Browsing by Author "Ruwanthika, RMM"

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item: Conference-Abstract
3D Environmental force : position impedance variation for different motion parameters
Ruwanthika, RMM; Harsha, AM; Abeykoon, S
The skill preservation of an expert has been a serious problem for countries with aging population because decrease of the number of successors. The concepts of haptic database and force sensor recorder which have been developed recently suggests solutions of using third multimedia type of haptic communication. Haptic information is a bilateral information of the law of action and reaction. The reaction from real world includes not only position and force information but also environmental impedance. In this paper, the behavior of environmental impedance has been studied with the changes of the different motion parameters like applied force, velocity, position and depth on the object 3D space. This idea is exemplified using a rubber balloon and a rubber sponge which is often modeled using simple linear equations. The experimental results show the importance of considering motion parameters when abstracting haptic information for a haptic database. Nonlinear impedance variations against the motion parameters suggest the necessity of adopting complex haptic abstraction techniques.
item: Conference-Full-text
3D Environmental Force:Position Impedance Variation for Different Motion Parameters
(2015-08-03) Ruwanthika, RMM; Harsha, AM; Abeykoon, AMHS
The skill preservation of an expert has been a serious problem for countries with aging population because decrease of the number of successors. The concepts of haptic database and force sensor recorder which have been developed recently suggests solutions of using third multimedia type of haptic communication. Haptic information is a bilateral information of the law of action and reaction. The reaction from real world includes not only position and force information but also environmental impedance. In this paper, the behavior of environmental impedance has been studied with the changes of the different motion parameters like applied force, velocity, position and depth on the object 3D space. This idea is exemplified using a rubber balloon and a rubber sponge which is often modeled using simple linear equations. The experimental results show the importance of considering motion parameters when abstracting haptic information for a haptic database. Nonlinear impedance variations against the motion parameters suggest the necessity of adopting complex haptic abstraction techniques.
item: Conference-Extended-Abstract
Bimanual tele rehabilitation robot
(Engineering Research Unit, 2023-12) Perera, KLM; Hettiarachchi, TI; Kumara, JAAS; Ruwanthika, RMM; Arunya, PSSD
Post-stroke patients lose their interlimb coordination and ability to do bimanual activities. This is common for arms, and usually, patients get one arm paretic. This is a heavy burden since everyday activities need both hands to do. For recovery, they need intensive bimanual therapy. The robotic approach is more effective than traditional rehabilitation for this kind of therapy. A bimanual master-slave robotic system can be used to do simultaneous exercises for patients’ both hands. Our focus is to implement the two most basic and critical movements into this robot. One is Flexion and Extension, and the other is Internal and external rotation. Stroke is one of the conditions that causes long-term disabilities. This causes a lot of struggles for patients to recover. To overcome that and speed up the recovery we propose a robotic approach, with reduced dependency on a therapist and increased repeatability and robustness. When doing these exercises, the patient’s shoulder must be in a relaxed position. Otherwise, the generated torques will depend on the shoulder position. Hence there must be adjustments for varying arm lengths as it changes the position of the elbow joint. Also, we are going to implement two exercises which are done in perpendicular planes into one 1 DOF (Degrees of Freedom), robot. And we need to provide methods to change the motor orientation for that.
item: Conference-Full-text
computer vision based fire alarming system
(IEEE, 2016-05) Gunawaardena, AE; Ruwanthika, RMM; Jayasekara, AGBP; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
Fire detection system in the surveillance system monitors the indoor environment and issues alarm as part of the early warning mechanism with ultimate goal to provide an alarm at early stage before the fire become uncontrollable. Conventional fire detection systems suffer from the transparent delay from the fire to the sensor which is looking at a point. The reliability of the fire detection system mainly depends on the positional distribution of the sensors. This paper proposes novel method of fire detection by processing image sequence acquired from a video. The proposed video based fire-detection system uses adaptive background subtraction to detect foreground moving object and then verified by the rule based fire color model to determine whether the detected foreground object is a fire or not. YCbCr color space is used to model the fire pixel classification. In addition to the motion and color the detected fire candidate regions are analyzed in temporal domain to detect the fire flicker. Some Morphological operations are used to enhance the features of detected fire candidate region. All of the above clues are combining to form the fire detection system. The performance of the proposed algorithm is tested on two sets of videos comprising the fire, fire colored object and non-fire. The experimental results show that the proposed system is very successful in detecting fire and /or flames.
