Research On AGV Control And Autonomous Tracking For Trackless Navigation

Since the emergence of automated guided vehicles,they have been replacing human beings with heavy mechanical tasks such as cargo handling and cargo traction.The original automatic guided vehicles need to be laid on the production site in advance to run.At present,this kind of automatic guided vehicles is still used in industry.With the development of science and technology,the technology related to the trackless guidance system is gradually maturing.The production cost and price of the equipment required for trackless guidance are further reduced,which allows the large-scale application of trackless guidance vehicles.Compared to the hardware part of the trackless navigation system,the vehicle motion control algorithm part of the system is more likely to limit the current trackless navigation system to transfer from research to product.This manuscript mainly studies the critical technologies of trackless guided vehicles.The main tasks are as follows:(1)A set of automatic guidance systems is built based on the chassis with a dual-differential steering drive,which is a layered model.The system includes the hardware layer and software layer.The software layer is divided into bottom layer control and upper layer control to facilitate the control system’s transplantation between different chassis.The upper control will calculate how the wheel motor rotates according to its position and the position to be reached,and the calculated result will be sent to the lower controller.The bottom layer receives instructions from the upper layer and sends commands to the wheel motors according to the instructions’ speed and steering to complete the wheels’ control.(2)Analyze the mathematical model and kinematics model of the differential motion chassis model,use MATLAB for kinematics modeling,track the target trajectory for tracking simulation,and compare the simulation trajectory with the target trajectory and the trajectory of the actual vehicle running to determine the credibility of the simulation model.Then use the simulation model to complete the experiment that the real car cannot.In kinematics modeling,the mass of the vehicle and the two driven wheels are ignored,the vehicle is simplified into a differential kinematics model with only two wheels,and the center point of the two wheels is used as the control point.(3)The traditional pure pursuit algorithm is improved,because the forward-looking detection distance of the traditional pure pursuit algorithm is fixed,and the forward-looking detection distance only determines the determination of the forward-looking point.In trajectory tracking,there are two kinds of problems in the process: cutting corner and overshooting phenomena.For these two phenomena,the concepts of curvature and radial distance of the target trajectory are introduced.After the curvature is introduced,the forward-looking detection distance is changed according to the target trajectory’s curvature,which dramatically changes the chamfering angle.The radial distance concept is introduced,and the forward detection point is determined by the forward-looking detection distance and the radial distance,which significantly changes the overshoot phenomenon.