Download or read book Design and Modeling of a Low Frequency MEMS Vibration and Motion Energy Harvester written by Rachid G. Aboukasm and published by . This book was released on 2011 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ambient motion and vibration frequencies of 1 to 16 Hz is the focus of this research for the design of a MEMS power generator to scavenge mechanical energy of a typical human body motion. A lead zirconate titanate coated cantilever, on which a proof mass is attached, is used as the energy harvesting structure. Lumpled element model is created adn overall performance of the device is predicted. Single crystal silicon is attached to the cantilever for large proof mass which results in high power density in the targeted spectrum. Deep reactive ion etching based micro fabrication processes are proposed for the fabrication of the structure without implementing the fabrication. COMSOL, a multiphysics simulation tool is used in structure design. Flip-bias charge-voltage converting interface is introduced, and a total power density of 370 [Greek letter mu] W/cm3 at targeted motion frequency can be harvested based on the COMSOL and circuit simulations.

Download or read book Low frequency Low amplitude MEMS Vibration Energy Harvesting written by Ruize Xu (Ph. D.) and published by . This book was released on 2018 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vibration energy harvesters work effectively only when the operating conditions match with the available vibration source. Typical resonating MEMS structures cannot be used with low-frequency, low-amplitude and unpredictable nature of ambient vibrations. Bi-stable nonlinear oscillator based energy harvesters are developed for lowering the operating frequency while widening the bandwidth, and are realized at MEMS scale for the first time. This design concept does not rely on the resonance of the MEMS structure but operates with the large snapping motion of the beam at very low frequencies when proper conditions are provided to overcome the energy barrier between the two energy wells of the structure. A fully functional piezoelectric MEMS energy harvester is designed, monolithically fabricated and tested. An electromechanical lumped parameter model is developed to analyze the nonlinear dynamics and to guide the design of the multi-layer buckled beam structure. Residual stress induced buckling is achieved through the progressive control of the deposition along the fabrication steps. Static surface profile of the released device shows bi-stable buckling of 200 [mu]m which matches very well with the design. Dynamic testing demonstrates the energy harvester operates with 35% bandwidth under 70Hz at 0.5g, operating conditions that have not been met before by MEMS vibration energy harvesters.

Download or read book Modeling and Design of a MEMS Piezoelectric Vibration Energy Harvester written by Noël Eduard Du Toit and published by . This book was released on 2005 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) A low-level (2.5 m/s2), low-frequency (150 Hz) vibration source is targeted for anti-resonance operation, and a power density of 313 [mu]W/cm3 and peak-to-peak voltage of 0.38 V are predicted per harvester. Methodologies for the scalar analysis and optimization of uni-morph and bi-morph harvesters are developed, as well as a scheme for chip-level assembly of harvester clusters to meet different node power requirements.

Download or read book Energy Harvesting Systems written by Tom J. Kaźmierski and published by Springer Science & Business Media. This book was released on 2010-11-01 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kinetic energy harvesting converts movement or vibrations into electrical energy, enables battery free operation of wireless sensors and autonomous devices and facilitates their placement in locations where replacing a battery is not feasible or attractive. This book provides an introduction to operating principles and design methods of modern kinetic energy harvesting systems and explains the implications of harvested power on autonomous electronic systems design. It describes power conditioning circuits that maximize available energy and electronic systems design strategies that minimize power consumption and enable operation. The principles discussed in the book will be supported by real case studies such as battery-less monitoring sensors at water waste processing plants, embedded battery-less sensors in automotive electronics and sensor-networks built with ultra-low power wireless nodes suitable for battery-less applications.

