Research Papers - Department of Electrical and Electronic Engineering

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Author: search.filters.author.Murray, IStart date: 2000

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Now showing 1 - 10 of 14
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    PublicationOpen Access
    A Context-Aware Doorway Alignment and Depth Estimation Algorithm for Assistive Wheelchairs
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025-07-17) Tennekoon, S; Wedasingha, N; Welhenge, A; Abhayasinghe, N; Murray, I
    Navigating through doorways remains a daily challenge for wheelchair users, often leading to frustration, collisions, or dependence on assistance. These challenges highlight a pressing need for intelligent doorway detection algorithm for assistive wheelchairs that go beyond traditional object detection. This study presents the algorithmic development of a lightweight, vision-based doorway detection and alignment module with contextual awareness. It integrates channel and spatial attention, semantic feature fusion, unsupervised depth estimation, and doorway alignment that offers real-time navigational guidance to the wheelchairs control system. The model achieved a mean average precision of 95.8% and a F1 score of 93%, while maintaining low computational demands suitable for future deployment on embedded systems. By eliminating the need for depth sensors and enabling contextual awareness, this study offers a robust solution to improve indoor mobility and deliver actionable feedback to support safe and independent doorway traversal for wheelchair users.
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    PublicationEmbargo
    Human Gait Modeling, Prediction and Classification for Level Walking Using Harmonic Models Derived from a Single Thigh-Mounted IMU
    (MDPI, 2022-03) Abhayasinghe, N; Murray, I
    The majority of human gait modeling is based on hip, foot or thigh acceleration. The regeneration accuracy of these modeling approaches is not very high. This paper presents a harmonic approach to modeling human gait during level walking based on gyroscopic signals for a single thighmounted Inertial Measurement Unit (IMU) and the flexion–extension derived from a single thighmounted IMU. The thigh angle can be modeled with five significant harmonics, with a regeneration accuracy of over 0.999 correlation and less than 0.5◦ RMSE per stride cycle. Comparable regeneration accuracies can be achieved with nine significant harmonics for the gyro signal. The fundamental frequency of the harmonic model can be estimated using the stride time, with an error level of 0.0479% (±0.0029%). Six commonly observed stride patterns, and harmonic models of thigh angle and gyro signal for those stride patterns, are presented in this paper. These harmonic models can be used to predict or classify the strides of walking trials, and the results are presented herein. Harmonic models may also be used for activity recognition. It has shown that human gait in level walking can be modeled with a harmonic model of thigh angle or gyro signal, using a single thigh-mounted IMU, to higher accuracies than existing techniques.
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    PublicationOpen Access
    Efficient, Authentication and Access control Implementation in Mobile Ad hoc Networks (MANET) as applied to Indoor Navigation Guidance System for Vision Impaired People
    (2012 International Conference on Indoor Positioning and Indoor Navigation, 2012-11) Rupasinghe, P. L; Abhayasinghe, N; Murray, I
    Indoor navigation systems are becoming increasingly popular. Blind and Low Vision users are prominently in need of indoor positioning and navigating systems as indoor navigation is a significant issue. Most of the efforts in creating such systems are using MANET (Mobile Ad-hoc Networks) as the base technology. However the properties of MANET’s inherently provide greater challenges in areas like security, reliability and performance. Most of research work was done on those different challenges in isolation. A holistic approach to address all these challenges in an implementation appears to be rare. Ad-hoc collaboration is usually an unplanned interaction or created "immediately on the fly". In MANET networks Authentication and access-control trust relations established through, on-line- available evidence, may be short-term and largely peer-to-peer, where the peers may not necessarily have a relevant network that can be placed into a recognizable trust hierarchy. Trust relations involving a captured node need to be invalidated, and new trust evidence need to be collected and evaluated to maintain node connectivity in the ad-hoc network This paper present the framework on Trust Relations based on friendships mechanism which is adopted from the theory of small-world phenomenon (i.e. six degrees of separation) initiated by Milgram, to provide rapid authentication. Continuity Efficient, Rapid Authentication is needed in practical implementations of an Indoor navigation system. Particularly when Low vision users are dependent on such system, a rogue node can be hazardous. Further research delivers a framework which combines reliability and performance, two important factors in practical implementation of an indoor navigation system.
