Lightweight inertial sensor makes a splash

 - February 5, 2007, 5:28 AM

Today pilots who have an inertial navigation system coupled with an advanced GPS aboard their airplanes are considered to be at the upper end of the profession, while the rest of us bumble along with just a plain vanilla GPS–maybe with a WAAS upgrade–and a couple of VORs plus one, maybe two, DMEs. But tomorrow might be different. Engineers at BEI Systron Donner have developed a combined, fully integrated INS/GPS unit that you could almost conceal in your hand, weighs less than 12 ounces, uses fewer than five watts of power from a 12-volt power supply and could one day give operators of small aircraft the capabilities of a business jet at a very small fraction of the price.

Introduced at the Institute of Navigation’s annual Conference in Long Beach, Calif. last fall, the company’s MMQ-G unit is based on micro-electro-mechanical systems technology–a new “black art” of the electronics industry that combines complex, tightly integrated circuits with mechanical sensors formed by micromachine etching of overlapping layers of silicon wafers to produce very small, but very precise, low-cost devices.

The miniature Systron Donner package, for example, includes an advanced, 28-state Kalman filter that integrates with the INS and GPS data to provide accuracy within 30 feet, and can refine this further with differential GPS corrections.

With a projected quantity selling price of somewhere above $10,000, it is likely to serve in a variety of civil roles, from fixed-wing aircraft and helicopters to railroads, while its ability to handle maneuvers of 200 degrees per second and to withstand 30g makes it a candidate for UAVs, smart bombs and missiles. In short, the unit is an example of where the avionics art is heading in the future.

The Future of GPS
But on Germany’s autobahns, one part of the future has already arrived. Effective January 1, commercial vehicles plying that country’s 7,500-mile expressway system–Europe’s largest highway network–were required to carry GPS receivers coupled with cellular radios as elements of Germany’s new Toll Collect program.

Germany provides the vehicle package to truckers and the unit establishes the vehicle’s position, tracks its route, calculates toll fees and transmits this data at regular intervals via the cellular radio to a data center for billing.

About 800,000 trucks use German highways each day. This year, the Toll Collect system is expected to raise around $3.7 billion in fees, with the money being used to invest in transportation infrastructure.