Performance Analysis And Experimental Study On Parallel Bionic Ankle Joint Of Humanoid Robot

The joint is an important component of humanoid robot,its performance directly decides overall performance of the humanoid robot.Ankle joint is both stable and flexible as a load-bearing joint,and it is a hub connecting humanoid robot with ground.In this paper,humanoid ankle is taken as the study object,spherical parallel mechanism with few DOFs is taken as prototype,configuration design,performance analysis,bionics design,functional experiment and others are conducted.The main contents are as follows:According to the principle of bionics design,the original UP+R+S configuration mechanism is modified with retaining the advantages of strong stiffness and static unloading,etc,four new configurations of bionic ankle joint mechanism are proposed,and the corresponding spherical parallel mechanisms with 2-DOFs are synthesized.One of the configurations is chosen to carry out subsequent development studies,the forward and inverse position solution,the Jacobian matrix of the selected configuration are obtained,and then,use MATLAB and ADAMS to verify the correctness of the inverse position solution.Trajectory planning of bionic ankle joint mechanism in joint space is conducted by using trajectory planning method with acceleration as symmetrical continuous function.The angular velocity and centroid velocity of the moving parts and the attitude angle of the side rod in the bionic ankle joint mechanism are solved.Based on the SolidWorks assembly environment,a method for calculating the inertial tensor of each moving part relative to the center of mass coordinate system in the initial pose state is put forward.In view of the Lagrange equation,the dynamic equation of the bionic ankle joint mechanism is established,and the driving force of the driving joint is obtained by combining virtual work principle.The MATLAB software is used to calculate the driving force,and the results are compared with the simulation results in ADAMS,to verify the correctness of the dynamic model.After the driving unit's style and model of bionic ankle joint selected,the structural design of key parts such as supporting ball hinge,moving platform,curved arc support,clamping mechanism and side limbs are accomplished.The whole model of prototype is finished and the specific dimensions of each component are determined.Planning the assembly sequence of the parts,the machining,debugging and assembling of the prototype are performed,developing a bionic ankle joint prototypeThe control scheme of the bionic ankle joint prototype is selected,and a set of open control system based on PC + multi-axis motion control card + AC servo unit is designed.The model and communication connection of each hardware of the control system are determined.The parameter-setting and debugging of relevant hardware of the control system are performed,and the relevant gain parameters of the servo control loop are adjusted.At last,experimental study on the performance and motion function of the prototype is carried out,to test the work space and motion function of the prototype,which provides the physical basis and practical guidance for further research of the bionic ankle joint prototype.