Browsing by Author "Chen, Sheng"
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Item Open Access Optimal Controller and Filter Realisations using Finite-precision, Floating- point Arithmetic.(Taylor & Francis, 2005-06-01T00:00:00Z) Whidborne, James F.; Gu, Da-Wei; Wu, Jun; Chen, ShengThe problem of reducing the fragility of digital controllers and filters implemented using finite-precision, floating-point arithmetic is considered. Floating-point arithmetic parameter uncertainty is multiplicative, unlike parameter uncertainty resulting from fixed-point arithmetic. Based on first- order eigenvalue sensitivity analysis, an upper bound on the eigenvalue perturbations is derived. Consequently, open-loop and closed-loop eigenvalue sensitivity measures are proposed. These measures are dependent upon the filter/ controller realization. Problems of obtaining the optimal realization with respect to both the open-loop and the closed-loop eigenvalue sensitivity measures are posed. The problem for the open-loop case is completely solved. Solutions for the closed-loop case are obtained using non-linear programming. The problems are illustrated with a numerical example.Item Open Access A Unified Closed-Loop Stability Measure for Finite-Precision Digital Controller Realizations Implemented in Different Representation Schemes.(IEEE Institute of Electrical and Electronics, 2003-05-01T00:00:00Z) Wu, Jun; Chen, Sheng; Whidborne, James F.; Chu, JianA computationally tractable unified finite word length closed-loop stability measure is derived which is applicable to fixed-point, floating-point and block- floating-point representation schemes. Both the dynamic range and precision of an arithmetic scheme are considered in this new unified measure. For each arithmetic scheme, the optimal controller realization problem is defined and a numerical optimization approach is adopted to solve it. Numerical examples are used to illustrate the design procedure and to compare the optimal controller realizations in different representation schemes.