Study On Strategies Of Restraining Surplus Torque In Electro-Hydraulic Load Simulator Based On Interior Pressure Feedback Principle

Electro-hydraulic load simulator is a Hardware-in-the-loop simulation equipment on ground. It is applied to check the qualification of rudder driving system by simulating aerodynamic load spectrum to the flight device rudder. Therefore, it is significant to national defense and military industry.Electro-hydraulic load simulator is a typically passive force (torque) servo control system, the final control objective is recurrent random load spectrum fast and correctly in general loop simulation. While simulation, active motion of rudder will have an extra torque effect to loading system which is connected to the rudder. This disturbance has large strength, existence at times and changes as rudder motion state changes, these characteristics affect the performance of Electro-hydraulic load simulator severely and make it difficult to realize control object of load system. Therefore, how to restrain and eliminate surplus torque became a key technology in Electro-hydraulic load simulator system.This research work builds up mathematical model of Electro-hydraulic load simulator system, explains the mechanism and characteristics of surplus torque. Some qualitative conclusions are drawn which are concerned with the relationship among system performance, surplus torque and related structure parameters by analyzing the mathematical model of system. Furthermore, the static and dynamic performance of loading system is studied. The dissertation offers a summer of methods that can restrain or eliminate the surplus torque in the electro-hydraulic load simulator system as well as analyze structure invariance principle which is a mutual method relatively. And then the dissertation offers new control strategies that are progressed based on the methods in existence.Clearance lag of response always exist due to the fixing of displacement sensor. As a result, structure invariance principle, which can eliminate surplus torque completely in principle, is not as perfect as in our mind's eye because for that the differential signal gained form displacement sensor is in company with big error. Interior pressure feedback principle referred in this dissertation takes the difference between antrums of the loading system hydraulic motor as feedback control quantity. It is easy and precise to measure this feedback control quantity because that there isn't clearance lag problem. On the other hand, due to the passivity of the loading system motion disturbance of rudder system's motor cause torque change of loading system firstly. The difference between the torque change and output torque cause the loading motor's motion following the rudder. Feeding back the difference quantity in advance can improve response and reduce lag of loading system.The dissertation, based on the mathematical model built in which, also offers another improving strategy which is different from traditional structure invariance principle. That is, to take the servo-valve control signal of rudder system to realize the angular velocity synchronization control of loading motor and the rudder motor. This strategy avoids to using the angle rate of rudder motor directly to make feed forward control. As a result it also avoids the error due to the measurement of displacement of rudder motor rotor in order that it can improve the control performance. It is easily to observe the effect of this method in restraining the surplus torque from simulations and experiments.Experiments are made on the Electro-hydraulic load simulator principle model machine. Performance experiments are made on simulative loading system. The validity of interior pressure feedback principle and angular velocity synchronization control using servo-valve control signal of rudder system is validated. Compare analyses between the new strategy and traditional structure invariance principle is made.