Feedback Stabilization And Platooning Control For Homography-Based Mobile Robot

For robot control system in the past,access to the surrounding environment information are mostly laser,radar,positioning system,etc.In recent decades,people have found a new approach to obtain information because of the development of machine vision,and then it gave birth to robot visual servo control.This kind of control mode enables robot to perceive more information of the surrounding environment by giving robot the ability of vision,and thus improve the degree of automation and intelligence of robot control system.As for mobile robot,the motion control tech-nology is the key of achieving intelligence of robot,therefore,the research in this dissertation aims to combine the visual servo control and the motion control of mobile robot,which reflected in the feedback stabilization and platooning control.Traditional image-based visual servo control usually utilizes fixed feature points as control variables.which is easily affected by noise and occlusions.While multiple view geometry contains more comprehensive information,thus it can reflect the relative position relations in better way.In this dissertation,based on kinematic model and the research object of wheeled mobile robot,we use homography which is a kind of multiple view ge-ometry to design novel feedback stabilization and platooning control laws respectively.The main work of the dissertation is detailed as follows:1.According to different process ways,the image processing of visual servo can be divided into two parts.In part 1,SIFT algorithm is used to extract and match feature points and we can calculate the homography matrix by pixel coordinates of feature points.In part 2,sparse optical flow method is used to track the feature points and calculate incremental homography.Then we can get the current homography according to its transitivity.In a nutshell,we will cost less time in this method and it improves the real-time performance of the system greatly.2.For kinematic model of non-holonomic mobile robot,a homography-based strategy of feed-back stabilization is present in this dissertation,which will use homography elements to construct error variables in lack of the depth.The switched controller can drive the robot to complete the task of stabilization under the satisfaction of the non-holonomic constraint.Theoretical analysis and simulation verify the feasibility and effectiveness of the strategy.3.For kinematic model of non-holonomic mobile robot,a homography-based strategy of platooning control for the leader-follower system is present in this dissertation.Under a given desired image and distance,the strategy will use homography elements to construct error variables and estimate the velocity of leader robot.The control law can drive the robot to complete the task of platooning under the satisfaction of the non-holonomic constraint.Simulation and experiment verify the feasibility and effectiveness of the strategy which method of velocity estimator included.