Towards packet-less ultrasonic sensor networks for energy-harvesting structures

This paper proposes and evaluates an energy-aware pulse switching architecture for a through-substrate ultrasonic sensor network. The network is run from vibration energy harvested on an airplane stabilizer structure, whose health is monitored using the through-substrate network. Pulse- switching-based protocols use single pulses instead of multi-bit packets for information delivery with ultra-high energy-efficiency. Pulse switching using ultrasound is particularly well suited for event reporting through metal / composite substrates used in structures such as bridges, aircraft wings, etc. This can eliminate the need for out-of-substrate radio or wired links. This paper presents a large-scale simulation model in which structural vibration modeling using finite element methods, energy harvesting modeling from such vibrations, and energy-aware pulse networking models are integrated for end-to-end architecture level performance evaluation. Simulation results are used for demonstrating the sensitivity of network performance to key system parameters, namely, structural vibration intensity, energy harvesting efficiency of the used piezoelectric material, and the energy storage capacity at the pulse switching sensor nodes. In addition to event reporting delay, the impacts of pulse loss have been thoroughly characterized using the integrated simulator.