| In the outdoor environment,AGV mostly use track guidance similar to magnetic navigation,but the path modification of track guidance is complex and the maintenance cost is high;In indoor positioning,SLAM algorithm based on two-dimensional LiDAR is mostly used.SLAM algorithm based on two-dimensional LiDAR obtains less environmental information,and the change of surrounding environment has a great impact on its positioning accuracy.To solve the above problems,in order to improve the accuracy,stability and completeness of navigation information of mobile robot in indoor,outdoor and indoor outdoor transition environment,this paper develops the outdoor positioning system based on differential GNSS and indoor positioning system based on SLAM algorithm of 3D LiDAR,As well as for the indoor and outdoor transition area positioning system dynamic switching system development.In the outdoor,because of the complex and changeable outdoor working environment,no fixed environmental characteristics,and the influence of light,fog and other weather,the commonly used indoor positioning methods can not operate stably all-weather outdoor.In order to obtain stable positioning information,the global navigation satellite system GNSS based on real-time dynamic carrier phase difference technology is used for outdoor positioning,It is combined with INS to improve the refresh rate and stability of outdoor positioning data.STM32f407 chip is used to develop positioning data analysis module;Gauss projection method is used to transform the latitude and longitude of geodetic coordinate system into millimeter level rectangular coordinate system,and the local coordinate system of positioning data is constructed in the outdoor operation area.Finally,the heading angle information of the robot is calculated by double satellite antenna measurement method,and the outdoor positioning and navigation information of the mobile robot is obtained.In the indoor environment,the satellite signal is relatively weak and the GNSS positioning information can not be calculated,but the indoor environment is basically stable and has fixed environmental characteristics.In order to make better use of environmental features,SLAM algorithm based on 3D lidar is used for location and mapping.Firstly,the synchronous positioning and mapping loam algorithm of lidar odometer is used to subscribe to the environment point cloud,extract the feature points,calculate the odometer information of two adjacent frames,calculate the real-time odometer information of three-dimensional point cloud and stacked three-dimensional point cloud,and interpolate the two kinds of odometer data,Finally,the 3D point cloud image of the working environment and the positioning information and heading angle information of the robot are output to provide indoor positioning and navigation information for the mobile robot.In the transition area of indoor and outdoor,in order to ensure the stable switching of location data of AGV or mobile robot;Firstly,the robot is moved to the outside working environment,and the local coordinate system origin of the working area is set;Then the robot is moved to the transition area indoor and outdoor.The data of two positioning systems coexist.The positioning data and heading angle data of GNSS are input into the loam algorithm.As the starting location data and heading angle data of 3D point cloud map for building indoor working environment,the algorithm can help the building of 3D point cloud map of the working environment,The coordinate system of the two kinds of positioning systems is unified;In the autonomous navigation of robot,dynamic switching of different data sources is carried out according to the detection of environment state of the two kinds of positioning systems,which provides stable positioning and navigation information for mobile robot in the transition area of indoor and outdoor.According to the positioning and navigation data obtained above,the octomap?server algorithm was firstly used to construct a two-dimensional raster map,then the Ray Ground Filter algorithm was used to Filter the Ground point cloud generated by the three-dimensional laser,and finally the Move?base navigation package was used for global path planning and local path planning.The experimental test shows that the accuracy of outdoor positioning data is ±1.5cm,the accuracy of heading Angle data is ±0.12°,and the data refresh rate is 100 Hz.The accuracy of indoor positioning data is ±2.5cm,the accuracy of heading Angle data is±0.1°,and the data refresh rate is 10 Hz.Before and after switching between the two positioning and navigation systems in the indoor and outdoor transition area,the positioning data accuracy is ±4cm,and the heading Angle data accuracy is ±0.5°.The experimental results show that the GNSS positioning system based on difference,SLAM system based on three-dimensional lidar and the combined navigation system make full use of the effective characteristics of the environment,improve the accuracy and refresh rate of indoor and outdoor positioning and navigation data,and are suitable for indoor and outdoor industrial environments. |
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