A vibrating cantilever footfall energy harvesting device

James M. Gilbert, Farouk Balouchi

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Human footfall is an attractive source of energy for harvesting for low-power applications. However, the nature of footfall is poorly matched to electromagnetic generators. Footfall motion is characterised by high forces and low speeds, while electromagnetic generators are normally most efficient at relatively high speed. This article proposes a novel mechanism for converting the low-speed motion of footfall to a higher speed oscillating motion suitable for electromagnetic power generation. The conversion is achieved using a cantilever beam which is deflected by the footfall motion using a special 'striker' mechanism which then allows the cantilever to oscillate freely at a relatively high speed. An arrangement of permanent magnets attached to the cantilever causes an alternating magnetic field, and a stationary coil converts this to a usable voltage. This article describes the mechanism and provides a mathematical model of its behaviour which allows the system parameters to be optimised and its performance predicted. The performance of a prototype device is presented, and it is shown that this is capable of generating up to 60 mJ/step and that the conversion efficiency is up to 55%.

Original languageEnglish
Pages (from-to)1738-1745
Number of pages8
JournalJournal of Intelligent Material Systems and Structures
Volume25
Issue number14
Early online date6 Feb 2014
DOIs
Publication statusPublished - 1 Sep 2014
Externally publishedYes

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Energy harvesting
Cantilever beams
Permanent magnets
Conversion efficiency
Power generation
Mathematical models
Magnetic fields
Electric potential

Cite this

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title = "A vibrating cantilever footfall energy harvesting device",
abstract = "Human footfall is an attractive source of energy for harvesting for low-power applications. However, the nature of footfall is poorly matched to electromagnetic generators. Footfall motion is characterised by high forces and low speeds, while electromagnetic generators are normally most efficient at relatively high speed. This article proposes a novel mechanism for converting the low-speed motion of footfall to a higher speed oscillating motion suitable for electromagnetic power generation. The conversion is achieved using a cantilever beam which is deflected by the footfall motion using a special 'striker' mechanism which then allows the cantilever to oscillate freely at a relatively high speed. An arrangement of permanent magnets attached to the cantilever causes an alternating magnetic field, and a stationary coil converts this to a usable voltage. This article describes the mechanism and provides a mathematical model of its behaviour which allows the system parameters to be optimised and its performance predicted. The performance of a prototype device is presented, and it is shown that this is capable of generating up to 60 mJ/step and that the conversion efficiency is up to 55{\%}.",
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A vibrating cantilever footfall energy harvesting device. / Gilbert, James M.; Balouchi, Farouk.

In: Journal of Intelligent Material Systems and Structures, Vol. 25, No. 14, 01.09.2014, p. 1738-1745.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Gilbert, James M.

AU - Balouchi, Farouk

PY - 2014/9/1

Y1 - 2014/9/1

N2 - Human footfall is an attractive source of energy for harvesting for low-power applications. However, the nature of footfall is poorly matched to electromagnetic generators. Footfall motion is characterised by high forces and low speeds, while electromagnetic generators are normally most efficient at relatively high speed. This article proposes a novel mechanism for converting the low-speed motion of footfall to a higher speed oscillating motion suitable for electromagnetic power generation. The conversion is achieved using a cantilever beam which is deflected by the footfall motion using a special 'striker' mechanism which then allows the cantilever to oscillate freely at a relatively high speed. An arrangement of permanent magnets attached to the cantilever causes an alternating magnetic field, and a stationary coil converts this to a usable voltage. This article describes the mechanism and provides a mathematical model of its behaviour which allows the system parameters to be optimised and its performance predicted. The performance of a prototype device is presented, and it is shown that this is capable of generating up to 60 mJ/step and that the conversion efficiency is up to 55%.

AB - Human footfall is an attractive source of energy for harvesting for low-power applications. However, the nature of footfall is poorly matched to electromagnetic generators. Footfall motion is characterised by high forces and low speeds, while electromagnetic generators are normally most efficient at relatively high speed. This article proposes a novel mechanism for converting the low-speed motion of footfall to a higher speed oscillating motion suitable for electromagnetic power generation. The conversion is achieved using a cantilever beam which is deflected by the footfall motion using a special 'striker' mechanism which then allows the cantilever to oscillate freely at a relatively high speed. An arrangement of permanent magnets attached to the cantilever causes an alternating magnetic field, and a stationary coil converts this to a usable voltage. This article describes the mechanism and provides a mathematical model of its behaviour which allows the system parameters to be optimised and its performance predicted. The performance of a prototype device is presented, and it is shown that this is capable of generating up to 60 mJ/step and that the conversion efficiency is up to 55%.

KW - Efficiency

KW - Energy conversion

KW - Energy harvesting

KW - Energy scavenging

KW - Footfall

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