A Micromechanical INS/GPS System For Guided Projectiles

Donald Gustafson, Ralph Hopkins, Neil Barbour, and John Dowdle

Abstract:	Recent advances in silicon microfabrication technology have led to the development of low cost, tactical performance grade, micromechanical inertial sensors. The inherent small size, low weight, and low cost of these sensors permit on-board insertion of gyroscopes and accelerometers for inertial instrument applications previously impractical because of size and cost considerations. Among the emerging opportunities for micromechanical inertial sensor insertion is the application to guided projectiles. This application is distinguished by the extremely high acceleration (high g) sensor measurement environment experienced during projectile launch; peak accelerations on the order of 100,000 g are possible during firing. Draper Laboratory has developed a range of l.raccelerometers to measure muzzle velocity and projectile flight acceleration, and a ltgyroscope to measure projectile attitude. Only the high g accelerometer is operational in the barrel; the other sensors operate outside the barrel but must be able to survive the launch environment. The total sensor system furnishes eight orders-of-magnitude acceleration dynamic range capability. A description of the sensors is given. Performance simulations for a high-dynamic range micromechanical inertial navigation system, coupled with a GPS receiver, are provided. GPS supplies position information at low frequencies, and the micromechanical instruments supply high-frequency information. The data are combined with a Kalman filter and navigator to generate high-frequency position, velocity, and attitude information. The high-frequency information is then used in the guidance and control of the projectile. Small micromechanical inertial sensors integrated with miniaturized multi-chip module GPS receivers will soon be available. By incorporating fast acquisition hardware, advanced signal processing techniques and adaptive antenna logic with the GPS receiver, a miniaturized integrated INS/GPS navigation system can be developed that exhibits high anti-jam (A/J) capability for guided projectile scenarios. This is the enabling technology that will lead to the development of GN&C sensors, electronics and pprocessor-based software for precision guided projectiles.
Published in:	Proceedings of the 51st Annual Meeting of The Institute of Navigation (1995) June 5 - 7, 1995 Antlers Doubletree Hotel Colorado Springs, CO
Pages:	447 - 455
Cite this article:	Gustafson, Donald, Hopkins, Ralph, Barbour, Neil, Dowdle, John, "A Micromechanical INS/GPS System For Guided Projectiles," Proceedings of the 51st Annual Meeting of The Institute of Navigation (1995), Colorado Springs, CO, June 1995, pp. 447-455.
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