In this paper, a novel heat energy harvesting system that is constructed by a combination of thermoelectric generators (TEG) and thermophotovoltaic (TPV) cells that are configured to operate in parallel is presented. The resulting hybrid TEG-TPV heat energy harvester can therefore generate significantly more electrical energy than is possible for a given TEG surface area. The hybrid TEG-TPV heat energy harvester is designed to generate electrical energy from sources with highly varying and high temperatures. The hybrid harvester is designed to provide a constant temperature gradient to TEG members and allow the TPV cells to operate within their allowable temperature range.
In this paper, the development of a novel technology for direct and rapid heating of battery electrolyte at low temperatures and maintaining the battery temperature at its optimal performance level is presented. The technology has been extensively tested on a wide range of primary and secondary batteries at temperatures as low as -54 deg. C without causing any damage to the batteries. The technology is applicable to almost all primary and secondary batteries, such as Lithium-ion, Lithiumpolymer, NiMH and lead-acid batteries. The technology is also applicable to super-capacitors and has been used to rapidly heat super-capacitors at temperatures as low as -54 deg. C without any damage.
Presented in this paper is the development of a novel class of heat energy harvesting systems that are designed to generate electrical energy from sources with highly varying temperatures that can be significantly higher than thermoelectric generators (TEG) can withstand. This class of TEG-based heat energy harvesters are designed to: (a) apply a constant temperature gradient to TEGs of the system while heat source temperature is varying and can be significantly higher than TEGs can withstand (thus, the total energy output is maximized); and (b) provides a passively operated switching mechanism for the protection of TEGs from overheating.
Novel piezoelectric-based self-powered impulse detecting switches are presented. The switches are designed to detect shock loading events resulting in acceleration or deceleration above prescribed levels and durations. The prescribed acceleration level and duration thresholds are adjustable. They are provided with false trigger protection logic. The impulse switches are provided with electronic and logic circuitry to detect prescribed impulse events and reject events such as high amplitude but short duration shocks, and transportation vibration and similar low amplitude and relatively long duration events. They can be mounted directly onto electronics circuit boards, thereby significantly simplifying the electrical and electronic circuitry, simplifying the assembly process and total cost, significantly reducing the occupied volume, and in some applications eliminating the need for physical wiring to and from the impulse switches. The design of prototypes and testing under realistic conditions are presented.
Currently available methods and systems for testing components for survival and performance under shock loading suffer from several shortcomings for use to simulate high-G acceleration events with relatively long duration. Such events include most munitions firing and target impact, vehicular accidents, drops from relatively high heights, air drops, impact between machine components, and other similar events. In this paper, a new class of shock testing machines are presented that can be used to subject components to be tested to high-G acceleration pulses of prescribed amplitudes and relatively long durations. The machines provide for highly repeatable testing of components. The components are mounted on an open platform for ease of instrumentation and video recording of their dynamic behavior during shock loading tests.
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.
In time critical power up applications, such as pre-launch preparation of smart munitions, both power and guidance information needs to be transferred rapidly from the host to the munitions. Tethered solutions are not practical and the existing magnetic inductive charging methods are slow and have limited data transfer rate capability. A wireless solution based on the use of high power laser diodes is presented. Custom dual-junction photo-voltaic cells achieve power conversion efficiencies exceeding 50% at a single wavelength of operation. Energy transfer times of 3.5 s have been achieved for energy levels of 90 J. Guidance and other control data is uploaded to on-board memory devices at a rate of 500 kb/s, through the use of an additional photodiode, which can receive a small fraction of the modulated power beam. A removable collar provides an alignment free charging/data solution enabling rapid deployment of multiple munitions.
Pulsed loading of piezoelectric transducers occurs in many applications, such as those in munitions firing, or
when a mechanical system is subjected to impact type loading. In this paper, an electronic simulator that can
be programmed to generate electrical charges that a piezoelectric transducer generates as it is subjected to
various shock loading profiles is presented. The piezoelectric output simulator can provide close to realistic
outputs so that the circuit designer can use it to test the developed system under close to realistic conditions
without the need for the costly and time consuming process of performing actual tests. The design of the
electronic simulator and results of its testing are presented.
