• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.6
• /
• pp.820-828
• /
• 2011

Energy saving is one of the most important factors for profits in marine transportation. In order to reduce the specific fuel oil consumption, the ship's propulsion efficiency must be increased as much as possible. The propulsion efficiency depends upon a combination of propulsion engine and propeller that has better efficiency as lower rotational speed. As the engine has lower speed the variation of rotational torque become larger because of the longer delay time in fuel oil injection process. In this study, robust control theory is applied to the design of engine speed controllers which are sub-optimal $H_{\infty}$ controller, $H_{\infty}$ loop-shaping controller and ${\mu}$-synthesis controller considering robust stability and robust performance. And the validity of these three controllers is investigated through the results of computer simulation.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1897-1900
• /
• 2004

In recent years, a lot of industrial equipments have serial communication channel such as FieldBus (CAN, Profibus, etc.) or Ethernet that provides real time communication between industrial equipments. Theses applications include gantry crane, robot, chip mounter, etc.. In this paper, we discuss the synchronization technique for networked multi-motor systems where controllers (commercial servo amps) are distributed and interconnected by CAN (Controller Area Networks). We first describe the equivalent model for the individual servo-amp and motor using the frequency response. We design the $H{\infty}$ controller for motion synchronization. Finally, the synchronization technique using the equivalent model and the $H{\infty}$ controller is verified by the simulation and the experiment.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.75.1-75
• /
• 2001

In this paper, we provide the synthesis of non-fragile H$\infty$ output feedback controllers for linear systems with affine parameter uncertainties, and dynamic output feedback controller with structural uncertainty. The sufficient condition of controller existence, the design method of robust and non-fragile H$\infty$ output feedback controller, and the region of controllers which satisfies non-fragility are presented. Also using some change of variables and Schur complements, the obtained condition to a compact set. We show that the resulting controller guarantees the asymptotic stability and disturbance attenuation of the closed ...

• Journal of Advanced Marine Engineering and Technology
• /
• v.20 no.3
• /
• pp.144-153
• /
• 1996

The magnetic levitation system has many advantages, such as little friction, no lubrication, no noise and so on. For this reason, the magnetic levitation system is utilized in the magnetic bearing of high-speed rotor. The method to obtain magnetic force is both the repulsive suspension method and the attraction suspension method need a stabilizing controller because it is a unstable system in natural. This paper presents the design of robust stabilizing servo controller in spite of being the model uncertainties in the magnetic levitation system by $\textit{H}_{\infty}$ control theory using the free parameter. And we investigated the validity of a designed controller through results of the simulation and the actual experiment.

• 제어로봇시스템학회:학술대회논문집
• /
• 1998.10a
• /
• pp.151-156
• /
• 1998

In this paper, we present new control method for robot manipulators. The design objective can be the implementation of minimax controller with H$_{\infty}$ performance via LMI approach to guarantee the robustness and to obtain the exact tracking performance for robot manipulators with system parameter uncertainty and exogenous disturbance. We show that the Algebraic Riccati equation (ARE) which is needed for the construction of H$_{\infty}$ controller can be recast into the Algebraic Riccati Inequality (ARI) and the optimal control gain can be obtained by convex optimization method. Then, we will apply the proposed controller to rigid robot manipulators for verifying the performance of our controller.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.4 s.175
• /
• pp.1065-1074
• /
• 2000

A robust nonlinear $H_2$/$H_{\infty}$ control method for a parallel inverted pendulum with structured perturbation and dry friction is proposed. By the random input describing function techniques, the nonlinear dry friction is approximated into the quasi-linear system. Introducing the quadratic robustness theorem, the robust $H_2$/$H_{\infty}$ control system is constructed for the quasi-linear perturbed system. But it is difficult to design a controller due to the nonlinear correction term in Riccati equation. With some transformations on the Riccati equation containing nonlinear correction term, the design of the robust nonlinear controller can be done easily. Hence when the stiffness and mass of the parallel inverted pendulum vary in certain ranges, the proposed control scheme has the robustness for both the structured perturbation and dry friction. The results of computer simulation show the effectiveness of our proposed control method.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1981-1986
• /
• 2004

In this study, the basic motor control system had been investigated. The controller for this study consists of two main parts, a feedforward controller part and a feedback controller part. Each part will deals with different control problems. The feedback controller deals with robustness and stability, while the feedforward controller deals with response speed. The feedforward controller, used to solve the tracking control problem, is adaptable. To make such a tracking perfect, an adaptive law based on Feedback Error Learning (FEL) is designed so that the feedforward controller becomes an inverse system of the controlled plant. The novelty of FEL method lies in its use of feedback error as a teaching signal for learning the inverse model. The theory in $H^{\infty}$-Control is selected to be applied in the feedback part to guarantee the stability and solve the robust stabilization problems. The simulation of each individual part and the integrated one are taken to clarify the study.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.44-47
• /
• 1996

An optimal preview controller based on the discrete-time $H_{.inf}$ control is presented. The preview controller is synthesized by considering the bounded unknwon disturbances as well as previewable commands and disturbances. The controller derivation procedure is analogous to the LQ-based scheme. The designed preview gain matrix has a similar structure as the LQ-based one. As the infinity norm .gamma. of the transfer function matrix tends to .inf., the preview gains obtained by $H_{\infty}$ control method approach to the gains by the LQR. The LQ-based preview gains are verified to be subsets of the $H_{.inf}$ -based preview gains..

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.37 no.4
• /
• pp.1-10
• /
• 2000

This paper deals with an H$_{\infty}$ output feedback control problem for linear systems with commensurate time delay in both state and input variables. The proposed output feedback controller also has commensurate time delay terms in the controller state. The controller can be synthesized based on the solution of the linear matrix inequalities(LMI) which can be easily solved using the convex optimization method. In order to demonstrate the efficacy of the proposed method, numerical examples are presented.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1304-1307
• /
• 1996

In this paper, we present a robust Two Degree of Freedom (TDF) $H_{\infty}$ controllers for a missile system. The feedback controller is designed to meet robust stability and disturbance rejection specifications while the prefilter is used to improve the robust model matching properties of the closed loop system. As the perturbed model, we use the normalized coprim factor perturbations. These controllers are designed using $H_{\infty}$ optimization procedures, and applied to a missile model via simulation.