Multiobjective control design is known to be a difficult problem both in theory and practice. Our approach is to search for locally optimal solutions of a nonsmooth optimization problem that is built to incorporate minimization objectives and constraints for multiple plants. We report on the success of this approach using our public-domain matlab toolbox hifoo 2.0, comparing our results with benchmarks in the literature.
We report on our experience with strong stabilization using HIFOO, a toolbox for H ∞ fixed-order controller design. We applied HIFOO to 21 fixed-order stable H ∞ controller design problems in the literature, comparing the results with those published for other methods. The results show that HIFOO often achieves good H ∞ performance with low-order stable controllers, unlike other methods in the literature.
Articles you may be interested inAnalysis and optimization approaches for wide-viewing-angle λ/4 plate in polarimetry for immersion lithographyIn the recent past, scaling of semiconductor fabrication systems has been dominated by wavelength and numerical aperture modifications. This is now no longer the case for 193-nm immersion projection lithography (193i) systems as there are no technical paths for continued benefit from the in these areas. Instead, a range of techniques including patterning processes and system optimization are being used to push the limits of the system. This paper will review the elements that are now driving scaling for a system of fixed wavelength and numerical aperture.
In web transport systems, the main concern is to control independently speed and tension in spite of perturbations such as radius variations and changes of setting point. This paper presents the application of nonsmooth nonconvex optimization techniques to design centralized fixed order and decentralized fixed order and fixed structure H ∞ controllers with model based feedforward for web winding systems. The approach provides improved web tension and velocity regulation. First, mathematical models of fundamental elements in a web process line are presented. A state space model is developed which enables calculation of the phenomenological model feedforward signals and helps in the synthesis of H ∞ controllers around the set points given by the reference signals. The H ∞ control strategies with additive feedforward have been validated on a nonlinear simulator identified on a 3-motor winding test bench.
We show that, for any rotationally symmetric projection with a single virtual viewpoint, it is possible to design a two-mirror rotationally symmetric system that realizes the projection exactly. These mirror pairs are derived from two coupled differential equations. We give examples in which the projections from the sphere at infinity are stereographic, perspective, and equiresolution.
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