**1. Introduction**

Automatic carrier landing for UAVs is one of most critical challenging operations; the marine environment can introduce various disturbances to UAV control when landing on a carrier. Carrier motion, disturbance due to carrier airwake and atmospheric turbulence make it very hard to ensure a safe landing operation. A lot of studies have been conducted on this problem and some control schemes have been proposed accordingly [1–4]. In [5], an MPC controller was designed for a linearized UAV system to handle the landing task with carrier heave motion. In [6], an autoregressive model was used to predict the carrier motion and a preview control scheme was used to reject the disturbances. In [7], an ADRC-based controller was designed for UAV control but only the pitch dynamics were considered. In this paper a detailed UAV model and disturbances model are introduced, and a control scheme with outer loop (navigation control) and inner loop (attitude control) is proposed based on the LADRC method to reject disturbances during the landing operation.

This paper is organized as follows: A typical fixed-wing UAV model and empirical models of atmospheric disturbances are introduced in Section 2. In Section 3, an ADRC double-loop control scheme is proposed and corresponding controllers are designed. Results of simulation experiments are illustrated in Section 4. And some concluding remarks are given in Section 5.

### **2. Mathematical Model**

In this section we briefly describe UAV dynamics, then the considered fixed-wing UAV model is given, followed by a model of atmospheric disturbances.
