Research On Frequency Characteristic Of Pneumatic Loader Simulator

A pneumatic load-simulator, as a typical passive force servo system, was a simulation equipment applied to check the qualification of rudder driving system by simulation aerodynamic load spectrum to the flight device rudder. The active motion of rudder had a disturbance to loading system, therefore the extra force appeared, and pneumatic servo system had phase delay increasing with the frequency rising. How to reduce the extra force and phase delay is one of research focus in load-simulator currently.Based on AMESim software, the load system with ideal rudder driving system was bulided and the requirement of ideal rudder driving system was given. A piecewise PID controller was used for dissymmetric cylinder in the simulation and the explain was given for the curves. Phase delay and extra force increased with the frequency was embodyed in the simulation result. The transfer function model of the motor was builded, then the experiment system model include crank-rocker was builded in AMESim and the characteristic was analyzed.By the mechanism model, the equation of pneumatic system was obtained and the reason of load system can not be controlled well was interfered by rudder driving system strongly. The mode of this disturbance affected to load system was two chambers pressure changed with piston dispalacement, viscous force and inertial force.The pneumatic system was simplifyed for designing the better controller and the parameters was get by system identification. The velocity compensator controller was designed for force aroused with the changing pressure in two chambers and it was valid for reducing phase delay and smooth track curve in simulation.The pneumatic load-simulator experiment system was established, and Matlab/xpc target was used for getting singals and output control in this system. The experiment included undisturbed test, extra force and dynamic characteristics test. The result of these test indicated the curves in simulation and experiment were consistency and it verifyed velocity compensator controller vaild for decreaseing phase delay and extra force.