Download or read book Piezoelectric Energy Harvesting written by Alper Erturk and published by John Wiley & Sons. This book was released on 2011-04-04 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transformation of vibrations into electric energy through the use of piezoelectric devices is an exciting and rapidly developing area of research with a widening range of applications constantly materialising. With Piezoelectric Energy Harvesting, world-leading researchers provide a timely and comprehensive coverage of the electromechanical modelling and applications of piezoelectric energy harvesters. They present principal modelling approaches, synthesizing fundamental material related to mechanical, aerospace, civil, electrical and materials engineering disciplines for vibration-based energy harvesting using piezoelectric transduction. Piezoelectric Energy Harvesting provides the first comprehensive treatment of distributed-parameter electromechanical modelling for piezoelectric energy harvesting with extensive case studies including experimental validations, and is the first book to address modelling of various forms of excitation in piezoelectric energy harvesting, ranging from airflow excitation to moving loads, thus ensuring its relevance to engineers in fields as disparate as aerospace engineering and civil engineering. Coverage includes: Analytical and approximate analytical distributed-parameter electromechanical models with illustrative theoretical case studies as well as extensive experimental validations Several problems of piezoelectric energy harvesting ranging from simple harmonic excitation to random vibrations Details of introducing and modelling piezoelectric coupling for various problems Modelling and exploiting nonlinear dynamics for performance enhancement, supported with experimental verifications Applications ranging from moving load excitation of slender bridges to airflow excitation of aeroelastic sections A review of standard nonlinear energy harvesting circuits with modelling aspects.

Download or read book Electromagnetic Vibration Energy Harvesting Devices written by Dirk Spreemann and published by Springer Science & Business Media. This book was released on 2012-02-15 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electromagnetic vibration transducers are seen as an effective way of harvesting ambient energy for the supply of sensor monitoring systems. Different electromagnetic coupling architectures have been employed but no comprehensive comparison with respect to their output performance has been carried out up to now. Electromagnetic Vibration Energy Harvesting Devices introduces an optimization approach which is applied to determine optimal dimensions of the components (magnet, coil and back iron). Eight different commonly applied coupling architectures are investigated. The results show that correct dimensions are of great significance for maximizing the efficiency of the energy conversion. A comparison yields the architectures with the best output performance capability which should be preferably employed in applications. A prototype development is used to demonstrate how the optimization calculations can be integrated into the design–flow. Electromagnetic Vibration Energy Harvesting Devices targets the designer of electromagnetic vibration transducers who wishes to have a greater in-depth understanding for maximizing the output performance.

Download or read book A MEMS Magnetic based Vibrational Energy Harvester written by Abraham Shin and published by . This book was released on 2018 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the design, fabrication, and testing of a MEMS vibration energy harvester that is to operate at low frequency to power machine health monitoring. The energy harvester converts external vibration into electricity via the Lorentz-force by allowing a permanent magnet, which acts as an inertial mass, to oscillate between coils wound above and below the magnet. Careful analysis and design of a fabricated silicon-based suspension, which holds the magnet, determines the important mechanical properties of the harvester, such as the internal loss and the selectivity of a single translational vibration. The harvester is designed to provide maximum power output at 0.5 g external acceleration at 50 Hz while its size is constrained to be less than 1 cm3. By incorporating mechanical and electromagnetic analyses, a full-system optimization is performed to determine the optimal dimensional parameters of the harvester and to estimate the power output to be observed. The fabricated and assembled energy harvester is tested and observed to produce an open-circuit voltage of 100 mV and a power output of 165 [mu]W at the resonance frequency of 45.7 Hz. The harvester’s power density is 382 [mu]W/cm3, which is higher than the highest reported value of 222 [mu]W/cm3 for existing MEMS energy harvesters, but the performance of the design presented in this thesis may be improved with some changes to the current design.

Download or read book Nonlinearity in Energy Harvesting Systems written by Elena Blokhina and published by Springer. This book was released on 2016-11-10 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a single-source guide to nonlinearity and nonlinear techniques in energy harvesting, with a focus on vibration energy harvesters for micro and nanoscale applications. The authors demonstrate that whereas nonlinearity was avoided as an undesirable phenomenon in early energy harvesters, now it can be used as an essential part of these systems. Readers will benefit from an overview of nonlinear techniques and applications, as well as deeper insight into methods of analysis and modeling of energy harvesters, employing different nonlinearities. The role of nonlinearity due to different aspects of an energy harvester is discussed, including nonlinearity due to mechanical-to-electrical conversion, nonlinearity due to conditioning electronic circuits, nonlinearity due to novel materials (e.g., graphene), etc. Coverage includes tutorial introductions to MEMS and NEMS technology, as well as a wide range of applications, such as nonlinear oscillators and transducers for energy harvesters and electronic conditioning circuits for effective energy processing.

