Browsing by Author "Jayawardena, T. S. S"

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Open Access
6-REXOS: Upper limb exoskeleton robot with improved pHRI
(SAGE Publications, 2015-04-29) Gunasekara, M; Gopura, R; Jayawardena, T. S. S
Close interaction can be observed between an exoskeleton robot and its wearer. Therefore, appropriate physical human-robot interaction (pHRI) should be considered when designing an exoskeleton robot to provide safe and comfortable motion assistance. Different features have been used in recent studies to enhance the pHRI in upperlimb exoskeleton robots. However, less attention has been given to integrating kinematic redundancy into upper-limb exoskeleton robots to improve the pHRI. In this context, this paper proposes a six-degrees-of-freedom (DoF) upperlimb exoskeleton robot (6-REXOS) for the motion assistance of physically weak individuals. The 6-REXOS uses a kinematically different structure to that of the human lower arm, where the exoskeleton robot is worn. The 6-REXOS has four active DoFs to generate the motion of the human lower arm. Furthermore, two flexible bellow couplings are attached to the wrist and elbow joints to generate two passive DoFs. These couplings not only allow translational motion in wrist and elbow joints but also a redundancy in the robot. Furthermore, the compliance of the flexible coupling contributes to avoiding misalignments between human and robot joint axes. The redundancy in the 6- REXOS is verified based on manipulability index, mini‐ mum singular value, condition number and manipulability ellipsoids. The 6-REXOS and a four-DoF exoskeleton robot are compared to verify the manipulation advantage due to the redundancy. The four-DoF exoskeleton robot is designed by excluding the two passive DoFs of the 6- REXOS. In addition, a kinematic model is proposed for the human lower arm to validate the performance of the 6- REXOS. Kinematic analysis and simulations are carried out to validate the 6-REXOS and human-lower-arm model.
Open Access
Accurate control position of belt drives under acceleration and velocity constraints
(Institute of Control, Robotics and Systems, 2003) Jayawardena, T. S. S; Nakamura, M; Goto, S
Belt drives provide freedom to position the motor relative to the load and this phenomenon enables reduction of the robot arm inertia. It also facilitates quick response when employed in robotics. Unfortunately, the flexible dynamics deteriorates the positioning accuracy. Therefore, there exists a trade-off between the simplicity of the control strategy to reject time varying disturbance caused by flexibility of the belt and precision in performance. Resonance of the system further leads to vibrations and poor accuracy in positioning. In this paper, accurate positioning of a belt driven mechanism using a feed-forward compensator under maximum acceleration and velocity constraints is proposed. The proposed method plans the desired trajectory and modifies it to compensate delay dynamics and vibration. Being an offline method, the proposed method could be easily and effectively adopted to the existing systems without any modification of the hardware setup. The effectiveness of the proposed method was proven by experiments carried out with an actual belt driven system. The accuracy of the simulation study based on numerical methods was also verified with the analytical solutions derived.
Open Access
Analysis and control of noise in a textile factory
(IJSRP publishes, 2014-12) Jayawardena, T. S. S; Perera, M. Y. A; Wijesena, G. H. D
Increased noise level with the technological advancement becomes a serious problem in the textile industry and it has become a crucial occupational hazard to its workers. Maximum noise level of some textile machines is as high as 95dB and locating many machines inside a single room causes to increase the cumulative noise level by at least 5dB beyond maximum noise level of a machine. So the noise level inside a textile factory is well above the limits specified by NIOSH and it amounts to be hazardous. This article analyzes the quality of noise and its distribution inside the factory. A mathematical model is developed to predict the noise distribution pattern and the model is validated with the noise data gathered following the standard methods. Economically viable noise control panels are designed and carry out a pilot implementation in order to prove the effectiveness of the noise control method experimentally. Further, authors present the potential applications of the proposed design and evaluate its usefulness.
