NZ611441B - Tunable vibration energy harvester and method - Google Patents

Abstract

electrical generator or energy harvester includes a piezoelectric cantilever 29 attached to a source of vibration 44 at one end and to a mass 88 at the free end. The preload on the non-linear tuning springs 32 which apply a spring force to the mass may be adjusted by actuators 46 by adjusting the distance D, the compression distance, so that the spring bias is adjusted to adjust the resonant frequency of the cantilever and the mass to be matched to the vibration frequency in order to maximise the strain on the cantilever and the power generated by the piezoelectric elements of the cantilever. distance D, the compression distance, so that the spring bias is adjusted to adjust the resonant frequency of the cantilever and the mass to be matched to the vibration frequency in order to maximise the strain on the cantilever and the power generated by the piezoelectric elements of the cantilever.

Description

HARVESTER AND TUNABLE VIBRATION ENERGY METHOD This application claims priority from United States Application No. l3l529,412 filed on2l June 2012,the contents of which are to be taken as incorporated herein by this reference.

THE INVENTION BACKGROLTND OF invention relates generally to energy The field of the particularly, energy harvester. harvesting and, more to a tunable vibration power Energy harvesting is a process for use in recovering that would otherwise be dissipated or lost in a system. For example, known energy harvesting may be used to obtain energy from light, heat, wind, vibrations, wave may be action, water currents, and the like. In many known systems, energy harvested provide po\ryer used in conjunction with battery power to to electronic devices.

Sensor assemblies are often used in industrial settings to machinery and operations thereof. Known sensor monitor the condition of associated are often battery-powered. However, labor costs associated with changing assemblies a regular basis may limit commercial viability of such sensor assemblies, batteries on especially if the sensors are in remote or inaccessible locations. Because of the limited frequent lifetime of batteries, the limited ability to recycle the batteries, and the cost of powering. battery change-outs, it is desirable to improve sensor herein to a patent document or other matter which A reference is given as prior art is not to be taken as an admission that that document or matter was general or the information it contains was part of the common knowledge known that priority date of any of the claims. as at the BRIEF DESCRIPTION OF THE INVENTION In one aspect, there is provided an energy harvester comprising: an energy conversion device configured to convert vibrational energy into electrical platform energy; an actuator; a first movably coupled to the actuator; a second platform platforms movably coupled to the actuator, wherein the first and second are movably coupled to opposite sides of the actuator; a mass coupled to said energy conversion device; and a first biasing mechanism having a first end coupled to said mass second to the first platform; and, a second biasing mechanism and a end coupled having a third end coupled to the mass and a fourth end coupled to the second platform; wherein the actuator is configured to selectively adjust a distance between platforms the first and second that adjust respective compression distances of the first second biasing mechanism and a resonance frequency ofsaid energy conversion device and said mass.

In another aspect, there is provided a system comprising: a producing frequency; sensor to the device; device vibrations at a driving a coupled harvester comprising an energy conversion device, a mass coupled to and an energy said energy conversion device and at least one biasing mechanism comprising a non- is the mass, and an actuator configured to selectively linear spring which coupled to adjust a compression distance of said at least one biasing mechanism to adjust the non-linear spring selectively adjust a resonance frequency of spring constant ofthe to said energy conversion device and said mass, and a controller configured to resonance frequency the automatically adjust the compression distance and the via actuator, wherein said sensor is powered by electrical energy generated by said energy provide harvester and is configured to feedback of the driving frequency to the and controller is confrgured, via the actuator, to automatically adjust controller, the the compression distance of the biasing mechanism to adjust the spring constant of the non-linear spring such that the resonance frequency substantially matches the driving producing frequency of the device vibrations. yet is provided a method of harvesting In another aspect, there producing at a driving frequency, said method energy from a device vibrations comprising: coupling an energy harvester to the device producing vibrations, wherein the energy harvester includes an energy conversion device configured to convert mass coupled to the energy conversion vibrational energy into electrical energy, a spring which is device, at least one biasing mechanism comprising a non-linear actuator coupled to the biasing mechanism and configured to coupled to the mass, an adjust the spring constant adjust a compression distance of the biasing mechanism to non-linear spring to adjust a resonance frequency ofthe energy conversion ofthe device and the mass; and a controller configured to automatically adjust the providing, and the resonance frequency via the actuator; compression distance , powered feedback of the driving frequency of the device to the controller via a sensor via the controller, the by the energy harvester; and automatically adjusting of the biasing mechanism to adjust the spring constant of the compression distance matches the driving non-linear spring such that the resonance frequency substantially producing frequency of the device vibrations.

