Optimisation and frequency tuning concepts for a vibration energy harvester

With current electronic designs becoming more versatile and mobile, applications that were wired and bulky before have now seen a great reduction in size and increase in portability. However, the issue is that the scaling down in size and cost of electronics has far outpaced the scaling up of energy density in batteries. Therefore, a great deal of research has been carried out to search for alternative power sources that can replace or enhance the conventional battery. Energy harvesting (also known as energy scavenging) is the process whereby ambient energy is captured and stored. The ambient energy here refers to energy that is pre-existing in nature, and is self-regenerating and has extended life time from a battery. After reviewing many possible energy scavenging methods, the conversion of ambient vibrations to electricity is chosen as a method for further research. There are plenty of different methods to transform ambient vibration to electricity, but in this research only piezoelectric and electromagnetic conversions are pursued. In order to harvest the most energy with the harvesting device, the harvester’s fundamental mode must be excited. However, this is not always possible due to fluctuations in the frequency of the vibration source. By being able to change the natural frequencies of the device, the harvester could be more effective in capturing ambient energy. In this thesis, the behaviour of the various types of energy sources is studied and the obtained information is later used to generate a vibration signal for subsequent simulation and experiments. A converter based on a piezoelectric bimorph is investigated. The resultant outputs from the design are compared to the model and the analysis is presented. The mechanical strain distributions on the beam’s surface for five different geometric structures are compared and discussed. This is followed by a discussion of the feasibility of improving the strain distribution by changing the beam’s depth (height) along the cantilever beam length. Lastly, a novel frequency tuning method, which involves applying a different effective electrical damping in different quadrants of the oscillating cycle, is proposed. The results of this analysis are presented, along with experimental results that indicate that the behaviour of the system can be changed over a limited range by changing the effective electrical damping during the oscillation cycle

ATS-4 study program, volume 3 Final report

Parabolic reflector design and fabrication, and thermal and structural dynamic analyses for Applications Technology Satellite-

Technology for large space systems: A bibliography with indexes (supplement 19)

This bibliography lists 526 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1988 and June 30, 1988. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

NASA Tech Briefs Index, 1976

Abstracts of new technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Emphasis is placed on information considered likely to be transferrable across industrial, regional, or disciplinary lines. Subject matter covered includes: electronic components and circuits; electronic systems; physical sciences; materials; life sciences; mechanics; machinery; fabrication technology; and mathematics and information sciences

The 29th Aerospace Mechanisms Symposium

The proceedings of the 29th Aerospace Mechanisms Symposium, which was hosted by NASA Johnson Space Center and held at the South Shore Harbour Conference Facility on May 17-19, 1995, are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, pointing mechanisms joints, bearings, release devices, booms, robotic mechanisms, and other mechanisms for spacecraft

Earth resources technology satellite spacecraft system design studies. Volume 2, book 1 - Subsystems studies Final report

Developing structure, payload, communication and data handling subsystems for ERT

NASA Tech Briefs, July 1999

Topics: Test and Measurement; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Software; Mechanics; Machinery/Automation; Bio-Medical; Books and Reports; Semiconductors/ICs

Nonlinear vibration energy harvesters for powering the internet of things

The ever decreasing power consumption in electronic devices and sensors have facilitated the development of autonomous wireless sensor nodes (WSNs), which ushered in the era of the Internet of Things (IoT). However, the problem of long-term power supply to the numerous WSNs pervasively dispersed to enable the IoT is yet to be resolved. This work focuses on the development of novel vibration energy harvesting (VEH) devices and technologies for effective transduction of mostly wide-band and noisy ambient mechanical vibrations to power WSNs. In this thesis meso-scale and MEMS-scale nonlinear and frequency tunable VEH devices have been designed, fabricated and characterized. The first meso-scale VEH prototype developed in this thesis combines a nonlinear bistable oscillator with mechanical impact induced nonlinearity, which exhibits upto 118% broadening in the frequency response over a standalone bistable system. The second meso-scale prototype combines magnetic repulsion induced bistable nonlinearity with stretching induced monostable cubic nonlinearity in a single device structure. The device effectively merged the beneficial features of the individual nonlinear bistable and monostable systems, and demonstrates upto 85% enhanced spectral performance compared to the bistable device. The third prototype is a MEMS-scale device fabricated using spiral silicon spring structure and double-layer planar micro-coils. A magnetic repulsion induced frequency tuning mechanism was incorporated in the prototype, and it was demonstrated that both linear and nonlinear hysteretic frequency responses could be tuned (by upto 18.6%) to match various ambient vibration frequencies. In order to enhance the power generating capability of MEMS-scale electromagnetic devices, an ultra-dense multi-layer micro-coil architecture has been developed. The proposed ultra-dense micro-coil is designed to incorporate double number of turns within the same volume as a conventional micro-coil, and significantly enhance the magnetic flux linkage gradient resulting in higher power output (~4 times). However, attempts to fabricate the ultra-dense coil have not been successful due to lack of proper insulation between the successive coil layers. Finally, a power management system combining diode equivalent low voltage drop (DELVD) circuit and a boost regulator module was developed. It was demonstrated that energy harvested from harmonic and bandlimited random vibrations using linear, nonlinear bistable, and combined nonlinear VEH devices could be conditioned into usable electricity by the power management system with 60% - 75% efficiency. In addition to developing new prototypes and techniques, this thesis recommends directions towards future research for further improvement in vibration energy harvesting devices and technologies

The Design of the Keck Observatory and Telescope

This report describes the design of the Ten Meter Telescope and Observatory. Since 1977 the University of California has been actively designing a ten meter telescope for visible and infrared ground-based astronomy. The University of California and the California Institute of Technology have now joined in a collaboration to construct and operate this telescope and observatory. A generous gift of seventy million dollars to Caltech from the W. M. Keck Foundation, announced in January 1985, will provide funds for the construction of the facility. In recognition the facility will be named the W. M. Keck Telescope and Observatory. The University of California will provide funds for its operation. We expect construction to be completed by 1990. The design of the telescope and observatory continues to be improved as the detailed design progresses. The description given here is current as of January 1985. Although many design details will change before construction, this description is accurate in the general concept and in many particulars. The details of the design are described in an ongoing series of Reports and Technical Notes. An index to this series is given in the Reference Section of this report

Micro/Nano Structures and Systems

Micro/Nano Structures and Systems: Analysis, Design, Manufacturing, and Reliability is a comprehensive guide that explores the various aspects of micro- and nanostructures and systems. From analysis and design to manufacturing and reliability, this reprint provides a thorough understanding of the latest methods and techniques used in the field. With an emphasis on modern computational and analytical methods and their integration with experimental techniques, this reprint is an invaluable resource for researchers and engineers working in the field of micro- and nanosystems, including micromachines, additive manufacturing at the microscale, micro/nano-electromechanical systems, and more. Written by leading experts in the field, this reprint offers a complete understanding of the physical and mechanical behavior of micro- and nanostructures, making it an essential reference for professionals in this field