Inverse kinematics method for space mechanical arm under single-joint locking failure

Abstract

The invention relates to an inverse kinematics method for a space mechanical arm under a single-joint locking failure. According to the characteristic relation between an SSRMS mechanical arm and an improved mechanical arm of the SSRMS mechanical arm, the inverse kinematics result of the equivalent mechanical arm of the SSRMS mechanical arm is used as the iterative initial value of the algorithm, and the time for the algorithm to be converged to the optimal value can be greatly shortened. During calculation, on the basis of the particle swarm algorithm, grouping operation is added, social behaviors of the biological boundary are simulated, communication between an elite group and a common group is carried out in each iteration, individuals with adaptive value differences are replaced, subgroup merging operation is carried out in the later stage of iteration, the convergence speed of the method can be improved, the calculation time of the algorithm is shortened. and the calculation time can be reduced on the premise of completing task requirements. The algorithm is a numerical solution method and can be analogically popularized to mechanical arms of other configurations, in addition, the method can further be used for calculation of inverse kinematics of the mechanical arm under the condition that joints are normal, and high universality is achieved.

Description

technical field [0001] The invention belongs to the field of inverse kinematics of space manipulators, and relates to a method of inverse kinematics of space manipulators under single-joint locking failure. , a solution method of inverse kinematics based on particle swarm optimization algorithm is proposed. Background technique [0002] With the development of space application technology, the space manipulator plays a very important role in space, including on-orbit service and assembly, space debris cleaning, etc. Most space manipulators are redundant manipulators. Compared with 6-DOF manipulators, redundant manipulators have great advantages in avoiding obstacles and avoiding strangeness. The cost of the space manipulator is high, and it is usually designed to perform as many tasks as possible. In the complex and changeable space environment, the joint actuators and sensors of the manipulator are likely to fail. Timely and effective maintenance is essential for space It...

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Problems solved by technology

[0003] Taking the 7-DOF SSRMS manipulator with offset shoulders, elbows, and wrists that has been applied to the International Space Station as an example, the existing literature has studied the inverse kinematics solution method of the SSRMS space manipulator under single-joint locking failure. After a systematic discussion, the locking of a certain joint of the robotic arm will degenerate into a 6-degree-of-freedom robotic arm. When the joints 1, 2, 6, and 7 are locked, the robotic arm meets the Pieper criterion, and the analytical solution of inverse kinematics can be obtained. When the joints 3, 4, and 5 are locked, the manipulator does not satisfy the Pieper criterion. In this case, a method for numerical iteration using the relationship between the actual manipulator and the improved manipulator is proposed in this paper. When iterating, due to the multiple solutions of the inverse solution, the calculation of the iteration increment is not unique, and there is no mention of which increment to select or how to select the increment to calculate the next iteration value, so this method exists during the execution process. some deficiencies

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