Wireless and distributed sensing of the shape of morphing structures

Monitoring the shape of morphing structures is essential for their effective and safe operation. However, current sensing systems such as fiber optic sensors are expensive, brittle, and unsuitable for monitoring large shape changes without being susceptible to failure or performance degradation. Therefore, a new class of sensors that does not suffer from these serious limitations is presented. The sensor system relies in its operation on a specially configured distributed network of wires that is embedded in the composite fabric of these structures. The output of the sensor network is wirelessly transmitted to a control processor to compute the linear and angular deflections, the shape, and maps of the strain distribution over the entire surface of the morphing. The deflection and shape information are vital to ascertain that the structure is properly deployed. The strain map ensures that the structure is not loaded excessively to adversely affecting its service life. The equations governing the operation of the sensor network are developed for a beam-like morphing structure using the non-linear theory of finite elements. The resultin,g equations will provide the sensor with its unique interpolation capabilities that make it possible to map the linear and angular deflection and strain field distribution over the entire surface of the morphing structure. The theoretical and experimental characteristics of the sensor network are determined under static and dynamic loading conditions. The results obtained are used to demonstrate the merits and potential of this new class of sensors as a viable means for monitoring the deflections of 1D morphing structures. Integration of the proposed sensor network with the supporting electronics and with arrays of flexible actuators will enable the development of a self-contained, actively controlled, and autonomously operating new generation of morphing. (C) 2007 Elsevier B.V. All rights reserved.