Original scientific paper

https://doi.org/10.17559/TV-20140917061048

Obstacle avoidance planning for redundant manipulator based on variational method

Xifeng Liang ; College of Mechanical and Electrical Engineering, China Jiliang University, 310018 Hangzhou, Zhejiang, China
Tao Zhou ; College of Mechanical and Electrical Engineering, China Jiliang University, 310018 Hangzhou, Zhejiang, China
Binrui Wang ; College of Mechanical and Electrical Engineering, China Jiliang University, 310018 Hangzhou, Zhejiang, China

Abstract

To reduce the excessive joints movement, this paper proposed a new obstacle avoidance method for a redundant manipulator. In this method, we designed the performance evaluation functional to realize the shortest joints motion path of manipulator, and deduced the gradient vector optimizing index by variational method to make the joint movement minimum during obstacle avoiding. Meanwhile, in order to avoid the obstacle avoidance algorithm failure or joints exceeding their limits, which arose from the great difference between least-norm solution and homogeneous solution of velocity inverse kinematics of the manipulator, this paper used 2-norm continuous function to adjust homogeneous solution factor of gradient projection method dynamically. To verify the validity of the proposed obstacle avoidance method in the paper, simulation experiments were conducted on a 7-DOF redundant manipulator. The results show that, compared to the traditional gradient projection method for obstacle avoidance, the proposed algorithm in this paper has decreased the displacement of joint 1 to joint 6 by 38,3 %, 83,3 %, 3,81 %, 7,85 %, 50,1 % and 45,6 % respectively, and the total displacement of prismatic joints and revolute joints has reduced 62,2 % and 26,4 %. At the same time, the changes of joint 1 to joint 6’s velocity and acceleration between initial time and final time during obstacle avoiding has been decreased 43,2 %, 97,3 %, 2,23 %, 36,6 %, 96,7 %, 72,7 % (velocity) and 91,04 %, 98,28 %, 73,33 %, 98,40 %, 93,86 % and 91,94 % (acceleration) respectively. The test validated that the proposed obstacle avoidance method based on variational method is feasible and practicable.

Keywords

gradient projection; obstacle avoidance; path planning; variational method; redundant manipulator

Hrčak ID:

183020

URI

https://hrcak.srce.hr/183020

Publication date:

15.6.2017.

Article data in other languages: croatian

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