Multi-objective Optimization Design And Control Of A Force Loading Platform Based On Parallel Mechanism

With the rapid development of domestic manufacturing industry,the reliability of CNC machine tools has received more and more attention.The traditional reliability research method of CNC machine tools has the shortcomings of long research period and high cost,which seriously restricts the development of reliability of domestic CNC machine tools.In response to these problems,this paper proposes a five-degree-of-freedom force loading platform based on parallel mechanism that can continuously apply a loading force to the machine tool to simulate the cutting forces in the five directions of the mechanism.The outstanding advantage is that it can continuously perform force loading for a long time,and simulates the cutting force,eliminating the cost of cutting the actual workpiece.The main content of this article has the following aspects:A force loading platform based on parallel mechanism is designed.The degree of freedom is analyzed.The parallel mechanism modeling methods such as vector loop method and virtual work principle method are used to model the kinematics and dynamics of the force loading platform.Then,using MATLAB software to simulate and verify the kinematics and dynamics model of the mechanism,it lays the foundation for the subsequent optimization design and control of the mechanism.The force loading platform based on parallel mechanism is optimized.Firstly,the singularity of the organization is analyzed to determine the singularity of the mechanism under certain special poses.Then,a method to optimize the singularity of the mechanism by optimizing the installation angle of the partial branches is proposed.After that,the optimization parameters of the mechanism,as well as the three optimization performance indexes of work space,force isotropic and stiffness are determined.The size and angle parameters of the mechanism are optimized by the map method,and the performance map and multi-objective of each performance index are obtained.Optimize the map and get the optimal area for optimal design.Finally,the performance indicators before and after the optimization of the organization are compared,and it is found that the performance indicators have a significant improvement after optimization.The derivation of the control system model based on the gas pressure servo control system is completed.The physical model of the single-channel gas pressure servo system is linearized and approximated,and the linearized transfer function model is obtained.The open-loop Bode diagram and closed-loop Bode diagram of the transfer function are analyzed to know that the system is stable.The time domain response of the step function is analyzed.Then,the PID controller is added to the control system model to obtain an excellent time domain response curve by adjusting the PID parameters.Finally,the five-channel gas pressure servo system is co-simulated,and the simulation curve and error curve of the PID controller and the PID controller are added.The results show that the system response speed is significantly improved and the error is significantly reduced after adding the PID controllerThe software and hardware system design of the parallel mechanism force loading platform is completed.The hardware system of the parallel mechanism force loading platform was built by selecting the air pressure servo system control mode.The corresponding electrical diagram is drawn.The control software of the parallel mechanism force loading platform is completely developed,including the control software main interface,kinematics and dynamics inverse program,C# to TwinCAT ADS connection program and machine tool communication connection program.