A robust onboard full angular orientation sensor solution, based on a polarization scanning reference source and polarized geometrical cavity orientation sensors is presented. The sensor system provides a new non-GPS and non-inertial approach to angle measurements, with several key advantages over other methods, which include traditional phased-array antenna systems and the like. In this novel approach, the angular orientation information is coded into a time dependent pattern, which is insensitive to noise, while making the angle measurement independent of distance from the referencing source. The manuscript presents data from a field deployable system.
Reserve power sources are used extensively in munitions and other devices such as emergency devices or remote sensors that have to be powered only once and for a relatively short duration. Current chemical reserve power sources, including thermal batteries and liquid reserve batteries require sometimes in excess of 100 msec to become fully activated. In many applications, however, electrical energy is required in a few msec following the launch event. In such applications, other power sources have to be provided to provide power until the reserve battery is fully activated. The amount of electrical energy that is required by most munitions before chemical reserve batteries are fully activated is generally small and can be provided by properly designed piezoelectric-based energy harvesting devices. In this paper the development of a hybrid reserve power source obtained by the integration of a piezoelectric-based energy harvesting device with a reserve battery that can provide power almost instantaneously upon munitions firing or other similar events is being reported. A review of the state of the art in piezoelectric-based electrical energy harvesting methods and devices and their charge collection electronics for use in the developed hybrid power sources is also provided together with the results of testing of the piezoelectric component of the power source and its electronic safety and charge collection electronics.
KEYWORDS: Sensors, Polarization, Antennas, Environmental sensing, Radar, Modulation, Finite element methods, Signal to noise ratio, Data modeling, Wave propagation
Angular orientation of both mobile and stationary objects continues to be an ongoing topic of interest for guidance and control as well as for non-GPS based solutions for geolocations of assets in any environment. Currently available sensors, which include inertia devices such as accelerometers and gyros; magnetometers; surface mounted antennas; radars; GPS; and optical line of sight devices, do not provide an acceptable solution for many applications, particularly for gun-fired munitions and for all-weather and all environment scenarios. A robust onboard full angular orientation sensor solution, based on a scanning polarized reference source and a polarized geometrical cavity orientation sensor, is presented. The full position of the object, in the reference source coordinate system, is determined by combining range data obtained using established time-of-flight techniques, with the angular orientation information.
This paper presents a review of piezoelectric based energy harvesting devices and their charge collection and storage electronics for use in very harsh environment of gun-fired munitions. A number of novel classes of such energy-harvesting power sources that have been developed for gun-fired munitions and similar applications, including one with integrated safety and firing setback event detection electronics and logic circuitry. The power sources are designed to harvest energy from firing acceleration and vibratory motions during the flight. As an example, the application of the developed piezoelectric based energy harvesting devices with event detection circuitry to the development of self-powered initiators or switching devices with full no-fire safety circuitry for protection against accidental drops, transportation vibration, and other similar low amplitude accelerations and/or high amplitude but short duration acceleration events is presented. The designs allow the use of a very small piezoelectric elements, thereby making such devices to be highly miniaturized. These devices can be readily hardened to withstand very high G firing setback accelerations in excess of 100,000 G and the harsh firing environments. The design of prototypes and testing in shock loading machines, air guns and actual firing are presented.
KEYWORDS: Sensors, Antennas, Modulation, Polarization, Global Positioning System, Distance measurement, Finite element methods, Radar, Environmental sensing, Signal to noise ratio
Angular orientation of an object such as a projectile, relative to the earth or another object such as a mobile platform continues to be an ongoing topic of interest for guidance and/or steering. Currently available sensors, which include inertia devices such as accelerometers and gyros; magnetometers; surface mounted antennas; radars; GPS; and optical line of sight devices, do not provide an acceptable on-board solution for many applications, particularly for gun-fired munitions. We present a viable solution, which combines open-aperture sensors with custom designed radiation patterns and one or more amplitude modulated polarization scanning reference sources. Subsequently, the sensor system presents a new approach to angle measurements, with several key advantages over traditional cross-polarization based rotation sensors. Primarily, angular information is coded into a complex spatiotemporal pattern, which is insensitive to power fluctuations caused by environmental factors, while making the angle measurement independent of distance from the referencing source. Triangulation, using multiple sources, may be also used for onboard position measurement. Both measurements are independent of GPS localization; are direct and relative to the established local referencing system; and not subject to drift and/or error accumulation. Results of laboratory tests as well as field tests are presented.
The state of art in shock resistant MEMS accelerometer design is to reduce the size of the proof-mass, thereby reducing the generated forces and moments due to shock loading. Physical stops are also provided to limit proof-mass motion to prevent damage to various moving components. The reduction of the proof-mass size reduces the sensor sensitivity. In addition, to increase the sensor dynamic response, proof-mass motion needs to be minimally damped, resulting in a significant sensor settling time after experiencing a high shock loading such as those experienced by gun-fired munitions during firing. The settling time is particularly important for accelerometers that are used in gun-fired munitions and mortars for navigation and guidance. This paper describes the development of a novel class of accelerometers that are provided with the means of locking the sensor proof-mass in its “null” position when subjected to acceleration levels above prescribed thresholds, thereby protecting the moving parts of the accelerometer. In munitions applications, the proof-mass is thereby locked in its null position during the firing and released during the flight to begin to measure flight acceleration with minimal settling time. Details of the design and operation of the developed sensors and results of their prototyping and testing are presented. The application of the developed technology to other types of inertial sensors and devices is discussed.
