2,964 research outputs found

    A review study on energy harvesting systems for vehicles

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    The widespread and increasing consumption of fossil-based fuels as an energy source causes a rapid decrease of these natural sources, as well as an increase of pollution in the atmosphere. Fuel oil, one of the products of fossil fuels, is today the commonly used energy source for transportation. The importance of contributing to the fuel economy and of increasing environmental consciousness have necessitated certain measures in the automotive sector, as well as in other industrial sectors. Therefore, the technological developments recently carried out in the automotive sector aim to reduce the consumption of fossil fuels, for example by recovering waste energy in vehicles. In this direction, efforts have been centered upon the development of energy harvesting systems that provide energy recovery from dynamic parts of the vehicles, such as suspensions. Moreover, the regenerative braking systems that recover some amount of kinetic energy of the vehicles slowing down have been developed and have been in use long since. In this study, research studies on providing the recovery of the vehicles’ waste energy are reviewed with their comparisons

    Development of a Compact Piezoworm Actuator For Mr Guided Medical Procedures

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    In this research, a novel piezoelectric actuator was developed to operate safely inside the magnetic resonance imaging (MRI) machine. The actuator based on novel design that generates linear and rotary motion simultaneously for higher needle insertion accuracy. One of the research main objectives is to aid in the selection of suitable materials for actuators used in this challenging environment. Usually only nonmagnetic materials are used in this extremely high magnetic environment. These materials are classified as MRI compatible materials and are selected to avoid hazardous conditions and image quality degradation. But unfortunately many inert materials to the magnetic field do not possess desirable mechanical properties in terms of hardness, stiffness and strength and much of the available data for MRI compatible materials are scattered throughout the literature and often too device specific . Furthermore, the fact that significant heating is experienced by some of these devices due to the scanner’s variable magnetic fields makes it difficult to draw general conclusions to support the choice of suitable material and typically these choices are based on a trial-and-error with extensive time required for prototype development and MRI testing of such devices. This research provides a quantitative comparison of several engineering materials in the MRI environment and comparison to theoretical behavior which should aid designers/engineers to estimate the MRI compatible material performance before the expensive step of construction and testing. This work focuses specifically on the effects in the MRI due to the material susceptibility, namely forces, torques, image artifacts and induced heating

    Advanced Energy Harvesting Technologies

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    Energy harvesting is the conversion of unused or wasted energy in the ambient environment into useful electrical energy. It can be used to power small electronic systems such as wireless sensors and is beginning to enable the widespread and maintenance-free deployment of Internet of Things (IoT) technology. This Special Issue is a collection of the latest developments in both fundamental research and system-level integration. This Special Issue features two review papers, covering two of the hottest research topics in the area of energy harvesting: 3D-printed energy harvesting and triboelectric nanogenerators (TENGs). These papers provide a comprehensive survey of their respective research area, highlight the advantages of the technologies and point out challenges in future development. They are must-read papers for those who are active in these areas. This Special Issue also includes ten research papers covering a wide range of energy-harvesting techniques, including electromagnetic and piezoelectric wideband vibration, wind, current-carrying conductors, thermoelectric and solar energy harvesting, etc. Not only are the foundations of these novel energy-harvesting techniques investigated, but the numerical models, power-conditioning circuitry and real-world applications of these novel energy harvesting techniques are also presented

