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Laguerre based design of fractional-order PD controller |
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Mohammad Tabatabaei, Romina Salehi(Khomeinishahr Branch, Islamic Azad University, Iran, Islamic Republic of) |
| In this paper, a fractional-order PD controller based on Laguerre orthonormal functions is constructed for commensurate fractional order systems. The main idea is to expand the transfer functions of the fractional order plant, the desired open loop gain, and the fractional order PD controller in terms of their Laguerre basis functions. The fractional order PD controller coefficients are obtained by matching the first two coefficients of the open loop gain Laguerre series with the desired one.The numerical simulations demonstrate the performance of the proposed fractional order PD controller. |
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Reset Control of Pressure-Drop Oscillations in Boiling Micro-Channel Systems |
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Masataka Iwai(MHI Nuclear Systems and Solution Engineering Co.,Ltd., Japan), Toshimitsu Ushio(Osaka University, Japan) |
| Boiling flow instabilities can occur in the cooling systems with micro-channel heat sinks. These pressure-drop oscillations are limit cycles. We model the system by a van der Pol equation. Using a describing function, we approximate the pressure-drop oscillation in the boiling micro-channel system controlled by a reset controller. Then we obtain a control parameter region where the pressure-drop oscillation is eliminated by the controller．By simulation, we also show that the pressure-drop oscillation is eliminated
by the reset controller. |
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Proposal of Vibration Control by Varying Stiffness in Repulsive Magnetic Bearing Using the Motion Control of Permanent Magnets |
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Takeshi Mizuno, Yuji Ishino, Masaya Takasaki, Masayuki Hara, Daisuke Yamaguchi(Saitama University, Japan) |
| The applicability of switching stiffness control is investigated for reducing radial vibration in a repulsive magnetic bearing using the independent motion control of the stator magnets. The magnetic suspension system using repulsive force between permanent magnets is inherently stable in the normal direction. However, damping in the normal directions is poor so that vibration is easily induced. It is proposed to attenuate such vibration by using switching stiffness control in a repulsive magnetic bearing using the independent motion control of the stator permanent magnets. |
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An Improved Algorithm for Computing Transfer Function Matrices of Descriptor Systems |
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Akitoshi Mutsuro, Masanobu Koga(Kyushu Institute of Technology, Japan) |
| In this paper, we propose a numerically reliable algorithm for computing the transfer function matrix of a descriptor system. The conventional algorithm makes use of QZ decomposition which can be used for computing generalized eigenvalues of a matrix pencil. However, when matrices have the repeated eigenvalues, numerical errors can be generated. Furthermore, as the algorithm is based on power method, the convergence time would be slower at that time. Since our algorithm avoids QZ decomposition, the repeated eigenvalues does not matter. Moreover, the computational time can be estimated. |
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Robust PID Controller Design Using Convex-Concave Optimization: Application to an Unstable System |
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Chawalit Thabthimratthana, Surachai Saelim, Suchol Tiewcharoen, Sudchai Boonto(King Mongkut's University of Technology Thonburi, Thailand) |
| This paper shows a PI with phase-lead controller design using convex-concave optimization. The phase-lead term is added to reduce a high frequency measurement noise effect. By fixing all parameters of the phase-lead part, the optimization program searches the remain parameters subject to robustness constraints. The optimization constraints are
functions in a frequency domain. The design problem can be solved by frequency gridding on a software package CVX. Experiments on an unstable magnetic levitation system are presented. |
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Dynamics and Vibrational Control of an Underwater Inverted Pendulum |
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Saqib Hasnain, Keum-Shik Hong(Pusan National University, Korea) |
| This paper discusses the dynamics and vibrational control of an underwater inverted pendulum system for the purpose of stabilization at upward unstable equilibrium position. We have used standard Lagrangian mechanics to model the dynamic motion of an underwater inverted pendulum system. Averaging method has been used to get the approximate solution of an underwater inverted pendulum system. The condition for stability of an underwater system is also presented. Furthermore, stability analysis in terms of lower stability boundary for an underwater inverted pendulum system is presented. |
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