Calibration of an smt robot assembly cell

Abstract

Abstract A new calibration method for an assembly robot cell is described. The proposed method is a combination of a model‐free, numerical, relative robot calibration procedure and a procedure for the robot periphery calibration. Two important simplifications based on the study of an assembly process are introduced into the calibration strategy. A robot is calibrated in a task (Cartesian) space. The robot workspace and the number of calibrated degrees of freedom (dof) in the task space are reduced in accordance with the difficulty measure of the task. An automatic measurement system for measuring the relative robot accuracy was developed. An original principle of transforming the robot endpoint approach distance into the one‐dimensional position displacement error is introduced. The accuracy errors of each particular calibrated dof in the task space is measured separately. The error tables are used in a direct robot calibration procedure that is based on the linear interpolation of the discrete position‐error functions. An iterative inverse calibration algorithm used in a particular robot cell is described. An efficient sensor‐based system for an additional simultaneous robot periphery calibration is presented. The implementation of the proposed calibration methodology in the pick‐and‐place robot cell for Surface Mount Technology (SMT) is presented. © 1994 John Wiley & Sons, Inc.