Managing the uncertainty of composite component inspection measurements using a polarized camera

Optical inspection methods based on the use of polarization camera are assuming an increasingly prominent role in the process control and assessment of high productivity manufacturing processes of composite components, like filament winding, due to their capability of giving reliable data with relatively inexpensive methods. In automotive and aerospace applications strength and safety requirements are crucial. Therefore, the accuracy of measurement of the most critical geometrical process parameters, such as the orientation of the tow during the manufacturing of axial components, is essential for ensuring to the quality of products and process. This paper is an extension of, where preliminary measurements were discussed with reference to a filament wound cylinder which provided information about the accuracy of measurements averaged on specific areas of a piece under examination. In this paper many aspects concerning the accuracy issues are discussed to better interpret the potentiality of polarization-based optical methods. This paper focuses on the effects the metrological characteristics of the polarized camera undergo depending on different elements, like the quality of manufacturing, the geometry of the surface, the selection of the region of interest for analysis, and how raw data are processed and presented. Moreover polarization-based methods are compared with other vision approaches for better assessing the quality of measurements. Paying attention to the aspects discussed in this work, the resulting measurement uncertainties of the winding angle is in the order of a few degrees. This is achieved also in case of punctual measurements, which is very important for real process control applications. • Calibration of a polarized camera. • Polarization camera data processing for composite component inspection. • Uncertainty of the orientation angle measurement in composite components using polarized cameras. • Comparison between different measuring methods for reproducibility assessment.