Recently, embedded systems and wireless sensor nodes have been gaining importance. For operating these devices several vibration-based energy harvesters have been successfully developed and reported, such as piezoelectric, electromagnetic, and electrostatic energy harvesters (EEHs). This paper presents the state-of-the-art in the field of vibration-based EEHs. Mainly, two types of EEHs, electret-free and electret-based, are reported in the literature. The developed EEHs are mostly of the centimeter scale. These energy harvesters, with resonant frequencies ranging from 2 Hz to 1.7 kHz, when subjected to excitation on the order of 0.25 g to 14.2 g, generate power that ranges from 0.46 nW to 2.1 mW.

No abstract

The most cost-effective electrical energy is produced by photovoltaic (PV) systems, and with the smallest carbon footprint, making it a sustainable renewable energy. They provide an excellent alternative to the existing fossil fuel-based energy systems, while providing 4% of global electricity demand. PV system efficiency is significantly reduced by the intrinsic non-linear model, maximum power point (MPP), and partial shading (PS) effects. These two problems cause major power loss. To devise the maximum power point tracking (MPPT) control of the PV system, a novel group teaching optimization algorithm (GTOA) based controller is presented, which effectively deals with the PS and complex partial shading (CPS) conditions. Four case studies were employed that included fast-changing irradiance, PS, and CPS to test the robustness of the proposed MPPT technique. The performance of the GTOA was compared with the latest bio-inspired techniques, i.e., dragon fly optimization (DFO), cuckoo search (CS), particle swarm optimization (PSO), particle swarm optimization gravitational search (PSOGS), and conventional perturb and observe (P&O). The GTOA tracked global MPP with the highest 99.9% efficiency, while maintaining the magnitude of the oscillation <0.5 W at global maxima (GM). Moreover, 13–35% faster tracking times, and 54% settling times were achieved, compared to existing techniques. Statistical analysis was carried out to validate the robustness and effectiveness of the GTOA. Comprehensive analytical and statistical analysis solidified the superior performance of the proposed GTOA based MPPT technique.

No abstract

No abstract

No abstract

No abstract

Limb loss is a traumatic event as it has physical and psychological effects on an amputee. Recent advancements in mechatronics and biomedical engineering have resulted in development of dexterous myoelectric prostheses for rehabilitation of amputees. In addition, evolution in manufacturing and sensing technology presents ample room for improvement in mechanical design and control system of prostheses to enhance amputee experience while using prosthetic devices. The present study is focused on design of a novel and cost-effective externally powered two-degree-of freedom prosthesis for assisting amputees to switch from body-powered devices to externally powered prosthesis. The control system of the developed prosthesis is based on the muscles signals acquired through force myography (FMG) technique. For precise integration of force-sensitive resistor (FSR) inside the socket to measure muscle activity, a stand-alone housing for FSR was designed with the feature of mechanical adjustment to control sensitivity of FSR and auto-calibrate its threshold to meet the requirements of individual amputees. The housing was designed to handle the fabrication inconsistencies during socket shaping process and thus ensures that sensor is in-firm contact with the muscle to sense volumetric changes. The developed mechanical design and FMG based muscle acquisition technique was successfully tested on a transradial amputee and extensive experimentation was performed for characterization of the prosthesis. FMG signal for various gestures was successfully extracted from muscles of the amputee to control the prosthesis according to the developed control technique. The results suggested that integration of FSR in the socket has significantly reduced the effect of sweat and volumetric changes on the performance of the sensor. Due to its novel design, embedded features, and cost-effectiveness the developed prototype holds the promise to be successfully commercialized to assist transradial amputees in becoming active citizens for contributing towards socio-economic growth of their country.