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Analysis of the Dimensional Change of Woven Fabrics from Loom State to Finished State
(IEEE, 2018-05-30) Kandemulla, K. A. S. M; Maduwantha, A. R. L; Fernando, E. A. S. K; Niles, S. N; Jayawardena, T. S. S
Dimensional change of a woven fabric is a challenge in woven fabric production. The phenomenon originates from the dimensional instability of the fabric. Shrinkage is a combined result of numerous factors such as relaxation, dyeing, finishing and the effect of machinery. The significance of this problem has been investigated by several researchers, who focused mainly on the geometry of the fabric during the weaving phase (loom stage) only. To investigate the dimensional changes that occur within a particular woven structure, a number of fabric samples were sent through various finishing processes such as, washing, dyeing & finishing, under the laboratory conditions. The changes were measured either in terms of dimensional change or EPI and PPI values. Using the experimental data and theoretical analysis, a mathematical model has been developed and validated. However initially the focus is laid on plain woven fabrics and it is expected to be further extended to the other woven structures as well.
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An automatic air inflated tubeless safety jacket for motorbike riders
(Emerald Publishing Limited, 2021-06-22) Bulathsinghala, R. L; Fernando, S; Jayawardena, T. S. S; Heenkenda, N; Jeyakumar, S; Packiyarasa, p; Gamage, H; Wijesena, D
Purpose – Motorcycle is one of the popular modes of transport in developing countries. However, the statistics related to accidents show that motorcycles are the most vulnerable vehicles. Research studies have revealed that half of all the possible types of motorcycle injuries could be reduced or prevented using effective protective clothing. Facts and figures emphasize that this is high time to develop a safety jacket for motorbike riders. This paper aims to develop an innovative, integrated automatic air-inflated tubeless jacket to prevent major injuries in fatal accidents. Design/methodology/approach – Two accelerometers integrated near the front axle, an angle sensor and the electronic control unit (ECU) were used to detect the collision or accident. The sensors were fixed on the bike and connected with the ECU via a bluetooth device that was always at the activated stage. The fused sensors were emulated with the ECU under laboratory conditions. The trigger signal generated by the crash discriminant algorithm triggered the chemical reaction to generate N2 gas and inflate the tubeless safety jacket. Findings – Under laboratory conditions, it was found that the signal generated by the ECU unit ejected approximately 15 litres of N2 gas in volume to fill the jacket within 100 milliseconds, which was less than the approximate estimated falling time of the rider 120 milliseconds. Originality/value – The existing developments of airbag systems in motorbikes are mounted on the motorbikes’ frame, following the airbag systems in automobiles. These developments cannot fully protect the rider due to differentiation in crash dynamics and respective positions of the rider at the point of impact. Though few safety jackets and airbag vests are developed, the airbag deployment is activated when rider and motorbike separated during a collision using a tether-triggering mechanism. The authors designed the jacket so that inflation is activated not only by crash sensors but also on the fusion of multiple sensors based on a crash discriminative algorithm. The airbag deployment mechanism is incorporated with the jacket and acts as a safety jacket during a collision
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An automatic air inflated tubeless safety jacket for motorbike riders
(Emerald Publishing Limited, 2021-06-22) Bulathsinghala, R. L; Fernando, S; Jayawardena, T. S. S; Heenkenda, N; Jeyakumar, S; Packiyarasa, P; Gamage, H; Wijesena, D
Purpose – Motorcycle is one of the popular modes of transport in developing countries. However, the statistics related to accidents show that motorcycles are the most vulnerable vehicles. Research studies have revealed that half of all the possible types of motorcycle injuries could be reduced or prevented using effective protective clothing. Facts and figures emphasize that this is high time to develop a safety jacket for motorbike riders. This paper aims to develop an innovative, integrated automatic air-inflated tubeless jacket to prevent major injuries in fatal accidents. Design/methodology/approach – Two accelerometers integrated near the front axle, an angle sensor and the electronic control unit (ECU) were used to detect the collision or accident. The sensors were fixed on the bike and connected with the ECU via a bluetooth device that was always at the activated stage. The fused sensors were emulated with the ECU under laboratory conditions. The trigger signal generated by the crash discriminant algorithm triggered the chemical reaction to generate N2 gas and inflate the tubeless safety jacket. Findings – Under laboratory conditions, it was found that the signal generated by the ECU unit ejected approximately 15 litres of N2 gas in volume to fill the jacket within 100 milliseconds, which was less than the approximate estimated falling time of the rider 120 milliseconds. Originality/value – The existing developments of airbag systems in motorbikes are mounted on the motorbikes’ frame, following the airbag systems in automobiles. These developments cannot fully protect the rider due to differentiation in crash dynamics and respective positions of the rider at the point of impact. Though few safety jackets and airbag vests are developed, the airbag deployment is activated when rider and motorbike separated during a collision using a tether-triggering mechanism. The authors designed the jacket so that inflation is activated not only by crash sensors but also on the fusion of multiple sensors based on a crash discriminative algorithm. The airbag deployment mechanism is incorporated with the jacket and acts as a safety jacket during a collision