BRIEF DESCRIPTION OF THE DRAWINGS power system; FIG. I is a block diagram of an exemplary is a schematic view of an exemplary energy harvester power system shown in that may be used with the of the is a cross-sectional view taken along line 3-3 energy harvester shown in is cross-sectional view of an alternate energy power system shown in and harvester that may be used with the FlG. 5 is a perspective view of an alternate energy harvester -2a- may used with the power system shown in that be DETAILED DESCRIPTION OF THE INVENTION power 10 FIG. I is a block diagram of an exemplary system provide generally includes an energy harvesting device 12 that may be used to that po\/er 14. Energy harvester 12 is a generation device that converts various to a load power. For example, energy harvesting types of mechanical vibrations into electrical generated motors, pumps, turbines, engines and the device 12 may use vibrations from like, depending on specific applications. varying In the exemplary embodiment, a rectifier 16 converts generated device 12 into a direct or alternating current (AC) by energy harvesting half-wave, full-wave, or (DC) signal. By way of non-limiting example, current circuits in voltage-doubling rectifiers may be used as well as voltage-multiplying from rectiflrer 16 is used to power load general. The rectified power output discharged device 18 may provide supplemental 14. Alternatively, an optional energy storage generated harvesting device 12 is insufficient po\Ner to load 14 if the power by energy energy storage device 18 is, for example, a to power load 14. In one embodiment, Lithium-ion baffery andlor a super capacitor. power system l0 is a schematic view of the exemplary includes a shaft 21 rotatably implemented with an exemplary motor 20, which to a motor driven system 23 supported by a bearing housing 22. Shaft 2l is coupled housing 22 of motor 20 rotates to power motor driven system 23. Bearing operation. Power system 10 is housed in a typically vibrates to some degree during 26 attached to bearing housing 22 via any known substantially cylindrical housing fastener, and/or adhesive, etc. Altematively, housing 26 means such as mechanical fabricated from any suitable material that enables system l0 may have any shape or be herein. to function as described harvesting device I 2 is a cross-sectional view of energy embodiment, energy taken along line 3-3. More specifically, in the exemplary device 24, a proof harvesting device 12 includes housing 26, an energy conversion embodiment, mass 30, and at least one biasing mechanism 32. In the exemplary energy conversion device 24 is a piezoelectric device 28. an alternative 24 is an electromagnetic, electrostatic, embodiment, energy conversion device that enables energy harvesting device 12 to magnetostrictive or any other device function as described herein. piezoelectric 28 is a In the exemplary embodiment, device piezoelectric beam 29 that includes a first end 34, a second end 36, a first cantilever 42. Piezoelectric device 28 layer 38, a second piezoelectric layer 40, and a substrate piezoelectric material 38 and 40 vibrational energy to electrical energy when converts is known. Piezoelectric device 28 may be is subjected to tension and compression, as material such as, for example, lead zirconate titanate fabricated from any suitable of piezoelectric (PZT). piezoelectric device may include any number In addition, herein. piezoelectric device 28 to function as described layers 38 and 40 that enables piezoelectric 28 may include a single in an alternative embodiment, device Further, piezoelectric layer that may or may not include a substrate. embodiment, piezoelectric device 28 extends In the exemplary housing 26. First end 34 of beam 29 is coupled to base 44 from a base 44 coupled to mass 30. Alternatively, first end 34 of beam 29 and second end 36 is coupled to a device that produces vibrations, such as motor be coupled to housing 26 or directly to reinforces first and second piezoelectric layers 38 and 40 and . Substrate 42 generation. thereon to increase electrical energy increases the tension and compression to base first and second ends 34 and 36 are each coupled In an alternative embodiment, housing 26 with mass 30 positioned between ends 34 and 36. 