Download or read book MEMS Energy Harvesters with a Wide Bandwidth for Low Frequency Vibrations written by Nuh Sadi Yuksek and published by . This book was released on 2015 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have designed and built macro-scale wideband electrostatic and electromagnetic power harvesters for low frequency vibration. Initially, MEMS capacitive plates for power harvesting have been designed, modeled and fabricated, and characterized. It was designed with a 2×2 mm2 movable metallic plate with a thickness of 10 [micro]m suspended by four straight beams above a fixed electrode with a gap of 10 [micro]m to form a variable capacitor. The suspension beams are made with a width, thickness and total length of 20 [micro]m, 10 [micro]m and 1500 [micro]m, respectively. It was found that the single cavity device can harvest almost 180 nW peak power across a 100 k[omega] load resistor at 5g. The harvested power was dependent on excitation amplitude and supplied DC voltage. The MEMS capacitive energy harvester was integrated with two impact oscillators at 18 Hz and 25 Hz for transferring energy from low frequency structural vibration with varying mechanical spectra to high frequency vibration of a high resonance frequency cantilever at 605 Hz. The results demonstrate that the device was able to harvest power on a wide range from 14 to 39 Hz at 1g excitation. The harvested power was 96 nW on a 100 k[omega] load resistor. We also studied a macro-scale electromagnetic power harvester with multi-impact oscillations to achieve a broad bandwidth at low frequency vibrations. The device consists of three low frequency cantilever designed to resonate at 12 Hz, 19 Hz and 40 Hz, a high frequency cantilever with resonance frequency of 210 Hz and a pick-up coil fixed at the tip of the high frequency cantilever. This results in a wide bandwidth response from 11-62 Hz at 1 g. A maximum output power of 23.5 [micro]W can be harvested at 1 g acceleration on an optimum load resistor of 22 [omega].

Download or read book Design of Vibration Energy Harvester for Low Voltage Power Supply Using Finite Element Methods FEM Analysis written by Afifah Shuhada Rosmi and published by . This book was released on 2018 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main aim of the present research is to design a lead-free material of ambient mechanical vibration and sound wave energy harvesterat low resonant frequency less than 200 Hz. The MEMS based piezoelectric power generator (PPG) sensor and passive voltage multiplier circuitry are proposed in harvesting the target vibration source as well as to rectify the gained output voltage into usable voltage level. Thus, the objectives can be summarized as follows ; to develop a cantilever beam type of ZnOPPG with resonant frequency less than 200 Hz in order to harvest the low frequency of ambient vibration energy source ; to evaluate the proposed PPG model performances for mounted and unmounted condition in harvesting the target vibration and transform into electrical energy using FEM module ; to propose the integration of passive voltage multiplier with the PPG model for output voltage rectification and step up to desired direct current (DC) voltage level using Advance Design System (ADS) software.

Download or read book The Design of Low frequency Low g Piezoelectric Micro Energy Harvesters written by Ruize Xu (S.M.) and published by . This book was released on 2012 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: A low-frequency, low-g piezoelectric MEMS energy harvester has been designed. Theoretically, this new generation energy harvester will generate electric power from ambient vibrations in the frequency range of 200~30OHz at excitation amplitude of 0.5g. Our previous energy harvester successfully resolved the gain-bandwidth dilemma and increased the bandwidth two orders of magnitude. By utilizing a doubly clamed beam resonator, the stretching strain triggered at large deflection stiffens the beam and transforms the dynamics to nonlinear regime, and increases the bandwidth. However, the high resonance frequency (1.3kHz) and the high-g acceleration requirement (4-5g) shown in the testing experiments limited the applications of this technology. To improve the performance of the current energy harvesters by lowering the operating frequency and excitation level, different designs have been generated and investigated. Moreover, a design framework has been formulated to improve the design in a systematic way with higher accuracy. Based on this design framework, parameter optimization has been carried out, and a quantitative design with enhanced performance has been proposed. Preliminary work on fabrication and testing setup has been done to prepare for the future experimental verification of the new design.