item: Conference-Full-text
Potential for improving green roof performance through artificial irrigation
(IEEE, 2016-04) Heendeniya, HKCB; Ruwanthika, RMM; Jayasekara, AGBP; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
Historically extensive green roofs were designed for natural precipitation with a plant selection focusing on hardy succulents such as sedums that can survive harsh, water stressed conditions. Although this seems a convenient solution to establish and maintain a green roof system, at a much broader level this does not optimize the functions and performance of the green roof. In this paper the influence of irrigation on green roof functions and performance is presented for an extensive green roof by an extensive literature study. Green roof energy saving potential under Sri Lankan climatic conditions is significant. The average water retention of green roof substrate under different climatic zone conditions in Sri Lankan context is simulated with hypothetical twelve extensive green roof types. Results justify the artificial irrigation requirement and provide key directions to develop water balance model considering locational factors to maintain set soil moisture target.
item: Thesis-Full-text
Reaction torque observer based force feedback gripper with force lock
Ruwanthika, RMM; Abeykoon, AMHS
Haptic information is a bilateral information of the law of action and reaction. Most of the researchers have done experiments on bilateral teleoperation but still they haven’t given much attention on force lock during bilateral teleoperation even though it’s important in the latest technology. This research proposes an enhanced force limiting gripper to avoid object deformation when it is in contact with the slave due to excessive forces imposed by the master operator in bilateral control. The force lock protects the gripped object on the slave and the attainment of the force limit is notified to the master operator via a small vibration. Master operator is expected to experience a spring effect if the operator presses his leaver towards the force increasing direction. The continuous copying of the slave position as the reference to the virtual spring controller’s spring equilibrium point allows smooth releasing. In addition to vibration the loss of reaction force coming from the slave environment could also be sensed by the master operator. Releasing logic of force lock can be determined by the operator. In this proposed system sensor-less sensing is used. Disturbance Observer (DOB) is used to estimate disturbances and Reaction Torque Observer (RTOB) estimates reaction forces. The reaction from real world includes not only position and force information but also environmental impedance. The griped object impedance variation with the motion parameters of the actuator should also be analyzed. In this research, the behavior of environmental object impedance has been studied with the changes of the different motion parameters of the actuator, like applied force, velocity, position and depth on the object 3D space. This idea is exemplified using a rubber balloon and a rubber sponge which is often modeled using simple linear equations. The proposed system is tested using hardware setup and results prove the applicability of RTOB and DOB for force feedback gripper for haptic teleoperation. The results of variable impedance model as function of its motion parameters suggests nonlinear impedance variations against the motion parameters of the environmental object.
item: Conference-Abstract
Simulation of enhanced force limiting gripper for bilateral teleoperation
Ruwanthika, RMM; Abeykoon, AMHS
This paper proposes an enhanced force limiting gripper to avoid object deformation when it is in contact with the slave due to excessive forces imposed by the master operator in bilateral control. The force lock protects the gripped object on the slave and the attainment of the force limit is notified to the master operator via a small vibration. Master operator is expected to experience a spring effect if the operator presses his leaver towards the force increasing direction. The continuous copying of the slave position as the reference to the virtual spring controller’s spring equilibrium point allows smooth releasing. In addition to vibration the loss of reaction force coming from the slave environment could also be sensed by the master operator. Reversing of the applied force on master handle releases the object attached to the slave. In this proposed system sensor-less sensing is used. Disturbance Observer is used to estimate disturbances and Reaction Force Observer estimates reaction forces. The proposed gripper is having a jaw opening of 0.15 m which has linear 1-DOF. Simulation is conducted using real world linear motor parameters and simulation results prove the applicability of proposed system.
item: Conference-Full-text
Vibro-haptic white cane with enhanced vibro sensitivity
(Institute of Electrical and Electronics Engineers, Inc., 2018-09) Abeysiriwardhana, WASP; Ruwanthika, RMM; Abeykoon, AMHS; Samarasinghe, R; Abeygunawardana, S
The traditional white cane allows blind persons to understand the environment by tapping the white cane against the objects. It has limited capabilities in detecting objects far from the person. Available electronic blind navigation systems require wearable devices that would cause discomfort to the blind person. This paper proposes a low cost but yet a rugged vibro-haptic white cane to be used as a navigational aid for the blind community. The proposed system allows a blind person to understand distant environment with haptic sensations without any additional wearable devices. The frequency of vibration utilized as the sensation of distance. Proposed device was tested with blind middle school students. The proposed controller was modified accordingly to create a linear distance perception.