Anti-disturbance dynamic surface trajectory stabilization for the towed aerial recovery drogue under unknown airflow disturbances

Abstract

This paper focuses on the anti-disturbance trajectory stabilization problem of the flexible cable towed aerial recovery drogue under multiple unknown airflow disturbances. Firstly, the 6 degrees of freedom (DOF) dynamics of the towed drogue are established in affine nonlinear form for nonlinear control design. Then, several finite-time convergent high order sliding mode observers (HOSMO) are designed to accurately estimate these lumped disturbances which include the effects of the unmeasurable tensions and airflow disturbance in each subsystem of the drogue’s dynamics. With the feed-forward compensations of these estimated disturbances, a HOSMO based anti-disturbance back-stepping controller is proposed to stabilize aerial recovery drogue subjecting to the unmeasurable cable tensions and airflow disturbances. The dynamic surface control (DSC) technique is used to avoid the “explosion of complexity” problem in the standard back-stepping. Also, the closed-loop stability is analyzed to show all the signals are ultimately bounded. Therewith, the proposed method’s performance and effectiveness for the aerial recovery drogue are compared with the case without any active stabilizer.