Harvester takes flight

An energy harvesting wireless strain sensing module has taken a flight test aboard a Bell helicopter to help track any damage to rotating parts.

The module, from Microstrain, will operate indefinitely without the need for batteries, by converting the component’s cyclic strains into DC power using piezoelectric materials.

MicroStrain’s modules, called ESG-LINK, feature a precision time keeper, non-volatile memory for on-board data logging, and a frequency agile IEEE 802.15.4 transceiver. Sampling rates, sample durations, sensor offsets, sensor gains and on-board shunt calibration are all wirelessly programmable.

Recent flight tests on the Bell helicopter showed that MicroStrain’s nodes could operate continually, without batteries, even under low energy generation conditions of straight and level helicopter flight.

By continuously monitoring the strains on rotating components, the nodes recorded operational loads, computed metal fatigue, and estimated remaining component life.

The critical component instrumented on the Bell M412 was the pitch link. The pitch link controls the rotor blade’s angle of attack as the rotor rotates through the air. Pitch link loads vary strongly with aircraft flight regimes, reaching much higher loads (6X) during pull ups and gunnery turns as compared to straight and level flight.