Surface reconstruction by means of a flexible sensor array

In recent years, an increasing popularity of flexible sensor systems has been observed, which can largely be attributed to their ability to continuously adapt the shape to deformable bodies with non-planar surfaces without losing functionality. In this paper, we present a self-sensing, ultra-thin and flexible sensor array foil, which allows for determining its actual shape by analyzing signals from 6x6 sensors. Raw sensor signals clearly show the dependence from strength and direction of bending. The local bending vector is determined from signals of sensors oriented in different directions using rules which are already applied for strain gauge rosettes. The algorithm for the surface reconstruction divides the sensor foil into discrete bending segments for which the bending and subsequently new coordinates of segment edges are determined. A sensor diagnostics routine intercepts failure of the complete system due to the failure of single sensors. The functionality of the sensor array and the surface reconstruction is demonstrated for a foil subsequently adapting to a tube in different orientations. The obtained surface reconstruction clearly correlates with the visually observed bending. Such surface reconstruction could provide diagnostic information and potentially be used to detect diseases like pneumothorax. It could not only help to improve medical treatments but also to monitor the structural health of technical constructions