Design and test verification of variable stiffness joint based on composite gear train

ObjectiveAiming at the problems of poor human-machine interaction and limited stiffness adjustment range of traditional joints, a new type of variable stiffness joint based on composite gear train was designed. By changing the rotation mode of the gear train, “stiffness adjustment” and “constant stiffness output” were realized to improve the environmental adaptability of the joint.MethodsFirstly, the variable stiffness principle, configuration and main structure of the joint were analyzed in detail, and its stiffness adjustment range was calculated. Secondly, kinematics analysis was carried out to explore the motion law of the composite gear train and the mathematical relation of stiffness adjustment. Finally, a prototype was fabricated, and a test platform was built to conduct stiffness measurement tests.ResultsThe results show that the adjustable range of the joint is 0-1.345×106 N·mm/rad. The similarity between the test curve and the theoretical curve is 0.92, which verifies that the designed joint has good variable stiffness characteristics.