• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.128-135
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• 2006

This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts tue vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.89-97
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• 2017

The tuned mass damper (TMD) system was first proposed as an efficient vibration control method for high-rise buildings, and multiple TMD (MTMD) system was then proposed for the purpose of improving the robust performance. Thereafter, the active TMD (ATMD) is proposed to improve the vibration control performance over the TMD and MTMD systems. However, this system may experience an system-instability problem in case of the actuator malfunction. In order to overcome such limitations of actuator malfunction causing the instability of the structural system, in this study, we investigate the feasibility of the multiple ATMD (MATMD) system that facilitates both advantages of the MTMD and ATMD. Numerical example demonstrates that, when the proposed system is designed to have the same capacity as the ATMD, it shows a similar control performance to the ATMD, but also has very good adaptive control performance against the emergency situations such as actuator failures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.196-202
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• 2002

In this work, we propose a new type of HDD suspension featuring shape memory alloy (SMA) actuator in order to prevent the contact between the slider and disk. The principal design parameters are obtained from the modal analysis using finite element analysis, and then the dynamic model is established to formulate the control scheme for Non-Contact Start/stop mode drive. Subsequently, a robust H$\_$$\infty$/ control algorithm is designed by integrating experimentally-Obtained SMA actuator dynamics to the proposed HDD suspension system. The controller is empirically realized and control results for the load/unload profiles are presented in time domain. In addition, the contact signal between the slider and disk is measured by the electrical resistance method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.1 s.118
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• pp.24-32
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• 2007

This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts the vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.805-815
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• 1992

In this paper, robust decoupling control scheme of miftivarlable systems Is studied. Design methods for Input-Output decoupling systems with robustness against signal failure In arbitrary feedback loop or actuator loop Is suggested based on the Riccati type matrix equation and state feedback, and is simulated In Turbo-Generator systems with B-Input, 2 output. The results of simulation represents the decoupled and stable response against the failure of signal In sensor or actuator loop. However, the system designed by conventional ,it ate feedback shows the unstable response. This method Is applied for robust decoupling control of the complicated multivariable systems.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.68-75
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• 2000

The flexibility of a manipulator inevitably yields vibration at the end effector. In this work, position and vibration control for a flexible robot arm was studied using a separate voice coil type actuator to raise the accuracy and speed of end tip. A flexible robot arm with a tip mass is modeled as an Euler-Bernoulli beam. An $H_$\infty$$ controller is adapted to get a robust control against unmodeled higher-order mode vibration, output sensor noise, and etc. Simulations and experiments show that the modeling of the system is acceptable and robust vibration control is also achieved.

• Transactions on Control, Automation and Systems Engineering
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• v.1 no.2
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• pp.121-127
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• 1999

In this paper, we present robust reliable H$\infty$ controller design methods of continuous and discrete uncertain time delay systems using LMI (linear matrix inequality) technique, respectively. Also the existence conditions of state feedback control are proposed . Using some changes of variables and Schur complements, the obtained sufficient conditions are transformed into an LMI form. The closed loop system by the obtained controller is quadratically stable with H$\infty$ norm bound for all admissible uncertainties, time delay, and all actuator failures occurred within the prespecified set. We show the validity of the proposed method through numerical example.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.479-486
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• 1998

In this paper, the design and the implementation of a robust adaptive controller for trajectory tracking of robot manipulator is presented. The proposed control scheme ensures that tracking errors are converged to some boundaries in the presence of a state-dependent input disturbances as well as the ideal case without any prior knowledge of the robot manipulator parameters. The 3 DOF robot manipulator including actuator dynamics is used for the implementation of the proposed control scheme. The experimental results show that the proposed control scheme is valid for trajectory tracking of the robot manipulator.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1834-1847
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• 2006

A robust minimum-time control (RMTC) strategy is addressed and it is extended to the dual-stage servo design. Rather than conventional switching type sub-optimal controls, it is a reference following control approach where the predetermined minimum-time trajectory (MTT) is tracked by the perturbation compensator based feedback controller. First, the minimum-time trajectory for a mass-damper system is derived. Then, the perturbation compensator to achieve robust tracking performance in spite of model uncertainty and external disturbance is suggested. The RMTC is also applied to the dual-stage positioner which consists of coarse actuator and fine one. To best utilize the actuation redundancy of the dual-stage mechanism, a null-motion controller to actively regulate the relative motion between the two stages is formulated. The performance of RMTC is validated through simulation and experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.92-99
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• 2001

This paper presents a simulation study using a robust controller to improve the roll stability of a vehicle. The controller is designed in the framework of an output feedback H$_{\infty}$ control scheme based on the 3DOF linear vehicle model, solving the mixed-sensitivity problem to guarantee the robust stability and disturbance rejection with respect to parameter variations due to laden and running vehicle conditions. In order to investigate the feasibility of the active roll control system in a real car, its performance is evaluated by simulation in a 10DOF full vehicle model with actuator dynamics and tire characteristics.