Simulation And Research On Attitude Control In Transition Of Tiltrotor Aircraft

Tiltrotor is a kind of new aerocraft that combines propeller aircrafts and helicopters. It can hover in the sky,fly both forward and backward and fly knife-wdge, as a helicopter does,or fly long-distance at a relatively high speed,as a propeller aircraft does. It enjoys the advantages of both helicopters and propeller aircrafts.The stress and difficult points of research at home and abroad lie in the control of its transitional process.On the basis of analyzing and summarizing the achievements of both foreign and domestic researches,this thesis sets out to deal with the following studies according to the non-linear model of its transitional process.First,this thesis is devoted to deriving the inverse model of non-linear systems in detail.It combines dynamic inversion method and singular perturbation theory to obtain and design the control laws of attitude angular velocity and loop of the tiltrotor and conducts tracking stimulation by imputing orders in different stages.It also tests the decoupling and dynamics of the dynamic inversion method and analyzes its disadvantages.Next,in accordance with the disadvantages of the dynamic inversion method in the model's precision and robustness,it proposes a single hidden layer neural network and its specific method on the basis of the inverse model,thus offsetting the errors between the inverse model and the controlled subject.Through stimulating and analyzing its robustness,this thesis verifies the effectiveness of combining dynamic inversion and the neural network.Finally,based on the dynamic inversion method,this thesis proposes a multimode transition pattern according to the feature of the tiltrotor in the transitional process,during which its controlled variables are constantly changing.It designs the hybrid mode control laws of ACAH and RCAH by using fuzzy control theory and conducts tracking stimulation of the tiltrotor during its tilting process from an angle of 0 to 90 deg rees with an even pace by imputing attitude angle orders,thus testifying its effectiveness.