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Control methodologies for upper limb exoskeleton robots
(IEEE, 2012-12-16) Gunasekara, J. M. P; Gopura, R. A. R. C; Jayawardena, T. S. S; Lalitharathne, S. W. H. M. T. D
An exoskeleton robot is kind of a man-machine system which mostly uses combination of human intelligence and machine power. These robotic systems are used for different applications such as rehabilitation, human power amplification, motion assistance, virtual reality etc. Successful operation of an exoskeleton robot depends on correct selection of design and control methodologies. This paper reviews control methodologies used in upper limb exoskeleton robots. In the review, the control methods used in the exoskeleton robots are classified into three categories: control system based on human biological signal, nonbiological signal and platform independent control system. Different types of control methods under each category are compared and reviewed.
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Design and Analysis of An Anthropomorphic Two-DoF Ankle-Foot Orthosis
(IEEE, 2019-04-19) Ranaweera, R. K. P. S; Abayasiri, R. A. M; Gopura, R. A. R. C; Jayawardena, T. S. S; Mann, G. K. I
This paper proposes a two-degrees of freedom passive-dynamic ankle-foot orthosis (AFO). In view of enhancing anatomical conformity, an anthropomorphic design is proposed to minimize mechanical interferences between ankle and orthosis. The biomimetic features such as passive stabilizers and dampeners in the proposed mechanism intrinsically support the ankle and foot to maintain stability and improve shock-absorbing ability. The mobility, ranges of motion, and manipulability measures for the proposed AFO have been investigated using mathematical modeling and simulation approaches. The analysis revealed the effectiveness of the proposed AFO in meeting the complex kinematics of ankle joint compared to the predecessors. Potentially, the proposed AFO can serve as a platform to carry out research and development on robotic orthoses for the lower extremity.
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Design and Analysis of An Anthropomorphic Two-DoF Ankle-Foot Orthosis
(IEEE, 2019-04-19) Ranaweera, R. K. P. S; Abayasiri, R. A. M; Gopura, R. A. R. C; Jayawardena, T. S. S; Mann, G. K. I
This paper proposes a two-degrees of freedom passive-dynamic ankle-foot orthosis (AFO). In view of enhancing anatomical conformity, an anthropomorphic design is proposed to minimize mechanical interferences between ankle and orthosis. The biomimetic features such as passive stabilizers and dampeners in the proposed mechanism intrinsically support the ankle and foot to maintain stability and improve shock-absorbing ability. The mobility, ranges of motion, and manipulability measures for the proposed AFO have been investigated using mathematical modeling and simulation approaches. The analysis revealed the effectiveness of the proposed AFO in meeting the complex kinematics of ankle joint compared to the predecessors. Potentially, the proposed AFO can serve as a platform to carry out research and development on robotic orthoses for the lower extremity.
Embargo
Design and fabrication of an automatic tension monitoring and regulation system for needle thread
(IEEE, 2019-07-03) Randima, L. M. L; Sandaranga, D. M. B. C; Jayawardena, T. S. S; Fernando, E. A. S. K
A matched needle and bobbin thread tensions is a major requirement of a seam and also to the quality of garment. This paper describes an attempt on the development of an automated needle thread tension regulating system for single needle lock stitch sewing machine. Historically, several experiments have been carried out to measure the thread tensions of both needle thread and bobbin thread of a lock stitch machine. However, no evident in favour of the development of a device to adjust the needle thread tension automatically. Despite a cyclic variation of the needle thread tension, a needle thread regulation system is developed to maintain an average needle tension during the cycle at a predetermined level. The developed system can be installed on an existing single needle lock stitch machine and capable of maintaining the required correct thread tension profile for sewing. The needle thread tension regulation system is a closed loop system and with a load cell as a sensing device and a geared DC motor adjusts the compression of the spring of the thread tensioner. A visual display of thread tension is indicated on a 16X4 LCD display and the required needle thread tension is set by 4x4 keypad. An Arduino board controls the electronic equipment in the system.
