Abstract: Designing a stiffness joint structure that accords with the elbow parameters of the human body， make it better to help people in practical applications. Based on the parameters of the human elbow joint， a new variable stiffness joint structure is presented， which is in line with the human joint configuration. The new joint consists of leaf springs， planetary gear train and crank-slider mechanism. The sun gear and the ring gear are driven by two different motors， and the rotations of the planetary gears are turned into the movement of the sliders. The supporting positions of the leaf springs change as the sliders move， and the stiffness of the joint is adjusted. Compared with that of the other similar designs， the structure and the layout of the new joint presented are in much more accord with the configuration of the human joint， and the new joint could be applied to other joint designs.

Key words: variable stiffness joint, structure design, elbow joint, bionic robot, experimental analysis