Download or read book Mechanical Design of Piezoelectric Energy Harvesters written by Qingsong Xu and published by Academic Press. This book was released on 2021-10-22 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanical Design of Piezoelectric Energy Harvesters: Generating Electricity from Human Walking provides the state-of-the-art, recent mechanical designs of piezoelectric energy harvesters based on piezoelectric stacks. The book discusses innovative mechanism designs for energy harvesting from multidimensional force excitation, such as human walking, which offers higher energy density. Coverage includes analytical modeling, optimal design, simulation study, prototype fabrication, and experimental investigation. Detailed examples of their analyses and implementations are provided. The book's authors provide a unique perspective on this field, primarily focusing on novel designs for PZT Energy harvesting in biomedical engineering as well as in integrated multi-stage force amplification frame. This book presents force-amplification compliant mechanism design and force direction-transmission mechanism design. It explores new mechanism design approaches using piezoelectric materials and permanent magnets. Readers can expect to learn how to design new mechanisms to realize multidimensional energy harvesting systems. Provides new mechanical designs of piezoelectric energy harvesters for multidimensional force excitation Contains both theoretical and experimental results Fully supported with real-life examples on design, modeling and implementation of piezoelectric energy harvesting devices

Download or read book Study of Electromagnetic Vibration Energy Harvesting with Free impact Motion for Low Frequency Operation written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This paper presents study of an electromagnetic vibration energy harvesting configuration that can work effectively at low frequencies. Unlike the conventional form of vibration energy harvesters in which the mass is directly connected to a vibrating frame with spring suspension, in the proposed configuration a permanent magnet mass is allowed to move freely within a certain distance inside a frame-carrying coil and make impacts with spring end stops. The free motion distance allows matching lower vibration frequencies with an increase in the relative amplitude at resonance. Hence, significant power could be generated at low frequencies. A nonlinear mathematical model including impact and electromagnetic induction is derived. Study of the dynamic behaviour and investigation of the system performance is carried out with the aid of case study simulation. The proposed harvester shows a unique dynamic behaviour in which different ways of response of the internal relative oscillation appear over the range of input frequencies. A mathematical condition for the response type at which the higher relative amplitude appears is derived, followed by an investigation of the system resonant frequency and relative amplitude. The resonant frequency shows a dependency on the free motion distance as well as the utilized mass and spring stiffness. Simulation and experimental comparisons are carried out between the proposed harvester and similar conventional one tuned at the same input frequency. The power generated by the proposed harvesting configuration can reach more than 12 times at 11 Hz in the simulation case and about 10 times at 10 Hz in the experimental case. Simulation comparison also shows that this power magnification increases by matching lower frequencies which emphasize the advantages of the proposed configuration for low frequency operation. Highlights: We present an electromagnetic vibration energy harvester based on free/impact motion. The proposed harvester has a resonant behaviour. However, it shows a unique way of oscillation. Its resonant frequency can be shifted to lower range with an increase in the resonant relative amplitude Simulation and experimental comparison between the proposed harvester and similar conventional one shows its advantages at low frequencies.

