Faculty of Engineering, Mechanical Engineering

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Browsing Faculty of Engineering, Mechanical Engineering by Author "Amarasinghe YWR"

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    item: Thesis-Full-text
    Design and development of intelligent home automation system (IHAS) for enhanced energy performance
    (2019) Basnayake BADJCK; Attalage RA; Amarasinghe YWR; Jayasekara AGBP
    With the growing distresses on carbon emission and sustainable energy concepts, the whole world appreciates the movements towards sustainable energy consumption. Statistics point out that over 50% of total electricity generation is consumed by three sectors, namely residential, commercial and public services. Among them, the residential sector alone consumes over 25% of total energy consumption which can possibly be attributed to heating, ventilation, air-conditioning (HVAC) and lighting used for occupants’ comfort. However, over 65% of global electricity generation is based on fossil fuel and natural gases, residential electricity consumption is accountable for a substantial extent of global carbon emission, consequently the present climate calamity. Researchers across the globe have figured out that the theories on sustainable energy consumption should start with our own home. It is required to focus on reducing the energy consumption by home HVAC systems, lighting systems and other appliances while keeping residential comfort level untouched. Home automation systems have shown their success towards the goal amidst several drawbacks. This research, proposes an intelligent home automation system (IHAS) with a real-time sensor network. The system has the ability to perform user preference based automation on the premises based on user comfort, safety and energy efficiency. The proposed system consists of a wireless sensor network, intelligent controller and device control interface. The sensory system monitors the environment and the identified information transferred to the intelligent central controller, which makes the accurate decision on most efficient configurations for the home appliances. It includes HVAC system, lighting systems and multimedia systems thus optimizing power consumption and improving user comfort. Finally, the device control interface delivers the obtained control decisions to the appliances through the default control interface. The developed non-interactive user identification system will recognize individual users within the premises and track their activities to obtained individual user preferences related to the comfort and multimedia devices. Based on those preferences and real-time ambient conditions measured through climatic sensor systems, the central controller will decide the configurations for the home appliances. The entire work includes the design and fabrication of different hardware systems and firmware implementations based on 8-bit and 16-bit microcontrollers. The central controller was developed on a single board computer which is powered by 32 Bit ARM Cortex A11 CPU. Fuzzy inference systems were used to implement the intelligent control algorithms of different control application of the proposed system.
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    Development of conductive polymer based tactile sensors for wearable bio-medical devices
    (2021) Sampath WHP; Amarasinghe YWR; Dao DV; Mitani A
    Tactile sensors are devices which acquire data from the physical world through sense of touch. These acquired data may be related to either, surface roughness, texture, force, or any other tactile parameter. Even though, tactile sensor systems are identified as a feasible method to acquire force feedback in robotics and automation systems, due to the requirement of physical interaction between the sensor and application, development of tactile sensors does not come to the spotlight during the past decades. Rather, researchers were more focused on developing non-contact sensors for various sensing modalities when comparing with the tactile sensors. Currently, importance of tactile sensors has come to the spotlight, as development of robotics, automation and biomedical applications are limited due to lack of tactile feedback. Also, many application areas are identified, where tactile sensors can be incorporated such as robotics, industrial automation, biomedical imaging, biomedical robotics, etc. With the recent advancements of the medical industry, wearable devices are used to support in controlling long-term or repetitive diseases or a disease that comes with time (i.e. chronic diseases) such as heart related diseases, diabetes and asthma by providing information on vital signs. Those vital signs can be heart rate, blood pressure, temperature in the body, blood oxygen level, etc. Other than that wearable biomedical devices are capable of producing smart and intelligent patient monitoring required for several diseases that capable of providing real-time feedback and assist in clinical based decision making. Tactile sensors are useful in measuring and monitoring point based and an area based force/pressure values in biomedical industry. Under this research, a novel tactile sensor has been developed using a conductive polymer-based sensing element. The incorporated sensing element is manufactured by polymer compression moulding, where the compound is based on silicone rubber and has enhancements by silica and carbon black, with Silane-69 as the coupling agent. Characteristics of the sensing element have been observed using its sensitivity and range. For the force scaling purpose and point based force/pressure measuring, a novel 3D printed cylindrical arch spring structure was developed for this highly customizable tactile sensor by adopting commonly available ABSplus material in 3D printing technology. By considering critical dimensions of the structure, finite element analysis was carried out to achieve nearly optimized results. A special electrical routing arrangement was also designed to reduce the routing complexities. A microcontroller based signal conditioning circuit was introduced to the system for the purpose of acquiring data. The concept was further improved to use as a tactile sensor array and hence a 3-DoF tactile sensor with a 3D printed square type spring system was also developed in this research. Under this research, a flexible conductive polymer based sensor that consists of a flexible electrodes sewn on a garment using conductive yarns, also developed. The flexible tactile sensor has been incorporated into a knee brace and tested for its performances of monitoring forces generated at the patella of the knee. The developed sensor attached knee brace is capable of differentiating human activities and posses.
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    item: Thesis-Full-text
    Investigation on thermal behavior of NITINOL based actuating elements for biomedical applications
    (2020) Perera HSL; Amarasinghe YWR
    In modern material world, important consideration is given to the group of fascinating materials called shape memory materials (SMMs) which respond quickly to a definite change of heat, light and chemical. The shape memory materials that have been established to date are shape memory alloys (SMA), shape memory polymers (SMPs) and shape memory hybrids (SMH). SMA play a significant role in various applications such as sensors, actuators, clamping devices, etc. Nickel – titanium (NiTiNOL) alloys are heavily used in SMA due to their strain recovery, excellent thermal characteristics, reliability and commercial availability, in addition to being used in macro and micro electro mechanical systems based biomedical applications (BMA) due to high biocompatibility, resistance to corrosion and high fatigue limit. Previous researches have focused on developing integration between thermal stability and SMA microstructure. But they don't have enough thermal behavior data with different heat treatment temperatures. Although phase transformation temperatures and microstructure patterns with different heat treatment temperatures are unique characteristics of NiTiNOL. The aim of this study is to investigate NiTiNOL characteristics and thermal behavior of SMA based actuating elements for biomedical applications. The overall objective of this research study is to investigate the phase transformation temperatures for NiTiNOL alloy during different heat treatment temperatures and to propose the appropriate geometric shape of the actuating element in BMAs. Therefore, a number of experiments were done at the laboratory level to characterize the thermal related behavior of the NiTiNOL alloy. Differential scanning calorimetry test measurements are used in this study to analyze the dissimilarities in phase transformation temperatures and properties of NiTiNOL (Ni-54 and Ti-46, weight percentages) alloy due to the variation of heat treatment temperature ranging from 400 °C to 600 °C. Further, microstructure and Energy – dispersive X-ray are determined using Scanning Electron Microscopy. It is found that most critical phase transformations are taken place between heat treatment temperatures of 550 °C and 600 °C and extraordinary unique behavior of phase transformations are exhibited by the respective specimens subjected to these temperatures. Further it is found that thermal behavior of actuator elements is dominated by the changes incurred in the microstructure of the NiTiNOL alloy during heat treatment.