By John Rhea
FORT WORTH, Texas — BAE Systems engineers are using microelectromechanical systems (MEMS) technology derived from their work in the auto industry — particularly for applications in dynamic braking — in missile guidance systems as a low-cost alternative to ring laser gyros.
Charlie Hopper, marketing and sales director for motion sensors in the U.S. operations of the British-based firm, says the new line known as the Silicon Inertial Measurement Unit (SiIMU) has already passed tests at the Royal Ordnance test site at Salisbury Plain in England. The tests, using 81-millimeter mortar rounds, involved shocks up to 16,000 Gs during the launch phase.
Hopper says company leaders are aiming at 20,000 Gs to enhance their market. For example, he notes, the British Seawolf vertically launched missile is subjected to shocks of only 1,000 Gs while gun-launched guided munitions can reach 45,000 Gs.
Each SiIMU contains six sensors, three to provide angular rate data and three to measure acceleration. In the automotive dynamic braking application, the sensors principally measure yaw.
BAE Systems experts have also tested the SiIMU sensors in a medium-range anti-tank missile, but are saying little about the tests except to claim they were first to use a MEMS guidance system in a missile.
The competition with conventional laser gyros will be decided solely on the basis of price, Hopper says, calling the market "volume-sensitive and mission-specific." He estimates BAE can get the price below $5,000 per unit in orders of 50,000 or more pieces. Since the SiIMU line is a family of generic devices, he adds, the units can be customized for a variety of applications.
