Research On Dynamic Control Of Vibration Isolation Platform Based On Parallel Mechanis

Ideal dynamic performance and high motion accuracy are the basic characteristics of parallel mechanism,so it can be used as a good vibration isolation configuration.The 6-RUS parallel mechanism is selected as the main mechanism of the vibration isolation platform in the design scheme.The dynamic control of the vibration isolation platform is analyzed and discussed emphatically.Dynamic model is the foundation of dynamic control,and its precondition is to establish a complete motion control system.The research of dynamic control mainly includes two aspects,namely,the establishment of dynamic model(6-RUS parallel mechanism)and the selection of control method.Dynamic analysis is essentially the theoretical basis of the construction of dynamic model,and kinematic analysis is the premise of dynamic analysis.Position analysis,velocity analysis and acceleration analysis belong to the category of kinematic analysis,but its core lies in the position analysis.The control strategy is divided into two kinds,that is,the control strategy based on kinematics characteristics and dynamics model of mechanism.Based on TwinCAT software,the motion control system of 6-RUS parallel mechanism vibration isolation platform was developed.Twin CAT HMI was adopted,and the required controls were taken from the control library.Real-time data variables were linked based on the interface design to complete the human-computer interaction design.The structural characteristics of vibration isolation platform of 6-RUS parallel mechanism are described.Meanwhile,Kutzbach-Grubler equation(modified version)is used to analyze the degree of freedom of 6-RUS parallel mechanism.It should be noted that overconstraint has been taken into account in this analysis.It lays a foundation for analyzing the dynamic coupling characteristics of 6-RUS parallel mechanism with different degrees of freedom by using the independent PD control strategy and the calculated torque decoupling control strategy.The inverse solution model of 6-RUS parallel mechanism vibration isolation platform was established based on component vector method.The velocity Jacobian matrix is obtained by vector derivative method.The mapping relationship(velocity of moving platform,input velocity of joint drive)is the focus of Jacobian matrix analysis.The mutual mapping between configuration coordinates and generalized coordinates is the key to the subsequent dynamics derivation.The dynamic model of vibration isolation platform(6-RUS parallel mechanism)was constructed based on virtual work principle.Combined with the known structural parameters of the mechanism,the inverse dynamics numerical simulation(based on Matlab software)was carried out,and the dynamic characteristics of the vibration isolation platform(6-RUS parallel mechanism)were analyzed.Simulation experiments were carried out on vibration isolation platform(6-RUS parallel mechanism)based on independent PD control and calculated torque decoupling control.The simulation results obtained by independent PD control and calculated torque decoupling control were analyzed and compared.The results show that the dynamic coupling inhibition ability and target signal tracking ability are higher when the calculated torque decoupling control is adopted.The dynamic performance of the controlled mechanism can be significantly improved.