Reserve power sources are used extensively in munitions and other devices, such as emergency devices or
remote sensors that need to be powered only once and for a relatively short duration. Current chemical reserve
power sources, including thermal batteries and liquid reserve batteries sometimes require more than 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 are needed 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 that is constructed
by integration of a piezoelectric-based energy harvesting device with a reserve battery to 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 provided together with the results of testing of the piezoelectric
component of the power source and its electronic safety and charge collection electronics.
This book is an introductory text describing methods of harvesting electrical energy from mechanical potential and kinetic energy. The book focuses on the methods of transferring mechanical energy to energy conversion transducers of various types, including piezoelectric, electromagnetic, electrostatic, and magnetostrictive transducers. Methods that have been developed for collecting, conditioning, and delivering the generated electrical energy to a load, as well as their potential use as self-powered sensors, are described. The book should be of interest to those who want to know the potentials as well as shortcomings of energy harvesting technology. The book is particularly useful for energy harvesting system designers as it provides a systematic approach to the selection of the proper transduction mechanisms and methods of interfacing with a host system and electrical energy collection and conditioning options. An extensive bibliography is provided to direct the reader to appropriate references for detailed material not included in the book.
High contrast imaging, in the presence of a bright background, is a challenging problem encountered in diverse applications ranging from the daily chore of driving into a sun-drenched scene to in vivo use of biomedical imaging in various types of keyhole surgeries. Imaging in the presence of bright sources saturates the vision system, resulting in loss of scene fidelity, corresponding to low image contrast and reduced resolution. The problem is exacerbated in retro-reflective imaging systems where the light sources illuminating the object are unavoidably strong, typically masking the object features. This manuscript presents a novel theoretical framework, based on nonlinear analysis and adaptive focal plane transmittance, to selectively remove object domain sources of background light from the image plane, resulting in local and global increases in image contrast. The background signal can either be of a global specular nature, giving rise to parallel illumination from the entire object surface or can be represented by a mosaic of randomly orientated, small specular surfaces. The latter is more representative of real world practical imaging systems. Thus, the background signal comprises of groups of oblique rays corresponding to distributions of the mosaic surfaces. Through the imaging system, light from group of like surfaces, converges to a localized spot in the focal plane of the lens and then diverges to cast a localized bright spot in the image plane. Thus, transmittance of a spatial light modulator, positioned in the focal plane, can be adaptively controlled to block a particular source of background light. Consequently, the image plane intensity is entirely due to the object features. Experimental image data is presented to verify the efficacy of the methodology.
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.
KEYWORDS: Free space, Free space optics, Solar energy, Radio optics, Data transmission, Semiconductor lasers, Diodes, Fiber lasers, Neodymium, Thermography
Design and experimental data for a high power laser diode based free space point-to-point optical power/data link is presented. In time critical power up applications, such as providing power and guidance information to a munition shell just prior to deployment, energy of the order of 100 J needs to be transferred in under 10 s. Current inductive technology is slow and broadcasts a radio-frequency signal which is undesirable for stealth operation. Rapid energy transfer times require high irradiance levels at the surface of the photovoltaic cells, typically, exceeding 1000X suns. Through efficient thermal design of heat sinks, high optical to electrical power conversion efficiencies of 50%, which are usually attainable at low power levels of 1 W, are achievable at higher power levels.
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 a prescribed threshold, 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 is released during the flight 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.
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 a prescribed threshold, 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 is released during the flight 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 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.
An adaptive spatial filtering technique is described for enhancing image contrast of objects viewed against the background of an intense light source, both in the transmitting and reflecting imaging modes. The spatial distribution of the source captured in the back focal plane of the imaging lens corresponds to the angular distribution of the source. The measured distribution of energy is used to adaptively control the transmittance of a spatial light modulator positioned in the back focal plane of the imaging lens. The spatial light modulator blocks the transmission of the high energy hot spots through to the image plane. Subsequently the image formed by the objective lens is free of the bright background. Thus, the digital image capture system can use the full dynamic range of the detector and the analog to digital converter, giving rise to a captured image with the highest contrast possible. Contrast enhanced images of MEMS accelerometer are presented.