44 andlor device 28 and mass 30 have a resonance Piezoelectric In the oscillatory deflection from a rested state. frequency corresponding to their mass resonance frequency of piezoelectric device 28 and exemplary embodiment, the vibration (i.e. adjusted) to substantially match the driving is mechanically tuned produced by motor 20 motor 20, which is the frequency of the vibrations frequency of frequency Matching the resonance frequency to the driving during operation. mass 30, thereby maximum oscillatory deflection of device 28 and facilitates power output. improving piezoelectric 28 may be adjusted or The design of device from which energy will be harvested. modified to fit specific applications or devices of device 28 may be varied to optimize device characteristics For example, the design minimum tuning range, power output, size, weight and such as resonance frequency mass example, the length, width, thickness, stiffness and/or base acceleration. For tune piezoelectric device 28 are variably selected to mechanically distribution of density power output. Similarly, the shape, weight, device 28 to facilitate optimizing be variably selected , as well as the location of mass 30, may also and size of mass piezoelectric device 28 has a power output. In the exemplary embodiment, to optimize More particularly, device 28 has a L between approximately 1 and 3 inches. length length L of approximately 2 inches. mass 30 includes a body 50 In the exemplary embodiment, 10022] embodiment, mass 30 first side 52 and a second side 54. In one exemplary having a I 12009. However, the design weight has a weight that is between approximately and piezoelectric power required to be produced by of mass 30 depends on the amount of generated may be variably selected. Power by device 28. Thus, the weight of mass 30 generally as the weight of mass 30 increases and vice piezoelectric device 28 increases that mass 30 is fabricated from a dense material versa. In the exemplary embodiment, small physical size. In the exemplary enables mass 30 to have a relatively generally cubic and each side has a length between embodiment, mass 30 is that Alternatively, mass 30 may have any other shape approximately 40 and 100 mm. harvesting to function as described herein. Moreover, enables harvesting device 12 more provided more compact design by utilizing one or device 72 may be with a provide of mass 30. For harvesting device 12 in mass 30 to the weight components of (not of actuatot 46, 46, a gearbox andior a motor shown) example, an actuator into mass 30. energy storage device 18 may be incorporated electronics 90 and/or resonance frequency of piezoelectric device 28 and mass 46. In the of biasing mechanisms 32 and/or actuator is varied through adjustments springs such as biasing mechanisms 32 are non-linear exemplary embodiment, be any other preloaded springs 60. Alternatively, biasing mechanisms 32 may conical is compressed, for spring constant that changes when the device device that exhibits a having such mechanical, magnetic, and/or electronic device example, any wire embodiment, biasing mechanisms32 are tapered characteristics. In an alternative increased spring constant when compressed. springs having an springs 60 each include a first In the exemplary embodiment, 100241 second end 66 having a second diameter 68 end 62 having a hrst diameter 64 and a first 62 are each respectively coupled that is larger than first diameter 64. Spring ends mass 30 such that mass 30 is positioned to first side 52 and to second side 54 of between springs 60. first In the exemplary embodiment, actuator 46 includes (not The may include a second surfaces 72, and a drive shown). drive surfaces 70, incorporated into mass 30, motor and gearbox (not shown) and be coupled to base 44, actuator 46 as described or positioned anywhere else that enables the drive to actuate to spring second ends 66, and second surfaces 72 herein. First surfaces 70 are coupled springs 60 may be inverted such that hrst are coupled to housing 26. Altematively, surfaces 70, and second ends 66 are coupled ends 62 are coupled to first actuator 72 away from The drive actuates actuator 46 to move surfaces 70 andlor mass 30.

