RESEARCH ON DESIGN AND CONTROL OF A NEW TYPE FLEXIBLE JOINT WITH VARIABLE STIFFNESS

Abstract

Aiming at non-linear problems existing in the principle of variable stiffness of robot joints, a class crank-slider and planetary gear mechanism are presented. The spring is pre-compressed by using the inter-agency geometric relations of fulcrum movement. The approximate linear variation of stiffness about fulcrum offset is realized. The problems of mechanism clearance, operational stability, and compact space are solved. The joint stiffness calculation method is derived, and the relationship between key parameters and stiffness outputs is analyzed. The stiffness control strategy is researched on, and a trajectory generator is designed based on Taylor series expansion. Static stiffness identification and dynamic stiffness following experiment are designed to test joint stiffness and position characteristics. The feasibility of joint is verified to achieve stiffness and position continuous adjustment within a certain range. This type of joint can be used in the field of medical treatment and rehabilitation to solve the problems of safety and environmental adaptability in the application process.