A Novel Position And Orientation Correction Method For Specific Robot Poses By Measuring An Array Of Standard Balls

Robot accurate positioning is a key task in robot-assisted casting process. The usual approach to improve positioning accuracy by the laser tracker is uneconomical and has low operability due to the on-site harsh environment (high vibration, cramped space, etc). In this paper, a novel approach is proposed to correct specific robot poses, where a 3D (three-dimensional) scanner is used to measure an array of standard balls in a robot 3D measurement system. The objective function is established with the help of a definition of the conversion between a 4 x 4 homogeneous transformation matrix and a 6D (six-dimensional) vector. In that definition, robot pose (position and orientation of the robot's end-effector) parameters are used instead of robot kinematics parameters (Denavit-Hartenberg parameters). Simulation and practical experiments are performed to test the effect of this approach on pose correction. By using this approach, the average diameter error of reconstructed standard balls is less than 0.1 mm, which can meet the precision requirements in robot-assisted casting process.