Arrangement of multi-sensor for spatio-temporal systems: application to sheet-forming processes

In sheet-forming process, we are dealing with a two-dimensional product, ro lls of paper or metal, polymer films etc. The control objective is to maint ain product quality, e.g., thickness, uniformity during continuous producti on. Despite recent advances in measurement technology, it is difficult to m easure all points on the entire sheet, Therefore, we have a two-dimensional product with scattered measurements. The location of measurement points no t only decides the correctness of the estimation, it also affects the contr ol performance. Previous study shows that, in the temporal mode, the optima l estimation implies equally spaced measurement updates. In this article, a n image-based approach is proposed to evaluate the appropriateness of measu rement patterns for interactive spatio-temporal systems. The method is base d on the concept of time to the next nearest neighbor(s) and the mean and s tandard deviation are utilized to discriminate among measurement patterns. It is useful in arranging multiple scanning sensors. The proposed approach is employed for the evaluation of multi-sensor arrangement for typical shee t-forming processes. Results show that the image-based analysis is effectiv e for the design of sensor trajectories for manufacturing of two-dimensiona l products. (C) 2001 Elsevier Science Ltd. All rights reserved.