Embargo
Design and fabrication of an automatic tension monitoring and regulation system for needle thread
(IEEE, 2019-07-21) Randima, L. M. L; Sandaranga, D. M. B. C; Jayawardena, T. S. S; Fernando, E. A. S. K
A matched needle and bobbin thread tensions is a major requirement of a seam and also to the quality of garment. This paper describes an attempt on the development of an automated needle thread tension regulating system for single needle lock stitch sewing machine. Historically, several experiments have been carried out to measure the thread tensions of both needle thread and bobbin thread of a lock stitch machine. However, no evident in favour of the development of a device to adjust the needle thread tension automatically. Despite a cyclic variation of the needle thread tension, a needle thread regulation system is developed to maintain an average needle tension during the cycle at a predetermined level. The developed system can be installed on an existing single needle lock stitch machine and capable of maintaining the required correct thread tension profile for sewing. The needle thread tension regulation system is a closed loop system and with a load cell as a sensing device and a geared DC motor adjusts the compression of the spring of the thread tensioner. A visual display of thread tension is indicated on a 16X4 LCD display and the required needle thread tension is set by 4x4 keypad. An Arduino board controls the electronic equipment in the system.
Embargo
Designing of Tension Control Device to Minimize Tension Variation across Weaver's Beam
(Emerald Group Publishing Limited, 2015-08-01) Fernando, E. A. S. K; Jayawardena, T. S. S
The tension variations across the width of the weaver's beam cause uneven tension in the fabric formation zone. As a result of the tension variation, the woven fabric tends to have fabric defects, such as non-uniform fabric density and differential dye take–up at various places on the fabric. As the warp ends are continuously subjected to varying tensions, warp breakage frequently occurs. As a result, the quality of the fabric produced suffers and there is reduced loom efficiency. However, uniformity in the fabric density is crucial, especially for technical and smart textiles. In this paper, the authors have attempted to model the varyingtensions across different segments of a warp sheet under a set of assumptions and derived a linear model. Furthermore, a prototype of an automatic tension control device is instrumentedwith two different positions which are located one meter apart and allows the tension variations across the warp-sheet to be practically observed. The measured average tension shows that variations in the internal tension on different segments of the warp-sheet can be minimized or even completely eliminated over time. With the implementation of a related experiment, the authors have shown the effectiveness of this automatic tension controller and its strong implications for the industry.
Open Access
Development of A Passively Powered Knee Exoskeleton for Squat Lifting
(Atlantis Press, 2018-05-01) Ranaweera, R. K. P. S; Gopura, R. A. R. C; Jayawardena, T. S. S; Mann, G. K
This paper proposes a knee exoskeleton with passive-powering mechanism to provide power assistance to the knee joint during squat lifting of objects from the ground. It is designed to capture and store 20% of the biomechanical energy dissipated at the biological knee joint during decent phase and return the harnessed energy in the ascent phase in a squatting cycle. The effectiveness of the proposed system was verified by evaluating performance of key muscles of knee joint using surface electromyography (sEMG) signals. Statistical data from experiments revealed a reduction of peak root-mean-square averages of sEMG signals of knee extensor muscles by 30 - 40% during squatting.