D between ltrst Thus, 46 enables selective adjustments of a distance housing. actuator surfaces 70 and 72 resulting in selective adjustment of a compression and second actuator 46 may have any distance 74 of springs 60. In an alternative embodiment, distance 74 as that enables actuator 46 to selectively adjust compression configuration herein. described embodiment, energy harvester 12 also In the exemplary processor (not electronics 90 such as sensors 92, a includes a controller 88 comprising Electronics 90 receive and analyze system data and control shown) and a memory 94. harvester l2 such as movement of actuator 46 and resonance frequency operations of piezoelectric device 28 and mass 30. In the exemplary embodiment, tuning of (FIG. of actuator incorporated into mass 30 3) and enable actuation electronics 90 are 26 any other 46. Alternatively, electronics 90 are coupled to base 44, housing andlor suitable location in energy harvester gather In the exemplary embodiment, sensors 92 data to enable 100271 driving resonance frequency of device 28 and mass 30 to the electronics 90 to tune the 26 measures the of motor 20. Sensor 92 positioned on base 44 or housing frequency , and sensor 92 positioned in or near mass 30 determines driving frequency of motor 46, compression distances 74, and/or drive motor distance D between actuators located 46. In an altemative embodiment, sensors 92 are revolutions of actuators function as described herein. Additionally, sensor anywhere that enables sensors 92 to current and/or power of the piezoelectric device 92 may measure the output voltage, In the exemplary embodiment, sensor 92 transmits a signal representing sensor measurements to electronics 90. Alternatively, or additionally, provides load 14 may include a sensor (not shown) that electronics 90 with a signal motor 20 or load 14. representing the driving frequency of motor 20 or other data about actuator 46 andlor may Data measured by sensors 92 may be used to selectively adjust if measured indicates harvester l2 is be stored in memory 94. For example, the data the driving frequency of motor 20, adjustments are made to out of tune with resonance frequency to the driving frequency. Memory 94 substantially match the pre-calibrated look-up table of driving frequencies, resonance frequencies, and stores a any other data that may enable tuning of energy harvester 12. Thus, if harvester 12 is harvester 12. out of tune, measured data and the look-up table are used to tune energy polynomial relationship Memory 94 may alternatively, or additionally, store a linear or frequency of device 28. correlating between a particular measurement and a resonance illustrates an exemplary altemative energy harvesting 100 is similar to energy harvesting device 12 (shown in , and device that to identify the same components in as identical reference numbers are used in Energy harvesting device 100 is similar to energy harvesting were used 12, except device 100 includes an alternative arrangement of actuator 46. In the device embodiment, actuator 46 is positioned between mass 30 and each biasing exemplary flrrst side 52 mechanism 32. More particularly, first actuator surfaces 70 arc coupled to and second side 54 of mass 30, respectively, while second actuator surfaces 72 coupled to spring first ends 62, respectively. Spring second ends 66 are coupled may be inverted such that first ends 62 are housing 26. Alternatively, springs 60 66 are to second actuator surfaces 72. coupled to housing 26, and second ends coupled distance D between surfaces 70 andlor 72 Actuator 46 is actuated to selectively adjust in of compression distancesT4. resulting selective adjustment illustrates an exemplary alternative energy harvesting (shown device 200 that is similar to energy harvesting devices 12 and 100 in FIGS. 3 and 4, respectively), and identical reference numbers are used to identify the same 200 is used in FIGS. 3 and 4. Energy harvesting device components in as were includes device l2 (shown in , except device 200 similar to energy harvesting particularly, mass 30 of mass 30 and actuator 46. More an alternative arrangement positioned between opposed first and second portions 232 and 234 includes opposed portions 232 234 are sections 236 and 238. First and second and third and fourth 236 and238 are coupled to to beam second end 36. Third and fourth sections coupled have respective arms 240 second portions 232 and234,respectively, and each f,rrst and 242 extendin g therefrom.

