Preliminary Research Of The Wind Tunnel Based Flight Control System All-physical Test Techniques

Flight control system(FCS)is the key point for guaranteeing the aircraft s stable and reliable flight.Before the first flight test of a new type aircraft,its FCS should be tested and evaluated by various simulation and test methods.As the hardware-in-the-loop simulation(HILS)has to build lots of models and the totally real flight test is of high risk,high cost and long period,a FCS test technique between the HILS and the flight test was proposed in this paper in order to evaluate the FCS more realistically,further enhance the reliability of the FCS,and reduce the flight test risk,aircraft developing cost and period.This technique was preliminarily researched,including the test technique s general research,the test system scheme research,the test and evaluation method research,and the test validation of the test technique.Firstly,the FCS mathematical simulation method and the FCS HILS method were briefly introduced.Their mathematical models and physically equivalent models were pointed out.The distances between these models and their real conditions were briefly analyzed.The wind tunnel based FCS all-physical test technique was proposed.The basic idea of this technique is:by putting the all-system integrated,full-scaled and all-physical aircraft inside the wind tunnel,the aircraft aerodynamics,rudder loadings,and attitude response can be all real so that the FCS can be tested and evaluated under all-system integrated aircraft,real aerodynamics,rudder loadings and attitude response conditions.Compared to the HILS,this technique can evaluate the FCS more realistically.Differences among this technique,the HILS and the flight tests were analyzed,which pointed out the advantages and limitations of this technique.The FCS performances that this technique can evaluate realistically were proposed,including the FCS rudder control performance,attitude control performance,the rudder stability boundary,the attitude stability boundary and the attitude disturbance boundary.Evaluation ability differences among this technique,the HILS and the flight tests were analyzed.Moreover,the future FCS test and evaluation procedure was pointed out.The technique requirements were analyzed,including the test system scheme requirements,the test and evaluation method requirements so as to provide a guide for further research of the test system schemes,the test and evaluation methods.Secondly,three stages' wind tunnel based FCS all-physical test system schemes were proposed.Their system compositions and the compositions' functions were definited.The differences between these system schemes and the HILS system were compared,which briefly explains the system advantages and the system evaluation advantages of these schemes over the HILS system.The key technologies of the system scheme were proposed,including the wind tunnel and aircraft test article technique,the test article support technique,the measuring technique,the real-time data acquisition and control technique.Requirements of these key technologies were listed.And the test article support technique was mainly analyzed.The influence of the support interference to the attitude response was quantitavely analyzed,and a method for compensating the influence of the support interference was given.Through the research of the wind tunnel based FCS all-physical test system schemes,test system scheme support for further research of the test and evaluation methods can be provided.And through the analysis of the system key technologies,research directions for future developing the wind tunnel based FCS all-physical test systems can be provided.Thirdly,the wind tunnel based FCS all-physical test and evaluation method was proposed,including the test method and the performance evaluation method.In the test method,the test type,test principle,test input and the test operation procedure for evaluating the rudder control performance,attitude control performance,the attitude stability boundary and the attitude disturbance boundary were determined.The performance evaluation method includes the performance index computation method and the performance determination method.In the performance index computation method,how to compute the rudder control performance indexes and the attitude control performance indexes with the original test data was determined.In the performance determination method,a method using basic index range and index level dividing to determine the FCS performances was given.The hypersonic aircraft pitching control system was taken as an example to illustrate the above test and evaluation method.The pitch rudder control performance,the pitch attitude control performance,the angle of attack stability boundary and the attitude disturbance boundary evaluation results were given,which preliminarily validate the test and evaluation method.Next,the preliminary test validation scheme for validating the wind tunnel based FCS all-physical test technique was proposed.In this scheme,the quantitative comparison criterion for comparing the rudder response and the attitude response of the wind tunnel based FCS all-physical test and the HILS was proposed.According to the preliminary test validation scheme,the static hypersonic wind tunnel based FCS all-physical test system was built,and the wind tunnel based rudder control test of the pitching control system was performed.The rudder control performance was determined,which preliminarily validates the wind tunnel based FCS all-physical test system scheme,the wind tunnel based FCS all-physical test and evaluation method.And the wind tunnel based FCS all-physical test technique for evaluating the FCS performance was preliminarily validated.Finally,the FCS hardware-in-the-loop simulation and the FCS flight test were performaned.According to the quantitative comparison criterion,their rudder response and attitude response were compared with the result of the wind tunnel based FCS all-physical test.Through this comparison,the feature that the wind tunnel based FCS all-physical test is more realistic than the HILS in the rudder loadings,the aerodynamics,and the attitude response was quantitatively validated.The fact that the wind tunnel based FCS all-physical test can obtain more realistic FCS evaluation results than the HILS was quantitatively validated.The advantage of the wind tunnel based FCS all-physical test technique was preliminarily validated.And the quantitative comparison criterion was also preliminarily validated.The wind tunnel based FCS all-physical test technique was preliminarily researched in this paper,which determines what the test technique is,why the test technique was proposed,what FCS performances the test technique can evaluate,what a test system should be constructed and how to test and evaluate the FCS performances towards this test technique.Through mathematical simulation and wind tunnel test,the test technique was preliminarily validated.Through the research in this paper,a more realistic ground test method for evaluating FCS was provided.