Study On Load Characteristics Of Friction Torque For Load Simulator

This thesis is based on a practical project.To study the performance of the aircraft servo control system,it is necessary to simulate the practical operating environment of the servo system on the ground.The load simulator is usually used to simulate the various load conditions that the servo system was subjected to during the flight.The friction torque is an important parameter of the load simulator,which is significant to keep the accurate simulation of the servo mechanism working conditions.This subject studies the nonlinear influence factors in friction loading,and strives to solve the problem of low accuracy of friction torque constant loading.A test platform was built to meet the load simulator application conditions.Through the experimental study of friction pairs for different materials,the effectiveness of the friction loading control method was verified.Through the analysis and design of the system,the platform of the friction loading test system which based on the sample test principle was established,and the measurement and control system was designed and debugged according to the research content of the subject.Using the combination of theoretical analysis and experimental testing,the precise mathematical model of the pneumatic loading system and drive system was determined through parameter identification.Due to the Stribeck effect of the friction pairs at low speed,a Stribeck model was established for this phenomenon.The GA was used to identify the model parameters of different friction pairs.Due to the poor rigidity and nonlinear influence factors of the pneumatic loading system,the classical PID and sliding mode variable structure control strategies were adopted to study the constant pressure loading characteristics of the system and related experiments were conducted.The constant loading of friction torque is one of the research difficulty issues to deal with.Non-model-based and model-based control strategies are adopted for the control of friction nonlinearity.The simulation analysis was carried out in Simulink and conduct experimental researches.The drive system is an important part for providing test system power,the vector control method based on SVPWM was used.The simulation model of the drive motor based on PI control and sliding mode variable structure control was established in Simulink for the analyzing of the servo motor response,and achieved high control performance.The research shows that the control strategy for friction nonlinearity effectively improves the control performance of friction torque constant loading.The test system can meet the requirements of the load simulator friction loading test,which provide the basic theory and test foundation for the design and optimization of friction torqueloading mechanism.