Singularity avoidance for manipulators with spherical wrists using the approximate damped reciprocal algorithm. (29th March 2021)

• Record Type: Journal Article
• Authors: Yu, Tiantian; Wang, Daqing; Gao, Lifu
• Is Part Of: International journal of advanced robotic systems. Volume 18:Number 2(2021)
• Publication Date: 2021-03-29
• Subjects: Singularity avoidance -- Jacobian matrix -- singular factor -- damped reciprocal -- spherical wrist; Robotics -- Periodicals; Robotics; Periodicals; 629.892
• DOI: 10.1177/1729881421995681
• Languages: English
• ISSNs: 1729-8806

Abstract

Due to the loss of freedom, the stability and tracking ability of the manipulator around the singularity become worse. This article aims at improving the accuracy of the manipulator and ensuring the stability of the system with the damped reciprocal method. Firstly, the singularities are separated into forearm and wrist singularities to obtain the singular factors of the manipulator respectively. Secondly, a new mathematical function of the approximate damped reciprocal of the singular factor is proposed. Thirdly, the singularities are avoided by modifying the Jacobian matrixes of the manipulator with the approximate damped reciprocal algorithm. Finally, the effectiveness and the stability of the system are proved by the simulations on a manipulator with the spherical wrist. The simulation results prove that this method can largely improve the accuracy of the end-effector and can ensure the stability of the system around the singular region.