KEYWORDS: Energy harvesting, Electronics, Weapons, Energy efficiency, Control systems, Prototyping, Chemical elements, Capacitors, Pollution control, Mathematical modeling
Novel designs are presented for piezoelectric-based energy-harvesting power sources that are attached to mortar tubes to
harvest energy from the firing impulse. The power sources generate electrical energy by storing mechanical potential
energy in spring elements during the firing. The mass-spring unit of the power source begins to vibrate after firing,
thereby applying a cyclic force to a set of piezoelectric elements to which it is attached. The mechanical energy of
vibration is thereby converted to electrical energy over a relatively long period of time and stored in electrical energy
storage elements such as capacitors. The power sources are shown to provide a significant portion of the required
electrical energy of the fire control system.
A novel class of piezoelectric-based energy-harvesting power sources has been developed for gun-fired
munitions which harvest energy from the firing acceleration. These piezoelectric-based devices have been
shown to produce enough electrical energy for many applications such as fuzing, where they provide an ultrasafe
power source, often eliminating the need for chemical batteries. An overview of the development of these
power sources is provided, along with methods and results of laboratory and field testing performed on
prototypes. Additionally, methods for integrating the generators into different classes of projectiles are
discussed along with strategies for manufacturing and a side-by-side comparison with competing
technologies.
KEYWORDS: Energy harvesting, Electronics, Weapons, Energy efficiency, Control systems, Prototyping, Chemical elements, Capacitors, Pollution control, Mathematical modeling
Novel designs are presented for piezoelectric-based energy-harvesting power sources that are attached to mortar tubes to
harvest energy from the firing impulse. The power sources generate electrical energy by storing mechanical potential
energy in spring elements during the firing. The mass-spring unit of the power source begins to vibrate after firing,
thereby applying a cyclic force to a set of piezoelectric elements to which it is attached. The mechanical energy of
vibration is thereby converted to electrical energy over a relatively long period of time and stored in electrical energy
storage elements such as capacitors. The power sources are shown to provide a significant portion of the required
electrical energy of the fire control system.
KEYWORDS: Energy harvesting, Electronics, Safety, Prototyping, Systems modeling, Packaging, Finite element methods, Sensors, Receivers, Microelectromechanical systems
Several novel classes of piezoelectric-based energy-harvesting power sources are presented for very high-G gun-fired
munitions (40,000 - 240,000 Gs). The power sources are designed to harvest energy from the firing acceleration and in
certain applications also from in-flight vibrations. The harvested energy is converted to electrical energy for powering
onboard electronics, and can provide enough energy to eliminate the need for batteries in applications such as fuzing.
During the munitions firing, a spring-mass system undergoes deformation, thereby storing mechanical potential
energy in the elastic element. After release, the spring-mass system is free to vibrate and energy is harvested using
piezoelectric materials. Two distinct classes of systems are presented: First are systems where the spring-mass elements
are loaded and released directly by the firing acceleration. Second are those which use intermediate mechanisms
reacting to the firing acceleration to load and release the spring-mass system.
Description and evaluation of various methods for loading and releasing the spring-mass system in the high-impact
environment, as well as packaging for very-high-G survivability are discussed at length. Also included are methods for
using the devices as hybrid generator-sensors, how the devices intrinsically provide augmented safety, and methods to increase the efficiency of such power sources for very high-G applications.
Examples of a number of prototypes for complete high-G energy harvesting systems are presented. These power sources have been designed using extensive modeling, finite element analysis, and model validation testing. The results of laboratory, air-gun and firing tests are also presented.
A novel class of piezoelectric-based event sensing and energy-harvesting power sources is presented for gunfired
munitions. The power sources are designed to harvest energy from firing acceleration and vibratory motions during
the flight. The piezoelectric element may be used to measure setback acceleration level, indicate the barrel exit time and
impact time and force levels for fuzing purposes. The developed power sources have the added advantage of providing
safety, since the fuzing electronics are powered only after the munitions have exited the barrel. The developed
piezoelectric-based energy harvesting power sources produce enough electrical energy for applications such as fuzing.
The power sources are designed to withstand firing accelerations in excess of 120,000 G. In certain applications such as
fuzing, the developed power sources have the potential of completely eliminating the need for chemical batteries. The
design of a number of prototypes, including their packaging for high G hardening, and the results of laboratory, air-gun
and firing tests are presented.
KEYWORDS: Sensors, Global Positioning System, Magnetometers, Magnetic sensors, Navigation systems, Electromagnetism, Signal attenuation, Control systems, Rockets, Magnetism
Efforts at the U.S. Army Research, Development and Engineering Center (ARDEC) at Picatinny, New Jersey are
focused on developing methods to counter GPS jamming and electronic warfare (EW) threat by eliminating GPS
dependency entirely. In addition, the need for munitions cost reduction requires alternatives to expensive high-grade
inertia components. Efforts at ARDEC include investigations of novel methods for onboard measurement of munitions
full position and angular orientation independent of GPS signals or high-grade inertia components. Currently, two types
of direct angular measurement sensors are being investigated. A first sensor, Radio Frequency Polarized Sensor (RFPS),
uses an electromagnetic field as a reference. A second sensor is based on magnetometers, using the Earth magnetic field
for orientation measurement. Magnetometers, however, can only provide two independent orientation measurements.
