Browsing by Subject "Saturation nonlinearity"
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Item Unknown Robust antiwindup compensation for high-precision tracking of a piezoelectric nanostage(Institute of Electrical and Electronics Engineers Inc., 2016) Liu, P.; Yan, P.; Zhang Z.; Özbay, HitayUltrahigh-precision tracking in nanomanipulations poses major challenges for mechanical design as well as servo control, due to the general confliction between the precision requirement and large stroke tracking. The situation is further complicated by input saturation, which is almost inevitable for microactuators. This paper presents a novel control architecture combining a parallel internal-model-based tracking design and a robust antiwindup control structure, such that asymptotic tracking can be achieved for nanoservo systems in the presence of saturation nonlinearity and model uncertainties. For the augmented system with internal-model dynamics, an I/O-based equivalent representation from control (free of saturation) to system output is derived by incorporating the dead-zone nonlinearity, saturation compensation blocks, as well internal-model units. The robustness condition on the saturation compensator is also derived based on the sector bound criterion and an H∞-optimal design is developed accordingly. The proposed robust antiwindup tracking control architecture is deployed on a customize-designed nanostage driven by a piezoelectric (PZT) actuator, where numerical simulations and real-time experiments demonstrate excellent tracking performance and saturation compensation capability, achieving tracking precision error less than 0.23%.Item Unknown Solving a stability problem by Polya's four steps(Istanbul Aydin University, Engineering Faculty, 2011) Alacacı, C.; Doğruel, M.In this paper, we consider the proof of stability of a nonlinear system. We found it useful to employ Polya’s general four step problem solving process to organize and present the solution and our thinking. Polya's ideas can help us become aware of how we think when we solve problems. Reflecting on how we solve a problem allows us make conceptual connections between a problem at hand and the problems we may need to solve in the future.