Design And Research Of Attack Angle Position Control System For FL2 Wind Tunnel Experiment

The position control of the Angle of attack is an important part in wind tunnel experiments.The Angle of attack is defined as the upwind Angle of the aircraft model in wind tunnel tests.The main work of this paper is to design the hydraulic position control system and computer control system,used to control the Angle of attack0°?90°continuous transformation,in order to meet the technical requirements.The experimental equipment uses the motor oil pump to supply high pressure oil,the relief valve to regulate the system pressure,the servo valve to control the flow,and the hydraulic motor to rotate according to the given position.The equipment adopts computer control,Angle sensor and servo valve to form a closed-loop control method.Firstly,the mathematical model and transfer function of the system are established.Due to the actual computer control mode,the open loop transfer function under discrete condition is further derived.The Bode criterion is used to analyze the stability under the discrete condition.According to the nonlinear characteristics of the hydraulic position control system in wind tunnel test,the AMESim dynamic response discrete model of the system was established under the discrete condition.The dynamic characteristics and accuracy are analyzed.Firstly,the system compares the dynamic response curve with or without correction,and then the system adopts PID control strategy.Only part of the positioning accuracy reaches the technical requirements,Then the system is controlled by the piecewise PID control strategy,and the simulation results show that the positioning accuracy of the system is improved.The influence of the opening of the damping hole,the flow gradient of the relief valve,the details and the sampling time on the dynamic response were analyzed and studied respectively by using AMESim simulation modeling,and the better control parameters were obtained.The results show that the piecewise PID control method is adopted in the hydraulic position control system of Angle of attack,and the position control system can meet the technical requirements in terms of response speed and position positioning accuracy.The dynamic response under the study of PID control and piecewise PID control is analyzed,and it is found that piecewise PID control is better for the multi-step experiment.The overall positioning accuracy can be improved by about 25%,which provides reference for related research with this conclusion for the high precision system.