Optimal redundant actuation of closed-chain mechanisms for high operational stiffness

This paper presents the optimal redundant actuation of closed-chain mechanisms for robotic applications requiring a high degree of operational stiffness, as well as the balance of force applicability and dexterity. First, by taking into account the distribution of active joints, the statics and the operational stiffness of a closed-chain mechanism are formulated with the analysis on the effects of actuation redundancy. Second, for given joint torque limit, task force, allowable disturbance, and allowable deflection, the task execution conditions of a closed-chain mechanism are derived along with the efficient testing formulas. Third, to achieve high stiffness while maintaining dexterity, the active joint distribution and the internal joint torque of a closed-chain mechanism is optimized. Finally, the simulation results for the optimal redundant actuation of a planar closed-chain mechanism are given