System Design And Error Analysis Of The Wheeled Train Uncoupling Robot With Four Degrees Of Freedom

Chinese railway marshalling station has been developed for decades and formed dozens of hump marshalling yards with new technical equipments. However, the automation of the train uncoupling has not been realized completely due to that automatic train uncoupling system has so many technical difficulties. It makes the train uncoupling work with high intensity and security risks. In order to liberate the workforce,improve work efficiency and eliminate safety hazards of workers' job, this paper proposed a novel form of automatic train uncoupling robot based on analyzing the process of uncoupling. It can replace the uncoupling workers to complete the automatic uncoupling, which fills the gaps in the automatic uncoupling field of the marshalling station.Firstly, based on a comprehensive analysis of the domestic and international technology status,system solutions and structural design criteria of the train uncoupling robot are determined. Adopting the idea of modularization, a new body structure of the train uncoupling robot is proposed and designed. The body structure of the train uncoupling robot is divided into uncoupling robotic modules, lifting module, sliding module and walking module. Driving devices drive the executable module respectively, finally, a control system controls the driving devices to ensure the coordinated motion of each module to complete the automatic uncoupling of the train coupler.Secondly, the kinematics model of the train uncoupling robot is established, and the positive solution and the inverse solution of the robot kinematics are calculated. The geometric drawing method and numerical method are used to analyze the operating space of the train uncoupling robot respectively to verify the feasibility of the uncoupling action. The trajectory plan of uncoupling manipulator is done based on the quintic polynomial interpolation method. It can be seen from the planning results that position is continuous during the movement process of the manipulator and there is no strenuous motion, such as vibration and shock. Then, on the basis of the robot kinematics model with D-H parameters,the dynamic equations of the robot based on the Newton-Euler method is established and its driving torque of each joint is obtained through the SimMechanics dynamics simulation.Finally, manipulator static pose error model based on the matrix differential method is established and the manipulator motion error of the train uncoupling robot is analyzed. The simulation of the manipulator pose error caused by the movement variable errors and structural parameter errors of the the robot kinematics model is performed. As can be seen from the simulation results, the influence of the angle parameter errors on the manipulator pose error is greater than the length parameter errors. Then, the influence that links flexible on the robot error is analyzed, and it can be seen from the results that the influence that link flexible on the robot error is so weak due to the robot's movement characteristics. Finally, the train uncoupling robot pose errors caused by a variety of factors is analyzed,through the analysis, the error caused by various factors are attributed to the error caused by robot kinematic model structural variables and motion parameters. Finally, make the error compensation to the robot using the input motion planning method, the compensation results demonstrate the effectiveness of this method.