Research On 3D Vision Based Special Steel Sample Rod Positioning And Robot Grasping Technology

During the production of special steel bars at the current steel mill,some sample bars are taken from the rolling line for quality inspection in each furnace.Usually the sampling of special steel bars are manually operated by grabbing the high temperature special steel sample bars in the sampling trolley in turn and placing them in the holding tank,but the large mass and high temperature of the special steel sample bars make it very easy for accidents and injuries to occur.Therefore,the study of 3D vision-based special steel sample bars positioning and robot gripping technology are important for the eventual formation of the special steel bars sampling robot product and the advancement of steel mill automation.According to the working scenario of the special steel bars sampling station in the steel mill,this paper analyses the process flow of special steel bars sampling,adopts 3D vision technology to identify the position of the special steel bars,designs the end operator to grasp the high temperature bars and uses an industrial robot instead of manual work,with Eye-to-Hand working method to complete the special steel bars sampling work.Firstly,the point cloud information of the special steel sample bars are obtained by photographing the bars with a 3D camera.Pre-processing operations are carried out to remove noise and simplify the point cloud information by using a combination of straight pass filtering,statistical filtering and voxel filtering.The point cloud is segmented and extracted using a random sampling consistency algorithm.The template point cloud is determined by robotic teaching and the target bars are determined by a combination of coarse and fine point cloud alignment algorithms.Next,the structure of the end handler is designed according to the specifications for gripping special steel sample bars in the diameter range 80 mm to 350 mm,and the key components of the end handler are subjected to force and temperature analyses.Next,the kinematics of the special steel sample bars gripping robot are analysed,the robot coordinate systems are established using the D-H parametric method,the kinematic equations of the robot are established,its inverse kinematics are solved using the separation of variables method,and the selected solution is completed.The external singularity of the robot is solved using the Monte Carlo method and the internal singularity of the robot is analysed using the differential transformation method to obtain the relationship between the joint variables of the singular position of the robot.Finally,the experimental platform for the special steel bars sampling robot is built according to the actual working conditions,the robot and camera are calibrated by hand and eye,and the homogeneous transformation matrices of the camera coordinate system to the robot base coordinate systems are solved.The control system software is developed according to the hardware requirements,the interface design and the communication between the devices are completed,the spatial positioning of the irregularly placed special steel sample bars and the automatic gripping of the robot are completed under laboratory conditions.The study of 3D vision-based positioning and robotic gripping technology for special steel sample bars can effectively solve the problems of difficult and injurious manual gripping of special steel sample bars and achieve automatic gripping of special steel sample bars.The design of the end-operator enable the solution to the problems of large variations in the diameter range of special steel sample bars,high masses,high temperatures and difficulties in gripping.The kinematics of the KUKA-KR210-2 robot are analysed and the motion control of the robot is realised.Integration of the robot hardware system and development of the robot software system to achieve automatic control of the gripping process of special steel sample bars,and verification of the stability and feasibility of the equipment under laboratory conditions.The research in this paper provides technical support for the automation of special steel bars rolling lines.