Wireless sensors with dual-controller architecture for active diagnosis in structural health monitoring

Wireless sensor technology, which integrates transducers with microcontrollers and wireless communication, has become increasingly vital in structural health monitoring (SHM) applications. However, the low I/O (input/output) throughput of conventional wireless sensors impedes their usage in applications using high-frequency signals, such as active diagnosis and passive acoustic emission (AE). In this paper, the limitations of extending conventional wireless sensors to handle high-speed acquisition are first identified and discussed. Based on the efforts made in improving wireless sensors with centralized system architecture, a novel dual-controller based architecture is proposed to facilitate high-speed data acquisition and improve power efficiency. Then, a wireless sensor platform, specifically designed for active diagnosis employing stress waves to localize damages, is presented. The newly developed wireless sensor with dimensions of 30 mm x 30 mm x 35 mm utilizes a field programmable gate array (FPGA) as a secondary controller and can support a sampling rate up to 20 million samples per second (Msps). Laboratory experiments for verification show that the wireless sensor can explore new applications at the opposite end of the spectrum from conventional applications: those involving high fidelity and high-speed data acquisition.