Faculty of Engineering

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Open 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.
Open 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.
Open 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.
Embargo
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.
Embargo
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.
Embargo
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.
Open 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.
Open Access
Domestic Energy Saver
(SLIIT, 2022-02-11) Kumarasinghe, R; Abhayasinghe, N
Most of the activities in the modern world are heavy power consumers. Therefore, wasting of power is identified as a critical factor which is badly impacted the environmental and economic growth. Using electrical appliances such as ceiling fans and bulbs in the commercial and domestic environment unnecessarily is identified as a main way of wasting power. As a solution, this paper proposes the designing and producing of a power saving device for ceiling fans and bulbs. Variables such as room temperature, light intensity and the number of people present in the location were considered as parameters to control ceiling fans and bulb automatically, so as to save power by changing the speed and turning off when not necessary. This device is consisting of six main units namely a main control unit using Arduino Nano microcontroller, bidirectional visitor counter unit using two Passive Infrared motion sensors, temperature and light intensity measuring unit using a LM35 temperature sensor and a light dependent resistor sensor, an output display unit using 1604 LCD display, ceiling fan controller unit using a fan regulator that was constructed using two RC circuits, a relay module and a bulb controller unit. Ceiling fan speed and the delay time to switch off the appliances is controlled using a fuzzy logic controller. Inputs of the fuzzy logic controller are temperature difference with the set temperature, rate of change of temperature difference within a five-minute interval, difference of the number of people inside the location with the set number of people and the rate of change of number of people within a five-minute interval. It was observed that, for the test cases, an average of 318Wh per day could be saved from a single bulb and a ceiling fan while avoiding unnecessary usage of appliances.
Embargo
An edge detection framework conjoining with IMU data for assisting indoor navigation of visually impaired persons
(Pergamon, 2017-01-01) Chan, K.Y; Engelke, U; Abhayasinghe, N
Smartphone applications based on object detection techniques have recently been proposed to assist visually impaired persons with navigating indoor environments. In the smartphone, digital cameras are installed to detect objects which are important for navigation. Prior to detect the interested objects from images, edges on the objects have to be identified. Object edges are difficult to be detected accurately as the image is contaminated by strong image blur which is caused by camera movement. Although deblurring algorithms can be used to filter blur noise, they are computationally expensive and not suitable for real-time implementation. Also edge detection algorithms are mostly developed for stationary images without serious blur. In this paper, a modified sigmoid function (MSF) framework based on inertial measurement unit (IMU) is proposed to mitigate these problems. The IMU estimates blur levels to adapt the MSF which is computationally simple. When the camera is moving, the topological structure of the MSF is estimated continuously in order to improve effectiveness of edge detections. The performance of the MSF framework is evaluated by detecting object edges on video sequences associated with IMU data. The MSF framework is benchmarked against existing edge detection techniques and results show that it can obtain comparably lower errors. It is further shown that the computation time is significantly decreased compared to using techniques that deploy deblurring algorithms, thus making our proposed technique a strong candidate for reliable real-time navigation.
Open 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.
Open Access
A gyroscope based accurate pedometer algorithm
(International Conference on Indoor Positioning and Indoor Navigation, 2013-10) Jayalath, S; Abhayasinghe, N; Murray, I
Accurate step counting is important in pedometer based indoor localization. Existing step detection techniques are not sufficiently accurate, especially at low walking speeds that are commonly observed when navigating unfamiliar environments. This is more critical when vision impaired indoor navigation is considered due to the fact that they have relatively low walking speeds. Almost all existing pedometer techniques use accelerometer data to identify steps, which is not very accurate at low walking speeds. This paper describes a gyroscope based pedometer algorithm implemented in a smartphone. The smartphone is placed in the pocket of the trouser, which is a usual carrying position of the mobile phone. The gyroscope sensor data is used for the identification of steps. The algorithm was designed to demand minimal computational resources so that it can be easily implemented in an embedded platform. Raw data from the sensor are filtered using a 6th order Butterworth filter for noise reduction. This is then sent though a zero crossing detector which identifies the steps. A minimum delay between two consecutive zero crossings was used to avoid fluctuations being counted and peak detection was used to validate steps. The algorithm has a calibration mode, in which the absolute minimum swing of data is learnt to set the threshold. This approach demonstrated accuracies above 96% even at slow walking speeds on flat land, above 95% when walking up/down hills and above 90% when going up/down stairs. This has supported the concept that the gyroscope can be used efficiently in step identification for indoor positioning and navigation systems.
