High Precision Positioning Platform Thermally Induced Error Compensation And Stiffness Model

In recent years, the high precision positioning platform is widely used insemiconductor fabrication, MEMS, biochip, biomedical and other fields. With the rapiddevelopment of precision machining technology, there is a higher requirement for precisionpositioning technology. Temperature and vibration are the main factors which influence theprecision of the positioning platform. In order to improve the accuracy of positioningplatform, reducing or eliminating the vibration of the thermal error and positioningplatform have drawn wide attention of the researchers around the world. On the basis ofestablishing the stiffness and thermal error model by the domestic and foreign scholars,this topic studied on the thermal error model and stiffness model of high precisionpositioning platform. Contents include as following:Based on the basic law of thermal, determine the main heat source and heat transfer ofthe positioning platform. Thermal and thermal stress coupling analysis was carried out onthe positioning platform by using the finite element simulation method. Determine thepositioning platform distribution regularity of temperature distribution and displacementvariation. In order to ensure the accuracy of the thermal error model, the choice of the keypoints is particularly important. Using grey correlation theory, select the points ofpositioning platform surface whose correlation between the value of temperature changeand the displacement as the critical temperature measurement points.In order to establish the thermal error model, temperature of measurement key pointsis as the input values of modeling. Using the multivariate linear regression modelingmethod, the BP neural network modeling method and RBF neural network modelingmethod establish thermal error model, respectively. By comparing the accuracy of three themodel, a most suitable one is determined.In order to provide theoretical foundation for the vibration analysis of the platform,propose a modeling method of the platform’s stiffness which changes with the temperature.Finite element stiffness analysis was carried out on the positioning platform to solve the stiffness value of positioning platform under different temperature value. Use the BP neuralnetwork method to establish the model of stiffness which changes with temperature.