Model-free Adaptive Control For A Small-size Unmanned Helicopter

Small unmanned helicopter is a special aircraft that does not need human drive.Such aircraft has been widely used in various fields,because they have the features of vertical taking-off and landing and low-flying.At the same time,because of the characteristics of unmanned helicopter such as strong coupling,nonlinearity and complicated mathematical model,the modeling and controller design of unmanned helicopter are more difficult.Therefore,this thesis mainly focuses on the attitude control of small unmanned helicopters,and designs two new controllers based on the model-free adaptive control theory.In this thesis,numerical simulation and actual flight experiments verify that the designed controllers have a good attitude tracking effect.Firstly,this thesis introduces the flight principle of the small unmanned helicopter,analyzes the characteristics of the kinematics and dynamics models of the small unmanned helicopter.The analysis not only considers the basic rigid body kinematics and dynamics,but also studies the characteristics of rotor dynamics and rotor wiggle dynamics.Secondly,a new model-free adaptive robust control law based on data-driven methodology is proposed for the attitude control of a small-size unmanned helicopter.Different from most exiting model based control algorithms which required exact dynamic model knowledge of the helicopter,the proposed control law depends only on the input and output data of the helicopters.By using the data-driven methodology,the dependence of the control algorithm on the prior knowledge of the helicopter dynamics model is reduced and the influence of the system uncertainties are compensated.The controller designing depends only on the measured input and output data of the unmanned helicopter,and the sliding mode reaching law improves the robustness of the system.The experiment results show that the control scheme proposed in this thesis achieves good control performance.Finally,aiming at the uncertainties and wind disturbance of small unmanned helicopter system,this thesis designs a nonlinear controller based on immersion and invariance theory and model-free adaptive theory.The controller uses the immersion and invariant theory to estimate the air resistance coefficient and compensate the controller output.At the same time,the traditional sliding mode control is improved,which further improves the system robustness and reduces the buffeting.Then the convergence of adaptive parameters and the stability of closed-loop system are proved.The experiment results show that the control scheme proposed in this thesis achieves good control performance.