2007 (Volume 17)
Detection of self navigational aids on radar image using ideas from immune systems
(Institute of Navigation and Hydrography, Naval University, Gdynia, Poland)
The problem of continuous position availability is one of the most important issues connected with human activity at sea. Because the availability of satellite navigational systems can be limited in some cases, for example during military operations, we should consider additional methods of acquiring information about ship's position. One of the solutions, which can serve to this purpose, is the method consisting in approximating a position based on a vector of bearings and distances to a set of previously selected navigational aids (superbuoys). Navigational radar is used to fix bearing and distance to every superbuoy, which constitutes an element of the positioning system. The problem is only to distinguish radar echoes of self superbuoys i.e. superbuoys that belong to the system from echoes of other objects. The method proposed in the article can be a solution of this problem. It is an adaptation of r-contiguous-bits scheme borrowed from immune systems. It compares coastlines visible on the radar image from every point suspected to be an echo of the element of the system and pattern coastlines generated from a chart and corresponding to actual components of the system.
keywords: detection, maritime navigation, immune systems
Non-iterative LMI output feedback controller design
|Vojtech Vesely and Danica Rosinova|
(Institute of Control and Industrial Informatics, Slovak University of Technology, Bratislava, Slovakia)
The paper addresses the problem of output feedback controller design for linear continuous and discrete-time systems using non-iterative linear matrix inequality (LMI) procedure with guaranteed cost. Numerical examples are given to illustrate the effectiveness of the proposed method.
keywords: static output feedback, guaranteed cost
A novel method for vibration surveillance during high speed ball end milling of flexible details
|Krzysztof J. Kalinski|
(Faculty of Mechanical Engineering, Gdansk University of Technology, Gdansk, Poland)
The paper is devoted to vibration surveillance of unsteady systems, which are idealized by the finite element method. Ball end milling of flexible details is observed very frequently in case of modern machining centres. Tool-workpiece relative vibration may lead to a loss of stability and cause a generation of self-excited chatter vibration. The paper proposes the method of minimizing vibration level, based on matching the spindle speed to the optimal phase shift. As result of a milling process modeling, we get a hybrid system in which are separated:
- Modal subsystem. It is a stationary model of one-side-supported flexible detail.
- Structural subsystem, i.e. non-stationary discrete model of ball end mill and cutting process.
- Connective subsystem as conventional contact point between tool and workpiece.
The method has been developed with success. Modal model of the workpiece allowed us to determine an optimal spindle speed. Modal assurance criterion (MAC) has been assessed and confirmed good agreement between experimental and theoretical modal model. Results of computer simulation, as well as - of experimental investigation on the Mikron VCP 600 milling machine mean to be in support. Hence amplitude values for chosen optimal spindle speed became relatively smaller than for the other ones.
keywords: high speed cutting, dynamics, vibration control, hybrid systems
Start-up of DC drive under load
|Grzegorz Sieklucki, Tadeusz Orzechowski, Rajmund Sykulski and Boguslaw Szostak|
(AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, Krakow, Poland)
The work describes the use of form criterion for parametric optimization of current regulator. Droop of the control system with respect to load is proved. A method of correction of the control system parameters is proposed in the case of drive start-up with non-zero load torque. Simulation results are included.
keywords: DC drive, cascade control structure, form criterion, load torque
A methodology for the design of a models set of light-weight robots components
(Department of Electrical Engineering and Informatics, Technical University of Rzeszow, Poland)
The paper gives an overview of precise mathematical modeling of light-weight robots components. Derived set of components contains dynamic models obtained with finite element method using Legendre polynomials and models of actuators (PWM power amplifiers), transmitters (harmonic drive and tooth-belt gearboxes) and sensors (PVDF, vision sensor and rotary encoder). The proposed gearboxes models taking into account such phenomena as: hysteresis, friction as well as torsional and longitudinal flexibility. The hysteresis has been modeled as weighted combination of individual Preisach cells to form a global operator. Friction model includes a lubricated contact force assuming dynamic behavior developed by Bliman and Sorine. The harmonic drive model describes the flexspline flexibility, that produces substantial transmission torsion. The original proposition assumes that the flexspline can be modeled as cylindrical shell FEM model based on 16 directional mesh. All analytical operations of process design stage have been done using the Maple symbolic language. The paper describes also the developed software which has been prepared as the dynamic library (C++/Cg) and as the s-function forms (for Matlab/Simulink). Both, the result of the theoretical analysis and the written software are used in ongoing research to develop variant of MRAC-type controllers for vibration cancelation.
