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Multiplicative Uncertainty (multiplicative + uncertainty)
Selected AbstractsNecessary and sufficient conditions for robust perfect tracking under variable structure controlINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 2 2003Andrea Balluchi Abstract The tracking control of linear MIMO systems with structured uncertainty is considered. A necessary and sufficient condition for robust asymptotic tracking employing variable structure techniques in the presence of multiplicative uncertainty is derived. The constructive proof of the theorem provides an explicit formula for controller synthesis. Copyright © 2002 John Wiley & Sons, Ltd. [source] ,YOU MIGHT AS WELL BE HUNG FOR A SHEEP AS A LAMB': THE LOSS FUNCTION OF AN AGENT,THE MANCHESTER SCHOOL, Issue 3 2008MARGARET BRAY Most of those who take macro and monetary policy decisions are agents. The worst penalty which can be applied to these agents is to sack them. Agents thus have loss functions which are bounded above. We work with a bell loss function which has this property. With additive uncertainty the certainty equivalence which holds for a quadratic loss function breaks down with a bell loss function when there are two or more targets. With multiplicative (Brainard) uncertainty policy is more conservative than in the absence of multiplicative uncertainty, but less so with the bell than the quadratic loss function. [source] AN AFM PROBE CONTROLLER DESIGN BASED ON ,-SYNTHESISASIAN JOURNAL OF CONTROL, Issue 1 2005Kuo-Jung Lan ABSTRACT The atomic force microscope (AFM) is one of the most important tools for measuring atomic resolution. The AFM system maintains constant force between a tip and the sample in order to track the sample topography. The controller that maintains the constant interaction force plays a significant role in measurement accuracy. This paper presents a ,-synthesis controller design to deal with model uncertainty and establish a measurement error bound. The system's nonlinearity and the set-point drift are lumped into a multiplicative uncertainty. The performance bound allows specification of the error magnitude over the frequency range. Simulation results show that the proposed control can tolerate uncertainties. The error spectrum from the experiments shows consistency with the design specifications. Images were taken to compare ,-synthesis control with a well-tuned PID control at a 480,m/s scan rate. The results verify the outstanding performance of the ,-controller. [source] Modeling And Robust Pi Control Of A Fluidized Bed Combustor For Sewage SludgeASIAN JOURNAL OF CONTROL, Issue 4 2002Yingmin Jia ABSTRACT Based on experimental data, a fluidized bed combustor is modeled as an interval system. Severe model uncertainty and large time delays lead to the main difficulties in solving the control problem. The design uses the stability test of closed-loop systems as the main guideline for developing a robust PI controller. In particular, a new formula to compute the maximal magnitude of an edge rational function at a fixed frequency is derived, which provides a way to deal with time delay by transforming it into multiplicative uncertainty. Both the theoretical and the experimental results show that the designed PI controller can satisfy the desired performance requirements. [source] | ||||||||||