Vibration damping and second-order sliding modes in the control of a single finger of the AMADEUS gripper

The vibration clamping problem relevant to a single element (finger) of the AMADEUS gripper is addressed. A simplified model of such an element, constituted by three bellows connected to two plates, one fixed and the other (the tip) free, has been derived The elastic constants in this model are assumed uncertain. Therefore, a sliding mode approach has been adopted to damp the oscillations and perform the dynamic decoupling between displacements and rotations. Then, the transmission delays have been taken into account and an unconventional adaptive sliding mode strategy has been designed. In order to avoid the chattering phenomenon and eliminate the drawbacks typical of hydraulic valves (low bandwidth and hysteresis), a new actuation system, driven by a new sliding mode control algorithm, has been developed and experimentally tested.