keywords: light-weight robots, links and joints flexibility, mathematical modeling, computer simulations
GA-JPDA and fuzzy data association algorithms coupled with IMM-PF estimator for highly maneuvering multiple-target tracking
|Mohand Said Djouadi and Yacine Morsly|
(Robotic Laboratory, Ecole Militaire Polytechnique, Algiers, Algeria)
In this paper, we present filtering algorithm to perform accurate estimation in jump Markov nonlinear systems, in case of multi-target tracking. With this paper, we aim to contribute in solving the problem of model-based body motion estimation by using data coming from visual sensors. The Interacting Multiple Model (IMM) algorithm is specially designed to track accurately targets whose state and/or measurement (assumed to be linear) models change during motion transition. However, when these models are nonlinear, the IMM algorithm must be modified in order to guarantee an accurate tracking. In order to deal with this problem, the IMM algorithm was combined with the Unscented Kalman Filter (UKF). Even if the later algorithm proved its efficacy in nonlinear model case, it presents a serious drawback in the case of non Gaussian noise. To deal with this problem we propose to substitute the UKF with the Particle Filter (PF). To overcome the problem of data association, we propose the use the JPDA approach. To reduce the computational burden of this technique, we choose firstly the most likely feasible events by applying a Genetic Algorithm; finally the derived algorithm from the combination of the IMM-PF algorithm and the GA-JPDA approach is noted GA-JPDA-IMM-PF. To insure a more reduction of the computation complexity of the latter data association approach, we propose a fuzzy data association approach which we combine with the IMM-PF estimator, the derived algorithm is noted fuzzy IMM-PF. Finally the two algorithms are compared according to the target loss rate inferred by each of them.
keywords: estimation, particle filtering JPDA, genetic algorithm, multi-target tracking, fuzzy logic, visual servoing, data association
Automatic balancing of rotating systems: control algorithm's implementation on FPGA systems
|Michal Manka, Grzegorz Karpiel and Tadeusz Uhl|
(Department of Robotics and Mechatronics, AGH-UST, Krakow, Poland)
The paper deals with automatic balancing of rotating systems during operation. After discussion of techniques' principles, balancing mechanisms designed on `AGH' University of Science and Technology are presented. After introduction into active balancing control algorithms, test results obtained during experiments are presented. The paper presents comparison between implementation process and results of experiments taken with two different control algorithms' implementation platforms: dSPACE rapid prototyping system and ALTERA FPGA system. The paper ends some conclusions about taken experiments and further works directions are presented.
keywords: automatic balancing, FPGA systems, SoPC
Active vibration reduction system with energy regeneration
|Janusz Kowal and Andrzej Kot|
(Department of Process Control, University of Science and Technology AGH-UST, Krakow, Poland)
Studies of the systems with energy regeneration have been carried out for years, since they primarily cover the assemblies with electrodynamic actuators. The paper addresses the issue of active reduction of mechanical vibration using DC motor as the actuator. Testing procedure is aimed to assess potential use of those assemblies in a different frequency band and force range than in electrodynamic actuators. The paper explains the operating principle of the system. The tested vibration reduction system is the physical model of 2 DOF suspension. Initial analysis has been conducted to explore the potential use of the energy produced by the vibration of sprung mass in the second degree of the suspension system in range of high frequencies, for power-supply to the active component incorporated in the same suspension degree in low frequencies range. Results of the experiments revealed that the mechanical parameters of the system can be selected in such a way that for specific interfering signals the accumulated energy should be at least equal to the energy used up by the system.
keywords: energy regeneration, active control, isolation, linear motor