Browsing by Author "Gopura, R"

Now showing 1 - 9 of 9

item: Article-Abstract
6-REXOS: Upper limb exoskeleton robot with Improved pHRI
Gunasekara, M; Gopura, R; Jayawardana, TSS
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, minimum 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.
item: Article-Full-text
Adapting concept of human-human multimodal interaction in human-robot applications
(Faculty of Graduate Studies, 2022-12) Priyanayana, S; Jayasekara, B; Gopura, R
Human communication is multimodal in nature. In a normal environment, people use to interact with other humans and with the environment using more than one modality or medium of communication. They speak, use gestures and look at things to interact with nature and other humans. By listening to the different voice tones, looking at face gazes, and arm movements people understand communication cues. A discussion with two people will be in vocal communication, hand gestures, head gestures, and facial cues, etc. [1]. If textbook definition is considered synergistic use of these interaction methods is known as multimodal interaction [2]. For example, , a wheelchair user might instruct the smart wheelchair or the assistant to go forward, as shown in Fig. 1(a). However, with a hand gesture shown in the figure, he or she might want to go slowly. In the same way as of Fig. 1(b), a person might give someone a direction with a vocal command ‘that way’ and gesture the direction with his or her hand. In most Human-Robot Interaction (HRI) developments, there is an assumption that human interactions are unimodal. This forces the researchers to ignore the information other modalities carry with them. Therefore, it would provide an additional dimension for interpretation of human robot interactions. This article provides a concise description of how to adapt the concept of multimodal interaction in human-robot applications.
item: Thesis-Full-text
Development of a prosthetic hand for power grasping applications
Herath, HMCM; Gopura, R; Lalitharathne, T
The human hand is an is an exceptionally significant part of the human body with a very complex biological system having bones, joints, and muscles, to provide many degrees of freedom. Among all the grasp patterns of hand, power grasping plays a crucial role in daily activities of a human. During the past few years, there was a rapid development in prosthetic limb technology to be used for the upper limb amputees. In this research, a prosthetic terminal device has been developed to assist the power grasping activities of daily living ofupper limb amputees. The designed terminal device includes four fingers, which generates eight degrees of freedom. In order to generate finger movements, a novel linkage mechanism has been proposed. Notably, the proposed mechanism can be characterized as a combination ofparallel and series links. The mobility of the system has been analyzed according to ChebychevGriibler-Kutzbach criterion for a planar mechanism. By considering the easy fabrication, the linkage finger mechanism was redesigned based on the design for manufacturing guidelines. With the intention of verifying the effectiveness of the mechanism, kinematics analysis has been carried out by means ofthe geometric representation and Denavit-Hartenberg parameter approaches. Subsequently, a Matlab program has been developed, in order to proceed with the numerical study. Furthermore, the motion simulation and static structural analysis proved that the mechanism is capable of generating the required finger movements for power grasping. Furthermore, trajectories and the configuration space of the proposed finger mechanism has been determined by using the motion simulations inbuilt with Solidworks software package. The movements of the finger mechanism, which is fabricated by 3D printing was experimentally tested. Experimental results proved the effectiveness of the proposed mechanism to accomplish the expected motion generation. In addition, the finite e
item: Article-Full-text
The Dexios hand: towards affordable and functional prosthetics
(Faculty of Graduate Studies, 2024) Bandara, H; Amarasinghe, D; Hettiarachchi, N; De Silva, M; Ranaweera, P; Gopura, R
Individuals who have experienced upper-limb loss often face significant challenges in regaining functional independence. The absence of a fully functional limb impairs their ability to perform daily tasks, diminishing both their physical capability and overall quality of life. According to global estimates, approximately 20 million people live with upper-limb loss related to traumatic events [1]. Functional prosthetic devices currently available in the market are prohibitively ex-pensive, and lack utility outside of basic grasping actions. This presents a considerable demand for affordable prosthetic solutions that are capable of restoring lost hand function. With this in mind, a research group from the Department of Mechanical Engineering at University of Moratuwa have developed an upper-limb prosthetic device capable of adaptive grasping, employing a novel mechanism to improve dexterity. The device thus developed, named the Dexios Hand, is a prototype electric hand prosthesis with motorised actuation, which is a more user-friendly alternative to body-powered and cosmetic prostheses. The key characteristics of this functional prosthetic hand are its dexterity and shape-adaptive grasping ability. Dexterity refers to the prosthetic hand’s ability to perform skilful movements, while shape-adaptive grasping allows the prosthetic hand to conform to the contours of various objects for a more secure grip. These features are favoured for restoring natural hand functionality in prosthetics since they widen the range of grasps that the device is capable of.
item: Article-Full-text
Have difficulty standing up? soft exosuitsare here to help!
