2002 (Volume 12)
End-Point Control of a Flexible-Link Manipulator Using State-Dependent Riccati Equation Technique
|Alaa Shawky, Andrzej Ordys, Michael J. Grimble and Lykourgos Petropoulakis|
(University of Strathclyde, UK)
The problem of modeling and controlling the tip position of a one-link flexible manipulator is considered. The paper discusses the control strategy based on the nonlinear state Dependent Ricatti Equation (SDRE) design method in the context of application to robotics and manufacturing systems. Lagrangian Mechanics and the Assumed Mode Method have been used to derive a proposed dynamic model of a single-link flexible manipulator having a revolute joint. The model may be used in general to investigate the motion of the manipulator in the horizontal plane rest-to-rest rotational maneuver. The nonlinear SDRE control law is derived as minimizing a quadratic cost function that penalizes the states and the control input torques. Simulation results are presented for a single-link flexible manipulator to achieve a desired angular rotation of the link while simultaneously suppressing structural vibrations, and the effect of payload on the system response and vibration frequencies is investigated. The results are illustrated by a numerical example.
keywords: robotics, control of one-link flexible manipulator, nonlinear state-dependent Ricatti Equation.
Self-tuning LQG control with amplitude-constrained input. Robustness aspects
|Andrzej Królikowski and Tomasz Kubiak|
(Poznań University of Technology, Poland)
Self-tuning tracking control of ARMAX system in the presence of amplitude constrained input is considered. An extension of the result presented in R.R. Bitmead, M. Gevers and V. Wertz: "Adaptive Optimal Control", Prentice Hall International, 1990, is given to the case of piecewise constant set-point. Stability and performance robustness are discussed on the basis of second-order ARMAX systems.
keywords: LQG tracking control, amplitude constraint, self-tuning.
Industrial Petri Nets
(Silesian University of Technology, Poland)
A new class of Petri nets, called "Industrial Petri Nets" (IPN) has been defined in the paper as a special case of Timed Coloured Petri Nets (TCPN). The purpose of IP-nets is modelling manufacturing processes, maintenance and data processing in CIM systems. For the IPN definition the relations between the basic notions of production planning and control were discussed. Thus a reference model for different types of processes and different control methods has been created. As an example the IPN graph of a stamping process in a car factory has been displayed.
keywords: computer integrated manufacturing (CIM), coloured Petri nets (CPN), production planning and control (PPC), discrete process modeling.
The implementation of the example-based machine translation technique for Spanish-to-Polish automatic translation system
(Academy of Mining and Metallurgy, Poland)
High-quality machine translation between human languages has for a long time been an unattainable dream for many computer scientists involved in this fascinating and interdisciplinary field of the application of computers. The developed quite recently example-based machine translation technique seems to be a serious alternative to the existing automatic translation techniques. In the paper the usage of the example based machine translation technique for the development of system, which would be able to translate an unrestricted Spanish text into Polish is proposed. The new approach to the example-based machine translation technique that takes into account the peculiarity of the Polish grammar is developed. The obtained primary results of the development of proposed system seem to be very promising and appear to be a step made in the right direction towards a fully-automatic high quality Spanish-into-Polish machine translation system for unrestricted text.
keywords: natural language processing, computational linguistics, machine translation.
Stability analysis of nonlinear control systems with unconstrained fuzzy predictive controllers
|Piotr Marusak and Piotr Tatjewski|
(Warsaw University of Technology, Poland)
Stability analysis of nonlinear control systems with unconstrained fuzzy predictive controllers using input-output plant models (e.g. DMC, GPC) and nonlinear plants with delays is discussed in the paper. The idea is precisely explained using an example of control systems with fuzzy DMC (FDMC) controllers. The considered FDMC controller is based on analytical formulation of the DMC predictive control algorithm and Takagi-Sugeno fuzzy modeling. The stability analysis of the closed-loop nonlinear control system is based on a transformation of its description to the appropriate state-space form. Then the Tanaka-Sugeno stability criterion can be applied, consisting in solving a set of Lyapunov-type inequalities. The design procedure including the stability analysis is illustrated on examples.
keywords: model predictive control, nonlinear systems, fuzzy systems, stability.
Minimum absolute error classifier design with generalization control
(Silesian University of Technology, Poland)
This paper introduces a new classifier design method, that is based on an extension of the classical Ho-Kashyap procedure. The proposed method uses absolute error rather than squared error to design a linear classifier. Additionally, easy control of generalization ability and outliers robustness is obtained. Finally, examples are given to demonstrate the validity of the introduced method.
keywords: classifier design, robust methods, generalization control.
On the admissible perturbations for discrete systems
|Mostafa Rachik and Ahmed Abdelhak|
(Faculté des Sciences Ben M'Sik, Maroc)
We consider a discrete system described by
with the output function
which is subject to the constraints
is given subset of
. Then we investigate the admissible nonlinear perturbations
, i.e., the ones such that the corresponding perturbed output function
remains in the constraints set
keywords: admissible perturbations, discrete systems, discrete delayed systems, nonlinear perturbations.