1,721,030 research outputs found
POG modeler: The web power-oriented Graphs modeling program
No full textIn this paper the Power-Oriented Graphs (POG) technique is introduced and a new modeling program named “POG Modeler”, freely available on the web, is presented. In the POG Modeler program the physical systems can be defined graphically using an ascii commend-line interface and referring to predefined graphic symbols. The POG Modeler automatically analyzes the given physical system and provides the following outputs: 1) the differential equations of the given system in symbolic form: 2) The POG block scheme of the considered system; 3) the Simulink block scheme of the given system ready for the Matlab environment. The POG systems are simple block schemes that can be easily used also by beginners
Third order trajectory generator satisfying velocity, acceleration and jerk constraints
No full textA third order continuous-time trajectory generator useful in motion control systems is presented. The proposed non linear system receives as input a standard reference signal r(t) (step, ramp, etc.) and provides as output a smooth signal x(t) satisfying the following constraints on velocity, acceleration and jerk: Vmin ≤ ẋ(t) ≤ Vmax, Ami ≤ ẍ(t) ≤ Amax and |x| ≤ U. The generated trajectory tracks the reference signal in minimum time compatible with the constraints on the time-derivatives. The performance of the presented trajectory generator is tested in simulation
Fast 4-way switching valve modeling by using Power Oriented Graph technique
No full textThis paper describes the modeling and simulation of a fast 4-way switching valve by using an energetic approach technique called Power Oriented Graph. The presented model is simple, characterized by a reasonable number of parameters and suitable for the control system design. The estimation of the system parameters has been obtained by using experimental data and optimization algorithms in a Matlab co-simulation environment. A good matching between the experimental and simulated data has been obtained. This matching shows that the considered simple model predicts correctly the time response of the 4-way switching valve. © 2012 IFAC
New formulae and graphics for compensator design
No full textIn this paper, two simple 'inversion formulae' for analytic design of lead and lag compensators are proposed, and a graphical interpretation for them is given. Their use in connection with both Bode and Nyquist diagrams is pointed out with some numerical examples
Positioning trajectory generator with nonlinear constraints
No full textA smooth trajectory generator useful in motion control systems is presented. The considered generator is a second order nonlinear system which receives as input a step reference signal and provides as output a smooth reference signal satisfying proper nonlinear constraints on the state variables as, for example, bounds on the first time-derivative ẋ of the output x, or bounds expressed in the form |ẍ| ≤ UM(x). The imposed constraints can also be changed during system operation without modifying the system stability. Moreover, almost minimum time response is ensured with guaranteed no overshoot. Finally, the performance of the the nonlinear generator is tested through simulation
Nonlinear frictions identification in time-variant automotive systems
No full textIn this paper, the problem of nonlinear frictions identification in a class of nonlinear systems embedding different automotive case studies is addressed. The power-oriented modeling of the system dynamics is first addressed. Next, the identification of the nonlinear friction coefficients representing the system losses, which can have different symmetric or asymmetric characteristics, is addressed using a parabolic interpolation. To show the versatility of the procedure, two automotive physical systems composing the vehicle powertrain are considered as case studies for the identification, namely a Full Toroidal Variator and a Gearbox. The novelty of this work consists of the proposal of a general approach to model nonlinear frictions in a wide class of automotive systems, and in their identification using the proposed least-square-based algorithm. With reference to the latter, we also provide a necessary condition to avoid the rank deficiency problem and considerations about how to increase the identification accuracy
Dynamic models of thermal systems using an energy-based modeling approach
No full textThe aim of this work is to give a new approach to obtain compact dynamic thermal models suitable for a variety of systems where the heat transfer can be caused by conduction, internal convection (not at the boundary), and evaporation/condensation of water. The structural properties of the proposed dynamic model are presented and discussed in this paper. These properties guarantee conservation of energy and mass within the system, thus giving a good confidence in the correctness of the model. This paper shows that the proposed model has a simple structure, can be easily implemented in SIMULINK, and provides simulation times much shorter compared with those usually obtained using CFD programs. The proposed model proves to be suitable for real-time simulations and for control design purposes
Modeling and electronic control of a lighting system
No full textIn the paper, the dynamic model of a lighting system is taken into account and control, strategies for controlling the amplitude of the load voltages and for minimizing the neutral current are presented. All the main components of the electronic system (supply, autotransformer, rectifier, capacitive filter, inverter, etc.) have been modeled in details by using the graphical modeling technique named Power-Oriented Graphs. Simulation results show the effectiveness of the presented control strategies. © 2002 IEEE
Atomic size adjusted calculation of the magnetically induced current density
No full textThe continuous set of gauge transformations for calculations of magnetically induced current densities has been investigated in details. Atomic size adjustments have been inserted employing the Bragg-Slater atomic radii and considering the bond critical points determined by the electron density distribution. By means of extensive calculations on a set of selected molecules and adopting a well suited series of basis sets, it is shown that these adjustments provide a systematic improvement of the approximate current density and related properties such as the magnetic shielding constants, which are calculated by integration for different kinds of nuclei and in nucleus independent positions
Hypertext-based on-line guide to electrical measurement laboratory practice with instruments simulator
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