Research On AGV Positioning System Based On Combination Of UWB And IMU

With the development of information and artificial intelligence technology,automated guided vehicle(AGV)with self-positioning technology is gradually widely used in industry,logistics and other fields.Among indoor wireless positioning technologies,ultra wide band(UWB)has attracted much attention due to its advantages of anti-multipath,low power consumption and high ranging accuracy.However,the positioning accuracy of UWB system is affected by non-light of sight(NLOS)error and uncertainty jump in wireless transmission.Therefore,the advantages of UWB and inertial measurement unit(IMU)are combined to meet the positioning requirements of reliability and continuity in indoor environment.Firstly,the UWB positioning principle,characteristics and error sources were introduced.UWB ranging methods of RSSI,TOA,TDOA were analyzed.Several UWB positioning algorithms such as Fang,Chan,Taylor are studied.Simulation calculation and comparative analysis were carried out to verify the above algorithms.Secondly,based on the positioning algorithm of the strap down inertial navigation system,the numerical simulation of the speed and position of the ground-moving carrier was carried out,and the influencing factors of the positioning error were analyzed.The EKF,CKF and IMMEKF algorithms were studied,and the linear and nonlinear predictive state and measurement equations of the two-dimensional motion space are established,which lays a foundation for the application of UWB and IMU positioning technology.Then,a set of UWB and IMU indoor positioning combined measurement system based on STM32 was designed,including the selection of UWB module,IMU module and wireless communication module,the software and hardware design of the combined measurement system,and the GUI software of data reading back and data processing based on Lab VIEW.Finally,the verification experiments ware carry out with the AGV car.The real-time motion parameters ware obtained by using different forms of motion trajectories in the experimental scene of one label and three base stations.The positioning and filtering algorithms ware used to calculate the independent positioning and combined positioning of UWB and IMU.The experimental results show that the combined positioning measurement system and IMMEKF algorithm are feasible and effective,which can solve the problems of uncertain jump and cumulative error caused by electromagnetic signal interference.