EXPERIMENTAL IDENTIFICATION OF CONFIGURATION DEPENDENT LINKAGE VIBRATION IN A PARALLEL ROBOT USING SMART MATERIAL ACTUATORS AND SENSORS

A new lightweight planar parallel robot is designed to achieve high acceleration and execute high-speed pick and place tasks. However, due to the lightweight structure of the system, unwanted structural vibrations are induced during motion of the platform. This work focuses on the investigation of the characteristics of this structural vibration utilizing distributed Lead Zirconate Titanate (PZT) transducers. Experimental Modal Analysis (EMA) tests were performed on an experimental three degree of freedom planar parallel robot with one flexible linkage, for cases in which the robot is stationary and in motion. For both cases, configuration dependency of link structural vibration is investigated by performing EMA in different configurations using different combinations of transducers. It is observed that FRFs obtained for the case in which the robot is in motion have more complex 'frequency compositions and more- significant configuration-dependency than those in which the robot is stationary. However, the two groups of analyses exhibit two nearly identical most-significant modes. Based on this observation, the transfer function from motor inputs to linkage vibration is simplified permitting an linear active vibration controller to be used