Research On Three-Dimensional Trajectory Tracking Control For Unmanned Aerial Vehicles In The Presence Of Uncertainty

It is highly necessary to track the trajectory precisely for unmanned aerial vehicles(UAVs)in the process of completing various missions.Due to the existence of uncertainties,such as wind field disturbance and model uncertainty,the UAV may deviate from the planned trajectory,and thus it might be impossible for the UAV to complete the anticipated task.Such mission failure is more likely to occur in the military task,as the UAV is anticipated to attack certain target at a specific time and from a particular position.In this paper,we mainly focus on investigating the control problems of UAV's three-dimensional(3D)trajectory tracking under wind field disturbance and model uncertainty.The main research contents are listed as follows.(1)A backstepping control law based on genetic algorithm(GA)is proposed for UAV's 3D trajectory tracking under constant wind field.Firstly,the back-stepping method is adopted to derive the control commands in order to track the 3D trajectory under constant wind field.Then,a GA based method is proposed in order to optimize corresponding parameters of the control law.Compared with other methods,the obtained position error by the proposed control law in this paper is much smaller and our method converges faster.(2)A robust optimal control law under unknown wind field disturbance is studied for the UAV's 3D trajectory tracking.The corresponding control law is derived with the adoption of linear quadratic regulator and robust control theory.By comparing with other methods in this work,the proposed control law is shown to be more accurate and converges faster under the unknown wind field disturbance.(3)For UAV's 3D trajectory tracking,an adaptive sliding mode control law under uncertainties is proposed.Such control law is derived by using sliding mode control theory and adaptive control theory.Simulation results indicate that the position errors obtained by other methods do not converge if uncertainties are incorporated.Nevertheless,corresponding errors derived by our method can converge.(4)We propose a multi-UAVs' 3D trajectory tracking consensus control law under constant wind field.In the cooperative tracking process under constant wind field,a multi-UAVs' trajectory tracking consensus control law is presented for the time-varying communication network.Furthermore,a multi-UAVs' trajectory tracking consensus control law is presented for the time-varying communication network with the incorporation of input constraints.Moreover,the formation problem of multi-UAVs is also studied with the corresponding control law being presented.The presented three control laws are referred as multi-UAVs cooperative 3D trajectory tracking consensus control laws in this work.Simulation results indicated that through the proposed control laws,the multi-UAVs are able to track 3D trajectory accurately while keeping the anticipated formation.(5)A multi-UAVs' 3D trajectory tracking consensus robust control law is also proposed under uncertainties.In the cooperative tracking process under uncertainties,a multi-UAVs' trajectory tracking consensus robust control law is presented for the time-varying communication network.If input constraint is incorporated,the coresponding control law is also presented.Furthermore,an input constrained formation trajectory tracking consensus robust control law is presented for the purpose of formation keeping.In this work,the proposed three control laws are called multi-UAVs cooperative 3D trajectory tracking consensus robust control laws.Simulation results indicate that the multi-UAVs are able to track 3D trajectory while maintaining the formation under uncertainties through the application of the proposed control laws in this paper.(6)The application of trajectory tracking control laws in cooperative attack missions is also studied.In this work,several cooperative attacking scenarioes are designed,in which the UAVs are anticipated to attack targets in a specific time and from a specific direction.Moreover,under uncertainties such as unknown wind field disturbance and model uncertainty,the trajectory tracking problems of multi-UAVs are also investigated with the adoption of the proposed control laws in this work.Correspondingly,the attack effectiveness of these control laws is evaluated.Simulation results indicate that the proposed trajectory tracking control laws are likely to improve the attack effectiveness to a large extent.