Dynamics and control of the hose whipping phenomenon in aerial refueling

Dynamic modeling of a hose-drogue aerial refueling system, derivation of a new set equations of motion of the time-varying inertia receiver, and a command filtered backstepping-sliding mode controller design for the hose whipping phenomenon during coupling are studied. To analyze dynamics of the hose whipping phenomenon, a dynamic model of the variable-length hose-drogue assembly is built with the hose restoring force due to bending. The hose is modeled by a sequence of variable-length links connected with frictionless joints. A set of iterative equations of motion of the hose is derived subject to hose reeling in/out, tanker motion, hose restoring force due to bending, gravity, and aerodynamic loads. Based on a fixed weight aircraft, a set equations of motion of the time-varying inertia receiver is derived. Then, an active control strategy based on the permanent magnet synchronous motor angular control for the hose whipping phenomenon is proposed. Command Filtered Backstepping is used to eliminate the analytic computation of command derivatives, and exponential sliding mode reaching laws of d/q axis current error are applied to enhance convergence speed, control accuracy, and robustness. Finally, dynamics of the hose whipping phenomenon and effectiveness of the control laws are analyzed by simulations.