Need exists for untethered transmission of electrical power and data to remote devices and sensors. Several wireless solutions, based on radiation and non-radiation are in existence. Here the focus is on the use of photonic power which is an optimized optical to electrical conversion solution, used for both wireless and guided transportation. High photonic conversion efficiencies of 50% and greater have been demonstrated for wavelength matched laser diodes and photovoltaic cells. However, these existing solutions do not meet the needs of rapid energy transfer to remote devices, such as munition shells prior to launch. We report on the design and fabrication of a 16-cell array of densely packed photonic power converters that can power a munition shell immediately prior to launch. A laser beam delivers power and data to the PPC array. Thermal simulation, using FEA shows that the each of the cells can be operated at an equivalent irradiance of 1000x suns, giving an energy transfer rate of 17.5 J.s-1 for the array. Thus, two 10 F super-capacitors, typically used in munitions, can be charged is under 5 seconds. Further, using the measured capacitance of 2.4 nF for the array, data can be transported to the munition on the laser power beam, at a rate exceeding 5 Mbps.
KEYWORDS: Sensors, Telecommunications, Epoxies, Data communications, Actuators, Electronic components, Composites, Packaging, Wireless communications, Control systems
Electronic systems comprising of subassemblies, distributed across different physical media, require seamless communication between processors and sensors embedded in the disparate volumes. For example, smart munitions systems embed sensors and other key control electronics, throughout the structure, in vastly different physical media. In addition to the obvious space constraints, these structures are subjected to high G forces during launch. Thus, communications through wire harnesses becomes cumbersome, make assembly process and testing difficult, and challenging to make survive high G firing. Here we focus on an approach that takes advantage of the partial optical transparency of epoxy material commonly used in potting electronic components in munitions, as well as the wave guiding that is possible through the body of the munitions wall which is made from composite materials. Experimental results show that a wireless optical link, connecting various parts of the distributed system, is possible at near IR frequencies. Data can be rapidly parsed between a processor, sensors and actuators. We present experimental data for a commercial epoxy system, which is used to embed a number of IrDA devices inside the cone of 120 mm mortar shell. IrDA devices using the FIR data rates establish point-to-point communication through various media, representative of the environment inside the 120 mm mortar cone.
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.
Photonic power conversion combined with a high power laser diode, is a high efficiency solution for rapid, wireless transfer of power to dormant sensors, which have sporadic need for electrical power. In particular, these devices replace, thermal/inductive power sources inside a munition shell, leading to a safe non-radiating environment. Experimental results with a 25 F double-layer, super-capacitor, indicate that the surface irradiance and laser power both determine the minimum energy transfer time. At a power level of 4 W, the energy transfer rate reduces from a 1 J/s to 0.35 J/s as the irradiance level changes from 1125 suns to 63 suns.
KEYWORDS: Polarization, Receivers, Transmitters, Unmanned aerial vehicles, Switches, Amplifiers, Sensors, Signal detection, Digital signal processing, Signal attenuation
On board measurement of attitude position, for example roll angle, of autonomous vehicles is critical to the execution of a successful mission. This paper describes a real-time technique, which combines a polarization scanning reference source and a priori knowledge of the scanning pattern. Measurements in an anechoic chamber, as well as, field tests in a busy parking lot, verify the efficacy of the technique, for both line of sight and non-line of sight capability.
Amplitude and phase control of two orthogonal linear polarized RF waves provide a very versatile means for producing a time varying linear polarization scanning reference source. Dynamic control of the state of polarization of the radiated EM wave offers unique scan patterns, which lead to robust recovery of attitude angular information of various flying platforms, such as unmanned aerial vehicles. Data taken in an anechoic chamber confirms the efficacy of the technique.
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.
