Optimal trajectory planning considering optimal torque distribution of redundantly actuated parallel mechanism

Abstract

Previous studies on the optimal operation planning of redundantly actuated parallel mechanisms have focused on optimal torque distribution for a predefined trajectory. However, the optimized result obtained for a predefined trajectory cannot guarantee an optimal operation plan, because the torque distribution ability of a redundantly actuated parallel mechanism is highly dependent on the shape of the end-effector trajectory. Therefore, we can expect the redundantly actuated parallel mechanism performance to be enhanced when both the trajectory and torque distribution are optimized during the optimal operation planning stage. We propose a novel redundantly actuated parallel mechanism optimization procedure that can optimize both the end-effector trajectory and torque distribution. The proposed procedure is composed of two stages of optimizers, i.e. upper- and lower-level optimizers that generate the end-effector trajectory and distribute the torques along the generated trajectory, respectively. Composition of these two stages of the optimization procedure allows optimization of both the trajectory and torque distribution, despite the correlation between them. The proposed optimization procedure is simulated using two types of cost functions. All the simulation results show that the proposed procedure facilitates optimization of the end-effector trajectory and the torque distribution concurrently. Also, the cost function value is minimized to a greater extent than in the result with the optimal torque distribution along the initial trajectory.

Dynamic modeling and power optimization of a 4RPSP+PS parallel flight simulator machine

“…The importance of this concept is testified by abundant literature including both theoretical and experimental studies for enhancing the energy efficiency in manipulators and automatic machines [23]. The main approaches to achieve this goal are: (1) the proper choice of the manipulator type, [24] (2) designing lightweight manipulators with lower inertia, [25,26] (3) optimization of manipulator structure, [27] using regenerative drive systems, [28,29] trajectory planning and motion planning, [30,31,32] applying redundancy on non-redundant manipulators, [33,34,35,36] optimizing location of the task with respect to the base of the manipulator [37,38] and joint force/torque minimization [13,39,40] and introduction of complaint or elastic elements into the manipulator [41,42].…”

Task-based torque minimization of a 3-PṞR spherical parallel manipulator

“…For this reason, some scholars have addressed torque/force minimization of robot manipulators. The main approaches are (i) trajectory planning of the manipulator [2,3,4], (ii) actuation or kinematic redundancy [2,5,6,7]. For instance, Park et al [2] proposed an optimization procedure to optimize both the end-effector trajectory and actuating torque distribution of a 2-DOF redundantly actuated parallel mechanism.…”

“…The main approaches are (i) trajectory planning of the manipulator [2,3,4], (ii) actuation or kinematic redundancy [2,5,6,7]. For instance, Park et al [2] proposed an optimization procedure to optimize both the end-effector trajectory and actuating torque distribution of a 2-DOF redundantly actuated parallel mechanism. Segota et al [3] studied torque minimization of a two 6-DOF robotic manipulators cooperating and carrying a weight in a point-to-point trajectory using evolutionary algorithms.…”