Download or read book Springless Electromagnetic Vibration Energy Harvesters written by Mohamed Bendame and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The abundance of environmental kinetic energy combined with advances in the electronics and MEMS industries have opened a window of opportunities for the design and fabrication of self-powered, battery independent, low-power electronic devices. Kinetic energy harvesting, the process that captures vibrations from the environment or surrounding systems and converts them into electrical power, o ers the prospects of unlimited power for such systems. Vibration energy harvesters (VEHs) are vibration-based micro-power generators that utilize mechanical oscillators to capture ambient vibration energy and convert it into electrical power using one of three main transduction mechanisms, electromagnetic, electrostatic, or piezoelectric. A key feature of VEHs is their ability to harvest maximum environmental vibration energy from low amplitude and low frequency vibrations from a wide spectrum of frequencies. Traditional VEHs use linear mechanical oscillators as their harvesting element and are tuned to harvest environmental vibrations at resonance frequency present within the application environment. These VEHs are usually designed to harvest energy from high frequency vibrations in a narrow band in the vicinity of the natural frequency of the mechanical oscillator, and outside this narrow band of frequencies their output power is signi cantly reduced. In environments where ambient vibrations are random and only available at low frequencies, conventional harvesters prove to be ine ective. Although such devices are capable of generating power from vibrations with frequencies close to their resonance frequency, the need for harvesters that can harvest energy from broadband vibration sources has become an interesting research topic in recent years. To overcome the limitations associated with traditional vibration energy harvesters, nonlinear phenomena, such as hardening and softening nonlinearities, magnetic levitation, and pact have been sought as a solution to broadband vibration energy harvesting. In this thesis we aim to address this challenge by investigating a new architecture of an electromagnetic vibration energy harvester, the electromagnetic \Springless" vibration energy harvester (SVEH). The new architecture di ers from traditional harvester as it uses a double-impact oscillator as its harvesting element as opposed to the linear model. Experimental results show that the new SVEH is capable of harvesting vibration energies with frequencies as low as 5Hz and amplitudes as low as 0.05 g in a frequency band of about 8Hz. The harvester generates maximum output power of 12 mWatt from vibrations with amplitude of 0.5 g and an optimal load of 3.6 ohms. Experimental results also show that the "nonlinear" center frequency of the harvester is not constant, as in the case of conventional harvesters, but depends on the amplitude and frequency of the external vibrations and whether the harvester is operated in the vertical or horizontal position. Experimental as well as the numerical frequency response curves of the SVEH also show the existence of hardening nonlinearity in the horizontal con guration and softening nonlinearity in the vertical con guration in the system. The hardening e ect allows harvesting of energy in the high frequency spectrum, about 25 Hz and a bandwidth of 7 Hz, while the softening e ect allows harvesting at the lower end of the frequency spectrum, which is around 5 Hz and a bandwidth of 8 Hz. Models of the SVEH in the vertical and horizontal con gurations were developed and nonlinear numerical and analytical methods were used to analyze the system to gain a deeper understanding of the system's behavior. The experimental data is then used to validate the models. The harvester's ability to harvest vibration energy from low frequency ( 25Hz) and low amplitude vibrations ( 0:5g) in a wide band ( 5Hz) is one of the unique features of the SVEH demonstrated in this work.

Download or read book Engineering Applications for New Materials and Technologies written by Andreas Öchsner and published by Springer. This book was released on 2018-01-25 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the expertise, skills, and techniques needed for the development of new materials and technologies. It focuses on finite element and finite volume methods that are used for engineering simulations, and present many state-of-the-art applications and advances to highlight these methods’ importance. For example, modern joining technologies can be used to fabricate new compound or composite materials, even those formed from dissimilar component materials. These composite materials are often exposed to harsh environments, must deliver specific characteristics, and are primarily used in automotive and marine technologies, i.e., ships, amphibious vehicles, docks, offshore structures, and even robots. To achieve the desired material performance, computer-based engineering tools are widely used for simulation, data evaluation, and design processes.

Download or read book Design and Development of MEMS based Guided Beam Type Piezoelectric Energy Harvester written by Shanky Saxena and published by Springer Nature. This book was released on 2021-04-06 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents device design, layout design, FEM analysis, device fabrication, and packaging and testing of MEMS-based piezoelectric vibration energy harvesters. It serves as a complete guide from design, FEM, and fabrication to characterization. Each chapter of this volume illustrates key insight technologies through images. The book showcases different technologies for energy harvesting and the importance of energy harvesting in wireless sensor networks. The design, simulation, and comparison of three types of structures – single beam cantilever structure, cantilever array structure, and guided beam structure have also been reported in one of the chapters. In this volume, an elaborate characterization of two-beam and four-beam fabricated devices has been carried out. This characterization includes structural, material, morphological, topological, dynamic, and electrical characterization of the device. The volume is very concise, easy to understand, and contains colored images to understand the details of each process.

