Muzzle velocity sensor for smart ammunition

Patent metadata

Field	Value
Publication number	US-9255776-B1
Application number	US-201414486005-A
Country	US
Kind code	B1
Filing date	Sep 15, 2014
Priority date	Sep 15, 2014
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

In a gun tube for firing rounds of smart ammunition, a sensor means applied to the ammunition which enables the calculation of muzzle velocity in the instant as the ammunition leaves the muzzle edge of the gun tube. The sensor relies on measurement of magnetic field induced voltages which are unique as the ammunition leaves the muzzle edge of the gun tube. Each round of ammunition has a planar transformer of wiring applied longitudinally on the side of the round, which aids in creating the necessary magnetic fields.

First claim

The invention claimed is:

1. In a gun tube having a defined longitude and a defined muzzle edge and a round of ammunition which is fired through said gun tube to exit past said muzzle edge, a round exit velocity measuring sensor to determine muzzle exit velocity of said round, said velocity measuring sensor comprised of:
a planar, air coil transformer attached longitudinally to the side of said round, comprised essentially of a primary coil wire and a secondary coil wire having output terminals thereon, and wherein the primary coil wire comprises several turns in a loop that surrounds the secondary coil wire, so as to create an approximately uniform magnetic field throughout the secondary coil wire, and wherein said secondary coil wire comprises multiple twists, so as to create numerous loops of alternating orientation in said secondary coil wire, wherein the loops proximate the ends of said secondary coil wire are smaller than the other loops, and the sensor further includes:
a current driving electronic circuit to drive a current in the primary coil wire;
a measuring and conditioning electronic circuit to measure and condition the voltage signal at the output terminals of said secondary coil wire, and;
an electronic signal processor that determines the muzzle exit velocity from the measured voltage signal at said secondary coil wire output terminals.

2. The velocity measuring sensor of claim 1 , in which:
the current driving electronic circuit is an oscillator, driving said primary coil wire with an AC signal of a specific frequency;
the measuring and conditioning electronic circuit is an amplifier in series with the output terminals of said secondary coil wire to receive a voltage signal therefrom, followed in series by a phase sensitive detector that synchronously demodulates such voltage signal while using said AC signal as a reference, to create a demodulated output signal pattern; and, the electronic signal processor is a circuit that determines time between zero crossings which may occur in the demodulated output signal pattern, and from which the electronic signal processor then determines muzzle exit velocity of the round.

3. In a gun tube having a defined longitude and a defined muzzle edge and a round of ammunition which is fired through said gun tube to exit past said muzzle edge, a round exit velocity measuring sensor to determine muzzle exit velocity of said round, said velocity measuring sensor comprised of:
a planar, air coil transformer attached longitudinally to the side of said round, comprised essentially of a
primary coil wire and a plurality of secondary coil wires, each respective secondary coil wire having secondary coil wire output terminals thereon, and wherein the primary coil wire comprises several turns in a loop that completely surrounds all of the secondary coil wires, so as to create an approximately uniform magnetic field throughout the secondary coil wires, and wherein
each respective said secondary coil wire comprises multiple twists, so as to create numerous loops of alternating orientation in said respective secondary coil wire, wherein the loops proximate the ends of each respective said secondary coil wire are smaller than the other loops in said respective secondary coil wire, and the remaining secondary coil wires, with the same geometry as the first secondary coil wire, are placed on axis longitudinally with the first secondary coil wire, but with each succeeding respective secondary coil wire positioned on axis longitudinally at a given respective distance after the preceding respective secondary coil wire; and, whereas said velocity measuring sensor further includes:
a current driving electronic circuit to drive a current in the primary coil wire;
a plurality of respective measuring and conditioning electronic circuits to respectively measure and condition the respective voltage signals at the output terminals of each respective said secondary coil wire, and;
an electronic signal processor that determines the muzzle exit velocity from processing the voltage signals measured at all the said secondary coil wire output terminals.

4. The velocity measuring sensor of claim 3 , in which:
the current driving electronic circuit is an oscillator, driving said primary coil wire with an AC signal of a specific frequency;
each respective measuring and conditioning electronic circuit an amplifier in series with the output terminals of a respective said secondary coil wire to receive a voltage signal therefrom, followed in series by a phase sensitive detector that synchronously demodulates such voltage signal, while using said AC signal as a reference, to create a respective demodulated output signal pattern; and
the electronic signal processor is a circuit that determines time between zero crossings which may occur in the respective demodulated output signal patterns, and from which the electronic signal processor then determines muzzle exit velocity of the round.

Assignees

• Barton Aaron
• Us Army

Inventors

• Barton Aaron

Classifications

• F42B30/006 Primary

  Mounting of sensors, antennas or target trackers on projectiles · CPC title

• G01P3/665

  for projectile velocity measurements · CPC title