Open Access
Development Of mathematical model to select best technological parameters In sizing
(2015-06) Fernando, E. A. S. K; Jayawardena, T. S. S
The sizing process does not add value to the grey fabric, but it is critical to the improvement of weaving efficiency especially for cotton and cotton blend fabrics. With the advent of technology, weaving speeds have been greatly ameliorated and the significance of correct size applications has been thoroughly explored. Since the correct size application is primarily characterized by the size percentage, the technological parameters for proper sizing were chosen through experimental trials and acquired prior knowledge. Thus, a scientific approach to determining the technological parameters is essential to the textile industry. To fulfill the aforementioned need, the authors have developed a mathematical relationship that relates technological parameters involved in size applications. The practical utility of the derived equations were also highlighted. Experimental trials, carried out with poly/cotton yarn on a single yarn sizing machine, confirm the validity of the model developed. Furthermore, empirical findings published in internationally renowned reference books on sizing were also in accordance with the analytical results established. The mathematical relationships developed can be exploited to calculate the optimum parameters of the sizing machine and to obtain the required quality of sized yarn.This approach does not require carrying out costly trials and therefore has positive industrial impacts.
Embargo
Dexterity measure of upper limb exoskeleton robot with improved redundancy
(IEEE, 2013-12-17) Gunasekara, M. P; Gopura, R. A. R. C; Jayawardena, T. S. S; Mann, G. K. I
Exoskeleton manipulators are used for different applications in robotic field. Human motion is highly complicated and flexible; therefore obtain human like motion from exoskeleton manipulator becomes a challenge to researches in this field. This paper presents an improvement of dexterity measure as a result of adding redundancy to upper limb exoskeleton manipulator. Proposed manipulator has four degree of freedom. This takes the effect of DOF at human elbow and wrist of the upper limb. Dexterity of the manipulator is measured using manipulability index and minimum singular value. All measures are based on Jacobian of the manipulator. This four DOF manipulator is then modified by adding two more degrees of freedom to make total of six. Therefore with respect to task defined in operational space; modified exoskeleton manipulator operates as redundant. Manipulability index and minimum singular value are again determined for six degree of freedom modified exoskeleton manipulator. The effect of redundancy in order to improve the manipulation in upper limb exoskeleton robot is investigated in this study.
Open Access
Evolution of 3D weaving and 3D woven fabric structures
(SpringerOpen, 2021-12) Perera, Y. S; Muwanwella, R. M. H. W; Fernando, P. R; Fernando, S. K; Jayawardena, T. S. S
3D fabric preforms are used as reinforcements in composite applications. 3D woven preforms have a huge demand in ballistic applications, aircraft industry, automobiles and structural reinforcements. A variety of 3D woven fabric reinforced composites and two dimensional woven fabric reinforced laminates can be found in the literature. However, the majority of the said products lack in delamination resistance and possess poor out-of-plane mechanical characteristics, due to the absence or insufficiency of through-thickness reinforcement. 3D fully interlaced preform weaving introduces a method of producing fully interlaced 3D woven fabric structures with through-thickness reinforcement, which enhances the delamination resistance as well as out-of-plane mechanical characteristics. 3D woven fabric preforms made from 3D fully interlaced preform weaving, using high-performance fiber yarns such as Dyneema, Carbon, Kevlar and Zylon, have exceptional mechanical properties with light-weight characteristics, which make them suitable candidates for high-end technical composite applications. In this work, a brief introduction is given to the history of weaving followed by an introduction to 3D woven fabrics. In the existing literature, an emphasis is given to the 3D fully interlaced preform weaving process, distinguishing it from other 3D woven fabric manufacturing methods. Subsequently, a comprehensive review is made on the existing literature on 3D fully interlaced preform weaving devices, such as primary and secondary mechanisms as well as modelling of 3D woven fabric structures produced by 3D fully interlaced preform weaving. Finally, the authors attempted to discuss the existing research gaps with potential directions for future research.
