Aeroservoelastic Analysis and Active Disturbance Rejection Control Scheme for the High-aspect-ratio UAVs

In a high-aspect-ratio UAV, the slender body profile and the utilization of light materials as well as the highaspect-ratio wings lead to strong coupling among the flight dynamics, the structural dynamics and the control system. To investigate the rigid/elastic coupling and the suppression of the vibrations, the present study develops a model of the rigid body/elastic body coupling of UAVs. The branch mode method is applied in the coupling model by treating the flexible fuselage as a free-free beam and the wings of the vehicle as two cantilever beams. The aeroservoelastic of the UAV is analyzed in the frequency domain, and the classical PID controller is used to guarantee the stability of the control system. In order to suppress the elastic vibrations, active disturbance rejection controller (ADRC) is developed, the elastic modes are treated as disturbances which can be observed by the extended state observer. The simulation results show that the enhanced controller with the notch filter & correction network and the ADRC is able to improve system stability and suppress the vibrations.