Modal analysis and shape-flight control of extreme multi-body full-wing configuration UAV

In view of the sensitive characteristics of the full-wing configuration to the time-varying compound disturbance, considering the strong coupling and nonlinear characteristics brought by the high dimensional multibody system, this paper proposes a novel coordinated controller for the extreme multi-body full-wing configuration unmanned aerial vehicle (UAV) to ensure the stable control of the shape-flight. Initially, a general multi-body dynamics model with aerodynamics and electric propulsion is established, and modal analysis is conducted to study the dynamic stability characteristics of different trim shapes. Then, the aerodynamic-driven shape-attitude control scheme is proposed based on the adaptive practical fixed-time sliding mode method, and the stability proof is proved by the Lyapunov theory. The convergence time corresponding to the shape-attitude control law has been rigorously proved to be independent of the initial state. The designed shape controller uses aerodynamic control surfaces to adjust the aerodynamic force and moment and indirectly adjusts the shape of the entire UAV without using direct command servo morphing mechanisms. The shape control logic also maintains a horizontal state while yawing and turning, which suppresses the special adverse morphing and rolling coupling effects under multi-body connections. In addition, the observer-based fixed-time airspeed-altitude control scheme and vector field-based path following control scheme are proposed to achieve stable flight under aerodynamic-driven morphing, which makes the UAV have the ability to fly automatically under the mission route. The simulation results show that the proposed controller fully releases the aerodynamic-driven morphing potential in the face of uncertainty and disturbance while maintaining the system stability.