Research On Control Method Of Position And Attitude About Plant-Protection UAV

With the development of moderm agriculture in our country,new plant protection technique represented by aviation plant protection has become a hot research topic.The quad-rotor plant protection UAV which is equipped with medicine cabinet and spray device is used for agricultural and forestry plant protection.Due to the simple structure,high mobility,easy operation,operating efficiency and other advantages,the quad-rotor plant protection UAV has played an important role in agricultural production with broad market prospect and application value.However,the complex working environment brings unknown interference to the quad-rotor plant protection UAV.Furthermore,the quality of UAV varies with the spray of liquid.In a word,attitude and position control of the quad-rotor plant protection UAV has important significance.Based on the analysis of the UAV’s flight principle,this thesis derives the line motion equation and angular motion equation to establish the system model which is prepared for the controller design.In order to improve the accuracy of the attitude angle,deviation brought by the sensor measurements should be eliminated by digital filter.Furthermore,to calculate more precise attitude angles,extended kalman filtering algorithm is adopted for data fusion.According to the under-drive nonlinear characteristics of the quad-rotor plant protection UAV,dual-loop structure in which the attitude is conrtrolled in the inner loop and the position in the outer is introduced.Then the controller is designed by backstepping method to complete the position and attitude control.After that,design effect is evaluated by Matlab simulation.The results show that the effect of attitude and position control by backstepping is well under the situation without interference.To inhibit interference,integral action is added into the controller,and the simulation result shows that integral backstepping is effective to inhibit constant and tiny interference.In order to eliminate the bad effect brought by UAV quality change or unknown disturbance,the adaptive control is proposed.Backstepping controller collaborated with adaptive control can further improve the anti-interference ability.Finally,Matlab simulation analysis shows that the new algorithm can solve the problems of position and posture instability,and the control effect is satisfactory.