This paper concerns the mechanism for harvesting energy from human body motion. The vibration signal from human body motion during walking and jogging was first measured using 3-axes vibration recorder placed at various places on the human body. The measured signal was then processed using Fourier series to investigate its frequency content. A mechanism was proposed to harvest the energy from the low frequency-low amplitude human motion. This mechanism consists of the combined nonlinear hardening and softening mechanism which was aimed at widening the bandwidth as well as amplifying the low human motion frequency. This was realized by using a translation-to-rotary mechanism which converts the translation motion of the human motion into the rotational motion. The nonlinearity in the system was realized by introducing a winding spring stiffness and the magnetic stiffness. Quasi-static and dynamic measurement were conducted to investigate the performance of the mechanism. The results show that, with the right degree of nonlinearity, the two modes can be combined together to produce a wide flat response. For the frequency amplification, the mechanism manages to increase the frequency by around 8 times in terms of rotational speed.
This paper presents some preliminary studies on the frequency-up conversion method for low frequency application energy vibration based harvesting device, mainly from human body motion, by employing the translation to rotary mechanism. Vibration signals from different parts of the human body were first measured when the human subject was walking at 5 km/h. The signals obtained from the measurement were then reconstructed using Fourier Transform and it was found that frequency content of human body motion was in the range of 1 Hz 25 Hz. A preliminary experiment was conducted to check on the ability of the mechanism to amplify the low excitation frequency. Although the experiment was not optimized, it is found that the device was able to amplify input frequency up to 3.6 times.
This study presents data measurements to identify the best navigation system in terms of its positioning accuracy. The data global positioning system measurements is done using a GPS South device measured in four locations which are one random point and three different places based on the Ground Control Points (GCP) in Universiti Kebangsaan Malaysia (UKM). The coordinates of these locations are already in the Cassini Soldner Selangor Coordinate system. The results and analysis of signal noise to ratio (SNR) and path loss is discussed to indicate the performance of positioning accuracy among the four existing Global Navigation Satellite System (GNSS). The Global Positioning System (GPS) signal is dominant in location A and China’s BeiDou Navigation Satellite System (BDS) signal is also dominant for other three locations. In general, the BDS signal had the highest number of signals detected in this experiment which is total of 57 signals in four locations. By evaluating the positioning accuracy can improve the environmental studies such as tracking, monitoring, surveying, and mapping of climate change.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.