(2021-12) Kulasekera, A; Arumathanthri, R; Chathuranga, D; Gopura, R; Lalitharathne, T
Soft robotics is a novel disruptive technology that is revolutionizing the fields of robotics. Innovative use of compliant materials by researchers has elevated soft robotics over contemporary technologies. The Computational Sensing and Smart Machines (CSSM) laboratory of the Department of Mechanical Engineering, University of Moratuwa, has been taking strides in the development of soft robotics, ranging from actuators, sensors, and applications.
item: Article-Full-text
Passively-powered knee exoskeleton to reduce human effort during manual lifting
(Faculty of Graduate Studies, 2024) Ranaweera, P; Gopura, R; Jayawardena, S; Mann, G
The proposed device consists of a system of helical elastic springs bilaterally located on the shank for capturing/storing waste biomechanical energy at the knee, a cable and pulley system to transmit power from and to the knee, a pulley locking/unlocking mechanism to achieve passive control of the device operation ensures no restrictions are posed by the springs during walking and applies a pre-tension on springs to prevent slacking of the Bowden cable using a return spring. However, when the wearer performs a squatting task, the springs engage/disengage energy springs when the knee flexes over a preset angle (i.e., 60 degrees). The energy dissipated and generated at the knee joint during decent and ascent phases from biomechanical studies were recorded as 45 J and 50 J respectively for an average human [3]. Accordingly, the selected energy springs can collectively capture and return approximately 20% of biomechanical energy at the knee.
item: Article-Full-text
Rehabilitation robot for carpal tunnel syndrome patients
(University of Moratuwa, 2023) Weerasoory, K; Nipun, W; Kumasaru, U; De Silva, M; Ranaweera, P; Gopura, R
Carpal Tunnel Syndrome (CTS) represents a prevalent neurological condition frequently encountered among individuals engaged in repetitive hand movements, particularly those involving the wrist and fingers. Preg- nant women, people employed in the tea and cinnamon industries, in the hospitality sector where chefs en- gage in repetitive cutting tasks, musicians who play and practice musical instruments for extended periods, and employees in the IT sector where repetitive finger movements are used, are all prone to be diagnosed with this ailment.
item: Article-Full-text
Soft robotics to ensure safe food handling
(2023-08) Lihini, C; Kulasekara, A; Chathuranga, D; Gopura, R
Soft robotics is a subfield of robotics that concerns the design, control, and fabrication of robots composed of compliant materials, instead of rigid links [1]. Using softer materials similar to those found in living organisms, researchers have developed a variety of actuators that are lightweight, fast acting, and compliant. Soft actuators are trending due to their increased flexibility and adaptability for different tasks like manipulating and grasping fragile objects, agricultural products, and food items. Harvesting, sorting, and packaging fragile food items like delicate fruits and vegetables have been predominantly done using human labour. Such exhausting and repetitive work leads to increased food wastage due to rough handling and human errors. The use of soft robotics for food handling could reduce damage during processing stages. This could enhance production efficiency and leads to improved food security in the future.
item: Article-Full-text
Will the new circular external fixator ease the surgeon’s burden?
(2022-09) Widanage, K; De Silva, M; Ranaweera, P; Lalithrathne, T; Dharmaratne, P; Bull, A; Gopura, R
Sri Lanka, like many other low-middle income countries, has been a victim of conflict for a long time. While the country is still recovering from the internal conflict that plagued it for over three decades, the shadows of these dark days still haunt these lands. The Sri Lankan soil is still not completely rid of antipersonnel landmines which were once weaponized against military and civilians alike. A more recent terrorist attack that happened in 2019 rekindled this age-old fear against explosions in the hearts of Sri Lankans. While prevention of such disasters is important, realistically, it is the duty of engineering researchers to equip medical professionals with devices that can aid and expedite the treatments if and when such unfortunate disasters occur.