Giant Magnetoresistance Sensors for Electronic Fuzes

The proposed research program will develop and demonstrate two giant magnetoresistance magnetic sensors for electronic fuzing: one sensor, which will detect gun tube exit of a projectile, will be for safety and arming of a non-spinning projectile, and the other sensor, a spin counter, will count projectile revolutions. Performance goals for the spin count sensor are: 0.02 Oe minimum detectable field, 10 ms recovery after removal of a 1000 Oe disturb field, operation from -50 to +145 F, accuracy of +/- 0.5% out to a target range of 1 km, and signal bandwidth of 500 kHz. The gun tube exit sensor will work with a sensor-to-gun tube gap of up to 2 inches. Both sensors will have CMOS compatible outputs with a +3 to +5 V power supply. The specific technical objectives of this program are to: a) complete a cost and producibility analysis for the proposed magnetic sensors, b) design both gun tube exit detection and spin count sensors which will meet the performance requirements, c) develop performance predictions for the sensors, d) fabricate and test prototypes of both GMR sensors, and e) deliver sensor prototypes for evaluation. The success of this Phase I effort will demonstrate the feasibility of the GMR spin counter and exit sensor, and provide the basis for development of fully integrated versions under a Phase II program. BENEFITS: The GMR spin counter demonstrated in this Phase I program will provide a high output, small size, and low cost alternative to existing spin rate sensors and spin counters in applications ranging from fuzes, motors, automobile engines, and machine tools, to robotics and toys.