Serhat Obuz

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—A robust controller is developed for uncertain, second-order nonlinear systems subject to simultaneous unknown , time-varying state delays and known, time-varying input delays in addition to additive, sufficiently smooth disturbances. An integral term composed of previous control values facilitates a delay-free open-loop error system and the development of(More)
In this paper, a tracking controller is developed for a class of nonlinear systems subject to time delay in the control input, uncertainties in the dynamic model, and additive disturbances. The control development is based on a novel predictor–like method to address the time delay in the control input. Lyapunov based stability analysis is used to prove(More)
Autonomous systems often use feedback from an imaging system for guidance, navigation, and control. Such feedback requires an image processing method that yields an inherent delay in state measurements. For some camera-to-hand applications, the image-based sensing and control computations may be computed by a more capable processor and then be transmitted(More)
— Previous results have shown experimental evidence that the muscle response to neuromuscular electrical stimulation (NMES) is delayed; the time lag is often referred to as electromechanical delay. NMES closed-loop control methods have been developed to compensate for a known constant input delay. However, as a muscle fatigues, this delay increases. This(More)
In the present work, a control method is developed to yield lower limb tracking with neuromuscular electrical stimulation (NMES), despite an unknown time-varying input delay intrinsic to NMES, uncertain nonlinear dynamics, and additive bounded disturbances. A novel filtered tracking error signal is designed to obtain a delay-free control expression in the(More)
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