Research On Flight Dynamics Modeling And Control Technology For Compound High-speed Helicopter

Due to the capabilities of vertical take-off and landing,aerial hovering and high-speed cruising,the compound high-speed helicopter has great application values in the field of defense and civilians,and is one of the most important research areas in the future.This thesis focus on the compound high-speed helicopter with "coaxial rigid rotor & propeller" configurations,and carried out a systematic study on flight aerodynamics and flight control of compound high-speed helicopter.The main contents of this thesis are follows:Firstly,the configuration and manipulation characteristics of the compound high-speed helicopter are briefly introduced.According to the aerodynamic principles and aerodynamic parameters the compound high-speed helicopter,the nonlinear flight dynamic model is established.Based on the small perturbation linearization model of the compound high-speed helicopter,the stability characteristics and the control interactions of the sample helicopter are studied by analyzing its motion modes and time-domain responses.Secondly,in order to deal with the uncertainties of aerodynamic model and constraints of the control inputs,this thesis proposed a unidirectional auxiliary surface sliding mode based attitude controller,within the framework of the expanded invariant set theory.The tracking errors of control variables are incorporated into the unidirectional auxiliary surface,which ensures the attitude tracking errors are always within the desired range.Additionally,a new variable exponential approaching law and a terminal attractor are applied to enhance the tracking capability while suppress the chattering effect of the controller.Simulations have shown that the proposed control algorithm is able to track the attitude command with designed requirements and avoids the saturation of the control inputs.Lastly,a linear parameters varying based controller is presented to deal with the varying flight mode when the flight speed of the sample helicopter changes dramatically.The dynamics of the sample helicopter is firstly divided into a family of overlapping sub-regions based on the flight speed,and then the optimal controller for each sub-region is obtained based on the gap metric and polytope theory,and a hysteresis switching logic is utilized to ensure smooth transient between specific operational subspaces.Simulations demonstrated that the proposed controller can accurately track the speed command with desired overall performances on the entire flight envelop.