This paper presents a review of piezoelectric based energy harvesting devices and their charge collection electronics for use in very harsh environment of gun-fired munitions. A number of novel classes of such energy harvesting power sources have been developed for gun-fired munitions and similar applications, including those with integrated safety and firing setback event detection electronics and logic circuitry. The power sources are designed to harvest energy from firing acceleration and vibratory motions during the flight. As an example, the application of the developed piezoelectric based energy harvesting devices with event detection circuitry for the development of self-powered initiators with full no-fire safety circuitry for protection against accidental drops, transportation vibration, and other similar low amplitude accelerations and/or high amplitude but short duration acceleration events is presented. The design allows the use of a very small piezoelectric element, thereby allowing such devices to be highly miniaturized. These devices can be readily hardened to withstand very high G firing setback accelerations in excess of 100,000 G and the harsh firing environment. The design of prototypes and testing under realistic conditions are presented.
A novel class of piezoelectric-based energy harvesting devices with integrated safety and firing setback event detection electronics and logic circuitry that can be used in gun-fired munitions is presented. In this paper, the application of the device to the development of initiators for thermal reserve batteries in gun-fire munitions is presented. The novel and highly efficient electrical energy collection and storage and event detection and safety electronics used allows the use of a very small piezoelectric element. As a result, such devices can be highly miniaturized for used in small reserve batteries. For thermal battery initiation, when the prescribed firing setback acceleration profile, i.e., the prescribed all-fire condition is detected, a highly efficient charge collection electronic circuitry routes the charges generated by the piezoelectric element of the device to the initiator bridge element, thereby causing the thermal battery pyrotechnic material to be ignited. For munitions powered by thermal reserve batteries, the present initiation device provides a self-powered initiator with full no-fire safety circuitry for protection against accidental drops, transportation vibration, and other similar low amplitude accelerations and/or high amplitude but short duration acceleration events. The device is shown to be readily set to initiate thermal batteries under almost any all-fire conditions. The device can be readily hardened to withstand very high G firing setback accelerations in excess of 100,000 G and the harsh firing environment. The design of prototypes and testing under realistic conditions are presented.
The U.S. Armament Research development Center (ARDEC) and the Army Research Laboratories in Adelphi, Maryland, and their small business collaborator (Omnitek Partners, LLC) have been developing alternatives to current reserve batteries for certain munitions applications. It is shown that using a novel passive method, efficiency of over 70 percent could be achieved in the transfer of generated electrical charges to appropriate selected storage mediums. The paper also describes the development of test-beds to simulate electrical charge generation of the energy harvesting power sources during the firing and the flight for use in the design and evaluation of the collection electronics.
KEYWORDS: Energy harvesting, Prototyping, Chemical elements, Weapons, Energy efficiency, Control systems, Pollution control, Mathematical modeling, Control systems design, Electronic components
A novel technique is presented for transmitting forces to piezoelectric elements in electrical energy harvesting
applications. The approach results in amplifying any force transmitted to the piezoelectric element. Additionally, the
frequency of any cyclical input force is doubled. The increased performance and scalability of the technique make
possible its employment in a wide variety of energy harvesting applications. The methods and designs may be mated to
a number of intermediate energy harvesting techniques, which are discussed in detail with analysis of complete energy
harvesting devices including specific applications in munitions.
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.
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.
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.
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.
This paper presents new class sensors for onboard direct measurement of the angular orientation of robotic mobile platforms relative to a fixed or moving coordinate system. The currently available sensors are either based on inertia, vision or optical means to measure the angular orientation of an object. The inertial based devices, however, generally suffer from drift and noise. The vision systems and optical sensors generally have relatively short range and require line-of-sight access. The novel class of sensors presented in this paper are wireless, are in the form of waveguides that are illuminated by polarized Radio Frequency sources. A mobile robotic platform equipped with three or more of such waveguide sensors can determine its 3D orientation relative to the ground or other mobile robotic platforms. The 3D orientation sensors require very low power for operation, may be located at relatively far distances from the ground source or the illuminating mobile platform, and can operate while out of line-of-sight of the illuminating source. In this paper, the design, operation, algorithms for calculating 3D angular orientation from the sensor output, and a number of experimental results of sensor performance are presented. In addition, a discussion of the methods to increase the performance of the sensor system and other related issues are provided.
The objective of this paper is to focus on recent efforts to test and characterize the performance of MEMS inertial sensors and the characterization of battery-free embedded sensors in munitions. This paper will also discuss the need to implement and integrate internal wireless communications in conjunction with smart electronics and smart materials in innovative microelectronics designs with built in capability of duplex wireless communications between sensors and telemetry. Embedded wireless telemetry will eliminate wires and the stress on long wire runs between MEMS sensor and processing microelectronics in harsh environments. Further advancements in this wireless area will facilitate the integration of smart sensing, control and actuation with unprecedented capability to permanently embed telemetry as a part of the standard munition components. The embedded wireless telemetry would have built in capability for smart munitions stockpile surveillance, in-flight duplex communication and the capability to communicate to a ground station. Future telemetry links for munitions will have a significant multi-use capability, designed to measure, maintain reliability, predictive surveillance, actuation and remote control functionality.
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