Browsing by Author "Liyanage, M. H"

Now showing 1 - 17 of 17

Embargo
Comprehensive Analysis of Convolutional Neural Network Models for Non-Instructive Load Monitoring
(IEEE, 2020-10-20) Herath, G. M; Thilakanayake, T. D; Liyanage, M. H; Angammana, C. J
Non-Instructive Load Monitoring (NILM) schemes have become more popular in recent years with the availability of smart meters. It provides energy use data to utilities and per-appliance energy consumption details to end users. This study carries out a comprehensive analysis of existing Convolutional Neural Network (CNN) architectures that have been used for NILM. Nevertheless, it provides an unbiased comparison of the existing architectures thereby helping to select the best performing model for NILM applications. The commonly used CNN disaggregation models were categorized into distinctive groups based on their architectures which considered structure of the Neural Network (NN) and outputs. It considers regression-based sequence to sequence and sequence to point mapping, classification-based sequence to point hard association and soft association-based mapping. The CNN models are improved and modified to bring them onto a common platform for comparison. Thereafter, a rigorous comparison was performed using indices which included accuracy, precision, F-measure and recall. The results reveal interesting relationships between architectures, appliances and measures.
Embargo
Design and control of a high performance SCARA type robotic arm with rotary hydraulic actuators
(IEEE, 2009-05-03) Liyanage, M. H; Krouglicof, N; Gosine, R
This study proposes a selective compliant assembly robotic arm (SCARA) with two revolute joints for poultry deboning. The joints of the arm are based on two high performance rotary type hydraulic actuators. These actuators are operated by servo valves, which control hydraulic fluid flow and direction. A PID based independent joint control system is considered for controlling the position of each joint. The system was modelled using the MATLAB-SIMULINK toolbox. The simulation results show that the arm was capable of covering a work envelope of 0.9 m times 0.9 m, reaching controlled velocities of up to 7.5 m/s with an average of 5.8 m/s. Obtaining such high speeds and torques would be a difficult task with electrical actuators of the capacity as the hydraulic counterparts considered here.
Open Access
Development and testing of a high speed hydraulic manipulator with single time scale visual servoing
(Memorial University of Newfoundland, 2014) Liyanage, M. H
Automation of production processes has enabled to meet the dramatic demand for manufactured products that has grown out of the increase in world population. In existing industries greater production requirements and improvement in product quality call for faster industrial robots. This study details the design and development of a high-speed visual servoing system for industrial applications. The proposed visual servoing system consists of a high speed robotic manipulator, a high-speed camera system and an embedded controller. The proposed robotic manipulator has the configuration of a Selective Compliant Assembly Robotic Arm (SCARA). It uses two custom-designed double vane rotary hydraulic actuators for driving the links of the robot. The SCARA system was mathematically modeled and simulated. Based on the simulation results, the hydraulic actuators were sized for optimal performance. A prototype actuator was subsequently designed, manufactured and experimentally evaluated. The test results show that the proposed actuator is capable of reaching torques of up to 460 Nm in 30 ms with a payload of 12 kg. This is not possible with electric motors of similar size. Then the proposed SCARA was designed and fabricated using the proposed actuators. The end effector of this manipulator was capable of reaching velocities of up to 2.7 ms⁻¹ with a payload of 5.3 kg. Comparable performance is not feasible with contemporary SCARA type robots. The proposed robot was designed for handling payloads up to 15 kg with speeds of up to 2 ms⁻¹. This often results in flexing of the links and twisting of the support column, adding external disturbances to the system. A high-speed camera system was designed and built to obtain the position of the end effector as feedback for the controller. It uses a two dimensional Position Sensitive Detector as the image sensor. An electronic circuit was designed and built for signal conditioning and data acquisition from the Position Sensitive Detector. It was then calibrated to account for non-linearities on the image sensor. The camera was constructed using this Position Sensitive Detector circuit, a lens and an infra red filter.It was then calibrated to estimate the extrinsic and intrinsic parameters. This camera was capable of carrying out measurements at frequencies of up to 1350 Hz. The measurements made by this camera produced an average absolute accuracy of 0.31 mm and 0.37 mm in x and y directions, respectively. A Field Programmable Gate Array was used in this study as the platform for developing an embedded controller for the robot. Using contemporary Field Programmable Gate Array technology, a powerful virtual processor can be synthesized and integrated with custom hardware to create a dedicated controller that out performs some of the conventional microcontroller and microprocessor based designs. The Field Programmable Gate Array based controller takes advantage of both hardware features and virtual processor technology. The input, output interfaces for this controller were implemented using hardware. Complex functions that are difficult to be implemented in hardware were implemented using a virtual soft processor. Four different types of controllers were implemented and tested. These include hardware proportional-derivative, software proportional-derivative, single time scale visual servoing and set point modification type controllers. The proposed implementation carried out single time scale visual servoing at frequencies of up to 330 Hz.
