Research On Attitude Control Of Bionic Flapping-Wing Aircraft

Bionic Flapping-wing aircraft is an aircraft that imitates bird flight.Its power source mainly depends on the flutter of wings,and the adjustment of flight attitude mainly depends on the tail.It has the advantages that other aircrafts do not have,such as strong flexibility,high propulsion efficiency and strong concealment.However,due to the complexity of flight mechanism and the difficulty of measuring some parameters,it is impossible to obtain accurate attitude control model,and the traditional attitude control algorithm cannot meet its control requirements.In this paper,the bionic flapping-wing aircraft is taken as the research object,and the attitude control of the bionic flapping-wing aircraft is studied from the aspects of reducing the attitude angle calculation error and designing the attitude control algorithm.In the process of attitude control,the current attitude angle information of the bionic flapping-wing aircraft needs to be calculated and fed back to the attitude controller.In order to improve the control effect of the controller and reduce the calculation error of the attitude calculation algorithm,an attitude solution algorithm based on the variable step momentum gradient descent method is proposed.Based on the gradient descent method,the algorithm designed an adaptive step size and introduced a momentum gradient optimization algorithm for each iteration direction,thereby improving the accuracy of the attitude angle solution after each iteration.The experimental results show that the algorithm converges quickly,the attitude angle output is stable,and it has high attitude accuracy in dynamic and static environments.Considering the difference of controlled object in time scale,the highly nonlinear attitude control model,internal model parameter disturbances and external disturbances,a closed-loop attitude control system with internal and external loop structure is established,and an adaptive terminal sliding mode algorithm is proposed as the attitude control algorithm of the system.The algorithm uses adaptive weighted reaching law to eliminate chatter and improve system tracking speed.At the same time,adaptive on-line estimation of system model parameter disturbances is performed to compensate the output of the sliding mode controller to reduce system steady-state error.Simulation results show that the algorithm not only eliminate the chattering problem,but also effectively overcomes the effects of external and internal disturbances.Finally,a prototype of a bionic flapping wing aircraft was built,and the bionic component verification experiment and preliminary attitude control experiment were carried out.Bionic functional verification experiments show that the prototype was able to generate a certain amount of lift and thrust,_Ia_Ind has the conditions for preliminary flight.The attitude control experiment shows that the attitude controller designed in this paper can effectively track the attitude angle command signal.