This paper describes the development and construction of an energy harvesting device to provide a safe, reliable source
of electrical energy onboard gravity-dropped weapons such as aerial bombs. The generators collect and store mechanical
energy as the weapon falls away from the aircraft. Only after the weapon has fallen away from the aircraft is the stored
mechanical energy released, generating electricity through a hybrid piezoelectric and electromagnetic generation method.
The design, construction, and testing of the generator is discussed at length. Conceptual designs for integrating the
described energy harvester alongside current and alternative sources of electrical power are also discussed.
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 two-stage piezoelectric-based electrical energy generators is presented for rotary machinery in which
the input speed is low and varies significantly, even reversing. Applications include wind mills, turbo-machinery for
harvesting tidal flows, etc. Current technology using magnet-and-coil rotary generators require gearing or similar
mechanisms to increase the input speed and make the generation cycle efficient. Variable speed-control mechanisms are
also usually needed to achieve high mechanical to electrical energy conversion efficiency.
Presented here are generators that do not require gearing or speed control mechanisms, significantly reducing
complexity and cost, especially pertaining to maintenance and service. Additionally, these new generators can expand
the application of energy harvesting to much slower input speeds than current technology allows.
The primary novelty of this technology is the two-stage harvesting system. The harvesting environment (e.g. wind)
provides input to the primary system, which is then used to successively excite a secondary system of vibratory elements
into resonance - like strumming a guitar. The key advantage is that by having two decoupled systems, the low-andvarying-
speed input can be converted into constant and much higher frequency vibrations. Energy is then harvested
from the secondary system's vibrating elements with high efficiency using piezoelectric elements or magnet-and-coil
generators. These new generators are uncomplicated, and can efficiently operate at widely varying and even reversing
input speeds.
Conceptual designs are presented for a number of generators and subsystems (e.g. for passing mechanical energy
from the primary to the secondary system). Additionally, analysis of a complete two-stage energy harvesting system is discussed with predictions of performance and efficiency.
A novel class of piezoelectric-based energy-harvesting power sources has been developed for gun-fired munitions
and similar high-G applications. The power sources are designed to harvest energy primarily from the firing acceleration,
but from in-flight vibratory motions as well. During the firing, a spring-mass element reacts to the axial acceleration,
deforming and storing mechanical potential energy. After the projectile has exited the muzzle, the spring-mass element
is free to vibrate, and the energy of the vibration is harvested using piezoelectric materials.
These piezoelectric-based devices have been shown to produce enough electrical energy for many applications such
as fuzing, and are able to eliminate the need for chemical batteries in many applications. When employed in fuzing
applications, the developed power sources have the added advantage of providing augmented safety, since the fuzing
electronics are powered only after the projectile has exited the muzzle and traveled a safe distance from the weapon
platform.
An overview of the development of these novel power sources is provided, especially designing and packaging for
the high-G environment. Extensive laboratory and field testing has been performed on various prototypes; the methods
and results of these experiments are presented. In addition to presenting the development and validation of this
technology, methods for integrating the generators into different classes of projectiles are discussed along with strategies
for manufacturing. This technology is currently validated to the extent that prototype devices have been successfully
fired on-board actual gun-fired projectiles, demonstrating survivability and indicating performance. Strategies for
designing the devices for a particular round and transitioning to commercialization are also discussed.
KEYWORDS: Wind energy, Energy harvesting, Chemical elements, Magnetism, Teeth, Energy conversion efficiency, Control systems, Electronics, Prototyping, Ceramics
A novel class of two-stage piezoelectric-based electrical energy generators is presented for rotary machinery in which the input speed is relatively low, varies significantly over time, and is even reversing. This class of energy generators is highly suitable for applications such as wind mills, turbo-machinery used to harvest tidal flows, and the like. Current technology uses magnet-and-coil-based rotary generators. However, to make the generation cycle efficient, gearing or other similar mechanisms have to be used to increase the input speed to the generator. Variable speed-control mechanisms are also usually needed to achieve high mechanical to electrical energy conversion efficiency. This novel class of electrical energy generators uses a decoupled two-stage system. The harvesting environment (wind, tidal flow, etc.) directly provides input to the primary system. The low and varying input motion is then used to successively excite an array of vibrating elements (secondary system). The key advantage is that by having two decoupled systems, the low speed and highly varying input motion is converted into constant and much higher frequency mechanical vibrations, which are then harvested using piezoelectric elements. As a result, by eliminating the need for gearing and speed control mechanisms, the system complexity and cost - including those related to maintenance and service - is significantly reduced. Additionally, these novel generators can expand the application of power generation to much slower input speeds than are harvestable using current technology.
