• Proceedings of the KIEE Conference
• /
• 2000.11d
• /
• pp.653-656
• /
• 2000

This paper presents an application of $H_\infty$ control design for a magnetic suspension system which has strongly nonlinearity and parameter variations. The designed controller is tested by numerical simulations and experiments.

• Journal of the Korean Data and Information Science Society
• /
• v.20 no.5
• /
• pp.913-917
• /
• 2009

The measures of leverage in linear regression has been extended to nonlinear regression models. We consider several curvature measures of nonlinearity in an estimation situation. The relationship between measures of leverage and statistical curvature are explored in nonlinear regression models. The circumstances under which the Jacobian leverage reduces to a tangent plane leverage are discussed in connection with the effective residual curvature of the nonlinear model.

• 제어로봇시스템학회:학술대회논문집
• /
• 1989.10a
• /
• pp.160-165
• /
• 1989

This paper deals with the robust controller design of robotic manipulator to track a desired trajectory in spite of the presence of unmodelled dynamics in cause of nonlinearity and parameter uncertainty. The approach followed in this paper is based on model reference adaptive control technique and convergence on hyperstability theory but it does away with assumption that process is characterized by a linear model remaining time invariant during adaptation process. A computer simulation has been performed to demonstrate the performance of the designed control system in task coordinates for stanford manipulator with payload and disturbances.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.2E
• /
• pp.20-26
• /
• 2000

A conceptual simplified model of Hartmann-Sprenger tube is suggested and investigated to decouple the regurgitant mode in the present paper. In spite of high nonlinearity, the acoustic behavior of this resonant tube system is dependent on wavelength and depth of the tube. The effect of forcing frequency and tube geometry on jet regurgitant mode are studied and discussed. With a conventional axisymmetric Euler code, sensitive acoustic problems are solved and validated by comparison with analytic theories.

• The Pure and Applied Mathematics
• /
• v.12 no.3 s.29
• /
• pp.179-191
• /
• 2005

In this paper we consider a Dirichlet problem in the unit disk. We show that the equation has a unique or multiple solutions according to the range of the parameter. Moreover, we prove that the equation admits a nonradial bifurcation at each branch of radial solutions.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.405-408
• /
• 2007

Vestibular hair cells, the sensory receptors of vestibular organs, selectively amplify miniscule stimuli to attain high sensitivity. Such selective amplification results in compressive nonlinear sensitivity, which plays an important role in expanding dynamic range while ensuring robustness of the system. In this study, negative stiffness mechanism, a mechanism responsible for the selective amplification by vestibular hair cells, is applied to a simple mechanical system consisting of an array of inverted pendulums. The structure and working principle of the system have been inspired by gating spring hypothesis proposing that opening and closing of transduction channels contributes to the global stiffness of vestibular hair bundle. Parameter study was carried out to analyze the effect of each parameter on the compressive nonlinearity of suggested model.

• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.1850-1851
• /
• 2006

The sliding mode control is acceptable for Autonomous Underwater Vehicle(AUV), since the dynamics of AUV are highly nonlinear and have several parameter uncertainty such as the added mass terms, the hydrodynamic coefficients. The sliding mode control can deal well with nonlinearity of the system and offers a robustness to controller with parameter uncertainty. Since sliding mode control has the defect of chattering problem, only in ideal case the actuator can respond by control law. Therefore we propose the sliding mode control with non-chattering. And computer simulations illustrate the performance of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.206-211
• /
• 1993

This paper presents a new identification method which utilizes fuzzy inference in parameter identification. The proposed system has an additional control loop where a real plant is replaced by a plant model. The control system to be designed is to satisfy the following specifications: 1) It has zero steady-state error. 2) It has adequate damping characteristics. 3) 1),2) satisfied, it has a shortest rise-time. Fuzzy rules describe the relationship between comparison results of the features and magnitude of modification in the model parameter values. This method is effective in auto-tuning because the response of the closed loop is verified. The proposed method is tested in simulation for several plants with high-order lags and dead-times.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.169.1-169
• /
• 2001

In general, for high performance pressure control system, hydraulic system with electo hydraulic servo valve controls flow rate, it contains many nonlinear term like square-root and change of bulk modulus by flow rate. But, DDV(Direct Drive Valve) contains pressure control loop itself, then it can eliminate nonlinearity and achieve linearity for hydraulic system. In this paper, parameter identification method which uses input and ouput data is applied to obtain DDV's mathematical model and parameter assuming that dynamic characteristic of DDV is first order system. Then, the state feedback controller was designed to implement the force control of hydraulic system , and the control performance was evaluated.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.1
• /
• pp.29-37
• /
• 2012

A simple and effective dead time compensation scheme for a PWM inverter-fed permanent magnet synchronous motor (PMSM) drive using the model reference adaptive control (MRAC) and coordinate transformation is presented. The basic concept is to first transform a time-varying disturbance caused by the dead time and inverter nonlinearity into unknown constant or slowly-varying one by the coordinate transformation, and then use the MRAC design technique to estimate this parameter in the stationary reference frame. Since the MRAC scheme is a suitable way of estimating such a parameter, the control performance can be significantly improved as compared with the conventional observer-based method tracking time-varying parameters. In the proposed scheme, the disturbance voltage caused by the dead time is effectively estimated and compensated by on-line basis without any additional circuits nor existing disadvantages as in the conventional methods. The asymptotic stability is proved and the effectiveness of the proposed scheme is verified.