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Mixed H2/H (mixed + h)

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Selected Abstracts

Mixed H,/H2 design of digital phase-locked loops with polytopic-type uncertainties

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 14 2002
V. Suplin
Abstract A robust H, control method is applied to the design of loop filters for digital phase locked loop carrier phase tracking. The proposed method successfully copes with large S -curve slope uncertainty and with a significant decision delay in the closed-loop that may stem from the decoder and/or the equalizer there. The design problem is transformed into a state-feedback control problem where phase and gain-margins should be guaranteed in spite of the uncertainty. Of all the loop filters that achieve the required margins the one that minimizes an upper-bound on the effect of the phase and the measurement noise signals is derived. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Guaranteed H, robustness bounds for Wiener filtering and prediction

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2002
P. Bolzern
Abstract The paper deals with special classes of H, estimation problems, where the signal to be estimated coincides with the uncorrupted measured output. Explicit bounds on the difference between nominal and actual H, performance are obtained by means of elementary algebraic manipulations. These bounds are new in continuous-time filtering and discrete-time one-step ahead prediction. As for discrete-time filtering, the paper provides new proofs that are alternative to existing derivations based on the Krein spaces formalism. In particular, some remarkable H, robustness properties of Kalman filters and predictors are highlighted. The usefulness of these results for improving the estimator design under a mixed H2/H, viewpoint is also discussed. The dualization of the analysis allows one to evaluate guaranteed H, robustness bounds for state-feedback regulators of systems affected by actuator disturbances. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A further result of the nonlinear mixed H2/H, tracking control problem for robotic systems

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2002
C. Q. Huang
The design objective of a mixed H2/H, control is to find the H2 optimal tracking control law under a prescribed disturbance attenuation level. With the help of the technique of completing the squares, a further result of the mixed H2/H, optimal tracking control problem is presented, by combining it with standard LQ optimal control technique. In this paper, only a nonlinear time-varying Riccati equation is required to solve the problem in the design procedure,instead of two coupled nonlinear time-varying Riccati equations, or two coupled linear algebraic Riccati-Iike equations,with some assumptions made regarding the weighting matrices in the existing results. A closed-form controller for the mixed H2/H, robotic tracking problem is simply constructed with a matrix inequality check. Moreover, it shows that the existing results are the special cases of these results. Finally, detailed comparison is performed by numerical simulation of a two-link robotic manipulator. © 2002 John Wiley & Sons, Inc. [source]

A new method for mixed H2/H, control with regional pole constraints

OPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 3 2003
Jenq-Lang Wu
Abstract In this paper, the problem of state feedback mixed H2/H, control with regional pole constraints is studied. The constraint region is represented by several algebraic inequalities. This constrained optimization problem cannot be solved via the LMI approach. Based on the barrier method, we instead solve an auxiliary minimization problem to get an approximate solution. We shall show that the obtained minimal solution of the auxiliary minimization problem can be arbitrarily close to the infimal solution of the original problem. An example is provided to illustrate the benefits of the approach. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Multi-objective state feedback control for linear delay systems

ASIAN JOURNAL OF CONTROL, Issue 4 2010
Wei Xie
Abstract This paper provides new linear matrix inequalities (LMI)-based formulae for mixed H2/H, state-feedback synthesis of linear continuous-time systems with state delays of any size. The proposed delay-independent LMI-based conditions enable us to parameterize a memoryless state-feedback controller without involving the Lyapunov variables in the formula. Compared with previous results based on a common Lyapunov variable, the proposed formula provides less conservative results. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society [source]