Felix Antritter

Flatness based control of a buck-converter driven DC motor

Abstract The aim of this contribution is to give a detailed account on the circuit and control design of a buck converter driven DC motor. The steps of design, as for example the choice of the coil, the switching devices employed are discussed at length, all in view of the control objective: tracking control of the DC motors shaft angular velocity. The dynamic system composed from converter/motor is shown to be differentially flat viewed from the angular velocity, which is a flat output. It is thus possible to derive a flatness-based tracking controller which achieves favorable properties like a smooth starting trajectory for the angular velocity.

Nonlinear tracking control of a dc motor via a boost-converter using linear dynamic output feedback

In this contribution a tracking controller for the shaft angular velocity of a DC motor connected to a boost type power converter is designed. This system is not flat and the internal dynamics with respect to the angular velocity are unstable. A linear dynamic output feedback controller is designed which stabilizes the linearized tracking error dynamics about the reference trajectory. To this end, the results in (J. Deutscher, 2002), (F. Antritter et al., 2004) for the design of linear tracking controllers for flat systems are extended to non-flat systems. The differences to the controller design using the state space approach for linear time varying systems are discussed

Robust analysis of flatness based control using interval methods

In this paper a new approach to the robustness analysis of flatness based tracking controllers using interval methods is proposed. This methodology allows us to explicitely determine admissible intervals for the uncertain parameters such that specified error bounds for the state space trajectories are not violated. In contrast to earlier approaches no additional controllers have to be considered to take robustness properties into account. The presented approach also poses no a priori restrictions on the velocity of the reference trajectory. The application of the robustness analysis is demonstrated for a feedforward as well as a feedback tracking controller for the Van de Vusse type continuous stirred tank reactor (CSTR).

Multivariable speed synchronisation for a parallel hybrid electric vehicle drivetrain

In this article, a new drivetrain configuration of a parallel hybrid electric vehicle is considered and a novel model-based control design strategy is given. In particular, the control design covers the speed synchronisation task during a restart of the internal combustion engine. The proposed multivariable synchronisation strategy is based on feedforward and decoupled feedback controllers. The performance and the robustness properties of the closed-loop system are illustrated by nonlinear simulation results.

A toolbox for the analysis of linear systems with delays

This paper considers linear time varying control systems with delays. Roughly speaking, a so called π-flat output of such a system, if it exists, allows to parameterize the states and inputs of the system using derivatives and delays of the π-flat output. Additionally, also predictions of the π-flat output are allowed, which are characterized by a prediction operator π. We present a toolbox for the computer algebra system Maple, which implements the algorithm recently been proposed in [1] for the computation of π-flat outputputs. We also give an equivalent description of hyper-regularity of polynomial matrices using one-sided inverses. This allowed us to replace the transformation to Smith-Jacobson form by the efficient method of row-/column-reduction for checking hyper-regularity. The implementation of the toolbox is illustrated and its application is explained by means of examples.

On Symbolic Computation of Flat Outputs for Differentially Flat Systems

Abstract This contribution deals with the formal computation of so-called flat outputs of nonlinear control systems using a Computer Algebra System. A toolbox is presented which assists the evaluation of the necessary and sufficient conditions for differential flatness derived in Levine (2006) using the formalism of systems on manifolds of jets of infinite order (see e.g. Martin et al. (1997); Fliess et al. (1999)). The functionality of the toolbox is illustrated by means of an example. Copyright

TRACKING CONTROL OF THE ANGULAR VELOCITY OF A DC-MOTOR VIA A BOOST-CONVERTER

Abstract In this contribution the tracking controller design for the shaft angular velocity of a dc motor which is attached to a boost type power converter using linear dynamic output feedback is demonstrated. This is a fairly challenging task due to the fact that the system under consideration is not flat and the angular velocity is a non-minimum phase output. The controller design is based on a differential operator representation of the linearized tracking error dynamics (see (Deutscher, 2002; Antritter et al., 2004; Antritter and Deutscher, 2006)). This approach yields a linear dynamic output feedback of very low order for the stabilization of the reference trajectory. The experimental results approve the favorable properties of the designed controller.

ROBUST FLATNESS BASED CONTROLLER DESIGN USING INTERVAL METHODS

Abstract Flatness based tracking controller design is one of the most important tools for the control of nonlinear systems. However, the tracking performance may become very poor if the actual plant parameters deviate too much from the nominal ones. In this contribution a robustness analysis using interval methods is applied in order to determine an optimal assignment for the desired tracking error dynamics such that the trajectories of the controlled system remain within specified tolerances around the reference trajectories for a maximum uncertainty of the unknown parameters. The robustness analysis is demonstrated for the Van de Vusse type continuous stirred tank reactor (CSTR).

On the computation of π-flat outputs for linear time-varying differential-delay systems

Abstract We introduce a new definition of π -flatness for linear differential-delay systems with time-varying coefficients. We characterize π - and π -0-flat outputs and provide an algorithm to efficiently compute such outputs. We present an academic example of motion planning to discuss the pertinence of the approach.

Flatness based control for electric and hybrid electric vehicle drivetrains

Up to now feedforward controllers are seldomly used for the control of automotive vehicle drivetrains. This is partially due to the fact that this popular approach which is based on the inversion of a nominal model may become rather involved. In this paper we illustrate the simplicity and efficiency of flatness based feedforward controller design for the drivetrains of electric and hybrid electric vehicles.