Integrated Guidance And Control For Unmanned Aerial Vehicle With Multiple Constraints

Due to the excellent capability and the low cost,unmanned aerial vehicles(UAV)have been widely employed in many civil and military applications.Distinct from the conventional aircrafts with experienced pilots,the embedded control system is required to accomplish the attitude tracking and the path following simultaneously.Namely,both the control objective and the guidance one should be achieved.With the development of the aeronautical technologies,the integrated guidance and control(IGC)has lately received great great interests.Meanwhile,during the flying of UAV,there are many constraints.For example,the actuators always exist the specified magnitude limitation,the angle of attack and the sideslip angle should stay within the safe region to maintain the lift,and the mission may raise the performance requirement.All those issues will bring about new challenges for the design of the IGC.Accordingly,this work will investigate the IGC design problem for the UAV system with multiple constraints.In the following,we summarize the contents of the thesis:Firstly,we investigates the flight control problem of the UAV attitude dynamics simultaneously considering the the user-specified tracking performance,the asymmetric input saturation,and external disturbances.By introducing the modification signals into the user-specified performance functions,we propose a flexible performance-based control(FPC)scheme,featuring the capability of avoiding the violation of the resulted modified performance functions(MPFs)due to the input saturation.Furthermore,the disturbance observer is utilized to estimate external disturbances and relieve the burden on the control input.With the developed flight control scheme,it is theoretically shown that the output of attitude dynamics can always track the reference signal and satisfy the constraints of the MPFs.The numerical simulation results are presented to show the effectiveness of the proposed flight control scheme.Secondly,we investigates the design problems of the active estimator and the resulted flight control for the UAV attitude dynamics with the wind disturbance and the system uncertainties.Through improving the Luenberger observer structure in the disturbance observer(DOB),we propose the disturbance interval observer(DIOB).Distinct from the conventional estimation schemes aiming to estimate the magnitude of the disturbance,the disturbance interval estimation approach is capable of approximating the time varying upper and lower boundaries for the disturbance.The resulted flight control scheme also embeds the prescribed performance-based control(PPC),the adaptive neural network(NN),and the dynamic surface control(DSC)technique.As a result,this control scheme is capable of accomplishing the performance-guaranteed reference tracking of the UAV attitude dynamics with the wind disturbance and the system uncertainties,which is illustrated with the numerical simulation.Thirdly,we further investigate the nominal IGC design problem under state constraints for the full-state UAV system.Based on the backstepping and nested saturation method,the guidance law and flight control are designed in the path and the time coordinates,respectively.Accordingly,the state-constrained IGC scheme is constructed to make the UAV follow the circle path.Instead of only employing Lyapunov method,the concept of immersion and invariance(I&I)is also applied to explicitly analyse the stability in both time and path coordinates,and the asymptotic stability of the closed-loop system is guaranteed.The numerical simulations demonstrate the effectiveness of the developed IGC scheme.Fourthly,we investigate the robust IGC design problem under state constraints for the UAV system with the wind disturbance and the system uncertainties.By choosing new states of the position dynamics,the nominally designed guidance law is improved to eliminate disturbances and uncertainties.Through embedding the adaptive NN,PPC,and DOB,the robustness of the nominally designed flight control law is enhance.Notably,distinct from the nominal IGC scheme achieving the asymptotic stability,the theoretical result of the robust IGC scheme is obtained under the bounded stability which processes more practical values.As a result,the developed robust IGC scheme can handle disturbances and uncertainties to make the UAV follow the path under state constraints,which is illustrated with the numerical simulation.Finally,we summarize the IGC design scheme under input,output,and state constraints for the UAV system with the wind disturbance and the system uncertainties.The DIOB is employed to estimate the reliable information of the background wind field.On the basis of the concept of the MPF,we further propose that of the conditional performance function(CPF).With the proposed CPFs,we can regard the satisfaction of the input/state constraints and the environmental requirement as the precondition of accomplishing the output constraints.The IGC design scheme under multiple constraints is obtained by integrating the CPF-constrained flight control law and the previous guidance law,and the numerical simulations demonstrate the effectiveness of the developed IGC scheme.