In the alternative exemplary embodiment, actuator 46 t0031] portions 232 and234. A portion of base 44 adjacent to first and second coupled to a surface 250 and pair platforms 244 and 246 is coupled a top and bottom actuator away from surfaces 252, rcspectively. Platforms 244 and 246 are moved towards and gearbox (not shown) of actuator 46. A 250 and252,respectively, by a motor 254 and FIG. for clarity) is positioned on either side of pair of guides 258 (one is removed in 5 guide platforms 244 and 246. A spring 60 is coupled actuator 46 to support and platform 244 and another spring 60 is coupled between arm242 between arm240 and platforms 46 selectively adjusts the distance D between and platform 246. Actuator in selective adjustment of spring compression distances 74. 244 and 246 resulting is selectively frequency of piezoelectric device 28 and mass 30 Thus, the resonance provided energy produced by device 28 is via connector adjusted. Resulting electrical 256 to rectifier 16. system 10 is coupled to a vibration During operation, generated by motot 20 are converted producing device, such as motor 20. Vibrations 12, 100 or 200. In the exemplary into electrical power by energy harvesting device sensor that is powered by energy harvesting device embodiment, load l4 is a wireless system 14 may be, for example, a machine condition monitoring 12. Wireless sensor pressures of critical indicators such as vibrations, temperatures and that measures key In the and tracks the information over time to look for abnormalities. machines, that assesses health, embodiment, wireless sensor l4 is an accelerometer exemplary data. For example, and/or balance of motor 20 based on captured vibration alignment changes may be generated by motor 20 change with aging of motor 20. The vibrations sensor 14 for storage or and transmitted to a remote location by wireless detected of motor 20 and its need for further processing, for example, to assess the condition maintenance.

