Displacement errors in active visual inspection

Displacement error is inherent in automated visual inspection systems. This paper discusses the effect of displacement error of the end-effector on the precision measurement of the dimension of an edge line segment. The position and orientation errors of the end-effector are assumed to be normal distributed. A probabilistic analysis in terms of the these errors is developed for the displacement errors. Given that the nominal orientation and position of the sensor are known, the effect of this error on the dimension measurement is also analyzed. Based on this analysis, we investigate whether a given set of sensor setting parameters in an active system is suitable to obtain a desired accuracy for specific line segment dimensional measurements. In addition, based on this approach, one can determine sensor positions and view directions which meet specific targets for tolerance and accuracy of inspection. Developing these mechanisms is central to achieving effective, economic, and accurate inspection systems.