Research On Humanoid Upper Limb System Based On Tensegrity Structure

Tensegrity structure is a kind of rigid-flexible hybrid structure composed of tension components and compression components.It has the characteristics of good flexibility,light weight and good impact resistance,and it is similar to the musculoskeletal system of organism.In recent years,more and more research and attention have been paid to the bionic tensegrity structure.Compared with the traditional rigid mechanism,the tensegrity structure has greater advantages in flexibility and adaptability.It has great application value in the field of flexible and bionic robot.At present,there are still many problems in the research of tensegrity structure,and the research on the bionic tensegrity structure is in its infancy.Based on the human upper limb structure,this paper proposes a kind of humanoid upper limb tensegrity structure,and makes theoretical research on its form finding,kinematics,stiffness calculation and analysis.It laid the foundation for the further application of the tensegrity structure to the upper limb structure.First of all,this paper introduces the tensegrity upper limb structure.On the basis of analyzing the lack of flexibility of the existing upper limb structure joints,two kinds of tensegrity hinge structures are used as the elbow joint and shoulder joint respectively,which make the elbow joint have one degree of freedom of rotation and the shoulder joint have two degrees of freedom of rotation,and it enables a wide range of motion.Secondly,in order to obtain the equilibrium position of the upper limb structure under different rope internal forces,this paper proposes a quasi-dynamic form-finding algorithm,and gives the selection method of virtual parameters,Further,the algorithm is developed as a static solution method of the structure under the action of external force,which can solve the equilibrium position of the structure under the action of gravity and load force.Aiming at the inverse kinematics problem of this structure,this paper introduces three methods which is a methods based on Jacobian matrix,a iterative search algorithm and a optimization method respectively,according to the known amount of pose parameters,and it is simulated and verified by NTRT.Then,the working space of the tensegrity humanoid upper limb structure is calculated by using the form-finding algorithm and the statics solution method,the joint stiffness of the structure is calculated by using the finite element method,and the change rule of the joint stiffness of the structure with the internal force of the rope and the position of the structure is analyzed.Finally,the method of virtual model modeling and simulation based on ROS and NTRT is introduced.The method is used to simulate the motion control of the structure.In addition,for the control of the actual physical model of the structure,the construction schemes of the two control systems are introduced.