Measurement process control by means of algorithms based on digital image processing

The real-time verification of the correct functioning of a measurement syst em is not only seldom performed, but also done using fairly ineffective sta tistical tools such as traditional Shewhart control charts. By considering measurement results reported in a control chart as a digital image, two dig ital-image-processing algorithms are proposed for the early fault diagnosis (detection and identification) of measurement processes. The first algorit hm exploits a uniform-approximation technique to face mainly problems of th e measurement process and/or instrument drifts. The second is based on the Hough transform to approach cyclic phenomena also for low signal-to-noise r atios. Results of the numerical characterisation and experimental validatio n demonstrate the practical applicability and the effectiveness of the prop osed algorithms.