Embargo
A gyroscopic data based pedometer algorithm
(IEEE, 2013-04-26) Jayalath, S; Abhayasinghe, N
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.
Embargo
A gyroscopic data based pedometer algorithm with adaptive orientation
(IEEE, 2018-06-12) de Silva, R; Perera, J; Abeysingha, C. P; Abhayasinghe, N
Orientation of an Inertial Measurement Unit (IMU) relative to earth is a critical factor to the step detection in gyroscopic data based pedometer algorithm. The orientation of the IMU will be often subjected to change while using the small scale electronic pedometers. Existing fixed axis gyroscopic data based pedometer algorithm may not be suitable to implement in the modern small scale embedded pedometer applications. In this paper we have developed an advanced version of the gyroscopic data based pedometer algorithm which can dynamically adjust for the changing orientation of the IMU. Step detection component of the proposed algorithm is based on the gyro readings and the orientation detection is based on accelerometer readings. The algorithm employs the gravity vector and linear acceleration vector of the pedestrian to identify the orientation of the IMU. The active gyroscopic data axis for the pedometer algorithm is chosen based on the orientation.
Embargo
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.
Embargo
Human gait phase recognition based on thigh movement computed using IMUs
(IEEE, 2014-04-21) Abhayasinghe, N; Murray, I
—Human gait analysis is a major topic in pedestrian navigation and geriatric care. Identifying gait phases is important in using human gait for pedestrian navigation and tracking. Most of existing gait phase identification techniques use multiple sensor modules attached to each section of the lower body. This paper discusses the feasibility of recognizing gait phases using a single inertial measurement unit (IMU) placed in a trouser pocket of the subject. The movement of the thigh is computed by fusing accelerometer and the gyroscopic data gathered from the of the IMU. Experimental results indicated that most of the major gait phases such as Initial Contact, Load Response, Mid Stance, Terminal Stance, Pre-Swing and Swing, can be identified by the movement of one thigh tracked by an IMU. It was also noted that the movement of the offside leg can also be estimated from the fused IMU data. This paper presents a method to recognize all major phases of human stride cycle during walking from movement of one thigh.
Embargo
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.
Open Access
Low Cost – Remote Passive Sensory Based Weather Prediction System with Internet of Things
(SLIIT, 2022-02-11) Tennekoon, S; Chandrasekara, S; Abhayasinghe, N
Climate effects many major daily aspects of the society, from the food sources and transport infrastructure to the choice of fashion and certain daily routines. Due to these reasons, the demand for means to accurately foresee climatic changes have increased. Weather forecasting, especially in Sri Lanka, has been hampered due to numerous reasons and this has resulted in erroneous predictions that has adversely affected many areas of development ranging from agriculture, irrigation, and the tourism industry to certain branches of engineering. Many researchers have analyzed and proposed solutions to these problems. However, the need for accurate predictions prevails due to the hardship of accurate data acquisition, processing, and transmission. To address these problems, in this paper, a system that adheres to the rules and regulations set forth by the World Meteorological Organization (WMO) to carry out well informed and reliably accurate weather predictions based on the data attained from a wireless passive remote sensory medium has been implemented. This task was carried out by means of feeding the relevant climatic parameter readings measured via multiple wireless passive remote sensory nodes placed within the proximity of a considered area to a selected computational model, which in turn was implemented to yield considerably accurate predictions compared to the weather prediction systems currently available in the market. The paper comprises of the implementation of the category, Low-Cost Automatic Weather Station (LC-AWS) specified by the WMO and Internet of Things (IoT), one of the latest technologies, for the transmission of attained data even in the absence of Wi-Fi. The research was further conducted to perform an analytical comparison between highly accurate weather stations and the implemented low-cost weather station when compromising accuracy due to low cost. The hardware and related software implementation yielded an acceptable success rate and was concluded successfully.