Embargo
Development and testing of a novel high speed SCARA type manipulator for robotic applications
(IEEE, 2011-05-09) Liyanage, M. H; Krouglicof, N; Gosine, R
This paper proposes using servo hydraulics for high speed robotic manipulation. It details the development of a novel double vane rotary type actuator custom designed for use in a Selective Compliant Assembly Robotic Arm (SCARA). The system, which is mathematically modeled and simulated, consists of an electro-hydraulic servo valve, double vane rotary actuator, manipulator and a controller. Based on the simulation results, hydraulic actuators were sized for optimal performance. A prototype of the proposed manipulator was built and tested. The test results show that the proposed actuator is capable of reaching torques of up to 860 Nm. The end effector of the manipulator is capable of reaching average velocities in excess of 2.7 ms -1 with a payload capability of 5.3 kg. Comparable performance is not feasible with contemporary SCARA type robots with electric motors.
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Economic Viability of Solar PV for Domestic Applications in a Middle-Income Country: A case Study of Sri Lanka
(IEEE, 2020-10-20) Wijesinghe, J. K; Najim, M. Y. M; Fernando, G. L; Liyanage, M. H
This study focuses on the economics of using solar Photovoltaics for residential in a middle-income country like Sri Lanka. It considers solar irradiance in the Colombo district to estimate the power generation potential by a selected 2.16kWp solar PV system throughout the year. It used solar irradiance data by NASA Surface Meteorology and Solar Energy (SSE), satellite solar insolation values for Sri Lanka and used the Liu and Jordan (LJ) method. Furthermore, it considered the economics of four different scenarios as model houses depending on appliance usage with net accounting. It was seen that without net accounting the Levelized cost of electricity could be as high as US0.69/kWh.However,withmechanismslikenetaccounting,itcouldbereducedtoUS 0.12 /kWh with full owners' contribution. Under the net accounting scheme houses that consume above 300 kWh/month will have the lowest payback period of 2 years and 9 months.
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Effects of carbon tax on greenhouse gas mitigation in Thailand
(Taylor & Francis Group, 2008-01-01) Shrestha, R. M; Pradhan, S; Liyanage, M. H
This study analyses energy system development and the associated greenhouse gas emissions in Thailand under a reference case and three different carbon tax scenarios during 2013–2050 using a bottom-up cost-minimizing energy system model based on the Asia–Pacific Integrated Assessment Model (AIM/Enduse) framework. It considers the role of the renewable energy technologies as well as some emerging GHG-mitigating technologies, e.g. carbon capture and storage (CCS) in power generation, and GHG reduction in the country, and found that the power sector will play a major role in CO2 emission reduction. Under the carbon tax scenarios, most of the CO2 emission reduction (over 70%) will come from the power sector. The results also indicate the very significant potential for CO2 emission reduction through a significant change in the transport system of the country by shifting from low-occupancy personal modes of transport to electrified MRTS and railways.
