Modeling Method and Control Strategy for Hose-Drogue Aerial Refueling System

Conventional method for hose-drogue model of aerial refueling system is known to be complex due to the flexible body of hose. And as reported, drogues are unstable in atmospheric turbulence, which greatly decreases docking success rates. This paper proposes a dynamic model for a hose-drogue aerial refueling system based on Kane equation and rigid multi-body dynamics, and analyzes its performance. Furthermore, the nonlinear dynamic model is linearized at the equilibrium point and simplified from full order to 2nd order. Based on the simplified 2nd order model, active control strategies, including proportion integral derivative(PID) and liner quadratic regulator(LQR) control laws, are designed to inhibit the pendulum movement of drogue due to, atmospheric turbulences. Numerical simulation results show the significant correctness of the proposed dynamic model by steady-state drag and balance position of drogue when the tanker flights under different conditions. Moreover, the steady state position error varies within 1 cm, thanks to either controller, when the drogue suffers from moderate-level atmospheric turbulences. Further, the PID controller exhibits better control effect and higher control precision than LQR controller.