Vibration control of linear robots using a piezoelectric actuator

This paper presents the results of vibration control strategy for high-speed linear robots using an auxiliary piezoelectric actuator. With acceleration reaching 3 g, rapid horizontal slewing motion inevitably excites the structural resonances of the robot and generates vertical vibration forces exceeding the tolerance of the end-effector. Instead of controlling the robot vibration from the main actuators (ac servomotors with limited bandwidth), a piezoelectric actuator is deployed to provide vibration suppression at the load in the z direction. This way the robot is treated as a disturbance generator while the piezoactuator is considered as the plant. A digital servocompensator is then designed and implemented to suppress these vibration modes. Typically, attenuation is achieved for the dominant mode with 30 dB and other modes with 15 dB. Suppression of vibration up to seven modes has been implemented satisfactorily.