Error analysis and planning accuracy for dimensional measurement in active vision inspection

Spatial quantization error and displacement error are inherent in automated visual inspection systems. This paper discusses the effect of spatial quantization errors and displacement errors on the precision dimensional measurements for an edge segment. Probabilistic analysis in terms of the resolution of the image is developed for two-dimensional (2-D) quantization errors. Expressions for the mean and variance of these errors are developed. The probability density function (pdf) of the quantization error is derived. The position and orientation errors of the active head are assumed to be normally distributed. A probabilistic analysis in terms of these errors is developed for the displacement errors. Through integrating the spatial quantization errors and the displacement errors, we can compute the total error in the active vision inspection system. Based on the developed analysis, we investigate whether a given set of sensor setting parameters in an active system is suitable to obtain a desired accuracy for specific dimensional measurements. In addition, based on this approach, one can determine sensor positions and view directions which meet the necessary tolerance and accuracy of inspection.