Browsing by Keyword "Parallel robot"
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Item Anti-windup design for saturation management during piezo-actuated vibration attenuation of the high-speed parallel robot Par2(IFAC Secretariat, 2013) Douat, Luiz R.; Queinnec, Isabelle; Garcia, Germain; Michelin, Micaël; Pierrot, François; Tarbouriech, Sophie; Tecnalia Research & InnovationThe two degrees of freedom parallel robot Par2 is designed for high-speed and high-accuracy industrial pick-and-place operation tasks. As a result of high acceleration trajectories, its end-effector undergoes some undesirable vibrations after reaching the stop position, compromising precision and leading to an increase in the operation cycle time. Accelerometer sensors placed on the end-effector and piezoelectric patch actuators wrapped around the robot arms are employed in order to actively reduce these vibrations. Without taking into account saturation limitations, a robust controller is designed, minimizing vibrations for the robot nominal operating point but failing for some extreme operating points, due to high control efforts. An anti-windup strategy is then employed to deal with the saturation of the actuator. Such a strategy presents the advantage, with respect to the strategy which would consider a controller with smoother control efforts, to maintain a good level of vibration attenuation on the whole operation domain. Simulations and experimental results attest the adequacy of the proposed solution.Item Optimal design of a 4-DOF parallel manipulator: From academia to industry(2009) Pierrot, François; Nabat, Vincent; Company, Olivier; Krut, Sébastien; Poignet, Philippe; Tecnalia Research & InnovationThis paper presents an optimal design of a parallel manipulator aiming to perform pick-and-place operations at high speed and high acceleration. After reviewing existing architectures of high-speed and high-acceleration parallel manipulators, a new design of a 4-DOF parallel manipulator is presented, with an articulated traveling plate, which is free of internal singularities and is able to achieve high performances. The kinematic and simplified, but realistic, dynamic models are derived and validated on a manipulator prototype. Experimental tests show that this design is able to perform beyond the high targets, i.e., it reaches a speed of 5.5 m/s and an acceleration of 165 m/s2. The experimental prototype was further optimized on the basis of kinematic and dynamic criteria. Once the motors, gear ratio, and several link lengths are determined, a modified design of the articulated traveling plate is proposed in order to reach a better dynamic equilibrium among the four legs of the manipulator. The obtained design is the basis of a commercial product offering the shortest cycle times among all robots available in today's market.