![]() We assign frames according to the inverse dynamics of a rigid body we derived in the previous video. Each link is a rigid body, and the center of mass of each link is shown. Consider an n-link robot with an end-effector. The comparison between the proposed algorithm and a heuristic exploring–based rapidly exploring random tree indicates that the algorithm can improve the efficiency of path planning and shows better kinematic performance in the task of obstacle avoidance.In this video we use the inverse dynamics of a rigid body that we derived in the last video to derive the Newton-Euler inverse dynamics algorithm for an open-chain robot. ![]() Finally, the proposed algorithm is verified by an 8-degree of freedom manipulator. The strategy use the distance between manipulator and obstacles instead of the collision state of manipulator to estimate the distance between new sample configuration and obstacle. In addition, a K-nearest neighbor–based collision detection strategy is integrated for accelerating the algorithm. Thus, it can stay the same for different obstacle avoidance path planning tasks. The potential field mainly considers indexes about manipulator itself, such as the minimum singular value of Jacobian matrix, manipulability, condition number, and joint limits of manipulator. On this basis, a potential field whose gradient is calculated off-line is established to guide expansion of rapidly exploring random tree. Firstly, some responding layer factors related to operational cost are used as optimization objective to improve the operational reliability. A rapidly exploring random tree optimization algorithm for space robotic manipulators guided by obstacle avoidance independent potential field is proposed in this article. The crucial problem of obstacle avoidance path planning is to realize both reducing the operational cost and improving its efficiency. The decline of vibration deformation of end effector is obviously larger than the rise of joint torque, which verifies the feasibility and effectiveness of the algorithm. The terminal deformation in two directions is reduced by 21.3% and 78.6%. Meanwhile, the running trajectory has excellent effect on vibration suppression of end effector of flexible manipulators. The forward torque of first joint increases 20.2% and that of second joint only increases 4.1% while the backward torque of both two joints decrease obviously. Finally, simulation result shows that the increase rate of joint torque is not very obvious based on the Particle Swarm Optimization algorithm compared with the experiment without vibration suppression. On the basis of decomposing the dynamic equation of the flexible redundant manipulator, the joint torque is optimized as well as restraining the terminal vibration through introducing the Lagrange multiplier. The bending deformation of flexible connecting rod is described by the assumed mode method and the dynamic model of space flexible manipulator system is derived by the Lagrange method. A joint torque optimization method of redundant space flexible manipulator with vibration suppression is proposed in this paper. However, the research has less consideration on joint torque optimization method with considering the influence of flexible factors on the manipulator. The space manipulator can exert its advantages of high efficiency and low cost, which can assist or even replace astronauts to complete a variety of space operations.
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