Abstract: Previous generation robots were originally designed for lead- through on-line programming and were found to be quite successful in that mode. During the past decade, some of these robots were retrofitted with additional software to perform straight line interpolation between program points taught using a teach pendant. Given this new `cartesian' model, a natural enhancement was to then use such robots in a simulation and off-line programming environment. However, the results of initial tests showed that while such robot systems was repeatable to within a few millimeters during playback of previously taught on-line programs, they could be inaccurate by as much as six inches when programmed off-line. This paper discusses the quantification of positioning errors for such an application using automatic coordinate measuring theodolites, the identification of the robot kinematic signature describing the differences of the actual robot kinematics from the nominal drawings, and the compensation of the geometric and non-geometric robot errors by modification of the robot software model and translator in a workstation based graphical off-line programming system.!3
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