Research Papers - Dept of Computer Systems Engineering
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Publication Open Access Analysis of Risks and Bottlenecks of a Poly Bag Manufacturing Factory -A Case Study(UNIVERSITY OF MORATUWA, 2008) Gopura, R. A. R. C; Jayawardene, T. S. SThe material prices of poly bags skyrocket to new heights and forecasters see no end to this trend. Also legal restrictions are imposed on some types of polythene products. In this situation, any entrepreneur engaging in the poly bag manufacturing process faces significant challenges. Therefore, a case study of an analysis of risks and bottlenecks of a poly bag manufacturing factory was carried out for the purpose of modeling and simulation of a poly bag manufacturing factory to improve the productivity to face the underlying challenges. This paper presents the analysis methods, and the results of the analysis are also discussed.Publication Embargo A study on a poly-bag manufacturing system preliminary analysis and simulation(IEEE, 2009-12-28) Gopura, R. A. R. C; Jayawardena, T. S. SThe material prices of poly bags increase with high degree of fluctuation and forecasters see no end to this trend. Further, legal restrictions imposed on certain types of polythene products adversely affect the demand. In the light of the above, entrepreneurs of the poly bag manufacturing face many challenges. In this study, an analysis and a simulation of a poly bag manufacturing system were carried out to improve the productivity to face the underlying challenges. This paper presents analysis, modeling and simulation methods of the system. In addition, a risk prioritization method was proposed at the preliminary analysis and also a simulation tool was developed.Publication 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, SBelt 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.Publication Embargo Casterless Wheelchair Robot Using Inverted Pendulum Control(IEEE, 2006-08-08) Abeygunawardhana, P. K. W; Toshiyuki, MPower assist wheelchair robot is playing a key role in the field of medical welfare robotics. But, to a certain extend, there is a setback in development due to presence of caster wheels. Hence, this paper proposes a casterless wheelchair and its control on a straight line path. That is, straight line driving of two wheel power assist wheelchair robot was proposed in this paper while keeping stability of wheelchair body itself. Balancing of wheelchair body is proposed to achieve by controlling the inverted pendulum mounted on the wheelchair. Control equations of the system are derived using Lagrange equation of motion. Two separate controllers are designed for two wheels. In addition to these two controllers, there is another controller for pendulum. Body controller is designed combining pendulum controller and wheel controller. Disturbance observer is used to cancel disturbance effects. Simulation was carried out to prove the applicability of the proposed systemPublication Embargo Vibration Suppression of Two Wheel Mobile Manipulator using Resonance Ratio Control(IEEE, 2008-12-02) Abeygunawardhana, P. K. W; Murakami, TTwo wheel mobile manipulator has the potential of becoming a multi-skilled robot in the field of robotics and it is already implemented by using inverted pendulum control. Centre of gravity position (COG) is controlled to achieve the balancing of robot. Since vibration of manipulator arms affect to the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, vibration control of manipulator arms of the mobile manipulator is proposed in this paper. Feedback signal for vibration suppression is introduced to null space of manipulator. Simulation and experiment was carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.Publication Embargo Self sustaining wheelchair robot on a curved trajectory(IEEE, 2006-12-15) Abeygunawardhana, P. K. W; Toshiyuki, MToday, aged population is increasing in the world, especially in developed countries. Handicapped people could not fulfill their own task without difficulties. Therefore, medical and welfare robotics has become important. Power assist wheelchair robot has been effective in this field for many years. But, to a certain extend, there is a setback in development due to presence of caster wheels. Turning, overcoming obstacles and reversing will be easy without casters. Casterless "wheelchair and its control on a straight line was presented in author's previous paper. Two wheel wheelchair robot on curved trajectory is proposed in this paper. Balancing of "wheelchair body is proposed to achieve by controlling the inverted pendulum mounted on the wheelchair. Control equations of the system are derived using Lagrange equation of motion. Body controller is designed combining pendulum controller and wheel controller. Disturbance observer is used to cancel disturbance effects. Simulation was carried out to prove the applicability of the proposed system.Publication Embargo Stability improvement of two wheel mobile manipulator by real time gain control technique(IEEE, 2007-08-09) Abeygunawardhana, P. K. WAbstract: Two wheeled mobile manipulator has significant role in industry as well as domestic environment when working space of robot is limited. On the other hand, improvement of two wheeled vehicle will explore the technology to improve welfare like wheelchair robot and industrial robots. Two wheeled mobile manipulator has been already implemented using inverted pendulum control. However, dynamic stability has to be improved further. And also, trajectory error has to be minimized. This paper propose the method to improve the stability of the robot by changing the controller gains on runtime based on the robot parameter during the running. Disturbance observer has been employed to cancel the disturbances.Publication Embargo Workspace control of two wheel mobile manipulator by resonance ratio control(IEEE, 2009-07-14) Abeygunawardhana, P. K. W; Murakami, TTwo wheel mobile manipulator has the potential of becoming a multi-skilled robot in the field of robotics and it is already implemented by using inverted pendulum control. Centre of gravity position (COG) is controlled to achieve the balancing of robot. Since vibration of manipulator arms affect to the COG positions of the inverted pendulum, balancing of the robot deteriorates. Therefore, vibration control of manipulator arms of the mobile manipulator is proposed in this paper. Feedback signal for vibration suppression is introduced at work space of manipulator. Simulation and experiment was carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.Publication Embargo An adaptive based approach to improve the stability of two wheel mobile manipulator(IEEE, 2007-11-05) Abeygunawardhana, P. K. W; Toshiyuki, MMobile manipulator with two wheel will play vital role when robot working with limited space. On the other hand, improvement of two wheel vehicle will explore the technology to improve welfare and industrial robots like wheelchair robot. Two wheeled mobile manipulator has been already implemented using inverted pendulum control. But system error is relatively large. Although the stability improvement using passivity theory was reported, it was not succeed with trajectory motion. Therefore, performance improvement which will be achieved through changing the PD controller gains is proposed in this paper. Disturbance observer has been employed to cancel the disturbances.Publication Embargo Environmental interaction of two wheeled mobile manipulator by using reaction torque observer(IEEE, 2008-03-26) Abeygunawardhana, P. K. W; Toshiyuki, MThere are so many industrial manipulators which involve in lot of task in the industry. Developing the mobile manipulator will expand the operational region of the manipulator. Moreover, two wheeled mobile manipulator will further expand the task of the mobile manipulator by being able to work in limited space and so on. However good mobile manipulator should be robust against environmental disturbance. Therefore, environmental recognition of two wheeled mobile manipulator is proposed in this paper. Reaction torque observer is implemented to recognize the environmental disturbance. Compliance control is used to compensate the environmental feedback. Experiment was carried out to show the effectiveness of the proposed method.