Research On Autonomous Flight Control And Obstacle Avoidance System For A Quadrotor

In recent years, benefit from technological innovation and theoretical innovation of the computer, MEMS, sensors and intelligent control and other fields, quadrotor, as a rising star, once again gets into the public view. Moreover, Quadrotor has won great attention of the major universities, research institutes and enterprises, etc. Technology research based on quadrotor and its application in civil field as well as military industry have obtained considerable development. However, the current domestic research in the field of quadrotor still cannot help it to achieve a complex task safely and stably, such as visual obstacle avoidance, multi-machine synergy, indoor navigation and other research still needs more practice and exploration.This paper achieves a study focusing on autonomous flight control and obstacle avoidance system for a quadrotor. Then, the paper briefly outlines the structure and characteristics of the quadrotor, and selects basics associated with this thesis to introduce. Moreover, the principle of motion control is analyzed from the point of view of kinematics and dynamics, which providing a theoretical basis and design guidance for aircraft controller.The controller of the quadrotor mainly includes two parts, position controller and attitude controller. In this paper, the design of controller is realized by the combination of cascade PID and logic control. Among them, the attitude controller, containing three axis angle control of pitch/roll/yaw, combined with height controller, constitutes the based control of the vehicle platform, which can realize the fixed high flight of the quadrotor. And the control of the plane position coordinate is finally reflected in the angle control through the logical solution. Combined with the former, those constitute the final position controller of the quadrotor, which realizing the hovering function.The design of obstacle avoidance system for quadrotor mainly includes two parts, obstacle detection and path planning. The algorithm of the two parts requires a higher processing ability of the processor, and the data processing is completed on the PC machine. Through the airborne monocular camera, quadrotor detects obstacles on the flight path, and transfer images to PC machine via Wi-Fi. In this paper, the obstacles are locked into the black and white chess board, and the detection algorithm is tested by the Harris corner detection algorithm. According to the character and size of the board, the three-dimensional space coordinates are obtained, and the environment map is updated in real time. On the other hand, the A* algorithm is used to realize 3D flight path planning, which can be used to recalculate the flight path of the aircraft when the map is updated every time. And then sending the track point to the quadrotor through the data transmission module, which is used to guide quadrotor avoiding all obstacles, thus helping it to reach the destination.Finally, this paper designed a series of experiments according to the research objectives, including system performance test, autonomous flight test and obstacle avoidance flight test and so on. These experiments verify the practicability and stability of the quadrotor platform and also carry out to provide reference for subsequent research contents.