Abstract:  The assisted training of rehabilitation robots could greatly relieve the pain of patients. Aiming at the current large size, heavy weight and unable to guarantee interaction with patients, a new four-node flexible mechanism design was proposed to absorb the vibration of the robotic arm and ensure the safety of patients. The Lagrangian method was used to dynamically analyze the spring, and the stress and strain of the spring were analyzed by finite element software. The safety factor of this flexible element was 2.94 and the minimum service life was 716.1 h. The experimental results show that the maximum stress of the flexible element is 440 MPa, the maximum deformation is 3.19 mm, the stress and deformation of the flexible element are linearly related to the torque, and the maximum strain energy is 0.546 MJ, which is nonlinear with the torque. The relationship can be used for the flexible connection of the robotic arm, and it also provides a technical verification method for solving such problems.

Key words:  rehabilitation robot; torsion spring; finite element analysis; fatigue life