Embargo
An Embedded System for a High-Speed Manipulator With Single Time Scale Visual Servoing
(American Society of Mechanical Engineers, 2017-07-01) Liyanage, M. H; Krouglicof, N
This study presents the development of an embedded system for controlling a high-speed robotic manipulator. Three different types of controllers including hardware proportional derivative (PD), software PD, and single time scale visual servoing are considered in this study. Novel field programmable gate array (FPGA) technology was used for implementing the embedded system for faster execution speeds and parallelism. It is comprised of dedicated hardware and software modules for obtaining sensor feedback and control signal (CT) estimation, providing the control signal to the servovalves. A NIOS II virtual soft processor system was configured in the FPGA for implementing functions that are computationally expensive and difficult to implement in hardware. Quadrature decoding, serial peripheral interface (SPI) input and output modules, and control signal estimation in some cases was carried out using the dedicated hardware modules. The experiments show that the proposed controller performed satisfactory control of the end effector position. It performed single time scale visual servoing with control signal updates at 330 Hz to control the end effector trajectory at speeds of up to 0.8 ms1 . The FPGA technology also provided a more compact single chip implementation of the controller.
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Energy and Environmental Implications of Green House Gas Mitigation Policies in the Transport Sector of Sri Lanka
(IEEE, 2018-10-24) Fernando, G. L; Liyanage, M. H; Samarasekara, G. N
This study analyzes the greenhouse gas mitigation policy options for the transport sector in Sri Lanka. It was carried out through the Asia-Pacific Integrated Assessment Model (AIM/Enduse), which is a bottom up type least cost optimization framework. A business as usual scenario and four alternative mitigation policy options were considered in this study. These policy options include two scenarios with 100 $/tonCO 2 , 500 $/tonCO 2 carbon tax, a subsidy scenario with tax rebates for electric, hybrid vehicles and a scenario which promotes pubic transport. The results show that the transport sector energy consumption is expected to increase from 5 Mtoe in 2015 to 19.5 Mtoe in 2045. The CO 2 emissions are expected to increase from 15 Mton in 2015 to 58 Mton in 2045. Out of the four scenarios, promoting public transport was most effective as it could reduce energy consumption by 52% and reduce CO 2 emissions by almost 36% in 2045. At current electricity prices and other costs, electric vehicles are not found to be economical in the analysis.
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Factors affecting CO2 emission from the power sector of selected countries in Asia and the Pacific
(Elsevier, 2009-06-01) Shrestha, R. M; Anandarajah, G; Liyanage, M. H
This study analyzes the key factors behind the CO2 emissions from the power sector in fifteen selected countries in Asia and the Pacific using the Log-Mean Divisia Index method of decomposition. The roles of changes in economic output, electricity intensity of the economy, fuel intensity of power generation and generation structure are examined in the evolution of CO2 emission from the power sector of the selected countries during 1980–2004. The study shows that the economic growth was the dominant factor behind the increase in CO2 emission in ten of the selected countries (i.e., Australia, China, India, Japan, Malaysia, Pakistan, South Korea, Singapore, Thailand and Vietnam, while the increasing electricity intensity of the economy was the main factor in three countries (Bangladesh, Indonesia and Philippines). Structural changes in power generation were found to be the main contributor to changes in the CO2 emission in the case of Sri Lanka and New Zealand.
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High speed electro-hydraulic actuator for a scara type robotic arm
(IEEE, 2010-10-18) Liyanage, M. H; Krouglicof, N; Gosine, R
This study details the development of a high performance servo-hydraulic actuator for a Selective Compliant Assembly Robotic Arm (SCARA). The arm is intended for high speed food processing applications; specifically on-line poultry deboning. The system is mathematically modeled and simulated. Based on the simulation results, the hydraulic actuators are sized for optimal performance. A prototype actuator is subsequently designed, manufactured and experimentally evaluated. The tests results demonstrate that the prototype actuator is capable of producing unprecedented torques and associated accelerations relative to its size and mass. Comparable performance is not feasible with contemporary electrical actuators of similar size.