Open Access
LP Gas Leakage Alarm
(SAITM Research Symposium, 2013) Wickramasinghe, M. G. D; Abhayasinghe, N
One of the most common types of energy source used in domestic is propane in which liquefied gas contains. Though the safety issues are considered by the company, leakage of gas has become very common accident which can cause damage to human lives and property. This paper presents a low cost, power efficient centralized LP gal leakage alarm system. The system has two main devices: the gas detector and the centralized alarm unit. The gas detector that is located close to the gas usage point (gas cylinder) is a battery operated device that is designed to operate up to 6 months with two AA size alkaline batteries. There can be more than one detector in the systems, which can be separately identified in the system. The centralized alarm unit detects the alerts sent by the detectors and releases the alarm. It has an indication of which detector has released the alert. The alarm unit is ac mains powered and has a battery backup to cater power failures. The components of the device have been chosen considering the power consumption and the time intervals have been calculated concerning the current consumption of each component.
Open Access
A novel approach for indoor localization using human gait analysis with gyroscopic data
(2012 International Conference on Indoor Positioning and Indoor Navigation, 2012-11) Abhayasinghe, N; Murray, I
— Way finding is one of the main difficulties that vision impaired people face, especially in indoor environments. Although Global Positioning System (GPS) based navigation is possible outdoors, the accuracy of GPS is not sufficient for indoor navigation and way finding. Most of the existing indoor localization and path finding techniques depend on additional infrastructure deployed in the environment. This paper proposes a novel technique for indoor localization based on human gait using single-point sensors embedded in mobile devices. It involves inertial sensors and other sensors such as magnetometer, generally embedded into the mobile devices. Progress made from data collection indicates that there is a better correlation of gyroscopic data than acceleration data to the gait of the person. Data was collected in different environments with the involvement of multiple male and female volunteers with no vision impairment or motor disability. The two carrying positions considered in this experiment were in the hip-pocket (pocket of the trouser) and clipped into the belt (hip). Various positioning experiments determined that a possible optimal location for the data gathering device was in the subject’s hip-pocket as compared to placement on the belt (hip region) as the movement of the thigh can be tracked when the device is placed in this position. It was also observed that the gyroscopic data can be used to identify different activities, such as walking on flat land, climbing up and down stairs and walking on inclined planes. Although the amplitude of the signal is small at the beginning and the end of the travel, the gyroscopic signal clearly identifies the step events. It is concluded that gyroscopic data gives promising results in indoor localization using gait analysis when the device is placed in the hip-pocket.
Open Access
PORTABLE SENSOR ATTACHMENT
(SAITM Research Symposium, 2013) Chandrasiri, L. H. R. P; Abhayasinghe, N
The rapid development of technology is placing an enormous demand for smart phones and similar devices as we are requiring more and more from these mobile devices. One of the major products which are becoming increasingly popular is the mobile phone. There are many sensors that may be used in such applications and some of which are: the accelerometer, digital compass, gyroscope, temperature, camera, etc. These sensors help enable new applications such as guiding systems, social network, health, gaming, entertainment, education, transportation, and many more. This paper presents the design, development and implementation of a portable sensor attachment that includes several sensors. The device includes sensors such as accelerometer, gyroscope, light level, atmospheric pressure, temperature and compass that may be used for human gait analysis, indoor/outdoor localization and navigation. This device can be coupled with any Bluetooth enable host device and data will be transferred to the host for further processing.