Structural health monitoring is certainly one of the key technologies required to provide the safety and the reliability of future aviation. Based on non-destructive testing, current on the ground periodical structural integrity inspections showed their limit as evidenced by the Columbia tragedy. For the time being, structural health monitoring technology has reached a good technology readiness level (TRL), but the integration of these solutions into future aerospace vehicle will require advanced system architecture. Further, improved SHM techniques and alleged assessment algorithm will be necessary to ensure an embedded integration, as well as to fully exploit their sensing capability. For now, most of high critical embedded systems are based on federate architectures, where each integrated calculator is dedicated to a specific function and to a unique kind of sensor. By consequence, the integration on the field of such solutions is highly difficult in aerospace industries due to the scale and the weight of the global electronics systems. Based on fully reconfigurable hardware, combined with versatile Input output interfaces, we propose a novel approach inspired from IMA (Integrated Modular Avionics) topologies. Signal amplification, conditioning and acquisition combined with digital calculation usually requires the use of multiple chips specialised whether in analog or in digital processing. Programmable digital electronics is not a challenge anymore, thanks to the widespread PLD and PGA's technologies. On the other hand, programmable analog electronics has much more of a challenge. Nowadays, programmable analog electronics can essentially be found in FPAA and some SoC such as Actel Smart-Fusion or Cypress PSoC. To understand the flexibility that such solutions could bring, two examples of embedded systems will be exposed: * Static embedded system based on a central CPU developed in accordance to the conventional V-model. The system is intended to monitor the integrity of a rotator Air blade and is currently integrated into A400M Aircrafts. * Dynamic and reconfigurable embedded system developed using "model based approach". In this module, multi diagnostic techniques based on PZT sensors are instrumented using a unique programmable SoC (System on Chip) which includes an ARM Cortex M3 32 bits CPU, analog and Digital CPLD. Damage assessments algorithms are therefore managed by the calculator, the sensor interface is performed through a charge amplifier inside the SoC and the data are transmitted by an Ethernet controller. To cover large areas, the system is fully scalable and accepts a hardware upgrade. Based on guided waves or electromechanical impedance analysis, the presented solutions are capable to detect different kinds of events such as impacts or flaws such as corrosion, cracks or delaminations ; no matter if the probed structure was made of composite or metallic alloy.
Etude et développement d'un noeud piézoélectrique intégré dans un micro-système reconfigurable: applications à la surveillance "de santé" de structures aéronautiques