Open Access
KERNEL-BASED CLUSTERING APPROACH IN DEVELOPING APPAREL SIZE CHARTS
(CiteSeerX, 2015-01) Vithanage, C. P; Jayawardena, T. S. S; Thilakaratne, C. D; Niles, S. N
With the industry revolution, apparel products also become more sophisticated moving from the basic purpose of clothing to aesthetic appeal of the garment embracing the concepts garment fitting and fashion. Garment fitting is a key technical essential for comfortable wearing. In garment fitting, size refers to a set of specified values of body measurements, such that it will provide a means for garments perfectly fit to a person. With the advent of computer software and improved data mining techniques, researchers attempted new advances in formulation of size charts with a better fit. This article suggests a kernel-based clustering approach in developing an effective size chart for the pants of Sri Lankan females. A new kernel based approach “Global Kernel K- means clustering ” was successfully deployed to cluster lower body anthropometric data of Sri Lankan females within the age range of 20-40 years. Through the proposed Kernel- based clustering method can effectively handle highly non-linear data in input space which is a key property of lower body anthropometric data and make it linearly separable in feature space without reduction in dimensions and also mathematically justified. Through this method promising results could be obtained and further clustering method was internally validated with kernel based Dunn’s index. The level of fitness of the developed size chart was also evaluated with the aggregate loss of fit factor. The proposed method has strong
Embargo
Machine learning-based approach for modelling elastic modulus of woven fabrics
(IEEE, 2020-07-28) Kularatne, S.D.M.W; Ranawaka, R. A. H. S; Fernando, E. A. S. K; Niles, S. N; Jayawardena, T. S. S; Ranaweera, R. K. P. S
There has been a shift of focus from aesthetic properties to mechanical and functional properties of textiles with the recent developments in technical textiles and wearable technology. Therefore, understanding how various fabric parameters influence the mechanical properties of fabrics is paramount. In applications where compression and stretching of fabrics are important, the elastic modulus is a key fabric property that needed to be controlled precisely. Woven fabrics are capable of providing superior elastic properties, but how various fabric parameters affect elastic modulus is not well understood. In this study, two machine learning techniques were implemented to model the elastic modulus of woven fabrics and were compared with multivariable regressions. The two machine learning techniques used are Artificial Neural Network (ANN) and Random Forest Regression. As input variables; weave factor (numerical representation of weave structure), warp yarn count and pick density were used. Both ANN and Random Forest Regression were able to generate reasonably accurate results with Random Forest Regression been the better of the two methods. Using Random Forest Regression, feature importance of the input variables was obtained, and it proved that the weave structure has a notable impact on the elastic modulus of woven fabrics.
Embargo
Mathematical analysis of startup mark in elastic tape on a narrow fabric loom
(IEEE, 2015-04-07) Dayaratne, H. D. C. T; Premakumara, R; Perera, T; Prince, T; Fernando, E. A. S. K; Jayawardena, T. S. S
Start-up marks are considered as one of the major defect in woven fabric, it occurs when the loom is restarted after loom stoppage due to various reasons. This defect is more prominent in high speed weaving looms especially with elastic warp yarns and is caused to deteriorate the fabric quality. This research paper deals with the mathematical analysis of the startup mark generation in elastic tape on narrow fabric loom. Mathematical analysis was carried out for both continuous operation condition and under stopping condition of the narrow fabric loom. A system simulation was carried out using the model developed and compared with the experimental results to show the accuracy of the model.
Open Access
Mathematical modeling of weft yarn tension in pirn winding
(Asian Transactions on Engineering, 2013-07) Fernando, E. A. S. K; Jayawardena, T. S. S
Pirn winding is an operation of winding yarn from supply yarn package onto pirns which are used for shuttle weft insertion. Firm and coherent winding tension is required to maintain in the pirn winding process to withstand the high forces produced by the deceleration of the shuttle at the end of each pick and to avoid permanent strains in yarns which will appears as fabric defects in weaving. The package size and its diameter vary due to subsequent winding of pirns. Hence the balloon effect varies and caused to change the thread tension at the winding point of the pirn. The thread tension variation is considerably significant from the first pirn wound from a package to the last pirn wound from the same if no tension controlling mechanism is devised. Placing dead weights on the disc tension controller which adds a tension to take off tension may help to compensate the yarn tension variation to some extent to combat with this problem. However, this is a stepwise manual compensation technique which needs the correct timing of compensation to avoid significant tension variations in pirn windings. The author attempted to theoretically analyze the tension variation in the yarn path of the pirn winding machine and theoretically model the tension variation with and without deadweight placement on the tensioners. Author also verified the accuracy and the validity of the model developed through the experimental results obtained at different locations along the yarn path.