Research On Dynamic Control Of 6-RUS Parallel Mechanism Based On Lie Group And Lie Algebra

Compared with the series mechanism,the parallel mechanism has the advantages of good stiffness characteristics,small self weight load ratio,strong bearing capacity and high accuracy,and it also saves more space in structure.Parallel mechanism has important application value in the fields of high-precision automatic positioning,multi degree of freedom control and so on.For the parallel mechanism with definite configuration,the establishment and analysis of the model and the selection of the control method have a crucial influence on its performance.In this dissertation,6-RUS parallel mechanism is taken as the research object.The perturbed molecular subspace base and the driving force subspace base are constructed,and the motion screw needed for dynamics analysis are obtained.The degree of freedom of the parallel mechanism is solved by using G-K modification method,and the choice of the driving pair of the parallel mechanism is verified.Based on D-H algorithm,the inverse solution of the mechanism is studied,then the simulation and numerical analysis of inverse kinematics position solution are realized by Matlab.Based on spinor theory,the generalized inverse jacobian matrix of the parallel mechanism is solved.The hessian matrix of the 6-RUS parallel mechanism is deduced,and a numerical example of the parallel mechanism is given.Based on the theory of lie group lie algebra,the inertial force spiral and gravity spiral of each part of the mechanism are analyzed.On this basis,the dynamic model is established by using the principle of virtual work,and numerical simulation is carried out.Through comparison and analysis,the dynamic algorithm of 6-RUS parallel mechanism based on lie group lie algebra is obtained.Based on the dynamic model,according to the control requirements of the end executor,respectively for fixed point control and trajectory tracking control problems analyzed.It is concluded that the dynamic control can make the controlled mechanism have good dynamic performance,and the calculated torque control method can effectively improve the control accuracy of the dynamic model,to realize accurate tracking of terminal motion trajectory.