Honeywell says micro electromechanical systems could lead breakthrough in sensor and weapon guidance technology

Honeywell is pursuing development of micro electromechanical systems (MEMS) as a "potentially disruptive" technology in aircraft avionics and weapon guidance. The company is already developing an attitude and heading reference system (AHARS) and standby display for commercial aviation applications using MEMS sensors.

MEMS combine micron-scale electrical and mechanical features on the surface of a silicon chip, and are batch-produced using integrated-circuit fabrication techniques. "MEMSis an enabling technology across Honeywell," says Eric Doremus, vice-president precision sensors and components. Applications range from biomedical sensors to aerospace devices including attitude and pressure sensors and inertial measurement units.

Doremus says MEMS offer significant reductions in cost, size, weight, volume and power over conventional sensors. The company is already producing air-data systems using MEMS precision pressure sensors. The next step is a flush-orifice air data system, now in development, which uses distributed pressure sensors to eliminate the pitot probe, he says. The first developmental MEMS-based inertial measurement units have been delivered to customers.

Honeywell is applying MEMS gyros to inertial systems small and robust enough to guide gun-launched projectiles. In the longer term, the technology promises to provide navigation-grade performance, allowing MEMS gyros and accelerometers to replace ring-laser and fibre-optic gyros in aircraft inertial systems. Doremus expects the Lockheed Martin F-35 Joint Strike Fighter's inertial navigator to be a MEMS-based device just 50cm3 (3in3) in size, compared with the F-16's 7,900cm3 laser-gyro unit.

Honeywell's MEMS-based AHARS is scheduled for introduction in 2004-5. GPS aiding will reduce errors, to provide an attitude accuracy of better than 0.1°, says Doremus. Back-up true-airspeed aiding will provide an attitude accuracy of 1-2°. The AHARS will be part of Honeywell's new flat-panel standby display, which will combine the unit with MEMS-based air data sensors and magnetometer. GPS integration and flight-control output will be optional features.

Honeywell has MEMS fabrication facilities in Redmond, Washington, and Plymouth, Minnesota. Both are capable of producing 150mm (6in)-diameter wafers, each containing 700 micro-scale gyros. The Plymouth site is being upgraded to handle 200mm wafers for the production of pressure sensors with 1.5 micron-sized features.

Source: Flight International