Command filtered backstepping sliding mode control for the hose whipping phenomenon in aerial refueling

Studied in this paper is the design of a command filtered backstepping sliding mode controller for the hose whipping phenomenon in aerial refueling. Firstly, a dynamic model of the variable-length hose-drogue assembly with the restoring force due to bending previously built by the authors is introduced as a control plant. According to the kinematics, the hose length control is transformed to the angular control of the permanent magnet synchronous motor to keep the hose tension stable and suppress the hose whipping. Then, an active control strategy based on command filtered backstepping sliding mode angular control of the permanent magnet synchronous motor is proposed. To maximize the output torque, the space vector modulation method is adopted. Considering the strict-feedback configuration of the angular velocity subsystem, command filtered backstepping is used to eliminate the analytic computation of high order command derivatives required in the previous control system design. In the current voltage subsystem, exponential sliding mode reaching laws of d-axis and q-axis current errors are applied to enhance convergence speed, control accuracy, and robustness. Results show that the control system is simplified substantially and the requirement on the number of sensors is also relaxed. Finally, the superiority of the control laws is analyzed by simulations.