A real-time impedance-based singularity and joint-limits avoidance approach for manual guidance of industrial robots. (17th September 2017)

• Record Type: Journal Article
• Authors: Mousavi Mohammadi, Ali; Akbarzadeh, Alireza
• Is Part Of: Advanced robotics. Volume 31:Number 18(2017)
• Page Start: 1016
• Page End: 1028
• Publication Date: 2017-09-17
• Subjects: Manual guidance -- singularity avoidance -- joint-limits avoidance -- impedance control -- path planning; Robotics -- Periodicals; Robotics -- Japan -- Periodicals; Robotics; Japan; Periodicals; 629.89205
• DOI: 10.1080/01691864.2017.1352536
• Languages: English
• ISSNs: 0169-1864

Abstract

Abstract: This paper studies real-time manual guidance considering singularity and joint-limits avoidance using impedance control in an industrial scenario. The operator is responsible for keeping the end-effector (EE) away from the robot's singularity and joint-limits. The proposed approach detects the singularity and joint-limits in real-time. Then, virtual stiffness and damping are added to target stiffness and damping as the robot is getting close to the singularity or joint-limit. A criterion is presented for detection of singularity by combining manipulability ellipsoid and condition number. Also a new joint to Cartesian space transformation is formulated in order to convert joint stiffness and damping to Cartesian stiffness and damping for joint-limits avoidance method. The presented approach is applied on a SCARA robot. An experiment is performed in this paper to investigate singularity and joint-limits avoidance separately as well as together. Increase in stiffness and damping warn the operator of the possibility of singularity or joint-limits allowing the operator to changes the EE path. The proposed approach, eliminates the need for a robotics expert by allowing any operator with no knowledge about robot singularity and joint-limits to interact and teach the robot in a safe, real-time and time-saving manner. Abstract :