Williston, VT, July 11, 2006 -- The U.S. Navy (NAVAIR) has recently awarded MicroStrain, Inc an SBIR Phase II contract to develop next-generation wireless strain sensors for damage tracking of Navy helicopters. MicroStrain's patent pending sensing systems will operate indefinitely on rotating helicopter components without the need for battery maintenance, by converting the component's cyclic strains into dc power using piezoelectric materials.
MicroStrain's miniaturized, programmable systems serve a range of vehicle health management functions, including: embedded test & evaluation (ET & E), health usage monitoring (HUMS), and structural health monitoring (SHM). Phase I demonstrations proved that MicroStrain's nodes will operate continually, without battery maintenance, even under low energy generation conditions of straight and level helicopter flight. By continuously monitoring the strains on rotating components, the nodes can record operational loads, compute metal fatigue, and estimate remaining component life. Data compression and fatigue algorithms are fully embedded in the nodes, and the strain vs number of cycles (S-N) curve may be wirelessly uploaded to suit the application's specific materials and geometries.
Reducing power consumption is a critical requirement for energy harvesting, because the energy "checkbook" must be balanced to support continuous operation. MicroStrain's engineers have recently published power consumption reductions that are eye-popping. In recent Navy demonstrations, MicroStrain's new wireless sensor nodes (strain gauges sampled at 40 times/sec, and with 70 meters wireless communications range), provided significant power savings: from the standard 72 milliwatts, down to only 0.9 milliwatts -- an improvement of 80 times.
The helicopter pitch link was selected as the rotating structure for demonstrations during MicroStrain's Phase I SBIR. The pitch link is a critical rotating element that adjusts the rotor blade's angle of attack as the rotor turns through the air. Pitch link loads depend strongly on flight regime; therefore, these loads are an indicator of structural usage severity. In tests replicating light usage (straight and level flight), MicroStrain's energy harvesters generated ~1 milliwatt. During tests replicating heavy usage (pullups, gunnery turns), the harvesters generated ~5 milliwatts. These demonstrations proved that a practical wireless damage tracking system could be operated indefinitely without batteries, under a wide range of operating conditions.
The Navy SBIR Phase II award provides approximately $750K over a two-year period. Combined with Phase I, U.S. Navy support totals about $900K. The Federal SBIR program is highly competitive, and funds only those small business innovations with significant commercial potential. More information on the Navy's SBIR program is available online.
