Research On The Localization Method Of Large Lpg Spherical Tank Climbing Robot

The wall-climbing robot in this project is mainly applied to the welding seam defect detection task of large liquefied petroleum gas spherical tanks.Problem of spherical storage tank welding zone location has become one of the key technologies to improve the safety and reliability of spherical storage tanks.However,in LPG spherical tank environments with few or no landmarks and lack of good lighting,the types of sensors available are limited,which makes the localization of wall-climbing robots more challenging.The traditional odometer localization and inertial navigation localization methods have low accuracy and obvious cumulative error.In this paper,the localization problem of wall climbing robot in spherical storage tank environment is studied as follows.(1)Structural design and analysis of wall climbing robot.Based on the analysis of the advantages,disadvantages and practicability of the existing schemes,this paper adopts a wall-climbing robot with differential gear system structure,which is characterized by its simple structure and easy control.In addition,an active adsorption control system is proposed,which adopts the active adsorption control method to improve the adsorption stability and safety of the wall climbing robot through the cooperation of permanent magnet and electromagnet.(2)Research on locating method of wall-climbing robot.The principle and error source of odometer localization and inertial navigation localization method based on Inertial Measurement Unit(IMU)are analyzed and studied.In view of its defects,a wall-climbing robot localization method based on the relative motion estimation principle of welding seams is proposed in this paper.Through equipped with auxiliary light source,the tank surface image is collected by using CCD camera installed on both sides of the wall-climbing robot.Through image processing technology to identify the characteristics of weld area and output the corresponding signal detection,through adjacent moment detection signal incremental calculation to estimate relative to the weld robot moving distance.The motion estimation information can be used to correct the linear and angular displacement estimation of the wall-climbing robot.(3)Research on multi-sensor data fusion localization technology.By analyzing the existing multi-sensor data fusion algorithm,the basic model of multi-source data fusion localization is proposed.The extended Kalman filter is used to fuse the motion estimation information of odometer,IMU and camera sensor,and the localization effect of wall-climbing robot is improved by complementing the advantages of each sensor.(4)In order to verify the actual effect of the multi-source data fusion localization method proposed in this paper,a multi-sensor based wall-climbing robot localization simulation experiment platform is designed to evaluate the effectiveness of the proposed method in the real scene and in the virtual environment with disturbance factors such as gravity.By analyzing the experimental data,the experimental results show that the proposed method can effectively improve the localization accuracy of the wall-climbing robot in the spherical tank environment with few or no landmarks and lack of good lighting conditions.