Abstract
We will discuss an energy harvesting method to convert mechanical vibrations into electric energy from systems of vehicles (fig.1), motorboats, trains, wall and bridges, etc., by way of an electromagnetic induction. The research has evolved from the analysis of International Roughness Index (IRI) which is the profile of a big-data of longitudinal mechanical vibrations produced by rough road surfaces. The central proposition of energy harvesting tehcnology is to discover minute or often infinitesimal vibrations and current-flux of heat or particles to be convertible into a form of electric energy capable for practical applications. For example, the piezo-electric device is most commonly used for energy conversion from mechanical vibrations, heat or particle current-flux into electric energy.
We investigated mechanical vibrations for a system of coupled sprung and unsprung masses as a model for vehicles by employing asimplified model Lagrangian with power functions and external forces. The analysis is supposed to investigate profiles of longitudinal bumps and corrugations of road-surface to study International Roughness Index (IRI), which has been used for the analysis of safety and 19 measurement of roughness of road surface. The big-data of IRI is affected by internal oscillations and trembles of mechanical systems, heat and energy dissipations, external waves and impacts.
Hence, it is difficult to find specific vibrations to be converted into electric energy because of complicated three dimensional random vibrations. From theoretical analyses of model simulations of IRI, we discovered minute mechanical oscillations which can be converted into electric energy, and we have been investigating a practical way of converting mechanical-vibration energy by way of electromagnetic induction. Some of our theoretical results will be shown.
The research can be extended and applied to other mechanical and engineering fields. The energy harvesting technology is an actively progressing field of research. It is useful for the development of interconnected domains of fields, such as sustainability of natural environment, ecology, economics and social welfare.

Keywords: International roughness index (IRI), energy harvesting, mechanical vibrations, electromagnetic induction