Research On Static Stiffness Of New 3-DOF Over Constraint Parallel Mechanism

Recently,the theory and experiment study of low-degree-of-freedom parallel mechanism has become one of the most important areas in robot science.Static rigidity means that a structure is able to remain in its present location when it is under a static load.If the stiffness is not enough,there will be big distortion,low accuracy and big amplitude in high-speed movement.The main content of this thesis is to study the stiffness of the new configuration of UP+SPU+SPR parallel mechanism.First,the reference frame of the parallel machine and the stationary platform is set up.Based on this,the movement of the mechanism is analyzed.Then,the key parameters are defined based on the restriction conditions.The Monte Carlo algorithm was used to plot the working space of the mechanism,and the flexible performance in the workspace was analyzed.Secondly,the static stiffness analytical model of the parallel mechanism is established.Since the branch chain will produce axial and torque,it is necessary to disassemble the deformation of the two parts.The static stiffness of the components of each branch chain of the mechanism was analyzed by virtual work principle and linear superposition method was used to obtain the branch chain stiffness.Then,the same method was used to obtain the overall static stiffness model.A rigidity index is determined to determine the rigidity of the machine.By analyzing the index,particle swarm optimization algorithm is used to optimize the mechanism to achieve the optimal solution.Then,the establishment of three-dimensional model of institutions,and the corresponding simplified.Selection of appropriate materials,finite element analysis in ANSYS,exerts the same force and in the end of the institutions around the misalignment of the deflection of the equivalent torque for institutions,the comparison results and calculation error.Finally,because there is coupling relationship between shaft and influence control performance,dynamic performance of the inertia will reduce the coupling characteristics of institutions and the serious influence the use of parallel mechanism.So on the basis of the dynamic model and extract inertia coupling characteristic index,using the numerical simulation of inertia coupling features,analysis of the trend of inertia coupling to the drive shaft is obtained.