Research On Driving Method And Optimal Design Of 6-Dof Parallel Attitude Adjustment Mechanism With Redundant Driving

Redundant parallel mechanism has higher load capacity and stiffness than non redundant parallel mechanism.It has been widely used in many fields,such as industrial robots,special material processing or multi degree of freedom machine tools,Aerospace Satellite folded antenna and special medical devices.However,due to the existence of over constraint,there are great difficulties in attitude adjustment,which restricts the redundant parallel mechanism The further application of driving parallel mechanism.This paper introduces a 7-sps redundant drive parallel mechanism suitable for large heavy load environment.Aiming at the requirements of high load,long intermittent adjustment time and high precision of ground radio telescope or other high precision equipment,a redundant drive parallel mechanism with simple structure and convenient attitude adjustment is designed.This paper mainly includes the following aspects:First,two methods for adjusting the attitude of the redundant-driven six-degree-of-freedom parallel mechanism are proposed.The first method is coordinated drive adjustment,and the entire adjustment process is redundant drive;the second method is less active input adjustment,and the adjustment process is non-redundant After the adjustment is completed,it will be redundant drive.Then according to the characteristics of the two adjustment methods,choose to use the faster and more accurate Newton iteration method to calculate the forward solution of the 7-SPS parallel mechanism,verify the correctness of the algorithm through the positive and negative solutions of the position,and compare the movement principle of the two adjustment methods.A numerical example analysis was carried out.Then the force analysis of the redundant drive parallel mechanism under two different driving methods is carried out,and the overall stiffness and the coordinated conditions of displacement and deformation are comprehensively considered to calculate the relationship between the 7 branch chains and the 6-dimensional external force on the movable platform.The non-over-constrained parallel mechanism in the adjustment process is directly obtained by the force Jacobian matrix,and discrete points are taken in the adjustment process to study the force situation in the whole process.Then,the simulation verification of the mechanism posture adjustment proves the feasibility of the adjustment of the six-freedom over-constraint parallel mechanism with less active input.The rigid body-flexible body coupling model is established and the force simulation is carried out for a certain configuration during the adjustment of the six-degree-of-freedom adjustment strategy with less active input,and the comparison with the foregoing theoretical calculations is carried out to ensure the correctness of the theoretical calculation of the force of the over-constrained mechanism.Finally,the dimensional parameters of the mechanism are optimized,and the optimal position of the upper and lower hinge points of the driving branch is found.Comparing the configuration of the optimized mechanism with the classic Stewart parallel mechanism to analyze the working space to explore the influence of the driving branch on the working space.Finally,the principle prototype will be built,and the experiment of position and posture adjustment will be carried out.