Research On Automatic Control System For Landing Of Quadrotor Based On Image Processing

Currently, unmanned aerial vehicles (UAVs) play a pivotal role and are extremely widespread in the field of information realization in both military and civil applications, and gradually become a potential hotpot of scientific research direction due to low cost, good adaptability and multiple functions. The issues on the extremely high failure rate in the process of landing have created an increasingly high demand for the intelligent landing system and necessitate the realization and improvement of the well-regulated landing. Especially, automatic control of landing, as a sophisticated technological key for the research and development of UAVs, should be highlighted to explore the precise location and safely landing technology. Based on it, this study focuses on designs of automatic landing control system of four-rotors UAVs (Quadrotor) based on image processing technique using monocular camera. The main work and innovations in this thesis are as follows.First, the research background, purpose, status and perspectives of the automatic landing system of UAVs are briefly described, and the control theory, use and characteristics of automatic landing of quadrotor are elaborated.Next, the Gaussian pyramid algorithm were employed to down sample in order to reduce the amount of digital data. Comparing with the performances of diverse algorithms, the binarization method with good real-time capability were selected to denoise the extracted image by image segmentation using threshold, open-close operation and Sobel operator, in order to achieve image contour extraction.Then, Hough Transform was used to extract features of the processed image. As one of the extracted features, corner information were processed to judge and correct flight position and orientation using the overlapping principle of coordinate frame between camera and the obtained image in the mode of waiting to land.Finally, Particle Swarm Optimization (PSO) was employed to design the controller of automatic landing system due to more rapid and smooth adjustment performance than classic PID method. The Simulink module of MATLAB offers an effective manner to analyze the stationary process of landing angle and altitude, and by experiments the effects of PID control part on the landing error were further discussed. The whole design process initially completed the automatic landing of quadrotor.In conclusion, the study of this thesis contributes the systematic research and design on automatic landing control of quadrotor with innovations in many aspects, and the implemented image process and the engineered flight controller would become the groundwork for related research topics.