Browsing by Author "Pathirana, CD"

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item: Article-Full-text
Hybrid navigation decision control mechanism for intelligent wheel-chair
(2023) Bandara, HMRT; Priyanayana, KS; Pathirana, CD; Jayasekara, B
he continuous rising of the elderly/disabled population has created a requirement for assistiverobotics devices to counter the lack of trustworthy servants. Intelligent Wheelchairs are developed forthat particular purpose. Intelligent Wheelchairs differ depending on the interactive modality and mostcommonly found modalities are speech-controlled. Since these are assistive devices that need to act as humancompanions, it is necessary to have a dialogue between the device and the user. Even though the wheelchair isfully automated, the user should have control over it at some point. However, this exchange of control shouldbe intelligent and transitions need to be executed in order to safeguard the user. Therefore the purpose ofthis paper is to propose an intelligent system that would navigate an intelligent voice-controlled wheelchairfacilitating the intelligent exchange of control between the user and the wheelchair. This control is notsimultaneous and one can override the other only when navigation could lead to collisions. In the proposedmethod, users can control the wheelchair using fixed vocal commands, and execution of those commandswill be performed using the spatial and control parameters. Control of the wheelchair will be exchangedbetween the user and the wheelchair itself considering specific parameters such as obstacle distance, collisiontime, the velocity of the wheelchair among others. User control mode has 5 definite vocal commands withclassifiers to identify any navigation command into the command model and considers uncertain terms suchas ‘little’ and ‘hard’ for ‘Turn’ commands. Command classification had produced a Cohen’s Kappa value of0.9462 and the classifier for the uncertain terms had produced a Cohen’s Kappa value of 0.7325. Both wereacceptable values for those particular classifications. As per the experiment results, the proposed systemreduced the vocal command frequency and risk of collisions through proper control of the velocity levelsand intelligent exchange of control at given locations. (1) (PDF) Hybrid Navigation Decision Control Mechanism for Intelligent Wheel-Chair. Available from: https://www.researchgate.net/publication/374131541_Hybrid_Navigation_Decision_Control_Mechanism_for_Intelligent_Wheel-Chair [accessed Nov 30 2023].
item: Conference-Full-text
Modeling and sizing of hybrid energy storage system for virtual synchronous generator
(IEEE, 2021-07) Wijetunge, SV; Gunasekera, S; Gamage, J; Pathirana, CD; Bolonne, S; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Renewable energy sources (RESs) play a major role in the modern power system to meet the increasing demand and to reduce environmental effects. But they are unable to perform frequency regulation resulting in higher frequency deviations with higher integration of RESs. To overcome this problem power converters are modified as synchronous generators using proper control mechanisms called as Virtual Synchronous Generators (VSGs). Energy Storage Systems are required to absorb and deliver excess energy. We have used a battery/ultracapacitor hybrid energy storage system (HESS) to achieve this. Power allocation for the two storage units is modeled such that fast-varying power fluctuations are compensated by ultracapacitor (UC) and low frequency power fluctuations are compensated by the battery. This is achieved by emulating the inertia by the ultracapacitor and emulating reheat turbine model, droop control etc. by the battery. Some research produces the modelling details of HESS but not the sizing considering required performance. To fulfil this research gap sizing of the HESS is presented through this research paper. Eventually, the proposed system was implemented and simulated in MATLAB Simulink. Results were analyzed to verify the proposed concept for different cases to prove that it gives outputs similar to conventional synchronous generator.
item: Conference-Full-text
Performance analysis of modified elliot function based temperature controller in the heating mode operation of ahu
(IEEE, 2021-07) Walgama, S; Kumarawadu, S; Pathirana, CD; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
(HVAC) systems are responsible for the majority of total global energy consumption and this fact has been increasing emphasis on innovative and efficient energy saving concepts for several years. With the dynamic nature of the indoor thermal conditions, optimum controlling of the operation of heat exchanger coils in Air Handling Units (AHU) is particularly required to ensure user comfort and energy efficiency. This can be accomplished by precisely adjusting the valve opening of the primary supply to heat exchangers. PID controllers are being commonly used as the conventional control method while many other control strategies are offering better performance and hence allowing significant energy saving. This paper introduces a novel modified Elliot function based controller which can be applied for regulating supply air temperature by adjusting the valve opening of the heat exchanger coil in AHU and analyses the performance for heating mode operation by comparing with PID, Fuzzy Logic, and Sigmoid function-based controllers. The results illustrate that the proposed controller outperforms conventional PID controllers and offers closer performance to Fuzzy Logic controllers with 20876 times reduced execution time.