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Author: search.filters.author.Jayasvasti, SubhawatSubject: search.filters.subject.Frequency up-conversion

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    Item type:Publication,
    Evaluation of harvesting energy from pedestrians using piezoelectric floor tile energy harvester
    (2021-11-01)
    Yingyong, Phonexai
    ;
    Thainiramit, Panu
    ;
    Jayasvasti, Subhawat
    ;
    Thanach-Issarasak, Nicharas
    ;
    Isarakorn, Don
    This study determined the influences of several pedestrian parameters on the amount of energy harvested by a piezoelectric energy harvesting floor tile (EHFT), for the goal of providing a realistic harvested energy specification for an application in a certain pedestrian environment. Experiments were conducts to measure the original harvested energy in a laboratory and the harvested energy under a variety of pedestrian parameter values. The main outcomes were the following: the original, unadjusted harvested energy provided by one pedestrian step obtained in the laboratory was 35 mW<inf>rms</inf>; when ten people, weighing less than 50 kg or over 70 kg, stepped on the floor tile, the harvested energy was about 11.0 mJ and 32.0 mJ, respectively; When 30 people walked or ran over it without any fixed pattern, the harvested energy was about 289.0 mJ and 736.9 mJ, respectively; when 30 people walking in a row, separated by a gap of 0.5, 1, and 1.5 m, walking over the tile one by one, the stored energy was 401.0 mJ, 406.0 mJ, and 452.0 mJ, respectively. To conclude, two pedestrian parameters affected the harvested energy strongly pedestrian body weight and pace (walking or running), but pedestrian density did not affect the harvested energy of our developed EHFT strongly. Therefore, in an adjustment of a laboratory-obtained harvested energy into a realistic specification, the influences of those two pedestrian parameters had to be included, while pedestrian density could be ignored. These findings should be directly useful to new researchers and developers in their effort to formulate a realistic harvested energy specification for their developed EHFT.
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    Item type:Publication,
    Design and evaluation of double-stage energy harvesting floor tile
    (2019-10-01)
    Isarakorn, Don
    ;
    Jayasvasti, Subhawat
    ;
    Panthongsy, Phosy
    ;
    Janphuang, Pattanaphong
    ;
    Hamamoto, Kazuhiko
    This paper introduces the design and characterization of a double-stage energy harvesting floor tile that uses a piezoelectric cantilever to generate electricity from human footsteps. A frequency up-conversion principle, in the form of an overshooting piezoelectric cantilever, plucked with a proof mass is utilized to increase energy conversion efficiency. The overshoot of the proof mass is implemented by a mechanical impact between a moving cover plate and a stopper to prevent damage to the plucked piezoelectric element. In an experiment, the piezoelectric cantilever of a floor tile prototype was excited by a pneumatic actuator that simulated human footsteps. The key parameters affecting the electrical power and energy outputs were investigated by actuating the prototype with a few kinds of excitation input. It was found that, when actuated by a single simulated footstep, the prototype was able to produce electrical power and energy in two stages. The cantilever resonated at a frequency of 14.08 Hz. The output electricity was directly proportional to the acceleration of the moving cover plate and the gap between the cover plate and the stopper. An average power of 0.82 mW and a total energy of 2.40 mJ were obtained at an acceleration of 0.93 g and a gap of 4 mm. The prototype had a simple structure and was able to operate over a wide range of frequencies.