An Improved EI Method For Optimal Sensor Placement

Optimal Sensor Placement(OSP) is one of the most important steps in structural health monitoring(SHM) system, the OSP results will affect the outcome of SHM system. The traditional OSP methods cannot meet the application requirement because of the complex and volatile environment in modal test and the complicated modern structural configurations. An effective independence-improved modal strain energy(EI-IMSE) method is proposed in this study, which includes the following contents:(1) The SHM system is introduced and the importance of OSP emphasized. Traditional OSP methods are reviewed with a focus on an overview of the EI method, then five evaluating criterions are also introduced.(2) The background of selecting suitable number of modes for OSP is introduced, and a trace-based matrix evaluating criterion is proposed to evaluate the Fisher information matrix(FIM). The existed methods, such as effective independence-driving point residue(EI-DPR), effective independence-average driving DOF velocity(EI-ADDOFV) and effective independence-average acceleration amplitude(EI-AAA) are introduced. For overcoming their deficiencies, the EI-IMSE OSP algorithm is proposed in this study.(3) The EI-IMSE OSP method is evaluated by some numerical simulations on 2D and 3D truss structures. Based on the criteria on MAC, trace of FIM, matrix condition number, and the least mean square error, the EI-IMSE OSP method is evaluated through comparing with the EI-DPR, EI-ADDOFV and EI-AAA methods The comparative studies show that the proposed EI-IMSE algorithm is a feasible OSP tool with a higher accuracy as well as a better effectiveness.(4) In order to evaluate the EI-IMSE OSP method experimentally, a rectangular hollow steel beam hinged at both ends is designed and used to obtain the modal parameters of structures through the experimental modal analysis, By comparing the modal frequencies and mode shapes identified by use of the different OSP combination due to existed OSP methods and due to the EI-IMSE, the good OSP performance of the proposed EI-IMSE is verified experimentally.