Anti-crosswind Autolanding of UAVs based on Active Disturbance Rejection Control

Abstract

The safe landing of unmanned aerial vehicles (UAVs) under various wind conditions has been a challenging task for decades. As the first step of landing, the longitudinal landing control has been well researched. But the lateral landing control, which is the second step of landing, is still facing a lot of challenges especially in crosswind conditions. In this paper, a UAV with wide span is researched. Due to its wide span, its wing tips may possibly touch the ground if the wings are not level at touchdown. An autolanding control scheme which consists of a longitudinal autolanding control system and a lateral autolanding control system is designed based on the Active Disturbance Rejection Control (ADRC) to enable the UAV to land safely in crosswind. The longitudinal autolanding control system is composed of a throttle control subsystem and an altitude control subsystem. The lateral autolanding control system is composed of a crabbing control subsystem and a decrabbing control subsystem. In contrast to previous methods, our approach can directly and real-timely estimate the UAV’s internal and external disturbances (e.g., system’s longitudinal and lateral couplings, wind disturbances) and then compensate for them. Simulations are done from the glide phase to the parking at the end of taxiing under wide range wind disturbances (e.g., constant crosswind, changing crosswind). Results show that our autolanding control scheme can land the UAV safely under wide range crosswind with the help of ADRC.