Research On Localization And Trajectory Accuracy Of Mobile Robots

Mobile robots have been widely used in industrial production,military scouting and other fields in recent years.In the related technology of mobile robot,navigation reflects the intelligence level of the mobile robot.In order to complete the navigation,the following four problems need to be solved: map building,localization,path planning and motion control.Localization and trajectory tracking control are the basic technologies to realize the intelligent of mobile robot.At the same time,higher localization accuracy and trajectory accuracy can effectively improve the performance of mobile robot.Based on the skid-steered mobile robot,this paper mainly studies the theory and algorithm of improving localization accuracy and trajectory accuracy.Firstly,the kinematics and dynamics model of the skid-steered mobile robot are studied.According to the motion characteristics of skid-steered mobile robot,the kinematic model with longitudinal and lateral slipping is derived.A complete dynamic model is derived based on wheel ground interaction.Secondly,combined with the localization method of JNPF four wheeled skid-steered mobile robot,the systematic error calibration method of odometry is studied.UMBmark is the most widely used systematic error calibration method but there are still shortcomings.After establishing a more perfect odometry systematic error model is established,this paper proposes an improved systematic error calibration method.The positioning accuracy of two methods is analyzed through physical experiments.It is show that the improved method proposed in this paper can effectively improve the localization accuracy of mobile robot and has better results.Thirdly,the trajectory tracking control of skid-steered mobile robot based on kinematics model is studied.The trajectory tracking error model under ideal state is derived,and a new reaching law is proposed based on sliding mode variable structure control.The reaching law consists of two parts,it can effectively reduce the chattering phenomenon and improve the rapidity and stability of the control system;for trajectory tracking control under slipping state,a sliding mode observer is established to estimate the slipping parameters,and the trajectory tracking error model under slipping state is derived.According to the kinematic model,the virtual variable between the lateral error and angle error is designed,and a trajectory tracking control method based on Backstepping is proposed.The simulation results show that the sliding mode observer can estimate the slip parameters accurately.Compared with the classical trajectory tracking method,two methods proposed in this paper can make the mobile robot converge to the desired trajectory quickly,and the motion performance and trajectory accuracy are improved.Fourthly,the trajectory tracking control problem of skid-steered mobile robot based on dynamic model is studied.In the actual operation of skid-steered mobile robot will produce lateral slipping inevitably.In this paper,the sliding mode variable structure trajectory tracking control of skid-steered mobile robot with lateral velocity is studied and the relationship between the torque of the left and right wheel and the longitudinal speed,lateral velocity and angular velocity is derived.The simulation results verify the effectiveness and feasibility of the proposed method.Finally,the linear trajectory tracking experiment is carried out based on JNPF four wheeled skid-steered mobile robot.The structure of control system,hardware system and software system of the mobile robot are studied;the communication between MATLAB and ROS,the compiling and conversion of code are studied.The experiment of linear trajectory tracking under ideal state based on sliding mode variable structure is completed and compared with the classical trajectory tracking control method.Summarily,in this paper,an improved systematic error calibration method is proposed in view of the shortcomings of the UMBmark and it effectively improves the localization accuracy of the mobile robot.The trajectory tracking control problem of mobile robot is analyzed based on the kinematic and dynamic model respectively and it effectively improves the trajectory accuracy of the mobile robot.Using JNPF four wheeled skid-steered robot as a test,the performance of the robot is improved.This paper focuses on the localization and trajectory tracking control method of mobile robot,at the same time,the exploration of practical application has certain theoretical reference value.