| 英文摘要 | Unmanned Aerial Vehicle, which is simplified as UAV, is an unmanned and reusable aircraft. It has attracted considerable attention due to their promising benefits in civil and martial applications. A flight of an aircraft which taxies on wheels can be separated into three phases: takeoff phase, flying in the air phase, and landing phase. Although the time spent at the takeoff and landing is much less than the time spent at the flying in the air phase, the takeoff and landing are the most dangerous phases which most accidents occur at. During the takeoff and landing phases, wind disturbances (turbulence, wind shear, gust, and crosswind) will threaten the aircraft severely, therefore, it is a significant problem to control the UAV to takeoff and land safely under various wind disturbances. The Active Disturbance Rejection Control (ADRC) technique has the unique characteristic of directly and real-timely estimating the UAV’s internal and external disturbances (i.e. wind disturbances) without measuring the disturbances or knowing the rules of the disturbances. Therefore, ADRC is involved to design the automatic takeoff control system and the automatic landing control system for the UAV. In this dissertation, the automatic takeoff control and the automatic landing control of certain UAV with wide span under various wind disturbances are deeply studied based on the ADRC technique. The main contributions of this dissertation include the following issues: Firstly, the three-wheel taxiing model, the two-wheel taxiing model, and the flying in the air model of the UAV are established. The formulas of supporting forces acting on the UAV’s nose wheel and main wheels by the ground are deduced from the three-wheel taxiing model and the two-wheel taxiing model. It can be concluded that the supporting forces of the main wheels are mutually complementary. In the UAV’s takeoff model, the supporting forces of the three wheels are used as indicators to switch the three-wheel taxiing phase, the two-wheel taxiing phase, and the flying in the air phase. Secondly, by reformulating the UAV’s model, we confirm that under some simplifications the throttle-velocity subsystem is of first-order, the elevator-pitch angle subsystem, the aileron-roll angle subsystem, and the rudder-yaw angle subsystem are of second-order respectively. Then, a first-order Active Disturbance Rejection Controller (ADRCer) is designed for the throttle-velocity subsystem. Besides... |
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