Research And Design Of Variable Stiffness Bionic Joint

Service robots is required to complete the various complex tasks, and in interacting with the human operator to ensure human safety and the robot itself. By installing the nonlinear elastic elements on the robot joint can change joint stiffness, when collision occured such flexibility based on mechanical systems can avoid the disadvantage of slow feedback and poor economic if use active safety. Selecting the appropriate variable stiffness element to achieve joint stiffness characteristic change is very important in antagonistically driven joints. In this paper conducted in depth research based on the parallel-driven variable stiffness elbow joint, the main contents include the following aspects:1. Analyzed the existing variable stiffness device mechanical structure and variable stiffness principle, determined the variable stiffness principle of the variable stiffness device and used the against parallel driven mode according to characteristics of the human elbow joint.2. Derived the reason of several typical unit combined nonlinear mechanism and linear spring to achieve varying stiffness and related formulas.3. Using MATLAB realized the variable stiffness element variable stiffness properties and their improved type’s performance analysis, and ultimately decided to adopt an isosceles obtuse triangle variable stiffness, S-type cooperating with the slider-crank and compression spring variable stiffness and slider-crank variable stiffness these three ways of variable stiffness do dynamic analysis under the external shocks.4. Using mechanical dynamics simulation software ADAMS to build the model of variable stiffness unit and virtual elbow joint, analyzed characteristics of the virtual joint installed two different variable stiffness element and slider-crank variable stiffness joint subjected to heavy shocks joint angle and force conditions, proved variable stiffness elbow joint can effectively absorb external shocks and joint which installed S type variable stiffness unit is able to achieve better protection of the robot itself.5. Finally use three dimensional modeling software CATIA completed variable stiffness unit and humanoid elbow modeling. By changing stiffness of the linear spring used in the joint can change the size of the elbow with a load capacity and its related dynamic performance.