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    PublicationEmbargo
    Inertial data based deblurring for vision impaired navigation
    (IEEE, 2014-10-27) Rajakaruna, N; Rathnayake, C; Abhayasinghe, N; Murray, I
    Image stabilization is very important in vision based indoor/outdoor navigation systems. Blurring is one main cause of poor image quality, which can be caused by a movement of the camera at the time of taking the image, a movement of objects in front, atmospheric turbulence or out-of-focus. Out of these factors, camera movement is dominant in navigation systems as the camera is continuously moving. This paper presents the preliminary results of deblurring performed using point spread function (PSF) computed using synchronized inertial sensor data. It uses data of the accelerometer and gyroscope to derive a motion vector calculated from the motion of the smartphone during the image capturing period. This motion vector is applied to the captured image so that the effect of motion is reversed during the debrurring process. This work is a part of an indoor navigation project that aims to assist people with vision impairment. Image processing form a significant part of the proposed system and as such clearly defined edges are essential for path and obstruction identification. Different deblurring methods are compared for their performance in reversing the effect of camera movement. Results indicated that deblurring can be successfully performed using the motion vector and that the resulting images can be used as a readily approach to object and path identification in vision based navigation systems, especially for blind and vision impaired indoor/outdoor navigation. The paper also proposes a novel deblurring algorithm that uses PSF computed for different portions of the image to deblur that portion of the image.
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    PublicationOpen Access
    Accurate Pedometer for Smartphones
    (2013) Jayalath, S; Abhayasinghe, N; Murray, I
    Accuracy of step counting is one of the main problems that exist in current Pedometers, especially when walking slowly on flat lands and performing different activities, such as climbing up and down stairs and walking on inclined planes. Although accelerometer based pedometers provide a reasonable accuracy when walking at higher speeds, the accuracy of them are not sufficient at slow walking speeds and performing different activities. This paper proposes a novel algorithm to detect steps using single-point gyroscopic sensors embedded in mobile devices. Preliminary analysis of data collected in different environments with the involvement of male and female volunteers indicated that gyroscope alone provides sufficient information necessary for accurate step detection. Algorithm was developed based on the gyroscopic data in conjunction with zero crossing and threshold detection techniques. The results proved that gyroscope based step detection algorithm provide a high accuracy when performing different activities and at slow paced walking.
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    PublicationEmbargo
    The application of “Off-the-shelf” components for building IMUs for navigation research
    (IEEE, 2014-10-27) Abhayasinghe, N; Murray, I
    Inertial measurement units (IMU) are commonly used in pedestrian and robotic navigation applications and research. Although many IMUs are commercially available, almost all of them are non-customizable and they process the collected raw data before presenting them to the user. However, this creates a limitation for researchers due to the fact that they have to rely on a set of per-processed data. Further, available resources and features such as SD card slots, wireless connectivity, available in the IMU may not suit one's research. This paper provides a survey on availability and usage of different off-the-shelf devices to build a custom made IMU. The authors considered open-source microcontroller platforms, low cost MEMS sensors and low cost accessories in this survey so that the IMUs will be affordable to many people. A range of sensors, their features, available processor options and different types of wired and wireless communication options available are discussed. Particular emphasis is made on the ability to modify or add functionality to commonly available hardware. Possible technical issues in assembling the IMU and calibrating sensors are also discussed in this paper. Technologies available for constructing a housing and mounting systems for the IMU best suited to the application are also discussed in this paper. As an example, IMUs developed and implemented by the authors with different housing designs specifically created for particular applications are presented. This survey indicated that off-the-shelf components can effectively be used to build custom-made IMUs to suit the particular research interest or application best.
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    PublicationEmbargo
    Alignment parameter calibration for IMU using the Taguchi method for image deblurring
    (Elsevier, 2015-04-01) Chan, K.Y; Rajakaruna, N; Engelke, U; Murray, I; Abhayasinghe, N
    Inertial measurement units (IMUs) utilized in smartphones can be used to detect camera motion during exposure, in order to improve image quality degraded with blur through long hand-held exposure. Based on the captured camera motion, blur in images can be removed when an appropriate deblurring filter is used. However, two research issues have not been addressed: (a) the calibration of alignment parameters for the IMU has not been addressed. When inappropriate alignment parameters are used for the IMU, the camera motion would not be captured accurately and the deblurring effectiveness can be downgraded. (b) Also selection of an appropriate deblurring filter correlated with the image quality has still not been addressed. Without the use of an appropriate deblurring filter, the image quality could not be optimal. This paper proposes a systematic method, namely the Taguchi method, which is a robust and systematic approach for designing reliable and high-precision devices, in order to perform the alignment parameter calibration for the IMU and filter selection. The Taguchi method conducts a small number of systematic experiments based on orthogonal arrays. It studies the impact of the alignment parameters and appropriate deblurring filter, which attempts to perform an effective deblurring. Several widely adopted image quality metrics are used to evaluate the deblurred images generated by the proposed Taguchi method. Experimental results show that the quality of deblurred images achieved by the proposed Taguchi method is better than those obtained by deblurring methods which are not involved with the alignment parameter calibration and filter selection. Also, much less computational effort is required by the Taguchi method when comparing with the commonly used optimization methods for determining alignment parameters and deblurring filter.
