Mechanical arm tail end trajectory tracking algorithm based on null space obstacle avoidance

A trajectory tracking and robotic arm technology, applied in manipulators, program-controlled manipulators, manufacturing tools, etc., can solve problems such as large end-track tracking errors, and achieve good results, simple numerical calculation, and improved trajectory tracking accuracy.

Active Publication Date: 2021-07-23
ANHUI UNIVERSITY OF TECHNOLOGY
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AI Technical Summary

Problems solved by technology

[0003] The technical problem of the present invention is: to overcome the deficiencies of the prior art, to provide a trajectory tracking algorithm for the end of the robot arm based on zero-space obstacle avoidanc

Method used

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  • Mechanical arm tail end trajectory tracking algorithm based on null space obstacle avoidance
  • Mechanical arm tail end trajectory tracking algorithm based on null space obstacle avoidance
  • Mechanical arm tail end trajectory tracking algorithm based on null space obstacle avoidance

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Embodiment Construction

[0037] The implementation process of the whole invention is shown in figure 1 , the specific implementation details are as follows:

[0038] (1) Establish the positive kinematics equation of the redundant manipulator

[0039] The homogeneous transformation matrix of each link

[0040]

[0041] Among them, q i is the joint angle, ai-1 is the connecting rod length, α i-1 is the torsion angle, d i Offset for the connecting rod. figure 2 It is a 7-DOF manipulator kinematics model diagram.

[0042] The positive kinematic equation of the tool coordinate system at the end of the manipulator relative to the base coordinate system is described as

[0043]

[0044] Among them, q=[q 1 ,q 2 ,q 3 ,q 4 ,q 5 ,q 6 ,q 7 ] T is the joint angle vector, R Tool is the end pose matrix, p Tool is the end position vector. The homogeneous transformation matrix T(q 1 )T(q 2 ),…,T(q 7 ), so that the positive kinematics equation T(q) of the redundant manipulator can be obtained...

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Abstract

The invention provides a mechanical arm tail end trajectory tracking algorithm based on null space obstacle avoidance. A minimum pseudo-distance in an analytic form is adopted to replace a traditional Euclidean distance to serve as a proximity index of obstacle avoidance, and a null-space obstacle avoidance task of a mechanical arm is completed in combination with a gradient projection method. A self-adaptive positive definite coefficient matrix K and a speed error saturation function sat(e<.>) are designed to feed back a real-time tail end trajectory operation result to a redundant mechanical arm kinematics inverse solution, and the joint angular speed is self-adaptively adjusted according to the feedback result so as to reduce the tail end trajectory tracking error. According to the mechanical arm tail end trajectory tracking algorithm based on the null space obstacle avoidance, the tail end trajectory tracking problem of the redundant mechanical arm is solved, and meanwhile the null-space obstacle avoidance task is completed; obstacle avoidance action can be taken in advance by adopting pseudo-distance, stable space operation of a mechanical arm joint is ensured, the trajectory tracking precision can be remarkably improved by adopting the tail end trajectory tracking algorithm, and a tail end main task is completed to the maximum extent; and the simulation experiment result of the redundant mechanical arm verifies the effectiveness and superiority of the algorithm.

Description

technical field [0001] The invention belongs to the field of motion planning algorithms of manipulators, and in particular relates to a trajectory tracking algorithm at the end of a manipulator based on zero-space obstacle avoidance. Background technique [0002] Redundant manipulators have better flexibility and operability due to the redundancy, and at the same time have great advantages in motion obstacle avoidance, singularity avoidance, joint torque optimization, etc., and have become a research hotspot in the field of robotic frontier technology. one. However, if the robot collides with obstacles during its movement, the robot arm will not be able to complete a given task, or even cause irreversible damage to its own robot arm. Collision-free motion planning has become an important prerequisite for its application in the industrial field. Robotic obstacle avoidance can be divided into zero-space obstacle avoidance and obstacle avoidance where obstacles appear at the e...

Claims

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Application Information

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IPC IPC(8): B25J9/16
CPCB25J9/1666B25J9/1605
Inventor 刘雪飞徐向荣朱佐君江杨林周攀朱永飞
Owner ANHUI UNIVERSITY OF TECHNOLOGY
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