As described above, energy harvesting devices 12, 100 and 200 convert vibrations into electrical energy. During operation, base 44 is subjected to piezoelectric energy movement of mass 30 and deflection of beam vibration causing generates 28. Deflection of first and second piezoelectric layers 38 and 40 AC voltage. into DC voltage that The AC voltage is delivered to rectifier l6 wherein it is converted power is provided to wireless sensor l4 to sensor operations. power During operation, energy harvester 12 output is (or frequency to optimized by substantially matching tuning) the harvester resonance modern industrial driving frequency of the source vibration. Because many known of harvester l2 is processes are often variable speed, the resonance frequency energy frequency of the changing source vibration. variably selected to substantially match the generated when the resonance frequency of harvester 12 Power is more effectively of motor 20. substantially matches the source frequency In the exemplary embodiment, the resonant frequency system, is equal energy harvester 12 depends on the total spring constant of the which piezoelectric 28 of springs 60. While the to the sum of the spring constant of beam and constant of spring constant of beam 28 is relatively constant due to design, the spring is increased. Thus, the resonant springs 60 increases as compression distance 74 compression distance 74 of frequency of energy harvester 12 is tuned by adjusting facilitated by selectively increasing each spring ó0. Tuning of energy harvester 12 is surfaces 70 and 72 or platforms 244 and or decreasing distance D between actuator of biasing mechanisms 32 are selectively 246, such that compression distances 74 varied. if harvester l2 is out of tune, electronics 90 During operation, actuator 46 based on the automatically adjusts compression distances 74 by actuating Compression distance 74 is adjusted frequency look-up table stored in memory 94. table stored in memory 94. More specifically, the based on the frequency look-up desired position of actuator surfaces look-up table includes data usable to determine a distance 74. 70 andlor 72 or platforms 244 and 246, andlot a desired compression 90 determines the required Based on the measured driving frequency, electronics required to match the driving frequency compression distance 74 inthe look-up table In the look-up table may store any other and adjusts actuator 46 accordingly. addition, 12 such as, but not limited to, temperature and data usable to tune harvesting device piezoelectric material and/or drive motor humidity adjustments, aging of the updated 46. Moreover, the look-up table may be automatically revolutions of actuator to improve system efficiency. the driving frequency of the vibration Sensor 92 measures determines compression distance 74 that corresponds to source 20, and electronics 90 94. The frequency based on the look-up table stored in memory the measured driving 74 corresponds to a range ofresonance frequencies range ofcompression distances 12. Thus, based on the measured driving frequency, actuator energy harvester resonance frequency of distances 74 to substantially match the adjusts compression . As such, energy 12withthe driving frequency of vibration source energy harvester Thus, in the exemplary of harvester 12 is facilitated to be maximized. output to automatically tune the resonance embodiment, electronics 90 are configured source 20 changes. frequency ofenergy harvester 12 as the vibration The exemplary energy harvester described above efficiently /er tuning the generates po\ over a wide range of vibration frequencies by automatically energy harvester to frequency ofthe harvester. Such adjustments enable the resonance because of the in physically small and/or remote locations. In addition, be useful is reduced and the harvester may be relatively few moving parts of the system, wear precision and/or consistency, as at a lower cost without the need for high manufactured mechanical damping is to known harvesters. For the same reason, compared output. Further, by harvesting power minimized, which facilitates a higher energy made self sufficient over their lifetime with from the environment, sensors can be energy harvester described herein can virtually no maintenance. Thus, the exemplary or systems for maintenance free machine-condition be built into wireless sensors used to power wireless sensors may be reduced monitoring. Furthermore, batteries reducing maintenance and environmental impact. size or even eliminated, thus disclose the This written description uses examples to person skilled in the art to invention, including the best mode, and also to enable any any devices or systems and practice the invention, including making and using patentable scope of the invention is performing any incorporated methods. The that occur to those skilled in dehned by the claims, and may include other examples to be within the scope of the claims if they the art. Such other examples are intended from the literal language of the claims, or if have structural elements that do not differ elements with insubstantial differences from the they include equivalent structural literal languages of the claims. "comprised" or Where the terms "comprise", "comprises", (including the claims) they are to be "comprising" are used in this specification presence of the stated features, integers, steps interpreted as specifying the precluding the presence of one or more other features, integers, components, but not or group thereto. steps or components, PARTS LIST power 10 system energy harvesting device load/wireless sensor rectifier l6 energy storage device .18 motor shaft bearing housing ...... motor driven system energy conversion device housing .26 piezoelectric device .28 beam ........ lnASS biasing mechanism .32 beam first end ....... beam second end .. first piezoelectric layer 38 piezoelectric 40 second layer substrate base .44 ......... actuator mass body ..... mass hrst side mass second side spnng spring first end spring first diameter ........,. spring second end ....... spring second diameter surfaces ......... frrst actuator second actuator surfaces compression distance controller electronics memory ...100 harvesting device energy .200 energy harvesting device portion .232 mass first .234 portion....... mass second mass third section mass fourth section .242 arïn .244 platform platform........... .250 surface top actuator bottom actuator surface ......... motor -1 3- .2s6 connector .258 guide AS FOLLOWS: THE

