Research On Outdoor Positioning And Trajectory Tracking Control Of Wheeled AGV In Park

With the rapid development of modern intelligent logistics and intelligent factories,the application of Automated Guided Vehicles(AGV)is becoming more and more extensive,and the market demand for AGV is increasing,and at the same time,their performance requirements are also getting higher and higher.Therefore,it is of great significance to develop an AGV with high positioning accuracy and good control performance.This paper takes the park wheeled AGV as the research object,and focuses on its positioning technology,trajectory tracking control technology and trajectory planning technology.The main research work of this paper is as follows:(1)According to the application scenarios and requirements of the AGV in the park,on the premise of analyzing the existing positioning technology,it is determined that the combination of the Global Positioning System(GPS)and the Inertial Navigation System(INS)The basic idea of AGV positioning.According to the specific AGV model,a combined GPS/INS positioning model based on Extended Kalman Filter(EKF)is designed.Aiming at the problem that GPS observation noise is difficult to obtain and easily changed by external interference,the improved Sage-Husa algorithm is used to estimate the GPS observation noise in real time.At the same time,aiming at the problem that GPS positioning outliers will affect the combined positioning accuracy,a GPS positioning outlier interference suppression method based on chi-square test is proposed.The simulation results show that the proposed combined positioning algorithm can effectively improve the accuracy of GPS positioning,can still have a better positioning effect under the condition of uncertain observation noise,and reduce the impact of outliers on combined positioning to a certain extent.(2)Based on the kinematics model of the wheeled AGV,the wheeled AGV trajectory tracking control law is designed according to the control principle of the backstepping method,and the performance of the control law is analyzed from both theory and simulation.Aiming at the problem that the traditional backstepping trajectory tracking control law has poor adaptability to speed,after analyzing the parameters in the control law,a parameter adjustment method based on fuzzy control is proposed to adjust the parameters in the control law online.In addition,considering the impact of the target trajectory on the tracking performance,in order to ensure the tracking accuracy and stability of the AGV,according to the actual operation requirements of the wheeled AGV in the park,a path/speed decoupled trajectory planning algorithm is proposed.The algorithm can produce path curves and speed curves that meet the physical constraints of the AGV,which can make the AGV run more smoothly and with higher tracking accuracy.Finally,the co-simulation model is established in Matlab/Simulink and Car Sim.The simulation results show that the trajectory tracking control algorithm designed in this paper can have a good tracking effect under various speed and various target trajectory conditions.(3)The wheeled AGV experimental platform is built,and the real vehicle experiments are carried out on the combined positioning algorithm and trajectory tracking control algorithm proposed in this paper.The experimental results show that the combined positioning algorithm and trajectory tracking control algorithm proposed in this paper have good performance and can meet the actual needs of park AGVs.