Stability control of a fixed full-wing layout UAV under manipulation constraints

The fixed full-wing layout unmanned aerial vehicle (UAV) has simple structure and high aerodynamic efficiency, but the special configuration and manipulation characteristics bring challenges to the controller design, which has little related research work. Aiming at the aileronless and rudderless manipulation mode, considering the disturbance and uncertainty, this paper proposes a comprehensive stability controller for the fixed full-wing layout UAV under manipulation constraints. First, adaptive neural network dynamic surface control schemes based on the asymmetric barrier Lyapunov function and auxiliary system are designed for pitch and yaw attitude control. Then, this paper combines the adaptive super-twisting observer, terminal sliding mode control, and double power reaching law to design the airspeed controller and the altitude controller, and further introduces the pitch angle command constraint in the altitude controller. In addition, an improved vector field-based lateral-directional path following control method is designed to realize straight-line and circular orbit path following control. In this paper, the approximation and compensation effects of the radial basis function neural network and robust compensator are fully verified. The design of the pitch angle command constraint specifically considers the characteristics of weak pitch manipulation ability, small available trim airspeed range, and low longitudinal moment of inertia. The developed path following control approach effectively prevents the nonlinear tracking differentiator from generating unreasonable yaw angle commands. Simulation results also show that the proposed controller can enable the fixed full-wing layout UAV to achieve the typical three-dimensional mission flight with high robustness and high precision, and make the fixed full-wing layout UAV remain stable even after suffering stall and manipulation saturation under the action of the gust wind field.