce the vibration simultaneously during trajectory tracking. And the control method can be used to control the trajectory of wafer transfer robot. Research limitations/implications - The transfer station is in the center of the robot body. When the transfer station may deviate from the center of the robot body, the synchronizing performance of three axes on the same plane must be considered. Practical implications - The proposed method can be used to solve the vibration and synchronizing performance problems on similar SCARA robots in semi-conductor and liquid crystal display industry. Originality/value - The proposed control method takes advantage of the cross-coupled synchronized control and input shaping control method. This combination has improved contour accuracy and reduced vibration than applying other methods, and it has achieved better performance than using single one control method only.