Concept

Nyquist stability criterion

Related publications (157)

Forced reattachment in separated flows: a variational approach to recirculation length reduction

Sensitivity analysis is used to design an open-loop control for separated flows. The length of the recirculation region

l_c

is expressed as a cost functional, and its sensitivity to actuation is derived analytically. This analysis allows to identify regi ...

2013

Sustained Nano-Mechanical Oscillation of a Resonant-Body Transistor by Frequency-Modulated Heterodyne Phase-Locked-Loop

Mihai Adrian Ionescu, Alexandru Rusu, Sebastian Thimotee Bartsch

Many applications based on resonant nanoelectromechanical systems (NEMS) require monitoring their natural frequency of oscillation over time with high precision, e.g. for gas sensing or nanomechanical mass spectrometry. In this study, we integrate a very-h ...

2013

On input design for direct data-driven controller tuning

Alireza Karimi

In recent years, noniterative Correlation-based Tuning (CbT) and Virtual Reference Feedback Tuning (VRFT) have been proposed as an alternative to the standard model-based approach for model-reference control design. In this work, the problem of input desig ...

2012

Dual-mode temperature compensation technique for laser stabilization to a crystalline whispering gallery mode resonator

Tobias Kippenberg, Albert Schliesser

Frequency stabilization of a diode laser locked to a whispering gallery mode (WGM) reference resonator made of a MgF2 single crystal is demonstrated. The strong thermal dependence of the difference frequency between two orthogonally polarized TE an TM mode ...

Optical Society of America2012

A solution to the flexible transmission benchmark by convex optimization

Alireza Karimi, Gorka Galdos Sanz de Galdeano

The flexible transmission benchmark was proposed in the European Journal of Control to evaluate some robust digital control approaches in 1995. With progress in convex optimization algorithms new methods for robust controller design are developed. A recent ...

SAGE Publications2012

On stable self-similar blow up for equivariant wave maps: The linearized problem

Roland Donninger

We consider co-rotational wave maps from (3+1) Minkowski space into the three-sphere. This is an energy supercritical model which is known to exhibit finite time blow up via self-similar solutions. The ground state self-similar solution

f_0

is known in c ...

2012

Avoiding Feedback-Linearization Singularity Using a Quotient Method -- The Field-Controlled DC Motor Case

Dominique Bonvin, Philippe Müllhaupt

Feedback linearization requires a unique feedback law and a unique diffeomorphism to bring a system to Brunovsk´y normal form. Unfortunately, singularities might arise both in the feedback law and in the diffeomorphism. This paper demonstrates the ability ...

2012

Control of a separated boundary layer: reduced-order modeling using global modes revisited

François Gallaire

The possibility of model reduction using global modes is readdressed, aiming at the controlling of a globally unstable separation bubble induced by a bump geometry. A combined oblique and orthogonal projection approach is proposed to design an estimator an ...

2011

Data-driven model reference control with asymptotically guaranteed stability

Dominique Bonvin, Alireza Karimi, Klaske van Heusden

This paper presents a data-driven controller tuning method that includes a set of constraints for ensuring closed-loop stability. The approach requires a single experiment and can also be applied to nonminimum-phase or unstable systems. The tuning scheme u ...

Wiley-Blackwell2011

On identification methods for direct data-driven controller tuning

Alireza Karimi, Klaske van Heusden

In non-iterative data-driven controller tuning, a set of measured input/output data of the plant is used directly to identify the optimal controller that minimizes some control criterion. This approach allows the design of fixed-order controllers, but lead ...

Wiley-Blackwell2011

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Forced reattachment in separated flows: a variational approach to recirculation length reduction

François Gallaire, Edouard Boujo

Sensitivity analysis is used to design an open-loop control for separated flows. The length of the recirculation region

l_c

is expressed as a cost functional, and its sensitivity to actuation is derived analytically. This analysis allows to identify regi ...

2013

On stable self-similar blow up for equivariant wave maps: The linearized problem

Roland Donninger

f_0

is known in c ...

2012