Low-Cost, Efficient Output-Only Infrastructure Damage Detection with Wireless Sensor Networks

Structural health monitoring (SHM), which is the process of gauging the health of instrumented structures, is becoming increasingly important as much of the world's transportation infrastructure ages and deteriorates. Wireless sensor networks (WSNs) have the potential to deliver continuous SHM at a low cost. We present a novel WSN system that monitors ambient structural vibrations and looks for deviations from a baseline response to assess the condition of the structure under observation. Efficiency is achieved by implementing our damage assessment process with an innovative wireless-sensor-based technique involving look-up tables. By using look-up tables we are able to minimize computations. Only 4-6 integer and two floating-point operations are required per damage assessment. This is in contrast to the majority of other methods that rely on precise engineering models of the monitored structures. Our look-up table technique is benchmarked against the brute force approach, which involves solving equations, by measuring the execution time of each implementation on a low-power Microchip microcontroller. Here, we were able to achieve a speedup of roughly five. In addition, we investigate a tradeoff between average transmission power and the number of measurements required to make a decision as to the structure's condition. Finally, we benchmark our damage assessment process using a case study to verify its efficacy for bridges.