Remote monitoring of structural integrity using a microcontroller based system

• Grant number: 12/02637-3
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2012
• End date: March 31, 2013
• Field of knowledge: Engineering - Electrical Engineering
• Principal Investigator: Jozue Vieira Filho
• Grantee: Renan Passerini Ferreira
• Host Institution: Faculdade de Engenharia (FEIS). Universidade Estadual Paulista (UNESP). Campus de Ilha Solteira. Ilha Solteira , SP, Brazil

Abstract

Structural health monitoring (SHM) has advanced significantly in recent years, with applications in different areas of engineering. By monitoring structures in real-time using a dedicated data acquisition system, the maintenance costs in complex structures, whether mechanical or not, can be significantly reduced. Among the various techniques available for SHM applications, one that has been successfully exploited is based on piezoelectric transducers, such as PZT ceramics (Pb-Lead zirconate titanate, lead zirconate titanate). These devices can be used in different ways. The excitation-response-based process methods have been receiving a lot of attention in recent years. In these methods, the system needs to generate appropriated signals to the PZT excitation and make the acquisition of the response signals within the standard specified in the methodology. These signals are processed according to the fault detection methods. In an SHM system based on EMI, the information about the structure should be obtained initially in a condition considered "healthy" to generate a reference signal called the baseline. This information is stored to be compared with the data obtained from the structure in operation. Differences based on consecrated metrics in the area as RMSD (the mean square deviation value) and CCDM (the correlation coefficient deviation) are obtained and used as a basis to determine if the structure has failed or not. The purpose of this work is part of an SHM research project which exploits the principle of electromechanical impedance (E/M), supported by FAPESP (Process 2011/20354 -6). The system proposed is based on a microcontroller and without any external connections, such as microcomputers, signal generators, etc. However, the system will be provided with a wireless interface, then data can be transmitted somehow to a central computer. The basic goal is to study and implement a wireless interface suitable for the system's remote operation, which should allow, among other possibilities: to define the operating frequency range; the amount of data; creation of the reference signal (baseline); start or stop the structure monitoring and provide data and results. The SHM system will be based on the PIC microcontroller family. The wireless interface will be defined from a basic study on three possibilities: 1 - direct link with its own protocol, 2 - connection using the ZigBee standard, and 3 - connection using GSM. The end result may be a single interface or a combination thereof.(AU)