Research On Dynamics Modeling And Trajectory Planning Of 7-DOF Redundant Manipulators

With the development of space defense technology, the role of space robots in space missions is more and more important. This paper researched three issues about seven- freedom space redundancy manipulator, which are flexible joint manipulator dynamics recursive algorithm, online trajectory planning algorithm and time optimal trajectory planning based on genetic algorithms.For complex multi- DOF manipulator system, the degree of freedom leads to its calculation of kinetic equations increase, which is difficult for real-time control. As a starting point, this paper studied an efficient and can be used for real-time control flexible joint manipulator recursive dynamics algorithms. In order to improve universal of the algorithms, modified DH parameters was used to describe the robot. In order to improve programming and computational efficiency, spinors were used to describe motion and kinetic parameters. On this basis, a dynamic model of the robotic arm was established. Forward dynamics researched Articulated Bod y Algorithm(ABA) and Composite Rigid Body Algorithm(CRBA). Inverse dynamics researched Newton-Euler algorithm. A flexible joint model was established, and used ABA to flexible joint manipulator. After simulating the algorithm, the correction of the algorithm was proved with the contrast of Sim Mechanics results, and the algorithm is real-time and universal.Manipulator must plan its trajectory before performing the various tasks. For continuous path, the planning needs in Cartesian space. To converse Cartesian space pose into the joint space, inverse kinematics in speed level is established. When the arm is around the singular position, joint torque is too big which is hard to achieve. In this paper, damped least square method is used to avoid singularity, and optimized its avoiding singularity indicator using its redundancy features. Linear and circular motion in Cartesian space was simulated. Simulink simulation proved the correction of trajectory planning and singularity avoiding.Reducing time of tasks can improve their work efficiency. This paper studies the optimal trajectory planning method with the constraints of joint angular velocity, angular acceleration and torque. Since the GA has the advantages of global search capability and more efficient co mputing, the genetic algorithm was used to optimize trajectory. Contrasting the trajectories before and after optimization, the results showed that the optimized trajectory can improve the efficiency of the robotic arm.In order to achieve visual simulatio n for algorithm, the paper wrote dynamics and trajectory planning simulation software. The software is applicable to the general manipulator system. Finally, the experimental results verify the manipulator trajectory planning algorithm is correct.