Contents I. Introduction
In The past few years, quadrotors have attracted considerable attention owing to their cost effectiveness, small dimensions, and ease of maintenance, and they have been used in applications related to forest inspection, agricultural automation, as well as transportation and logistics among others [1]. Attitude control is an indispensable function in various flight missions, and numerous control methods have been developed over the years, such as backstepping control [2], robust control [3], proportional–integral–derivative (PID) control [4], and active disturbance rejection control [5]. However, these algorithms cannot ensure that quadrotor transient and steady-state behaviors invariably remain within the safety envelopes in practical operational environments and for various reference trajectories, and the literature on practical attitude control schemes for quadrotors with dynamic safety geofencing in complex flight environments is limited. Motion geofencing control for quadrotors, including asymmetric or symmetric attitude envelope constraints resulting from narrow terrains and physiographic barriers, such as densely packed buildings and obstructed forests, as well as static attitude constraints due to the physical structure of quadrotors in real-world flight, can simultaneously ensure operational safety and maneuvering controllability. Meanwhile, unknown perturbations, such as random wind gusts as well as air drag, hamper flight stationarity and maneuverability within the safe region. Hence, the development of a high-performance robust disturbance rejection control strategy is essential.
