Choi, Junho Park, Sunchul Lee, Woosub Kang, Sung-Chul 2024-01-19T13:09:38Z 2024-01-19T13:09:38Z 2022-03-07 2008 1050-4729 https://pubs.kist.re.kr/handle/201004/116082 A robot joint with a variable stiffness unit is presented. The variable stiffness unit (VSU) is composed of a motor, two rings that consist of arc-shaped magnets separated by spacers, and a linear guide to change the cross-sectional area of the two rings. Angular displacement between two rings causes the magnets to generate torque, which acts as a nonlinear spring. The stiffness of the joint is varied via changing the overlapping area of the magnets. The VSJ exhibits nearly zero stiffness, which enables robot manipulator to be harmless to humans at a wide range of operating speed. Connected to a joint motor in series, the stiffness by the VSU and the position of the joint are controlled independently by two motors. The torque generated by the magnets is analyzed. Using dynamics of the joint, feedback linearization method is adopted to control the VSJ. In addition to feedback linearization, an integral controller is augmented in order to reduce the effect of model uncertainty and disturbances. English IEEE Design of a robot joint with variable stiffness Conference 10.1109/ROBOT.2008.4543455 1 IEEE International Conference on Robotics and Automation, pp.1760 - 1765 IEEE International Conference on Robotics and Automation 1760 1765 US Pasadena, CA 2008-05-19 2008 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1-9 000258095001067 2-s2.0-51649120178 Proceedings Paper