| In this paper,the single-degree-of-freedom,one-translation,two-rotation space parallel vibrating screen mechanism and the three-translation2P4R(Pa)-PR(Pa)R parallel mechanism proposed by the team are analyzed in reverse dynamics and forward dynamics;at the same time,according to the dynamics The analysis results are optimized for dynamics to improve the dynamic performance and operational stability of the two parallel mechanisms.First,according to the topology design method of the parallel mechanism based on the POC equation and the kinematics solution method based on the topological feature,the parallel vibrating screen mechanism and the three translational 2P4R(Pa)-PR(Pa)R parallel mechanism are respectively topologically analyzed and kinematics analysis,the POC set,degree of freedom,coupling degree and other topological characteristics of the two mechanisms,as well as speed and acceleration,are obtained,which lays the foundation for the dynamic analysis of the mechanism.Then,the ordered SOC method based on the Newton-Euler and virtual work principle and the Lagrange method were used to model the parallel vibrating screen mechanism in reverse dynamics;the traditional virtual work principle method and the sequence based on the virtual work principle were used.The SOC method performs reverse dynamic analysis on the three-translational 2P4R(Pa)-PR(Pa)R parallel mechanism,and obtains the change curve of driving force and torque;further,by comparing the calculated value of the theoretical formula with the result of the simulation value,it is verified the correctness of the kinetic modeling process;at the same time,the SOC method is compared with the traditional virtual work principle method and the second type Lagrange method to show the advantages of this method.Then,using the ordered SOC method based on the principle of virtual work,the two mechanisms are modeled in forward dynamics,and the dynamic response equation is established,the dimension of which is exactly the DOF of the mechanism;first,a special assignment is made to the generalized velocity,Determine the coefficient matrix elements of the dynamic response equation;then use the Euler method to solve the numerical solution of the differential equation of motion.Further,compare the calculated value of the theoretical formula with the simulated value of ADAMS to verify the correctness of the ordered SOC method based on the principle of virtual work.It reveals the real law of motion of the screen surface of the vibrating screen mechanism and the moving platform of the three translational parallel mechanism.The method is simple in form and greatly reduced in calculation,which provides a technical basis for the subsequent dynamic control of the mechanism.Finally,the length and quality parameters of the rod are used as design variables,and the two performance indicators of reachable working space and energy transfer efficiency are used as the objective function.The kinematics and dynamics performance of these two mechanisms are optimized and designed to obtain these two The optimal solution of the mechanism under the above two performance indicators. |
