Extra Insensitive Shapers for Flexible Articulated System to Minimize Residual Vibration in Presence of Modeling Errors

Input shaping is an effective method of minimizing vibration in flexible systems. In particular in space robotics the design of light-weight manipulators is motivated by the increasing demand for high-speed performance and low energy consumption assembly and the control of such systems deals with the great flexibility of these structures. Input shaping (IS) is a feedforward-control strategy characterized by simplicity and effectiveness and it can be used in addition to feedback control approaches. One important property of input shapers is the robustness to frequency modeling errors and it can be measured using a sensitivity plot. This paper shows the goal of the input shaping design method to match a minimum time delay of the maneuver with a sufficient insensitivity to system parameters variation. Greater insensitivity can be reached by using robust shapers such as Extra-Insensitive (EI) input shapers which allow a small amount of vibration at the modeled frequency but a considerably wider insensitivity curve. Experimental results carried out on the Test-bed for Microgravity Simulation in Robotic Arm Dynamics (TeMSRAD), set up at the Department of Structural Engineering, Università di Pavia are presented.