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An Image Based Approach of Energy Signal Disaggregation Using Artificial Intelligence
(IEEE, 2021-12-09) Senarathna, M; Herath, M; Thilakanayake, H. D; Liyanage, M. H; Angammana, C. J
Non-Intrusive Load Monitoring (NILM) is the real-time monitoring of energy consumption data of individual appliances through the decomposition of composite energy signal captured at the household smart energy meter. Most of the existing NILM techniques utilize one-dimensional (1D) time-series signal analysis to predict the individual appliance energy signals. The utilization of image-based methods for the disaggregation of energy signals is a relatively new approach in the NILM domain. This paper presents a study of a novel computer vision-based Artificial Intelligence (AI) approach when compared to the traditional time series-based NILM methods. Gramian Angular Fields (GAF) and Recurrence Plots (RP) have been widely used in recent literature to encode time series signals as images. Novel image classification techniques with the use of Convolutional Neural Networks (CNN) simplify the extraction of nuclear load features from encoded two-dimensional (2D) images. The results considered the indices validation accuracy and validation loss in comparing the performance of different vision-based AI approaches. The results reveal that Gramian Angular Difference Field (GADF) outperforms both Gramian Angular Summation Field (GASF) and RP with a training accuracy of 97.9% and a validation accuracy of 94.2%. A comprehensive analysis and comparison are presented with an in-depth evaluation using multi-state appliances and it was concluded that GADF is the most suitable 1D to 2D conversion method for the representation of time series energy data for disaggregation purposes.
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Optimization of controller gains for FPGA-based multivariable motion controller using response surface methodology
(IEEE, 2015-05-03) Sekaran, H. P; Liyanage, M. H; Krouglicof, N
Field Programmable Gate Arrays (FPGA) have become increasingly popular in recent years for control applications. Using contemporary FPGA technology, a powerful virtual processor can be synthesized and integrated with custom hardware to create a dedicated controller that outperforms conventional microcontroller and microprocessor based designs. The FPGA based controller takes advantage of both hardware features and virtual processor technology. This study details the development of a cascaded type PD controller for an inverted pendulum system implemented on a single FPGA device. The controller includes a hardware based implementation of the IO modules including quadrature decoders/counters and a Pulse Width Modulation (PWM) controller for the motor driver. The NIOS II processor was synthesized to implement the cascaded PID controller algorithm. This study also proposes a novel method for obtaining the optimal controller gains for the system. It uses the Central Composite Design (CCD) in Response Surface Methodology (RSM) for obtaining these gains. A classic inverted pendulum system was selected to demonstrate the applicability of the proposed approach. The gains provided by the RSM were verified experimentally to validate the proposed controller tuning method.
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The Potential Role of Carbon Tax in Achieving the Paris Agreement Targets for a Developing Country: A Case Study of Sri Lanka
(IEEE, 2020-10-20) Fernando, G. L; Liyanage, M. H
This study assess the effect of carbon taxes on energy and emissions of the Sri Lankan energy sector during 2015-2050. Along with a Business As Usual (BAU) scenario, three alternative carbon price trajectories were considered. These scenarios have been proposed based on fifth Shared Socioeconomic Pathway (SSP5) to achieve the 2°C Paris target for Asia. The Carbon Price trajectories proposed by AIM/CGA, REMIND-MAgPIE and GCAM were considered. The energy-economic-environmental system was modelled using the AIM/Enduse model. It considered both energy supply and demand sectors. The results show that in the BAU scenario the GHG emissions are expected to increase from 19.8MtCO 2e in 2015to 106.2MtCO 2e in 2050. Out of three carbon tax scenarios the prices proposed by AIM/CGA has been the most efficient for reduction of GHG emissions as it could reduce final energy consumption by 26% and GHG emissions by 24% in 2050 as compared to BAU scenario.
