Abstract. This paper presents an observer output-feedback load frequency control for power systems with uncertain parameters and time delays in communication networks. First, an observer-based controller is designed dependent on only the observer output. Therefore, the conservatism is reduced and the robustness is enhanced. It also both save computing time and make the control method simpler. Second, the stability of both the observer error system and closed-loop control system is proven via the Lyapunov direct method. Moreover, simulation results show that the proposed observer output-feedback load frequency controller results in shortening the frequency's transient response, maintaining required control quality in the wider operating range, and being more robust to uncertainties as compared to some existing control methods.KeyWords: load frequency control, interconnected power systems, observer output.
In this study, the authors' afford is to solve three basic problems remaining in current Knee Continuous Passive Motion (CPM) machine, that is designing to reduce production costs in accordance with the conditions of Vietnam, structural adaptive design to help minimize relative sliding between leg, thigh and device's linkages and design the controller with the purpose of having diversity operation modes, user-friendly interface and easy operation. Furthermore, many attempts were made to ensure the device appearance, stability and safety. In order to minimize relative sliding, parallelogram joint mechanism was proposed, designed, verified and implemented. Both simulation results and experimental result reflect very good results and fulfill the design objective. Furthermore, controller was design to help diversify the operation mode and increase the interaction between user and device. Index Terms-knee physical training, CPM machine, parallelogram mechanism
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