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    PublicationOpen Access
    Bluetooth embedded inertial measurement unit for real-time data collection for gait analysis
    (2013 International Conference on Indoor Positioning and Indoor Navigation, 2013-10) Chandrasiri, R; Abhayasinghe, N; Murray, I
    —Inertial Measurement Units (IMUs) are often used to measure motion parameters of human body in indoor/outdoor localization applications. Most of commercially available low-cost IMUs have limited number of sensors and are often connected to a computer by a wired connection (usually by USB). The disadvantage of using wired IMUs in human gait measurement is that, the wires disturb the natural gait patterns. The existing IMUs with wireless connectivity solve that problem, but are relatively high cost. This paper describes the development and testing of a miniature IMU that can be connected to a Windows based computer or an Android based mobile device through Bluetooth. The IMU consists of a 3-axis accelerometer, 3-axis gyroscope, 3-axis magnetometer, a temperature sensor, a pressure sensor and an ambient light sensor. Sensors are sampled at a frequency configurable by the user with a maximum set at 100 Hz. Raw sensor data are streamed through the integrated Bluetooth module to the host device for further processing. The IMU is also equipped with a microSD card slot that enables on-board data logging. The power usage of the Bluetooth transmitter is optimized because only the sampled sensor data are transmitted. The windows application can be used to view sensor data, plot them and to store them into a file for further processing. Android application can be used to view data as well as to record data into a file. The small size of the device enables it be attached to any part of lower or upper human body for the purpose of gait analysis. Comparison of the performance of the device with a smartphone indicated that the output of the IMU is comparable to the output of smartphone.
  • Thumbnail Image
    PublicationEmbargo
    The application of “Off-the-shelf” components for building IMUs for navigation research
    (IEEE, 2014-10-27) Abhayasinghe, N; Murray, I
    Inertial measurement units (IMU) are commonly used in pedestrian and robotic navigation applications and research. Although many IMUs are commercially available, almost all of them are non-customizable and they process the collected raw data before presenting them to the user. However, this creates a limitation for researchers due to the fact that they have to rely on a set of per-processed data. Further, available resources and features such as SD card slots, wireless connectivity, available in the IMU may not suit one's research. This paper provides a survey on availability and usage of different off-the-shelf devices to build a custom made IMU. The authors considered open-source microcontroller platforms, low cost MEMS sensors and low cost accessories in this survey so that the IMUs will be affordable to many people. A range of sensors, their features, available processor options and different types of wired and wireless communication options available are discussed. Particular emphasis is made on the ability to modify or add functionality to commonly available hardware. Possible technical issues in assembling the IMU and calibrating sensors are also discussed in this paper. Technologies available for constructing a housing and mounting systems for the IMU best suited to the application are also discussed in this paper. As an example, IMUs developed and implemented by the authors with different housing designs specifically created for particular applications are presented. This survey indicated that off-the-shelf components can effectively be used to build custom-made IMUs to suit the particular research interest or application best.
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    PublicationOpen Access
    Accessbim model for environmental characteristics for vision impaired indoor navigation and way finding
    (2012 International Conference on Indoor Positioning and Indoor Navigation, 2012-11) Jayakody, J. A. D. C. A; Abhayasinghe, N; Murray, I
    Most blind people require assistance to navigate within buildings as there is often insufficient information about the buildings available to them. To address this problem, this paper describes the “AccessBIM” model as an approach to facility management in which a digital representation of the indoor building features is used to facilitate the exchange and interoperability of real-time information in digital format which can assist blind people to independently access unfamiliar building indoor environments. This paper discusses conceptual communication model driven architecture that can be implemented for way finding and data synchronization, generating, in real-time, an AccessBIM for a remote user.