Research On The Accurate Positioning Method Of AGV For Material Transportation

The accurate positioning method in the material transportation system has important research significance as the premise of whether the automatic guided vehicle(AGV)can complete the material transportation.The current positioning methods of industrial AGVs can be mainly divided into two methods: guide rail positioning and autonomous positioning.However,rail positioning requires a lot of labor costs and poor robustness,so it cannot be quickly deployed and used.Autonomous positioning also has problems such as poor positioning accuracy and excessive parking clearance.Therefore,this thesis,taking the production workshop parts transfer as the research background and the accurate positioning in material transportation as the research purpose,proposes a lidar-based material transportation AGV accurate positioning method,which can realize trackless autonomous transfer and meet the positioning accuracy requirements of AGV in different scenarios.First,to improve the quality and accuracy of the constructed map,this thesis uses the cartographer algorithm that can save all sensor measurement information during map creation to build a map of the production environment.Then,according to the different operating areas of the AGV,this thesis proposes a navigation and positioning method for the navigation area,and pinpoint docking methods for berthing areas.In the navigation area,this thesis studies and analyzes the principle and implementation process of the Monte Carlo positioning algorithm.Given the shortcomings of the algorithm,an improved MCL positioning method based on EKF fusion is proposed,which solves the positioning "kidnapping" and particle consumption of the original positioning algorithm,and improve the positioning accuracy.The method provides accurate and credible real-time pose data for the material handling robot in the navigation area.Secondly,in the accurate parking area,this thesis proposes a accurate positioning and parking method suitable for differential material conveying AGVs.This method can be divided into two parts: accurate positioning algorithm and parking trajectory planning algorithm.The positioning algorithm based on corner point recognition is analyzed and improved,and a accurate positioning algorithm based on the characteristics of specific triangle points is proposed.The horizontal parking trajectory planning algorithm based on the introduction of the concept of minimum parking radius solves the problem that the steering deviation is too large during docking and cannot be parked.Then,the experimental comparison on Matlab verifies the rationality of the parking trajectory planning algorithm proposed in this thesis,which can meet the needs of short-range lateral parking of differential AGVs.Finally,combined with the existing software and hardware platform and the actual environment,this thesis designs experiments to verify and analyze the above methods.The superiority of the cartographer algorithm selected in this thesis in terms of map quality and map accuracy is verified through experimental comparison.Repeated navigation and positioning experiments are designed to analyze the deviation between the arrival position of the experimental platform and the actual target point,which proves that the navigation and positioning method in this thesis meets the requirements of the index in terms of accuracy.The overall verification of the accurate positioning and parking method is carried out on the semi-physical simulation verification platform,which proves the feasibility of the method in this thesis,and the parking process is simulated in the actual environment,and the positioning accuracy of the accurate positioning algorithm is analyzed.The positioning accuracy of the accurate positioning and parking method meets the requirements of the index.