Optimal Path Following for Small Fixed-Wing UAVs Under Wind Disturbances

Abstract

This article presents a novel path-following algorithm for fixed-wing unmanned aerial vehicles by virtue of a nonlinear optimal control approach and wind disturbance observers. Different from some exiting algorithms, the proposed algorithm formulates the path-following problem into a control problem by introducing auxiliary dynamics for the path parameter. The proposed controller is designed in an optimal and systematic manner where the control action is generated according to a well-defined cost function. This framework does not require any complex geometric coordinate transformation and can be easily tuned to accommodate curved reference paths, making it straightforward to deploy in different flight missions. Moreover, the wind influences on the path-following performance is explicitly compensated by the proposed algorithm based on the wind estimates provided by nonlinear disturbance observers. The closed-loop stability, including the auxiliary dynamics for path parameter and observer dynamics for wind estimation, is also analyzed. The feasibility and effectiveness of the proposed algorithm have been thoroughly validated in simulation studies and realistic flight tests. Index Terms-Disturbance observer, optimal control, path following, unmanned aerial vehicle (UAV). I. INTRODUCTIONR ECENT years have witnessed many successful applications of unmanned aerial vehicles (UAVs) in different domains, ranging from environmental monitoring, search, and rescue to surveillance and reconnaissance. Most of the common UAV tasks require to cruise along a predefined geometric path [1], [2]. This function also forms the basis

Stochastic H∞ Robust Decentralized Tracking Control of Large-Scale Team Formation UAV Network System With Time-Varying Delay and Packet Dropout Under Interconnected Couplings and Wiener Fluctuations

“…The Wiener process is used to model the system parameter variation of the UAV during flight process caused by disturbed component characteristics in the UAV NCS. We set 25 independent Wiener process {W i (t)} 25 i=1 for the each UAV in the stochastic 25-UAV team formation NCS. The wind gust is considered as an external disturbance of UAV, which is set to be zero-mean Gaussian noise with unit variance in each UAV.…”

“…During the actual UAV flight process, the state of the UAV will inevitably be disturbed by the wind external disturbance [25] and [26], and intrinsic random fluctuation due to non-ideal component characteristics. Moreover, in a nonideal large-scale team formation flight environment, UAVs have the opportunity to suffer couplings from other UAVs which induce coupling effect among subsystems in the largescale UAV team system such as communication co-channel interference [27]- [31].…”

Finite‐time disturbance observer‐based modified super‐twisting algorithm for systems with mismatched disturbances: Application to fixed‐wing UAVs under wind disturbances

“…In recent years, there have been various applications of disturbance observer-based control (DOBC) to the path following mission of fixed-wing UAVs. [17][18][19][20][21][22] With regard to this control objective, the fixed-wing UAV is required to travel on some predefined geometric paths, in which the UAV does not need to arrive at a specific location in a pre-specified time as in the trajectory tracking control objective. 21,22 When the fixed-wing UAV works for the path following task, it provides many attractive features including operating at a constant airspeed, consuming reasonable energy, and reducing the difficulty for control design.…”

“…[17][18][19][20][21][22] With regard to this control objective, the fixed-wing UAV is required to travel on some predefined geometric paths, in which the UAV does not need to arrive at a specific location in a pre-specified time as in the trajectory tracking control objective. 21,22 When the fixed-wing UAV works for the path following task, it provides many attractive features including operating at a constant airspeed, consuming reasonable energy, and reducing the difficulty for control design. 21,22 However, we should mention that the operation of the fixed-wing UAV is highly affected by the environmental wind conditions/disturbances due to its aerodynamic feature.…”

“…21,22 When the fixed-wing UAV works for the path following task, it provides many attractive features including operating at a constant airspeed, consuming reasonable energy, and reducing the difficulty for control design. 21,22 However, we should mention that the operation of the fixed-wing UAV is highly affected by the environmental wind conditions/disturbances due to its aerodynamic feature. 21 Hence, the disturbance observer-based control plays a crucial role in path following control (PFC) of fixed-wing UAVs.…”