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Mechanical arm autonomous robust singularity avoidance method for improving path tracking performance

A technology of path tracking and manipulators, applied in manipulators, program-controlled manipulators, manufacturing tools, etc., can solve problems such as unanalyzed and reduced path tracking performance, and achieve robust results

Active Publication Date: 2018-07-06
NORTHWESTERN POLYTECHNICAL UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Although the above method can avoid the singularity problem, it will reduce the tracking performance of the path. At the same time, the situation with multiple subtasks is not analyzed.

Method used

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  • Mechanical arm autonomous robust singularity avoidance method for improving path tracking performance
  • Mechanical arm autonomous robust singularity avoidance method for improving path tracking performance
  • Mechanical arm autonomous robust singularity avoidance method for improving path tracking performance

Examples

Experimental program
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Effect test

Embodiment 1

[0075] Single-task avoidance: the desired task in this embodiment is to track a circle in the workspace, and the time is 10s.

[0076] where α 0 =20,σ if =0.05,σ uf =0.02, K=diag(100,100) is used as the adjustment parameter, and the simulation that uses the STR method of the present invention to obtain is as figure 2 shown.

[0077] figure 2 It shows the simulation results of a 3-DOF planar manipulator tracking a circular trajectory in the task space using the STR method of the present invention. Figure (a) shows the tracking in the x-y plane, Figure (b) shows the tracking error in the task space, Figure (c) shows the variation curve of the minimum singular value during tracking, and Figure (d) shows the change of joint velocity curve. It can be seen that if the singularity avoidance strategy is not used, the singularity problem will occur between 4-5s. Using the STR method, the newly generated path effectively escapes the singularity area and ensures that the minimum ...

Embodiment 2

[0079] Multiple subtasks to avoid oddities: add a second task x 2 , keeping the orientation of the end effector at 90°, and verifying the robustness and singularity avoidance of the method for subtasks with task priorities.

[0080] The control parameter is K 1 =diag(1.5,1.5),K 2 =0.5; the obtained simulation results are as follows image 3 shown.

[0081] image 3The simulation results of a 3-DOF planar manipulator tracking a circular trajectory in task space while maintaining the orientation of the end-effector using the STR method are shown. Figure (a) shows the tracking in the x-y plane, Figure (b) shows the change curve of the joint velocity, Figure (c) shows the tracking error of the first task, Figure (d) shows the first task correlation during the tracking process The variation curve of the minimum singular value of the Jacobian matrix, figure (e) shows the tracking error of the second task, and figure (f) shows the variation curve of the minimum singular value of...

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Abstract

The invention discloses a mechanical arm autonomous robust singularity avoidance method for improving path tracking performance. The method comprises the steps that a maneuverable ellipsoid of a mechanical arm is built according to an inverse kinematics model of the mechanical arm and a mechanical arm speed model, wherein the semi-major axis of the maneuverable ellipsoid is in the direction of theU longitudinal row of a unitary matrix, and the length of the semi-major axis corresponds to singular value of a Jacobian matrix; and then the path of an end effector is amended in the mth spindle direction of the maneuverable ellipsoid, and the singularity avoidance path of the mechanical arm is built. The method can be used for planning the autonomous singularity avoidance path of the mechanical arm, can keep the tracking performance of the path, and can also achieve the multi-task singularity avoidance path planning on the basis of task priority based on the method.

Description

technical field [0001] The invention belongs to the technical field of space robot path planning and relates to an autonomous robust singularity avoidance method for a mechanical arm that improves path tracking performance. Background technique [0002] When the end effector of the manipulator autonomously tracks the path of the task space, when some configurations are close to singularity, a small speed change in the task space requires a huge speed in the joint space to complete, so the singularity will lead to a large tracking Deviation, but also has great damage to the mechanical arm structure. Therefore, it is necessary to establish a singularity-avoiding trajectory plan for the manipulator. [0003] A well-known method for dealing with singular problems is the extended Jacobian method proposed by C.A. Klein et al. The extended Jacobian can be applied to redundant manipulators, ensuring that the closed-loop joint-space trajectory corresponds to the closed-loop task-sp...

Claims

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Application Information

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IPC IPC(8): B25J9/16
CPCB25J9/1605B25J9/1664
Inventor 王明明罗建军袁建平朱战霞
Owner NORTHWESTERN POLYTECHNICAL UNIV
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