Flight controller design for aircraft low altitude airdrop

Abstract

Purpose During low altitude airdrop operations, the heavy cargo moving inside and the sudden dropping out exert serious threats on the aircraft safety and mission performance. This paper aims to propose an efficient flight control method for the airdrop operations. Design/methodology/approach A novel controller which combines feedback linearization with nonlinear integral sliding mode control is proposed. The aircraft airdrop model is decoupled and linearized by using the feedback linearization technique. On this basis, an integral sliding mode controller is designed to stabilize the speed and pitch attitude of the aircraft. In the sliding manifold, one class of nonlinear functions with the property of “smaller errors correspond to bigger gains and bigger errors correspond to saturated gains” is introduced to form the integral term; thus, the overcompensation of the integral term to big errors is omitted, and the dynamic response performance is improved. Lyapunov-based stability analysis shows that the controller could completely reject model uncertainties by choosing proper controller parameters. Findings The flight control system with strong robustness could meet the low altitude airdrop indexes in the maximum weight cargo airdrop task. Originality/value This paper fulfils an urgent need to study how to control the aircraft to guarantee mission performance and flight safety during the low altitude airdrop operations.