2007 (Volume 17)
Reachability and controllability to zero of cone fractional linear systems
(Bialystok Technical University, Faculty of Electrical Engineering, Bialystok, Poland)
A new class of cone fractional linear discrete-time systems is introduced. Necessary and sufficient conditions for the reachability and controllability to zero of the cone fractional systems are established.
keywords: cone fractional system, linear, discrete-time systems, controllability to zero, reachability
Application of machine learning and soft computing techniques in monitoring systems' data analysis by example of dewater pumps monitoring system
(Institute of Computer Sciences, Silesian University of Technology, Gliwice, Poland, and Center for Mining Electrification and Automation EMAG, Katowice, Poland)
Application of machine learning method for creation of equipment diagnostic model is presented in the paper. Dewater pump working in abyssal mining pump station has been chosen as the illustrative example. In the second section, dewater pumps monitoring system is presented, and necessity of the pump diagnostic model creation is justified. Next sections present application of data clustering algorithm and algorithm of decision trees induction. Methods of reduction the get diagnostic model is also developed. The reduction leads to more legible data models. Results of analysis done for two different type of pumps are presented in the last part of the paper.
keywords: equipment diagnostic, data clustering, classification, decision trees, decision rules, rules postprocessing
Active control of two degrees-of-freedom building-ground system
|Jan Awrejcewicz and Pawel Olejnik|
(Technical University of Lodz, Department of Automatics and Biomechanics, Lodz, Poland)
The presented idea of active control of buildings is valid for the general concept of stabilization of some constructions subjected to an excitation coming, for instance, from earthquakes. The problem is analyzed in a two case studies describing not excited and externally loaded two degrees-of-freedom dynamical system. 2-DOF linear system is used to model the building-ground interactions. Algorithm that actively controls the system has been implemented and tested as well. The task finally reduces the investigations conducted in the work to estimation of the control force which could guarantee the sufficient minimization of the cost function proposed. On the basis of both analytical derivations and numerical analysis performed a few time histories of convergence of control force, components of the matrix of gain and accelerations of system masses have been illustrated and shortly described.
keywords: active control, constructions stabilization, 2-DOF dynamical systems
Decentralized direct adaptive fuzzy control of non-linear interconnected MIMO system class
|Abdelhalim Tlemcani, Hachemi Chekireb, Mohamed Seghir Boucherit and Salim Labiod|
(Ecole Nationale Polytechnique, Laboratoire de commande des processus, Algers, Algeria)
In this paper, we propose a decentralized direct adaptive fuzzy control method for a class interconnected MIMO non linear plant encountered mainly in robotics. The establishment of the control law introduces very simplest assumptions. Indeed, the functions incorporating the plant dynamic must be continuous and the interconnection terms are bounded by unknown bounds. The fuzzy direct adaptive law is designed to compensate for the interconnections effect and to ensure the closed-loop stability, convergence of the controlled outputs and `boundedness' of adaptation parameters. The proposed method is tested by simulation on the robot Puma 560. In this test the robot is controlled in the operational space as that the robot tip follows a prescribed curve on the sphere where the orientation of the last link (sixth) is maintained radial related to the center of this sphere.
keywords: interconnected MIMO systems, direct adaptive control, fuzzy systems, Lyapunov function, robot Puma 560
On the quasi optimal distribution of PZTs in active reduction of the triangular plate vibration
(Laboratory of Acoustic, Technical University of Rzeszow, Rzeszow, Poland)
(Institute of Technology, University of Rzeszow, Rzeszow, Poland)
Active reduction of transverse vibration of the triangular plate is considered. The C-F-F boundary conditions are imposed. The plate is excited with harmonic acoustic wave. Since it is unsymmetrical boundary problem, the places of bonded PZTs are not obvious. To solve the problem it is based on an idea, that PZTs should be attached at points in which the curvatures of the surface locally take their maximum (quasi-optimal places). Numerical experiments are performed to confirm the validity of the idea. The bending moment and shearing force at the clamped side are calculated for two cases. First case when PZTs are attached at quasi-optimal places and second one, when PZTs are somewhat shifted. The numerical calculations show that better results are obtained at the first case. It confirms the validity of the idea of quasi-optimal distribution of PZTs on the triangular plate surface in the vibration reduction problem.
keywords: triangular plate, PZT (Piezoelectric Zirconate Titanate), C-F-F (Clamped-Free-Free) boundary condition, active vibration reduction
Nonlinear control design of active suspension based on full car model
|N. Lagraa, D. Boukhetala, and F. Boudjema|
(Laboratoire de Commande des Processus, Ecole Nationale Polytechnique, Alger, Algerie)
(Centre de Recherche en Atomatique de Nancy (CRAN UMR 7039), Nancy-University, CNRS, Nancy, France)
This paper develops a nonlinear backstepping design scheme for the active control of vehicle suspension systems using a nonlinear full car model with seven degrees of freedom. The non-linear control law is designed to improve ride comfort and reduce the displacement and the acceleration of the sprung mass in the heaving, rolling, and pitching directions. To demonstrate the effectiveness of the proposed control strategy, several simulations are performed on the nonlinear system. They show that active suspension based on backstepping scheme gives superior performances over passive suspension.
keywords: active suspension, backstepping design, nonlinear control, full-car model
Optimal control of active rotor suspension system
|Zdzislaw Gosiewski and Arkadiusz Mystkowski|
(Bialystok Technical University, Faculty of Mechanical Engineering, Department of Automatics and Robotics, Bialystok, Poland)
In the paper active magnetic bearings system was used for non-contact suspension of a rigid rotor. Optimal robust control method was applied to stabilize and reduce the rotor vibrations. The rotor is supported by two radial heteropolar magnetic bearings and additionally with one axial passive bearing with permanent magnets. The position of the rotor was measured in two radial directions of each active magnetic bearing and in axial direction of the passive magnetic bearing by the eddy-current sensors. The power amplifiers (PWM) were used to generate a current control signals. For pre-investigations a simple local PID controllers were designed. The PID controllers were used to stabilize nominal model of unstable open-loop system. Based on the performances of the PID closed-loop system the H-infinity optimal control laws were derived. The robust controllers were designed for augmented model of the plant. Next, the computer simulations and experimental investigations were carried out. The robust controller was designed according to Safonov, Limebeer and Chiang formulae. The control algorithm was implemented in a digital signal processor. The experimental and simulation results show the magnetic suspension system has good transient responses and tracking abilities. The H-infinity controller ensures the robust performance and stability of the closed-loop system in spite of disturbances and good vibration compensation.
keywords: robust control, H_infinity-norm, active magnetic suspension, heteropolar magnetic bearing, vibration compensation