Bobby Bodenheimer

Mixed /spl Hscr//sub 2/ and /spl Hscr//sub /spl infin// performance objectives. II. Optimal control

This paper considers the analysis and synthesis of control systems subject to two types of disturbance signals: white signals and signals with bounded power. The resulting control problem involves minimizing a mixed /spl Hscr//sub 2/ and /spl Hscr//sub /spl infin// norm of the system. It is shown that the controller shares a separation property similar to those of pure /spl Hscr//sub 2/ or /spl Hscr//sub /spl infin// controllers. Necessary conditions and sufficient conditions are obtained for the existence of a solution to the mixed problem. Explicit state-space formulas are also given for the optimal controller. >

Mixed /spl Hscr//sub 2/ and /spl Hscr//sub /spl infin// performance objectives. I. Robust performance analysis

This paper introduces an induced-norm formulation of a mixed /spl Hscr//sub 2/ and /spl Hscr//sub /spl infin// performance criterion. It is shown that different mixed /spl Hscr//sub 2/ and /spl Hscr//sub /spl infin// norms arise from different assumptions on the input signals. While most mixed norms can be expressed explicitly using either transfer functions or state-space realizations of the system, there are cases where the explicit formulas are very hard to obtain. In the later cases, examples are given to show the intrinsic nature and difficulty of the problem. Mixed norm robust performance analysis under structured uncertainty is also considered in the paper. >

Optimal control with mixed H2 and H¿ performance objectives

This paper considers the analysis and synthesis of control systems subject to two types of disturbance signals: signals with bounded power spectral density and signals with bounded power. The resulting control problem involves minimizing a mixed H₂ and H_∞ norm of the system. It is shown that the controller shares a separation property similar to those of pare H₂ or H_∞. controller. It is also shown that the mixed problem reduces naturally to H₂ and H_∞ problem in special cases. Some necessary and sufficient conditions are obtained for the existence of a solution to the mixed problem. Explicit state space formulae are given for the optimal controllers.

Optimal linear parameter-varying control design for a pressurized water reactor

The applicability of employing parameter-dependent control to a nuclear pressurized water reactor is investigated. The synthesis technique produces a controller which achieves specified performance against the worst-case time variation of a measurable parameter which enters the plant in a linear fractional manner. The plant can thus have widely varying dynamics over the operating range. The controllers designed perform well over the entire operating range.

Identification and H/sub /spl infin// control design for a pressurized water reactor

The objective of this paper was to design controllers for a pressurized water reactor using model based control techniques. To this end, the physical system was identified from experimental data using a multi-input multi-output state-space description; an H/sub /spl infin// controller was designed using a lower order model of the plant. Of particular importance, the frequency weighting functions were chosen to reflect the robust stability and nominal performance requirements. Although a nonlinear controller is required, the results demonstrate the effectiveness of the proposed controller in a relatively wide operating range.<<ETX>>

Mixed H2 and H¿ control

Mixed H₂ and H_∞ norm analysis and synthesis problems are considered in this paper. It is shown that the mixed norm analysis combined with structured uncertainty can be used to give bounds on robust H₂ and H_∞ performance. It is also shown that the mixed norm controller shares a separation property similar to those of pure H₂ or H_∞ controllers. The obvious advantage for a mixed norm is that it gives a natural trade-off between H₂ performance and H_∞ performance, and provides a potential framework for extending the μ-synthesis framework to address robust H₂ performance. A simple example is used to motivate the possible advantages such a framework might have over a pure H_∞ theory.

LMI-based model reduction for a vectored-thrust ducted fan

This paper contains the first experimental application of model reduction methods developed for systems represented by a linear fractional transformation (LFT) on a repeated scalar uncertainty structure. These methods provide for reduction of both the state order, and the uncertainty descriptions. LFT models of a vectored-thrust flight control experiment are reduced in order to make controller synthesis feasible. Recent linear parameter varying design techniques are used to synthesize the controllers.