    Vibration Isolation for Rotorcraft Using Electrical Actuation

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    The Active Control of Structural Response (ACSR) vibration suppression system, where hydraulic actuators located between the gearbox and the fuselage are used to cancel vibration in large helicopters, has been used successfully for many years. However the power consumed by the actuators can be high, and using hydraulic actuation for smaller rotorcraft has not been seen as practical. In contrast to active vibration reduction systems, passive vibration isolation systems require no external power. Passive vibration isolation systems however have the disadvantage of being limited to working at one specific frequency which will not be acceptable as slowed rotor flight becomes more common for fuel efficiency and noise legislation reasons. In this thesis two electrically powered actuation concepts, one piezoelectric, and one electromagnetic were initially evaluated. An electrically powered actively augmented passive, or hybrid, vibration reduction system based on an electro hydrostatic actuator (EHA) concept was proposed to be developed further. This hybrid actuator will have a wider range of operating frequencies than a purely passive system, and have lower power consumption than a purely active system. The design is termed a “Resonant EHA”; in that the resonant frequency of the coupled fluid, pump and electric motor rotor inertia matches the fundamental vibration frequency. The hydraulic cylinder, fluid and pump act as a single stage gear ratio, and the. brushless electric motor’s inertia is the main resonating mass as in a Dynamic Antiresonant Vibration Isolator (DAVI) passive vibration reduction system. The electrical power is used to compensate for friction in the actuator and other losses, and if needed can shift the operating point away from the resonant frequency. Simulation results indicated that a hydraulic circuit in which the pump leakage is fed back into the low pressure line would introduce unacceptable disturbances in the flows to and from the cylinder. To eliminate the source of the disturbances, a fully integrated electric motor and pump circuit design was chosen in which the electric motor is immersed in hydraulic fluid. An EHA demonstrator was built sized for a 1.5 tonne rotorcraft. For sizing comparison purposes the frameless brushless D.C motor for each strut of 1.5 tonne rotorcraft has a rotor and stator mass of approximately 1 kg, and can produce a continuous stall torque of 2 Nm. The bidirectional pump has a displacement of 1.5 cm3/rev, the mean system pressure was taken as 90 bar, and the double ended hydraulic cylinder has a 32 mm diameter bore, and 18 mm rod. Initial test results for the proof of concept EHA showed highly significant free play with a reversal of torque direction, resulting in unacceptable loss in transmission stiffness. The free play was traced to the gear pump and a hypothesis for the origin of the free play was put forward. To avoid torque reversals the EHA was further tested with a constant offset torque bias which proved successful in restoring a sufficient stiffness to the transmission. The sizing of the electric motor and power consumed with a non-zero offset torque is greater than a torque reversing motor, which limits the immediate application of the device in the present form. Future research investigating the use of other transmission elements, such as a piston pump, to obtain a more linear stiffness is recommended. As a hybrid vibration isolation system a Root Mean Square (RMS) reduction by a factor of four and near elimination of the fundamental frequency vibrations was achieved for the frequency range of 10 to 20 hertz.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

    PKM mechatronic clamping adaptive device

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    This study proposes a novel adaptive fixturing device based on active clamping systems for smart micropositioning of thin-walled precision parts. The modular architecture and the structure flexibility make the system suitable for various industrial applications. The proposed device is realized as a Parallel Kinematic Machine (PKM), opportunely sensorized and controlled, able to perform automatic error-free workpiece clamping procedures, drastically reducing the overall fixturing set-up time. The paper describes the kinematics and dynamics of this mechatronic system. A first campaign of experimental trails has been carried out on the prototype, obtaining promising results

    Pjezorobotų trajektorijų valdymas nanopalydovų stabilizavimui

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    Rapid industrial advancement requires novel ideas, new scientific approaches and effective technologies that would ensure quality and precision. Application of piezoelectric actuators in robotics opens many possibilities to create systems with extreme precision and control. A very important step in the development of autonomous robots is the formation of motion trajectories. Classical interpolation methods used for formation of the trajectories are suitable only when robots have wheels, legs or other parts for motion transmission. Piezorobots that are analyzed in this dissertation have no additional components that create motion, only contact points with the static plane. Therefore, traditional motion formation methods are not suitable and a problem arises how to define motion trajectory of such device. The aim of this work is to create a trajectory control algorithm of multi-degrees-of-freedom piezorobot used for nanosatellite stabilization. In order to achieve the objective, the following tasks had to be solved: to analyze constructions of precise piezorobots, their operating principles and motion formation methods; to analyze stabilization problems of satellites and application of multi-degrees-of-freedom piezorobots for nanosatellite stabilization; to create piezorobots’ motion formation algorithms according to electrode excitation schemes, to perform an experimental research; to determine quantitative characteristics of the constructed piezorobots and their motion trajectories. The introduction describes the importance and novelty of this thesis, goals of this work, its practical value and defended statements. The first chapter analyses the principals of ultrasonic devices, gives a thorough review of constructions of ultrasonic devices with multi-degrees-of-freedom. The second chapter provides a review of satellite stabilization principles and how multi-degrees-of-freedom piezorobots can be applied for nanosatellite stabilization. Motion formation methods for ultrasonic devices with multi-degrees-of-freedom are presented. The third chapter presents the detailed analysis of different piezorobots. In the fourth chapter experimental results are provided. Trajectory planning of piezorobot is shown, results are compared to numerical calculations performed in the third chapter. The conclusions about applicability of piezorobots’ motion formation algorithms according to electrode excitation schemes are given. Seven articles focusing on the subject of the dissertation have been published, two presentations on the subject have been presented in conferences at international level. The research for the dissertation has been funded by the Lithuanian State Science and Studies Foundation: European Regional Development Fund, Project No. DOTSUT-234 and Research Council of Lithuania, Project No. MIP-084/2015.Dissertatio