Open Access
A QUADCOPTER WITH AUTOMATED TAKE-OFF AND LANDING ON MOBILE ROBOT PLATFORM
(SHEFFIELD HALLAM UNIVERSITY ENGINEERING PROGRAM, 2016-12) Sandaruwan, B. A. S; Mithun, S; Rathnayake, R. M. K. M; Liyanage, M. H
In this thesis, a controller is designed for an off the shelf quadcopter to give it the ability to autonomously takeoff, hover at a given altitude, follow and land on a mobile robot platform. This is a small part of a much bigger system which is a quadcopter and a mobile robot combined fully autonomous surveillance system. This system has the ability to navigate and complete a given task without any human interaction. Different types of sensor are used to determine the position of the quadcopter in 3D space. A PID controller is implemented to keep the quadcopter at a given altitude. Different types of sensors and technologies were used to achieve our target. A discrete PID controller will be used to hold the altitude of the quadcopter. Real-time image processing is used to determine the position of the quadcopter relative to the mobile robot platform. An ideal quadcopter simulation and a 3D simulation of the task is done to understand in detail how a quadcopter works and how to controller it the way we desire. Kalman filter is used to produce accurate and precious angular data of the quadcopter. The project is separated into several parts and divided among all the members of the group. The simulation of the complete system and the implementation of the takeoff, altitude holding and landing algorithms for the test system are done by me. Determining the position of the quadcopter using image processing and design and implementation of the Mobile robot platform is done by Rathnayake R.M.K.M. Implementation of Kalman filter to be used with Gyro and accelerometer sensors and the simulation of an ideal quadcopter model in Matlab is done by S. Mithun.
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Scenario-based analyses of energy system development and its environmental implications in Thailand
(Elsevier, 2007-06-01) Shrestha, R. M; Malla, S; Liyanage, M. H
Thailand is one of the fastest growing energy-intensive economies in Southeast Asia. To formulate sound energy policies in the country, it is important to understand the impact of energy use on the environment over the long-period. This study examines energy system development and its associated greenhouse gas and local air pollutant emissions under four scenarios in Thailand through the year 2050. The four scenarios involve different growth paths for economy, population, energy efficiency and penetration of renewable energy technologies. The paper assesses the changes in primary energy supply mix, sector-wise final energy demand, energy import dependency and CO2, SO2 and NOx emissions under four scenarios using end-use based Asia-Pacific Integrated Assessment Model (AIM/Enduse) of Thailand.
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A single time scale visual servoing system for a high speed SCARA type robotic arm
(IEEE, 2014-05-31) Liyanage, M. H; Krouglicof, N
A high speed image based visual servoing (VS) technique is developed in this study for a Selective Compliant Assembly Robotic Arm (SCARA) manipulator with rotary hydraulic actuators. This study has developed a 2D position measuring system which comprise a high speed camera with a position sensitive detector as the image sensor. The input output interface and the controller for the VS system was implemented using a field programmable gate array (FPGA) providing a single chip solution for the embedded system. This camera was capable of providing position measurements of the end effector (EE) with an accuracy of up to 0.95 mm at a frequency of 1340 Hz. The proposed control strategy produced a better tracking performance with an EE payload of 12 kg with speeds of up to 1.3 m/s.
Open Access
Sustainable Energy Options for Sri Lankan Transport sector
(National Energy Symposium 2019, 2019) Fernando, G. L; Ruzaik, M. A; Liyanage, M. H
Transport sector of Sri Lanka accounts for 29% of total energy consumption and almost half of greenhouse gas (GHG) emissions in Sri Lanka. This study is to investigate the possible sustainable energy options for the transport sector. Sri Lankan transport sector is modelled using the Asia Pacific Integrated/Endues (AIM Endues) model for the planning horizon from 2015 to 2045. This study analyses four countermeasures along with the business as usual (BAU) scenario. The first countermeasure scenario is promoting residential solar electricity for electric vehicles. Other three scenarios modelled with 20%, 30% and 40% subsidy for electric and hybrid vehicles. Out of the four scenarios, promoting residential solar electricity for electric vehicles is the most effective countermeasure as it could reduce the transport sector energy consumption by 16.4 Mtoe and CO2 emissions by 35% in 2045. At the current vehicle and electricity prices, providing 20% subsidy will not be effective as 30% and 40% subsidies in achieving significant reduction in energy consumption and CO2 mitigation Sri Lankan transport sector.