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Optimization of Kinematic Redundancy and Manipulability Analysis of a Dual-Arm Cam-Lock Robot

Rezaeian Jouybari, Behnoush | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 42926 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Ghaemi Osguei, Kambiz; Meghdari, Ali
  7. Abstract:
  8. Cooperative systems have been widely studied in literature. The Dual-Arm Cam-Locked (DACL) robot manipulators are reconfigurable arms formed by two parallel cooperative manipulators which operate redundantly but they may lock into each other in specific joints to increase structural stiffness in the cost of losing some degrees of freedom. Obtaining the optimal configuration demands lots of computational time and is not practical in real-time applications. In the present work, considering the kinematics of the manipulator, the optimal control problem of redundancy is formulated in the framework of tasks with the order of priority. The optimal control formulation is derived by using the Pontryagin's maximum principle. The integrated value of pseudokinetic energy is used as a global criterion for redundancy utilization. To lessen the computations, a computational algorithm is proposed in such a way that the problem is reduced to a minimum-value search problem in a space of as many dimensions as the degrees of redundancy. Among all initial value adjusting methods a shooting procedure is applied to solve this two-point boundary value problem. Using the proposed globally optimal control scheme, the optimal joint values of the manipulator for each different lock configuration has been found. To show the effectiveness of the scheme and compare the optimal performance index for all distinctive configurations, the problem is investigated with several different desired trajectories of the end-effector. The Optimal joint values and performance indices are shown through separate graphs for distinct lock configurations and specific grasper’s trajectories. During the procedure it is assumed that the robot is carrying a point mass; therefore, the trajectory of the end-effector does not have any rotational component and is a two-dimensional vector with horizontal and vertical components in plane of the motion. Using the Lagrange's method, the dynamic model of the robot for all different configurations is developed. The robot joints trajectories are generated and utilized to simulate the dynamics. The end-effector resultant forces and moment are simulated.
  9. Keywords:
  10. Shooting Method ; Dynamic Modeling ; Dual Arm Cam-lock Robot ; Kinematic Optimization ; Pontryagin Minimum Principle

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