Research On Trajectory Tracking Accuracy Of Spatial Complex Welding Seam For Vehicle-Mounted Flexible Manipulator

With modern industry scale expanding gradually,the demand for large-scale welding structure grows rapidly in some areas such as large ship manufacturing and ocean platform chunk manufacturing.Since the mobile welding robot won't be confined in the immovable station and the posture of the flexible manipulator can be adjust flexibly in order to fit different forms of spatial welding seams,the mobile welding robot has become one of research hotpots in the intelligent welding research area.Due to the welding quality is influenced by the trajectory tracking accuracy of the vehicle-mounted flexible manipulator significantly,researching on factors that affect the tracking accuracy and methods that will improve the tracking accuracy has great significance.First of all,the complex vehicle-mounted flexible manipulator is simplified into two-dimensional flexible linkage mechanism and the spatial complex welding seam is simplified as sawtooth waves in the plane.And then,the kinematics model of the vehicle-mounted flexible manipulator is built.Based on Kineto-Elastodynamic Analysis,the building process of the mathematical model and the system model is explained in detail,which can provide the analysis of elastic vibration and the calculation of tracking error with theoretical basis.After that,analysis the main cause of the strong elastic vibration in flexible manipulator through the trajectory tracking simulation which is performed on the condition that the vehicle moves at constant speed.In order to reduce the influence that comes from the vehicle movement,a variable speed motion scheme of the vehicle is put forward.Based on geometrical representation of manipulator dynamics theory,the optimum vehicle position which can provide the manipulator with the favorable work space is determined.Based on the optimum vehicle position,another variable speed motion scheme of the vehicle is put forward.Then,the tracking error of different motion schemes is compared with each other.At last,the basic vibration property of this kind manipulator is analysis through the mass-spring-damp model which can simulate the flexible manipulator with macro-micro structure proximately.Based on the different effects of the macro part and the micro part on the manipulator system,two kinds of macro-manipulator trajectory plans are put forward for different size welding seams.The effectiveness of the vehicle-mounted flexible macro-micro manipulator can be confirmed by trajectory tracking simulation.Then,factors that affect the tracking accuracy of the flexible macro-micro manipulator such as structure parameter,material coloration,localized mass and the trajectory of macro-manipulator are analysis through further simulation.Much valuable information for the design and control of the mobile welding robot is achieved.