A Visual Navigation System For Patrol Robot Based On Few Vertical Landmarks

The progress of science and technology has led to the rapid development of robot field,more and more artificial work can be replaced by intelligent robot,such as patrol along the substation,factory workshop equipment abnormal detection,logistics industry inspection and transportation.Positioning and navigation system is the basis of various applications of intelligent patrol robot.At present,the mainstream robot navigation technologies include electromagnetic navigation,inertial navigation,laser navigation,GPS navigation and visual navigation.Among them,the visual navigation cost is low,which is to obtain external information through the camera.It has a wide range of applications and can be applied to a variety of different navigation environments in theory.With the deepening of visual research and the reduction of the cost of visual system,the navigation method based on artificial landmarks is becoming a hot spot in the application of visual navigation for patrol robots.In outdoor navigation environment,artificial landmarks laid on the ground are inevitably affected by dust and snow.When indoor navigation,artificial landmarks are placed on the ground or ceiling more,but in many workshop indoor ground does not allow laid mark object,and the ceiling of certain workshop is too tall or the structure is too complex,install artificial landmark hard.Therefore,it is necessary to carry out research on visual navigation application of patrol robot.In this thesis,a vertical landmark is designed,which is placed on the equipment or wall on both sides of the inspection path.In order to reduce the transformation of the navigation environment,as few vertical landmarks as possible are used to realize the positioning and navigation of the patrol robot.This puts forward higher requirements for the landmark detection and robot positioning algorithm,that is,not only to ensure the real-time algorithm,but also to improve the accuracy of positioning,to ensure the navigation accuracy of patrol robot.The main work of this study is to design a vertical artificial landmark applied in a specific navigation environment,and develop a set of landmark detection and visual navigation methods to achieve real-time and accurate detection of artificial landmark and navigation of inspection robot.The main research contents are as follows:(1)In order to satisfy the limitation of navigation environment and improve the accuracy of robot navigation in the case of a few landmarks,and at the same time reduce the transformation of navigation environment as much as possible,the artificial landmarks placed on the equipment on both sides of the path or on the wall are designed as vertical highlights,and the landmarks are kept perpendicular to the direction of the inspection path,In order to minimize the sharp reduction of the area of long-distance landmarks in images caused by perspective effect and improve the detection effect of landmarks.The colored reflective strips are used as the significant visual features of the local positioning landmarks,which improves the real-time detection of landmarks.Using a modified two-dimensional code as global positioning landmarks,improved coding recognition accuracy.With topological map,patrol robot can be implemented global navigation.(2)Map expression.A topology map using adjacency matrix is designed for this navigation system,the topology nodes are mapped to the global positioning landmarks to realize the path planning of the patrol robot.(3)Landmark recognition algorithm.A small number of vertical landmarks are used to realize the navigation of the patrol robot.To meet the real-time and accuracy of the navigation,a landmark detection algorithm is designed.By extracting the multi-color space features and edge features of the local positioning landmarks,the landmarks area can be accurately extracted,this algorithm improve the detection accuracy and speed of the landmark.(4)Autonomous positioning and navigation.During the travel of the patrol robot,the current travel offset is calculated by using the camera's internal parameters and the parameters acquired by the landmark detection algorithm,and the travel direction of the robot is corrected by the fuzzy control method.At the same time,according to the identified global positioning landmark and the topological map,the travel path of the robot is planned.This research proposes an effective solution to the problem of patrol robot navigation in practical application environments.The main innovations are the design of artificial landmark and the research of landmark detection algorithms.