Claims (1)

1. CLAIMS 1. DEFINING THE TNVENTION ARE l. An energy harvester comprising: energy into electrical conversion device configured to convert vibrational an energy energy; an actuator; a first platform movably coupled to the actuator; first and second platform movably coupled to the actuator, wherein the a second platforms movably coupled to opposite sides of the actuator; device; and a mass coupled to said energy conversion to said mass and a second end a f,rrst biasing mechanism having a first end coupled to the f,rrst platform; and, coupled a fourth end mechanism having a third end coupled to the mass and a second biasing platform; coupled to the second selectively adjust a distance between the first wherein the actuator is configured to distances of the first and second second platforms that adjust respective compression said energy conversion device and said mechanism and a resonance frequency of biasing lnASS. device The energy harvester of Claim 1, wherein said energy conversion electrostatic device, one of a piezoelectric device, an electromagnetic device, an comprises and a magnetostrictive device. 2, wherein said piezoelectric device further 3. The energy harvester of Claim piezoelectric layer, and a substrate extending comprises a first piezoelectric layer, a second therebetween. hrst biasing harvester of any one of Claims I to 3, wherein the 4. The energy spring and the second biasing mechanism comprises mechanism comprises a first non-linear a second non-linear spring. fìrst The energy harvester of any one of Claims I to 3, wherein the biasing comprises a a first conical spring and the second biasing mechanism mechanism comprises spring. second conical said first conical spring comprises a 6. The energy harvester of Claim 5, wherein larger a second end having a second diameter that is than first end having a hrst diameter and said f,rrst diameter. 1 to 6, further comprising a sensor 7 . The energy harvester of any one of Claims position of said actuator, the respective compression configured to sense at least one of a said biasing mechanisms, one or more motor revolutions of distances of said hrst and second ofan object said harvesting device is configured to couple actuator, and a driving frequency one of Claims 1 or 7, further comprising a 8. The energy harvester of any programmed to control said actuator based controller comprising a memory, said controller in said memory. on a look-up table of resonance frequencies stored A system comprising: frequency; a device producing vibrations at a driving to the device; and a sensor coupled device, a mass coupled to said an energy harvester comprising an energy conversion least one biasing mechanism comprising a non-linear spring energy conversion device and at actuator conf,rgured to selectively adjust a compression which is coupled to the mass, and an mechanism to adjust the spring constant of the non-linear distance of said at least one biasing device and said adjust a resonance frequency ofsaid energy conversion spring to selectively mass, adjust the compression distance and the and a controller configured to automatically resonance frequency via the actuator, generated is powered by electrical energy by said energy wherein said sensor provide feedback of the driving frequency to the controller, and harvester and is configured to -t6- distance the controller is configured, via the actuator, to automatically adjust the compression spring such the of the biasing mechanism to adjust the spring constant of the non-linear that producing resonance frequency substantially matches the driving frequency of the device vibrations. 9, wherein said energy conversion device comprises one 10. The system of Claim of piezoelectric device, an electromagnetic device, an electrostatic device, and a magnetostrictive device. 9 or 10, wherein said sensor is conflrgured to I L The system of any one of Claims provide said device producing vibrations to a remote monitoring system. data about 9 1 1, wherein said sensor is configured to 12. The system of any one of Claims or motor, turbine, and an industrial process. monitor the health of at least one of an engine, a a producing 13. A method of harvesting energy from a device vibrations at a driving frequency, said method comprising: harvester to the device producing vibrations, wherein coupling an energy the energy harvester includes an energy conversion device configured to convert vibrational energy into electrical energy, a mass coupled to the energy conversion device, is to the mass, an least one biasing mechanism comprising a non-linear spring which coupled distance actuator coupled to the biasing mechanism and conhgured to adjust a compression of the biasing mechanism to adjust the spring constant of the non-linear spring to adjust device the mass; and resonance frequency ofthe energy conversion and a configured to automatically adjust the compression distance and the controller resonance frequency via the actuator; providing, feedback driving frequency of the device to the controller via a of the powered by the energy harvester; and sensor of the biasing automatically adjusting via the controller, the compression distance the resonance mechanism to adjust the spring constant of the non-linear spring such that producing frequency substantially matches the driving frequency of the device vibrations a controller includes a memory, wherein 14. The method of Claim 13, wherein -17 - biasing mechanism comprises adjusting the said adjusting the compression distance of the based on a look-up table stored in the compression distance of the biasing mechanism memory. 26-- I 2 18 LOAD HARVESTER RECTIFIER BATTERY 10 3 MOTOR DRIVEN SYSTEM 24t28 46----;\ -t -1 .G-62 r 4 \ --32 26 t