**3. Installation and Demonstration**

To demonstrate the application of the developed system, the system was assembled as a floor tile with the dimension of 40 × 40 × 15 cm and installed by three sets of the floor tiles side-by-side without wiring at an exhibition hall of a 100-year-old engineering building at Chulalongkorn University, on the mechanical engineering project exhibition day. Figure 21 shows the photo of the system. Then the exhibitors were invited to walk on the floor tiles. Once they stepped on the floor tiles, the system generated power to store in the battery and lit up the array of LEDs, as seen in Figure 21. This demonstration made exhibitors relive the importance of green energy and energy harvesting in their daily lives. The benefit of the designed system can apply for a lot of applications, such as a wireless sensor and Internet of Thing applications.

**Figure 21.** Installation and demonstration.

#### **4. Conclusions**

The paper presented a design of an energy harvesting floor capable of converting mechanical energy from people's footsteps to electrical energy. The system, comprising the translation-to-rotation conversion mechanism, the EM generator, and the power management circuit system, generates electricity from people's footsteps. For the EM generator, the conversion mechanism for linear translation to rotation was designed by using the rack-pinion and lead-screw mechanism. Based on simulation analysis, the averaged energy of the lead-screw model is more than that of the rack-pinion model. Moreover, the design of lead-screw model elements was studied. The results show that the lead-screw model with 45◦ lead angles can generate more averaged energy than others, and the 12-V-DC generator can provide more energy than the 24-generator due to the resistance during the transience, and the softer spring can convert translation motion to higher rotational speed of the generator which can produce more power. Although the softer springs are theoretically desirable, they should be sufficiently hard enough to restore the system back to equilibrium due to the friction of the system. Then, Genpath prototype-II with 12-V-DC generator, lead-screw mechanism, and allowable displacement of 15 mm was built. It was significantly improved when compared to the prototype-I [16]. This Genpath prototype produces an average energy of up to 702 mJ (or average power of 520 mW). The energy provided by Genpath prototype-II is increased by approximately 184% when compared to that of the prototype-I [16]. The efficiency of the EM-generator system is 26% based on the power generation from the heel strike of a human's walk of 2 W per step. Next, the power management and storage circuit were developed to harvested energy into the batteries and to supply other parts to specific loads. The experiment showed that the circuit has the overall efficiency of 74.72%. The benefit of the designed system can apply for a lot of applications, such as a wireless sensor and Internet of Thing applications.

**Author Contributions:** Conceptualization, T.J., S.S., and G.P.; methodology, T.J., S.S., and G.P.; software, T.J., S.S., and G.P.; validation, P.K., P.C. and C.U.-v.); formal analysis, T.J.; investigation, P.K., P.C. and C.U.-v.; resources, T.J.; data curation, G.P.; writing—original draft preparation, T.J., S.S., and G.P.; writing—review and editing, T.J., S.S., and G.P.; visualization, T.J.; supervision, T.J.; project administration, G.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Ratchadaphiseksomphot Endowment Fund Chulalongkorn University, grant number CU\_GI\_63\_07\_21\_01.

**Acknowledgments:** We would like to thank W. Lowattanamart, V. Suttisung, and S. Sintragoonchai who initiated and supported the idea on the project and built up Genpath prototype-I.

**Conflicts of Interest:** The authors declare no conflict of interest. Also, the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
