Abstract:In view of the complex coupling of the linear tilt multi-rotor plant protection UAV model and the interference of natural wind and plant protection actuators during the process of plant protection, a model compensation linear active disturbance rejection control algorithm is proposed in this study. Firstly, the kinematics and dynamics models of UAVs are formulated and the effectiveness of the centrifugal nozzle on the torque during the process of plant protection is analyzed. Then, the control decoupling and control allocation strategies are designed, which is based on the under-actuated characteristics of the UAV. Meanwhile, the model compensation-extended state observer is introduced to estimate other total disturbances inside and outside the system while regarding the fixed part of the operating model as the known disturbance. Therefore, the design of the pose controller is completed. The simulation results show that the maximum angle deviation and recovery time of the proposed algorithm are less than 0. 2° and 0. 55 s, respectively, during the process of plant protection. Compared with the PID algorithm and the linear active disturbance rejection algorithm, the maximum angle deviations are reduced by 3. 4° and 0. 9°, respectively, and the recovery time is reduced by 3. 1 and 0. 99 s, respectively, which shows that this algorithm has strong robustness. The flight experiments indicate that the UAV can track the plant protection trajectory well, and the maximum position steady-state error is less than 15 cm, which can meet the needs of plant protection.