Mechanism Design And Positioning Accuracy Analysis Of Shield Assisted Tool Change Robot

With the expansion of the construction scale of underground space,shield tunneling technology has been widely used in tunnel excavation construction because its high degree of automation and rapid construction characteristics.However,in the process of tunneling,the strata are complex and variable,and the hobs on the cutter head inevitably wear out,requiring frequent replacement,seriously affecting the tunneling efficiency.The traditional hob replacement method has low safety,long cycle,and high cost.The difficulty and risk of tool replacement severely limit the development of shield tunneling.Therefore,replacing people with robots for tool replacement is the development direction of intelligent shield tunneling in the future.This research is aimed at the research on the key technologies of the mechanism design,finite element analysis,trajectory planning,kinematics solution,motion control and other aspects of the auxiliary tool changing robot of the shield machine for the large slurry balance shield machine with a diameter of 12 meters.The main research contents are as follows:(1)Determination of the design scheme for the tool changing robot system.After consulting relevant information,conducting on-site engineering research,and comprehensively analyzing the internal environmental characteristics,working principles,and manual tool changing environment of the slurry water balance shield machine,the design functions and indicators of the tool changing robot,as well as the installation location of the tool changing robot,have been determined.(2)Research and design of the body system of a tool changing robot.According to the internal characteristics of the large slurry shield machine,the end actuator,telescopic arm,fixed two-way rotating joint,base boom and mobile base of the tool changing robot are designed and the drive source is selected,and the six degrees of freedom hydraulic drive tool changing robot scheme that meets the needs of tool changing is determined.(3)Finite element statics analysis of tool changing robot.The analysis results show that the design scheme of the body system of the tool changing robot meets the application requirements of the strength and stiffness of the tool changing robot.(4)Research and design of trajectory planning for tool changing robots.Analyze the motion limitations of each joint and determine the shortest movement time of each joint;With the goal of fast,stable and impact free tool change,the characteristics of trapezoidal speed curve,quintic polynomial curve and seventh degree polynomial curve are compared,and the seventh degree polynomial is selected as the trajectory planning curve to reduce the jerk during tool change;Based on the seventh degree polynomial trajectory planning curve for simulation verification,the results show that the motion process of each joint is smooth and impact free,and the replacement time of the hob is within 21 minutes,meeting the requirements of fast,stable,and impact free tool replacement.(5)Kinematics solution and working spatial analysis of tool changing robot.Using the improved D-H method,the linkage coordinate system of the tool changing robot is established and its kinematic equations are derived;Using Matlab robotic toolbox to verify the correctness of the established kinematics model of the tool changing robot;Using the Monte Carlo sampling method to solve the workspace of the tool change robot,the analysis results show that for a 12 meter slurry water balanced shield machine,the cutter head hob replacement rate can reach 97.5%,and all 17/19 inch hobs have been replaced,meeting the requirements for the tool change range of the tool change robot.(6)Research and design of motion control algorithms for tool changing robots.Based on the Lagrange method,establish a dynamic model of the tool changing robot;Analyze the error causes of the tool changing robot,propose a fuzzy adaptive PD compensation control algorithm,and conduct Simulink control simulation.The simulation results show that the displacement error of the moving joint is within 1mm,and the error of the rotating joint is within 0.5°.The positioning accuracy meets the control requirements,verifying the feasibility of the control system algorithm for the tool changing robot.