Unknown Environment Of Mobile Robot Obstacle Avoidance Based On Visual Information Research

In recent years,with the continuous progress of science and technology,mobile robots have been widely applied to sea and air exploration,home services,military and other high-tech fields.In the process of mobile robot running,avoiding obstacles effectively is the first prerequisite for the robot to complete the task.Dealing with the image acquired by mobile robot with computer vision technology can realize the function of ranging and geometric modeling,which has become the mainstream of research direction in the field of obstacle detection.In this thesis,the problem of obstacle avoidance for mobile robot based on visual information obstacle detection in unknown environment is studied.The main contents are as follows:(1)The dynamic and static obstacle detection is realized by using the mobile robot to acquire image of environment information in real time.Complete outline and speed detection of dynamic obstacle by pyramid LK optical flow method.At the same time,using Sobel edge detection operator to determine the specific edge of dynamic and static obstacles,the search window in the trapezoidal region of interest is used to get the exact coordinates of the obstacle.Especially in view of the shadow effect of the image,using the method of light independent to remove the shadow area.Through the transformation of image coordinate system,camera coordinate system and world coordinate system,the accurate position information of obstacle can be obtained.(2)After position information of obstacles detected is known,the improved artificial potential field method is used to control the mobile robot to avoid obstacles.Firstly,the edge of the obstacle is discretized to make the obstacle information more accurately to apply to the artificial potential field.At the same time,the velocity factor is added to the repulsion field to solve the obstacle avoidance problem of the dynamic obstacle.An improved method is proposed by aiming at the problems of target unreachable,local minima and deadweight collision,the mobile robot can realize obstacle avoidance function under the condition of complex obstacle.(3)Completed the Qbot ground mobile robot obstacle avoidance study of hardware-in-the-loop simulation based on visual information in unknown environment.Firstly,the kinematics model of Qbot is set up,and the running speed,steering mode and obstacle influence range of Qbot are set with Quanser hardware-in-the-loop simulation platform.Obstacle avoidance simulation model of Qbot mobile robot is built by Simulink,which applied to the actual obstacle avoidance task of Qbot to complete the autonomous obstacle avoidance of mobile robot.