    Energy Harvesters and Self-powered Sensors for Smart Electronics

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    This book is a printed edition of the Special Issue “Energy Harvesters and Self-Powered Sensors for Smart Electronics” that was published in Micromachines, which showcases the rapid development of various energy harvesting technologies and novel devices. In the current 5G and Internet of Things (IoT) era, energy demand for numerous and widely distributed IoT nodes has greatly driven the innovation of various energy harvesting technologies, providing key functionalities as energy harvesters (i.e., sustainable power supplies) and/or self-powered sensors for diverse IoT systems. Accordingly, this book includes one editorial and nine research articles to explore different aspects of energy harvesting technologies such as electromagnetic energy harvesters, piezoelectric energy harvesters, and hybrid energy harvesters. The mechanism design, structural optimization, performance improvement, and a wide range of energy harvesting and self-powered monitoring applications have been involved. This book can serve as a guidance for researchers and students who would like to know more about the device design, optimization, and applications of different energy harvesting technologies

    The Roles of Piezoelectric Ultrasonic Motors in Industry 4.0 Era: Opportunities & Challenges

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    Piezoelectric Ultrasonic motors (USM) are based on the principle of converse piezoelectric effect i.e., vibrations occur when an electrical field is applied to piezoelectric materials. USMs have been studied several decades for their advantages over traditional electromagnetic motors. Despite having many advantages, they have several challenges too. Recently many researchers have started focusing on Industry 4.0 or Fourth Industrial revolution phase of the industry which mostly emphasis on digitization & interconnection of the entities throughout the life cycle of the product in an industrial network to get the best possible output. Industry 4.0 utilizes various advanced tools for carrying out the nexus between the entities & bringing up them on digital platform. The studies of the role of USMs in Industry 4.0 scenario has never been done till now & this article fills that gap by analyzing the piezoelectric ultrasonic motors in depth & breadth in the background of Industry 4.0. This article delivers the novel working principle, illustrates examples for effective utilization of USMs, so that it can buttress the growth of Industry 4.0 Era & on the other hand it also analyses the key Industry 4.0 enabling technologies to improve the performance of the USMs

    Multi-physics phenomena influencing the performance of the car horn

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    Usually cars are equipped with disk horns. In these devices electromagnetic energy is converted into mechanical energy of two nuclei that vibrate and impact each other \u2013 the impacts excite the disk that radiates sound. This paper aims at understanding the results of acoustic tests carried out on horns with different excitation voltages and different mounting brackets. Since many non-linear phenomena are inherent in the vibrations of the nuclei, a detailed model of the electromechanical system is developed. Results show the dependence of operating frequency on the input voltage and the role played by the various mechanical and electrical parameters on the dynamics of the horn. Particular nonlinear effects, like sub-harmonic excitation, are presented and discussed. A general agreement between experimental results and numerical simulations is found

    Microsystems technology: objectives

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    This contribution focuses on the objectives of microsystems technology (MST). The reason for this is two fold. First of all, it should explain what MST actually is. This question is often posed and a simple answer is lacking, as a consequence of the diversity of subjects that are perceived as MST. The second reason is that a map of the somewhat chaotic field of MST is needed to identify sub-territories, for which standardization in terms of system modules an interconnections is feasible. To define the objectives a pragmatic approach has been followed. From the literature a selection of topics has been chosen and collected that are perceived as belonging to the field of MST by a large community of workers in the field (more than 250 references). In this way an overview has been created with `applications¿ and `generic issues¿ as the main characteristics
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