Design on altitude control system of quad rotor based on laser radar

In this paper, a four-rotor UAV is built as the control object. The paper comes up with a mixed agricultural plant protection UAV designation with high precision positioning system based on accelerometer and laser range finder in order to solve the problem of poor stability, limited positioning precision and being unable to provide high accurate and stable height data for agricultural plant protection UAV in a complicated environment. Through this system, we can effectively make up for the lack of GPS in the complicated environment, improve the positioning accuracy of UAV agricultural plant protection, which has a significant influence on the technology development of agricultural plant protection UAV. In order to achieve a high degree of control and make it meets the accuracy requirements in the autonomous flight. Laser range finder is used to get feedback of altitude information. Meanwhile, the vertical acceleration data is used for compensation. Firstly, the paper introduces the basic structure of aircraft. Then, to get the altitude control of micro multi rotor aircraft, a measuring method is proposed with the combination of laser range finder and acceleration which can measure the altitude of flight instead of GPS at low altitude. Furthermore, establish the mathematical modeling on altitude with PID controller. At last, the stability and tracking performance of the designed controller are verified by experiments.