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.
Harvesting mechanical energy from ocean wave oscillations for conversion to electrical energy has long been pursued as an alternative or self-contained power source. The attraction to harvesting energy from ocean waves stems from the sheer power of the wave motion, which can easily exceed 50 kW per meter of wave front. The principal barrier to harvesting this power is the very low and varying frequency of ocean waves, which generally vary from 0.1Hz to 0.5Hz.
In this paper the application of a novel class of two-stage electrical energy generators to buoyant structures is presented. The generators use the buoy's interaction with the ocean waves as a low-speed input to a primary system, which, in turn, successively excites an array of vibratory elements (secondary system) into resonance - like a musician strumming a guitar. The key advantage of the present system is that by having two decoupled systems, the low frequency and highly varying buoy motion is converted into constant and much higher frequency mechanical vibrations. Electrical energy may then be harvested from the vibrating elements of the secondary system with high efficiency using piezoelectric elements.
The operating principles of the novel two-stage technique are presented, including analytical formulations describing the transfer of energy between the two systems. Also, prototypical design examples are offered, as well as an in-depth computer simulation of a prototypical heaving-based wave energy harvester which generates electrical energy from the up-and-down motion of a buoy riding on the ocean's surface.
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.
A novel class of vibration-based electrical energy generators is presented for applications in which the
input rotary speed is relatively low and varies significantly over time such as wind mills, turbo-machinery used
to harvest tidal flows, and the like. Current technology uses magnet and coil based rotary generators to generate
electrical energy in such machinery. However, to make the generation cycle efficient, gearing or other similar
mechanisms have to be used to increase the output speed. In addition, variable speed mechanisms are usually
needed to achieve high mechanical to electrical energy conversion efficiency since speed variation is usually
significant in the aforementioned applications. The objective of the present work is the development of
electrical energy generators that do not require the aforementioned gearing and speed control mechanisms,
thereby significantly reducing complexity and cost, particularly those related to maintenance and service. This
novel class of electrical energy generators operates based on repeated vibration of multiple vibrating elements
that are tuned to vibrate at a fixed prescribed frequency. The mechanical energy stored in the vibration elements
is transformed into electrical energy using piezoelectric elements. The present generators are very simple, can
efficiently operate over a very large range of input speeds, and should require minimal service and
maintenance. The project is at the early stages of its development, but the analytical modeling and computer
simulation studies using realistic system and component parameters indicate the potentials of this class of
piezoelectric-based generators for the indicated applications.
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 operating speed and precision of computer controlled machines such as robot manipulators are limited mostly by the dynamic response limitations of their primary actuators. The dynamics of systems such as robot manipulators with revolute joints, even when the structural flexibility is not considered is highly nonlinear. The presence of dynamics nonlinearity places an even greater demand on the dynamic response of the prime actuators. This is the case since due to the nonlinear dynamics of such systems, the actuating torques (forces) required for accurate tracking of the desired motions must contain higher harmonics of the joint trajectory harmonics. Such higher harmonic components of the actuating torques become increasingly more significant as the operating speed of the system is increased and can cause serious vibration and control problems. In this paper, a systematic method is presented for optimal integration of smart (active) materials based actuators into the structure of robot manipulators for the purpose of minimizing the high harmonic components of the required actuating torques (forces). The proposed approach is based on the Trajectory Pattern Method (TPM). It is shown that with properly synthesized low harmonic motion trajectories and by minimizing the high harmonic components of the required actuating torques with properly sized and placed smart actuators, such computer controlled machines can operate at higher speeds, greater tracking precision and minimal vibration and control problems.
