<title>MAGSONDE (patent pending): a device for making angular measurements on spinning projectiles using magnetic sensors</title>

Abstract

Accurate measurement of angular motions of spinning bodies with on-board sensors has long been recognized as a daunting task. Recent advances in magnetic sensor technologies have yielded devices small enough. rugged enough, and sensitive enough to be useful in systems making high-speed, high-resolution measurements of attitude relative to magnetic fields when installed on free-flying bodies. Such a measurement system, called a "MAGSONDE" (MAGnetic SONDE), has been designed for use in spinning projectiles for the estimation of in-flight angular orientation with respect to the earth's magnetic field. The MAGSONDE is comprised of both an apparatus and a methodology that determines orientation from sensor phase measurements. Sensor scale factor variations will not affect MAGSONDE performance. Other significant features of MAGSONDE are its day/night and all weather capability and its use of non-emissive, passive sensors. Potential applications for MAGSONDE include, but are not limited to, navigation aids and determination of angular motion histories of experimental, developmental and tactical projectiles.

Safety and arming method for Fuzes based on geomagnetic field signal

“…When the projectile rotates n cycles, and the projectile flies n times leads. Although air friction may change the lead, it can be ignored within a bit of distance from the muzzle, and the muzzle arming distance S can be expressed as following [6] :…”

A Point-wise Solution for the Magnetic Field Vector

“…Since the value of the ratio is equivalent to knowledge of the magnetic roll angle, the performance of Equation (7) depends on both the accuracy of the measurement of the roll angle and the actual value of the magnetic roll angle. Harkins and Hepner [2] discuss another method of using zero crossings to solve for the spin axis angle to the magnetic field. A variation of Equation (7) can be found by the use of the output of Sensor 1 as input to Equation (2) when the reading is zero.…”

“…The background information for this report is contained in Harkins and Hepner [2], who use zero crossings of the magnetometers to find the direction to the magnetic field.…”

“…Harkins and Hepner [2] discuss a method to find the orientation of the spin axis by the use of solar and magnetometer information. We can find the angle between the spin axis and the magnetic field by using the zero crossings of two magnetometers.…”

A microcontroller solution for AMR magnetic sensing in flying munitions systems

“…The magnetic sensor needed is a 3-axis magnetometer or a combination of three one-axis magnetometers, which can pick up the projection of the Earth's magnetic field on each axis. These data can be used to determine the azimuth (heading direction) and the spin rate of the flying vehicle [1][2][3][4][5]. The magnetometer we chose is an anisotropic magnetoresistive (AMR) sensor [6][7], which consists of four permalloy thin-film resistor stripes deposited on a silicon wafer and arranged in a Wheatstone bridge configuration, The permalloy is an alloy of nickel and iron with high magnetic permeability.…”