AUTOMATIC MAINTENANCE OF ROBOT PROGRAMS

After writing programs for a production robot, an operator must manual ly teach hundreds or thousands of poses, Teaching poses is extremely t ime consuming and, unfortunately, periodic reteaching is necessary, Th e need to reteach is commonly due to: wear, repair, slight movements o f workpieces, or replacement of the robot and its tools. Our experienc e has shown that conventional methods of adjusting pose data(1) do not work reliably. This paper discusses an automatic reteach method. The method has been tested on a production robot in a laboratory environme nt, In spite of changes in the robot and environment, we want constant shaped and sized tools to arrive consistently at taught work location s within desired tolerances, This means tool pose relative to the work piece is invariant, To assure this invariance, we establish a coordin ate frame on the work piece and identify the tool locations relative t o this frame, We apply a calibration algorithm to the pose data to acc omplish our goal, This paper demonstrates an automatic, economic imple mentation of kinematic calibration on an industrial manipulator. The m ethod is retrofit to a manufacturing system and does not require real time solution of the calibrated inverse kinematic problem, As a result , the method applies to most manipulators in use today.