Robot manipulators with parallel kinematics chains and two or more robots manipulating an object form closed kinematics chains. When revolute joints are used in the construction of such robotic manipulation systems, the presence of closed chains and their associated kinematics nonlinearity demands high harmonic motions in at least a number of the actuated joints. This is the case even if all the links are relatively rigid and attempt is made to synthesize the joint motions with minimal harmonic content. The presence of high harmonic components in the actuated joint motions is undesirable since as the operating speed is increased, their frequencies would rapidly increase and move beyond the dynamic response limitations of the actuating drives, thereby causing vibration and control problems. The performance of the system in terms of cycle time, tracking precision and the like would therefore suffer. This is particularly the case since the dynamics of such systems is also highly nonlinear and require higher harmonic components in the actuating torques (forces). In this paper, a systematic method is presented for optimal integration of smart (active) materials based actuators into the structure of cooperating robots and robot manipulators with parallel kinematics chain for the purpose of eliminating the high harmonic components of their actuated joint motions. As the result, the potential excitation of the natural modes of vibration of such systems and their related control problems can be greatly reduced. The resulting robotic systems should therefore be capable of operating at higher speeds with increased precision.
One of the primary factors limiting the performance of high speed and precision computer controlled machinery such as robotic systems is the dynamic response limitation of their actuation mechanisms. This is particularly the case when revolute joints are used in the construction of a machine, thereby resulting in systems with highly nonlinear dynamics. In such systems, even if the joint motion trajectories were synthesized with low harmonic contents, the actuating torques required for accurate tracking of the synthesized motions would contain high harmonic components. The higher harmonic components are generated to the nonlinearity in the dynamics and kinematics of the system. As the operating sped of such machines is increased, the high harmonic component of the required actuating torques become more significant and at some point move beyond the dynamic response limitations of the main drives. The performance of the system would therefore start to degrade and vibration and control begins to become problematic. In this paper, a method is presented for minimizing the high harmonic components of the required actuating torques using smart materials based actuators. The effective dynamic response of the system drives is thereby enhanced. In this paper, the development of the general methodology is presented. The method is then applied to a plane 2R robot manipulator. The effectiveness of the proposed approach in reducing the higher harmonic components of the primary drives and thereby enhancing the performance of the system is illustrated by computer simulation.
KEYWORDS: Control systems, Vibration isolation, Optical isolators, Fourier transforms, Complex systems, Active isolation, Signal attenuation, Space operations, Prototyping, Actuators
Payloads are attached to launch vehicles by structural adapters known as Payload Adapter Fittings (PAF). The adapters are substantially rigid; therefore, the launch vehicle vibration is transmitted without isolation to the payloads. The payload cost includes a substantial component for provision to withstand the severe launch vibration environment. In this paper, a novel three degree-of-freedom isolation system built in the footprint and within the existing PAFs is presented. The vibration isolator consists of a mechanical constraining mechanism that prevents the rotation of the payload relative to the launch vehicle in both rocking rotation and rotation about the long axis of the launch vehicle. The above rotational motion restraining mechanism would therefore only allow axial and lateral vibration of the payload relative to the launch vehicle. The second major component of the system consists of isolation components that are used to reduce vibration in the latter to directions, i.e., in the axial and the lateral directions. The proposed isolating payload adapter fitting also has a stand-alone thrust-support preload adjustment component that adjusts for the varying quasi-static acceleration seen in different flight regimes in a passive- adaptive control mode. The advocated isolation system is structurally modular and parameterizable such that a range of launch vehicle platforms could be accommodated. Through the utilization of the advocated isolating payload adapter fitting, a fifty percent reduction in vibration transmission is achieved at 10 Hz in the axial direction and 20 Hz in the lateral directions. A 40 db reduction is achieved at frequencies above 100 Hz. Active actuating elements may easily be included in the prosed design to attain an active isolation unit.
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