Publications by Roland Longchamp

Related publications (32)

Frequency Domain Controller Design by Linear Programming Guaranteeing Quadratic Stability

Alireza Karimi, Roland Longchamp, Marc Kunze

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

Model-Free Precompensator and Feedforward Tuning Based on the Correlation Approach

Alireza Karimi, Roland Longchamp

High performance output tracking can be achieved by precompensator or feedforward controllers based on the inverse of the closed-loop system or the plant model. However, it has been shown that these inverse controllers can affect adversely the tracking per ...

2005

Robust Loop Shaping Controller Design for Spectral Models by Quadratic Programming

Alireza Karimi, Roland Longchamp, Gorka Galdos Sanz de Galdeano

A quadratic programming approach is proposed to tune fixed-order linearly parameterized controllers for stable LTI plants represented by spectral models. The method is based on the shaping of the open-loop or closed-loop frequency functions in the Nyquist ...

2007

Robust Controller Design by Linear Programming with Application to a Double-Axis Positioning System

Alireza Karimi, Roland Longchamp, Marc Kunze

A linear programming approach is proposed to tune fixed-order linearly parameterized controllers for stable LTI plants. The method is based on the shaping of the open-loop transfer function in the Nyquist diagram. A lower bound on the crossover frequency a ...

2007

Interactive applications to explore the parametric space of multivariable controllers

Roland Longchamp, Yves Henri Philippe Piguet

This paper describes interactive applications used to illustrate an advanced course on multivariable control. The direct manipulation of features in graphics, such as eigenvectors in the phase plane or observer eigenvalues in the complex plane, gives the s ...

2011

Gain-Scheduled Controller Design by Linear Programming

Alireza Karimi, Roland Longchamp, Marc Kunze

A linear programming approach is proposed to tune fixed-order linearly parameterized gain-scheduled controllers for stable SISO linear parameter varying (LPV) plants. The method is based on the shaping of the open-loop transfer functions in the Nyquist dia ...

2007

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

Alireza Karimi, Roland Longchamp, 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 Systems with Polytopic Uncertainty Using LMIs

Alireza Karimi, Roland Longchamp

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 Control of Polytopic Systems by Convex Optimization

Alireza Karimi, Roland Longchamp

Robust control synthesis of linear time-invariant SISO polytopic systems is investigated using the polynomial approach. A convex set of all stabilizing controllers for a polytopic system is given over an infinite-dimensional space. A finite-dimensional app ...

2007

H∞ Controller Design for Spectral MIMO Models by Convex Optimization

Alireza Karimi, Roland Longchamp, Gorka Galdos Sanz de Galdeano

A new method for robust ﬁxed-order H∞ controller design by convex optimization for multivariable systems is investigated. Linear Time-Invariant Multi-Input Multi- Output (LTI-MIMO) systems represented by a set of complex values in the frequency domain are ...

Elsevier2010

Robust Controller Design by Convex Optimization based on Finite Frequency Samples of Spectral Models

Alireza Karimi, Roland Longchamp, Gorka Galdos Sanz de Galdeano

Some frequency-domain controller design problems are solved using a finite number of frequency samples. Consequently, the performance and stability conditions are not guaranteed for the frequencies between the frequency samples. In this paper, all possible ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010

Model-Free Precompensator Tuning Based on the Correlation Approach

Alireza Karimi, Roland Longchamp

High performance output tracking can be achieved by precompensator or feedforward controllers based on the inverse of either the closed-loop system or the plant model, respectively. However, it has been shown that these inverse controllers can adversely af ...

2008

A Statistical Analysis of Certain Iterative Learning Control Algorithms

Alireza Karimi, Roland Longchamp

Iterative Learning Control (ILC) is a technique used to improve the tracking performance of systems carrying out repetitive tasks, which are affected by deterministic disturbances. The achievable performance is greatly degraded, however, when non-repeating ...

2008

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

Alireza Karimi, Roland Longchamp, 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

Robust Control of Polytopic Systems by Convex Optimization

Alireza Karimi, Roland Longchamp

Robust control synthesis of linear time-invariant SISO polytopic systems is investigated using the polynomial approach. A convex set of all stabilizing controllers for a polytopic system is given over an infinite-dimensional space. A finite-dimensional app ...

2007

PID Controller Design for Multivariable Systems Using Gershgorin Bands

Alireza Karimi, Roland Longchamp, Daniel Garcia

A method to design decentralized PID controllers for MIMO systems is presented in this paper. Each loop is designed separately, but the Gershgorin bands are considered to take interactions into account. The method uses different design parameters: The infi ...

2005

Robust Pole Placement of Systems with Polytopic Uncertainty Via Convex Optimization

Alireza Karimi, Roland Longchamp

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 controll ...

2007

PID Controller Design with Specifications on the Infinity-Norm of Sensitivity Functions

Alireza Karimi, Roland Longchamp, Daniel Garcia

A controller design method using a frequency criterion is proposed in this paper. The frequency criterion is defined as the weighted sum of squared errors between the specified and computed values of the design parameters. These are the infinity-norm of th ...

2005

PID controller design with constraints on sensitivity functions using loop slope adjustment

Alireza Karimi, Roland Longchamp, Daniel Garcia

This paper presents a PID controller design method for stable minimum- phase systems. The approach is similar to the one proposed in the so-called modified Ziegler- Nichols method, where only one point on the frequency response of the plant is measured and ...

2006

Robust PID controller tuning with specifications on the infinity-norm of sensitivity functions

Alireza Karimi, Roland Longchamp, Daniel Garcia

An overview of the recent works on proportional integral derivative (PID) controller tuning methods based on specifications on the infinity-norm of the sensitivity functions is presented. The presented approach is very flexible relative to the controller s ...

2007