Study And Design Of Flight Control Systems For Small-scale Quadrotor Unmanned Aerial Vehicles Based On Backstepping

Due to its advantages such as precise hovering,vertical taking off and landing(VTOL),and simple mechanical structure,the quadrotor unmanned aerial vehicle(UAV)has become hotspot in the unmanned aerial vehicle area,and whether in the military field or in the field of civil,the vehicle has been widely used.The vehicle is a typical uneractuated system,and it has six degrees of freedom and four control input.The mathematical model has the characteristics of strong coupling,nonlinear,multivariable,and modeling imprecision and uncertainty factors such as external disturbance,are complicated flight control.So this paper adopts control method based on the backstepping to study and design the flight control system of the vehicle and through the simulation to the control system analysis and verification.Firstly,this paper takes the vehicle as a rigid body,selects the appropriate coordinate system,and analyzes the aerodynamic characteristic and the flying principle.On this basis,the mathematical model of the vehicle is derivated and established.Secondly,without considering various uncertain factors,this paper introduces in detail the flight control system design based on the backstepping.In the design process,the whole control structure can be divided into position loop control and attitude loop to design respectively.Thirdly,for the aircraft attitude loop under the existence of the compound disturbance,this paper adopts the backstepping and RBFNN strategy.Using the characteristic of the RBFNN to approximate arbitrary nonlinear continuous function to estimate the compound disturbance online and compensate the approximation error.The controller can guarantee the vehicle to track the desired trajectory.Finally,for the position loop and attitude loop under the existence of the compound disturbance,this paper adopts the backstepping and RBFNN strategy.For avoiding the complex calculation,the interference is observed by ESO online and the algorithm composites the interference in the control law.For avoiding the problem of “explosion of terms” in backstepping control and improving the robust,the dynamic surface control method and the sliding mode surface are applied to design the controller.