Showing papers by "Hyunseok Yang published in 2002"

Robust roll control of a vehicle: Experimental study using a hardware-in-the-loop set-up

Abstract: This paper presents a simcopy IMulation and experimcopy IMental study of a vehicle with an electrically actuated roll control system. The controller is designed in the framework of an output feedback H∞ control scheme based on the three-degree-of-freedom linear vehicle model. Various parameters which affect the roll dynamics are considered for robust stability and disturbance rejection. In order to investigate the feasibility of the active roll control system, its performance is evaluated by simcopy IMulation in a full vehicle model with non-linear tyre characteristics. After that, an electrically actuated roll control system is devised, which imcopy IMproves the high frequency isolation during inoperative periods. Finally, its performance is investigated by experimcopy IMental work using a hardware-in-the-loop set-up with the devised control system. Language: en

Swing-arm-type PZT dual actuator with fast seeking for optical disk drive

Abstract: In this paper, a swing-arm-type dual positioning mechanism using a voice coil motor (VCM) and bimorph PZT actuators is proposed for the possible application to the future optical disc drive actuator. A VCM is used as a coarse motion actuator, and a set of piezoelectric actuators is used for fine motion. The two pairs of PZT actuators are arranged in parallel and are carefully designed to deflect in `S' shape such that tension and compression forces are generated simultaneously and thus the hysteresis is minimized. The static and dynamic analyses are performed and the parameter studies on the key dimensions of the set of PZT actuators are investigated. For fast seeking motion, time optimal control scheme combined with PD algorithm is adopted for the fast seeking motion of VCM. Positive position feedback (PPF) control is used to suppress residual vibration for the PZT actuator beams by activating it at the end of VCM swing motion. The feasibility of the suggested actuator system and the control scheme is demonstrated through simulations and experiments.

A study on singularity avoidance and robust control of redundant robot

Abstract: Up to the present, a number of performance indices have been proposed for measure of dexterity of manipulators. There are many problems connected to the physical and mathematical meanings of these measures. In this paper, a new performance index considering aspect maintenance, computational burden, representation of an identical unit without regard to the robot and the effectiveness of the algorithm is proposed. This performance index is called the reduced minor index. Inverse kinematics is indispensable to robot control. The singularity-robust inverse is used and it offers a feasible motion close to the desired trajectory even at or in the neighborhood of singular points. Control of the redundant robot utilizing the upper reduced minor index and singularity-robust inverse is applied to the a 4 DOF wire-driven robot. The effectiveness of the proposed control algorithm is illustrated with simulation and experiment results.

Robust Vibration/Force Control of a 2 D.O.F. Arm Having One Flexible Link with Artificial Pneumatic Actuators

Abstract: A flexible link of a manipulator has an advantage over a rigid link in the sense that, not only is it light-weighted and thus can move fast using a small-sized actuator, but also that it is safer w...

Investigation of Dynamic Absorbing System in the Gas-operated Gun with High Transmitted Shock Force

Abstract: In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

Design, dynamic analysis and control of milliactuator embedded suspension for dual-stage actuator system in hard disk drives

Abstract: To achieve higher track density of HDDs, a new dual-stage actuator system, based on suspension, is proposed, with a design parameter study and sensitivity analysis through FEM. Based on simulation results, the prototype milliactuator embedded suspension is fabricated and experiments are carried out to identify the dynamic characteristics. It is confirmed that the suggested suspension has the structural qualifications for fine tracking as a secondary actuator, high-shock resistance and flying stability. Using the new dual-stage actuator, the attenuation related to disturbances is examined by a classical control scheme with a systematic approach. In the decoupled master-slave control structures, the attenuation is increased at all frequencies under the servo bandwidth compared with the single-stage control.