PURPOSE: To properly set investigation distance between the work center point and an investigation point without increasing the work failure frequency. ;CONSTITUTION: The variance distribution is measured for the relative position between hole and ramp of a base board before the work is started. Distribution function of the work success rate is calculated based on the measured dispersion distribution and an allowable work success error. When the success rate is measured at the work center point, the position of this success rate is estimated in the work success rate distribution. Then, the distance from a point where the work success rate is maximized is set as an investigation distance. If the work fails and the work center point is corrected, the investigation distance is set again based on the success rate calculated at a new work center point. As the investigation point is variable, the correcting point quickly comes near to the highest success rate point when the correcting point is set distant away from the highest success point. Meanwhile, the correcting point can surely get closer to the highest success rate point without passing over this point when the correcting point is set close to the highest success point.;COPYRIGHT: (C)1996,JPO
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