Design Method For A Bionic Upper Limb Forearm Based On Tensegrity Structure

According to the biological characteristics of the human body and based on the tensegrity structure,a bionic wrist joint of upper limbs is proposed,which is lighter in weight,smaller in volume and equivalent to the tensegrity structure.This stretched bionic wrist joint realizes its movement characteristics by contracting and extending springs to simulate the contraction of human muscles.The traditional bionic upper limb structure design is limited by the motion pair and cannot guarantee the flexibility of the mechanical structure.Therefore,the tensegrity structure is used to perfectly solve this problem,that is,the flexible and rigid system is combined with the benefits of the structure in the traditional design.The joint can not only make the robot joint work in unpredictable environment,but also meet the characteristic requirements of functional flexibility and structural adaptability.The main research contents of this article are as follows:(1)The tensegrity structure has the characteristics of high deformability,strong self-adaptability,and resistance to multi-directional impact.According to the biological characteristics of the upper limbs of the human body,an anatomical study is performed on the upper limb wrist joints that achieve adduction/abduction,flexion/extension,in order to obtain the relationship between the movements of the related bones and muscles,and to simplify the shape and structure of the wrist.Equivalent mapping of a mechanical model based on two-bar tensile properties.Through the contraction and stretching of the spring,the movement characteristics of the human muscles are realized,and the optimized bionic upper limb wrist tensioning robot without motion pair is further obtained.(2)The inverse dynamics method is used to solve the motion position of the mechanism,and the formula for calculating the size parameters of the elastic elements of the bionic wrists is derived and the spring stiffness coefficient is matched,which the theoretical method of mechanism motion analysis is given.(3)On this basis,Adams simulation is used to verify that the bionic tensile wrist can simulate the change movement of the human wrist,and the correctness of the theoretical calculation formula.The experimental platform was built and a physical prototype was made and the prototype was tested.The results show that the bionic tensile wrist can realize the adaptive motion characteristics of human wrist well and stably,which proves the validity and feasibility of this design method.Finally,the simulation modeling verifies that the designed wrist exoskeleton robot has good comfort and practicability.