The RFPS may also be used to make full object position and angular orientation measurement relative to a reference
coordinate system, which may be moving or stationary. The potential applications of novel RFPS sensors is in
providing highly effective inexpensive replacement for GPS, which could be used in a "Layered Navigation" scheme
employing alternate referencing methods and reduce the current dependency on GPS as a primary reference for guided
gun-fired munitions. Other potential applications of RFPSs is in UAVs, UGVs, and robotic platforms.
Presented here is an innovative class of piezoelectric-based generators for application in gun-fired
munitions and other similar devices. The generators are designed to produce electrical energy as a result of
the firing acceleration with enough output to power certain on-board electronic circuitry, such as lowpower
fuzing. In this class of piezoelectric-based generators, a novel mechanism is provided with which the
strain applied to the piezoelectric stack can be maintained at its in-firing peak value throughout the flight of
the projectile. As a result, the generated charge can be harvested efficiently during a significantly longer
period of time. In addition, in some munitions applications this can totally eliminate the need for storing the
generated electrical energy in another storage medium. This class of impact-based piezoelectric generator
devices is intrinsically robust in design which makes it suitable for high-G applications. Also, since the
present devices produce energy due to the firing acceleration, a high degree of safety is guaranteed because
the electronics are not powered until the projectile is fired. A basic proof-of-concept design and a
deployable prototype concept are presented which will demonstrate the scalability of the present devices as
well as their survivability in high-G environments.
A novel class of piezoelectric-based energy-harvesting power sources is presented for gun-fired munitions and
other similar applications that require very high G survivability. The power sources are designed to harvest energy from
the firing acceleration as well as vibratory motion of munitions during the flight and convert it to electrical energy to
power onboard electronics. The developed piezoelectric-based energy harvesting power sources produce enough
electrical energy for applications such as fuzing. The power sources are designed to withstand firing accelerations in
excess of 100,000 G. In certain applications such as fuzing, the developed power sources have the potential of
completely eliminating the need for chemical batteries. In fuzing applications, the developed power sources have the
added advantage of providing additional safety, since with such power sources the fuzing electronics are powered only
after the munitions have exited the barrel and have traveled a safe distance from the weapon platform. The design of a
number of prototypes, including their packaging for high G hardening, and the results of laboratory and air-gun testing
are presented. Methods to increase the efficiency of such energy-harvesting power sources and minimize friction and
damping losses are discussed.
This paper presents a new class of piezoelectric based energy harvesting power sources for use in gun-fired munitions or other similar applications requiring high G survivability . These power sources are designed to harvest energy from the firing acceleration as well as vibratory motion and spinning of munitions during their flight and convert it to electrical energy that could be used directly by power consuming electronics onboard munitions or stored. The power sources are designed to withstand firing accelerations in excess of 100,000 G. The power sources have been shown to have the potential of completely eliminating the need for chemical batteries in many fuzing applications, while having the added advantage of providing for considerably more safety and long shelf life. Prototypes of a number of designs of this class of energy harvesting power sources for various power requirements have been constructed and successfully tested in the laboratory and by the U. S. Army (ARDEC) using air guns.
This paper presents a new class of highly efficient piezoelectric based energy harvesting power sources for mounting on platforms that vibrate at very low frequencies as compared to the frequencies at which energy can be efficiently harvested using piezoelectric elements . These energy harvesting power sources have a very simple design and do not require accurate tuning for each application to match the frequency of the platform vibration. The developed method of harvesting mechanical energy and converting it to electrical energy overcomes problems that are usually encountered with harvesting energy from low frequency vibration of various platforms such as ships and other platforms with similar vibratory (rocking or translational) motions. Omnitek Partners has designed several such energy harvesting power sources and is in the process of constructing prototypes for testing. The developed designs are modular and can be used to construct power sources for various power requirements. The amount of mechanical energy available for harvesting is obviously dependent on the frequency and amplitude of vibration of the platform, and the size and mass of the power source.
Future sensing technologies are needed to provide higher accuracy, lower power consumption and occupy small real estate within munitions. The novel ideas being supported at the Army Research Development Engineering Center (ARDEC) at Dover, New Jersey, uses principles of electromagnetic propagation and the properties of waveguide cavities with various geometries to develop a new class of sensors for onboard direct measurement of the angular orientation and position of objects in flight and applications such as mobile robotic platforms. Currently available sensors for munitions are based on inertia, optics or heat. Inertia based sensing generally suffers from drift, noise and the currently available sensors cannot survive high firing accelerations while maintaining the required measurement sensitivity. Optical technologies generally have short range and require line-of-site. The sensing technologies presented in this paper employ radio frequency, make direct measurement of position and orientation, and do not require added information for their operation. The presented sensors employ waveguide cavities that are embedded into the structure of munitions. It is shown that the geometry of the waveguide cavity can be designed to achieve high angular orientation sensitivity with respect to a reference, polarized electromagnetic field. In this paper, the theoretical fundamentals describing the operation of the developed sensors are described. Studies of the interaction of the polarized signals with various waveguides and cavity geometries are presented. Simulations results as well as experimental results validating the theoretical and the simulation results are provided. The simulation and experimental results clearly demonstrate the potentials of the developed position and angular orientation sensors in general, and to munitions in particular.
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