Download or read book Investigation of Potential Platforms for Low Frequency MEMS based Piezoelectric Energy Harvesting written by Mehdi Rezaeisaray and published by . This book was released on 2014 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: MEMS based energy harvesters have recently been investigated for scavenging, otherwise useless, ambient vibration energy. Piezoelectric materials are fabricated on micro-devices to convert the mechanical vibration energy into electrical energy. The main focus for these harvesters is low frequency (under 500 Hz) ambient vibration which is the source of a fundamental challenge with MEMS oscillators. The smaller the oscillator is, the higher its natural frequencies will become. Various techniques have been proposed to decrease the natural frequency of micro-energy harvesters such as increasing the length of the devices or assembling extra proof mass to the fabricated devices which could potentially affect the mass production of the MEMS devices. Another challenge is that most of the reported piezoelectric energy harvesters in the literature have cantilever designs. These structures have a high mechanical quality factor providing a sharp peak at their resonant frequency. Since microfabricating resonators with a resonant frequency exactly matching their designed value is very challenging, linear cantilever designs seem to be less practical for real applications where excitation frequency could change. Therefore, some techniques in vibration have been adapted to widen the frequency bandwidth of the harvesters. One of the most effective methods to broaden the frequency bandwidth is taking advantage of large deflection effect of oscillators. However, some of the proposed designs such as a fixed-fixed beam design have high resonant frequencies (≥1 kHz), whereas the focus for energy harvesters is low frequency range. In this work, a silicon based structure has been designed and fabricated to carry an electronic chip and potentially provide in-situ supplementary power for it. This design provides capability of harvesting at three different frequencies because the resonant frequencies of this structure at its first three mode shapes are within the low ambient vibration frequency range. The widening frequency bandwidth has been investigated for this design. Natural frequencies as low as 71.8, 84.5, and 188.4 Hz have been measured using a laser vibrometer. A frequency bandwidth of ~10 Hz has been obtained for the 2nd mode shape of the structure under the base excitation of 0.2g. A maximum open circuit voltage of ~1V and maximum power output of 136nW have been obtained using this harvester. In addition, as opposed to the conventional silicon-based harvesters, polymeric materials have been investigated as the main structural material for energy harvesters. Due to the much lower stiffness of polymers compared to silicon, the resonant frequency of the harvesters could be reduced. To prove the concept, a SU-8 (ESU-8=5GPa vs. ESi=160GPa) membrane has been designed and fabricated with Aluminum Nitride harvesting elements. The membrane configuration provides the capability to widen the harvester's frequency bandwidth. Testing results reveal a linear resonant frequency of 381 Hz, frequency bandwidth of 146Hz, maximum output power of 1.37μW, and power density of 3.81 μW/cm2 at the base excitation of 4g with this design. The much lower resonant frequency of polymeric structures compared to the similar silicon-based structures (more than 5 times lower) makes them a strong candidate for the future harvesters. The objective of this thesis is to develop a platform using silicon-based and polymer-based energy harvesters to improve the performance of the energy harvesters by reducing the resonant frequencies and widening the frequency bandwidth. Throughout this research, all stages including design, fabrication, packaging, testing, and characterization of both silicon- and polymer-based harvesters have been developed or adapted for the purpose of this work. Finite element simulations have been conducted to examine the mechanical response of the structures as well as their electrical output at the design stage. A scalable microfabrication process flow has been developed in this work to fabricate piezoelectric layers on SU-8 micro-structures. An improved approach for cleaving fabricated devices from the silicon substrate has been developed to overcome challenges of the dicing process. Various 3-D micro-assembly techniques have been adapted to package the fabricated harvesters. In addition, 3-D printed parts were used to enhance the yield of the packaging and testing stages. This technique could potentially be used for bio-compatible packaging, as well. In conclusion, the polymer-based and wideband energy harvesters seem promising for real applications at low ambient vibration frequencies. This research introduces opportunities to further improve the performance of the harvesters by decreasing their resonant frequencies.