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Alireza Karimi

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Related publications (165)

Non-iterative data-driven controller tuning with guaranteed stability: Application to direct-drive pick-and-place robot

Dominique Bonvin, Alireza Karimi, Klaske van Heusden

This paper illustrates the practical application of non-iterative correlation- based tuning with guaranteed stability. In this method, a sufficient condition for closed-loop stability is defined as the H infinity-norm of a particular error function. This n ...

2010

Fixed-order H-infinity Controller Design for Nonparametric Models by Convex Optimization

Alireza Karimi, Gorka Galdos Sanz de Galdeano

A new approach for robust fixed-order H-infinity controller design by convex optimization is proposed. Linear time-invariant single-input single-output systems represented by nonparametric models in the frequency domain are considered. It is shown that the ...

2010

Data-driven tuning of linear parameter varying precompensators

Alireza Karimi, Mark Edward John Butcher

Methods for direct data-driven tuning of the parameters of precompensators for LPV systems are developed. Since the commutativity property is not always satisfied for LPV systems, previously proposed methods for LTI systems that use this property cannot be ...

Wiley-Blackwell2010

H-infinity Controller Design for Spectral MIMO Models by Convex Optimization

Roland Longchamp, Alireza Karimi, Gorka Galdos Sanz de Galdeano

A recent method for robust fixed-order H-infinty controller design by convex optimization proposed in [1] is investigated in this paper for the tuning of multivariable controllers. Linear Time-Invariant Multi-Input Multi-Output (LTI-MIMO) systems represent ...

2009

Modeling and Control of a Magnetically Levitated Planar Motor

Roland Longchamp, Marc Kunze, Alireza Karimi, Vincent Reymond

This paper deals with the modeling and control of a magnetically levitated planar motor. The actuator considered has moving coils and stationary magnets. The principal objective is to develop a model which can be implemented in simulation. Therefore, the d ...

2009

An Alternative to the Youla Parameterization for H infinity Controller Design

Alireza Karimi, Hamid Khatibi

All H infinity controllers of a SISO LTI system are parameterized thanks to the relation between the Bounded Real Lemma and the Positive Real Lemma. This new parameterization shares the features of Youla parameterization, namely the convexity of H infinity ...

2009

Data-driven controller validation

Dominique Bonvin, Alireza Karimi, Klaske van Heusden

This paper proposes a data-driven test for closed-loop stability. The test is based on a non-conservative stability condition that can be veriﬁed without having to actually implement the controller. It uses a set of measurements from the plant but does not ...

2009

Linear Parameter Varying Iterative Learning Control

Alireza Karimi, Mark Edward John Butcher

In this paper an Iterative Learning Control (ILC) algorithm is proposed for a certain class of Linear Parameter Varying (LPV) systems whose dynamics change between iterations. Consistency of the algorithm in the presence of stochastic disturbances is shown ...

2009

Electronic origin of the isostructural decomposition in cubic M1-xAlxN (M=Ti, Cr, Sc, Hf): A first-principles study

Alireza Karimi

We have used first-principles calculations to investigate the mixing enthalpies, lattice parameters and electronic density of states of the ternary nitride systems Ti1-xAlxN, Cr1-xAlxN, Sc1-xAlxN and Hf1-xAlxN in the cubic B1 structure where the transition ...

2008

Off-axis texture in nanostructured Ti1-xAlxN thin films

Alireza Karimi

Standard theta-2 theta and pole figure X-ray diffraction techniques were used to study structural properties and preferred orientation of nanostructured TiAIN thin films prepared using cathodic are deposition. Systematic collection of reflections from latt ...

R Deposition2008

First-principles study of the effect of nitrogen vacancies on the decomposition pattern in cubic Ti1-xAlxN1-y

Alireza Karimi

The effect of nitrogen substoichiometry on the isostructural phase stabilities of the cubic Ti1-xAlxN1-y system has been investigated using first-principles calculations. The preferred isostructural decomposition pattern in these metastable solid solutions ...

AIP American Institute of Physics2008

Closed-loop Identification of Multivariable Systems: With or Without Excitation of All References?

Dominique Bonvin, Ljubisa Miskovic, Alireza Karimi

A variance analysis of the parameters of a plant, belonging to a class of multivariable systems, estimated in closed-loop operation is performed. More specifically, having in mind the control applications where it is not desirable to excite all external re ...

2008

Iterative Learning Control based on Stochastic Approximation

Roland Longchamp, Alireza Karimi, Mark Edward John Butcher

In this paper stochastic approximation theory is used to produce Iterative Learning Control algorithms which are less sensitive to stochastic disturbances, a typical problem for the learning process of standard ILC algorithms. Two algorithms are developed, ...

2008

Frequency Domain Controller Design by Linear Programming Guaranteeing Quadratic Stability

Roland Longchamp, Marc Kunze, Alireza Karimi

In a recent work, a frequency method based on linear programming is proposed to design fixed-order linearly parameterized controllers for stable linear multi- model SISO systems. The method is based on the shaping of the open-loop transfer functions in the ...

IEEE2008

Fixed-Order Controller Design for Systems with Polytopic Uncertainty Using LMIs

Roland Longchamp, Alireza Karimi, Hamid Khatibi

Convex parameterization of fixed-order robust stabilizing controllers for systems with polytopic uncertainty is represented as an LMI using KYP Lemma. This parameterization is a convex inner-approximation of the whole non- convex set of stabilizing control ...

2008

Robust fixed-order H infinity Controller Design for Spectral Models by Convex Optimization

Roland Longchamp, Alireza Karimi, Gorka Galdos Sanz de Galdeano

A new approach for robust fixed-order

H_\infty

controller design by convex optimization is proposed. Linear time-invariant single-input single-output systems represented by a finite set of complex values in the frequency domain are considered. It is show ...

IEEE2008

Fixed-Order Controller Design for Polytopic Systems Using Rank Deficiency in a Sylvester Matrix

Roland Longchamp, Alireza Karimi, Hamid Khatibi

Fixed-order controller design for LTI-SISO polytopic systems is investigated using rank deficiency constraint on the controller Sylvester resultant matrix. It is shown that the non-convexity of fixed-order controller design problem can be gathered in a ran ...

2008

On the Consistency of Certain Identification Methods for Linear Parameter Varying Systems

Roland Longchamp, Alireza Karimi, Mark Edward John Butcher

The consistency of certain identification methods for Linear Parameter Varying systems is considered. More precisely, methods for the identification of SISO input-output models are analysed. In order to perform a consistency analysis the application of erg ...

2008

Data-driven controller tuning with integrated stability constraint

Dominique Bonvin, Alireza Karimi, Klaske van Heusden

This paper presents a data-driven controller-tuning algorithm that includes a sufficient condition for closed-loop stability. This stability condition is defined by a set of convex constraints on the Fourier transform of specific auto- and cross-correlatio ...

IEEE2008

Data-driven Precompensator Tuning for Linear Parameter Varying Systems

Roland Longchamp, Alireza Karimi, Mark Edward John Butcher

IEEE2008

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