• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.284-290
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• 2012

In this research, a new type of haptic master device using electrorheological(ER) fluid for minimally invasive surgery(MIS) is devised and control performance of the proposed haptic master is evaluated. The proposed haptic master consists of ER bi-directional clutch/brake for 2 DOF rotational motion(X, Y) using gimbal structure and ER brake on the gripper for 1 DOF rotational motion (Z). Using Bingham characteristic of ER fluid and geometrical constraints, principal design variables of the haptic master are determined. Then, the generation of torque of the proposed master is experimentally evaluated as a function of applied field of voltage. A sliding mode controller which is robust to uncertainties is then designed and empirically realized. It has been demonstrated via experiment that the proposed haptic master associated with the controller can be effectively applied to MIS in real field conditions.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.540-545
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• 2004

This article describes the time delay control of the 3-dimensional motion of the container cranes used in dockside container terminals. The container is suspended by four flexible cables via spreader, and due to the disturbances such as the wind and acceleration of cranes, the container undergoes translational(sway) and rotational position errors. And due to the uncertainty of weight and rotational inertia, accurate position control of container crane is difficult to realize. This paper, based on the analysis of 3-dimensional dynamics of container moving systems, develops time delay control algorithm [1]. The developed control algorithm is shown effective in controlling the container position in the presence of gust and parameter uncertainties.

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.362-367
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• 2014

In this study, a postural change detection sensor module (PCDSM) was developed to detect postural changes in activities of daily living (ADL) and falls. The PCDSM consists of eight mercury sensors that measure angle variations in $360^{\circ}$ rotation and $90^{\circ}$ tilting. From the preliminary study, the output characteristics of the PCDSM were confirmed with the angle variations of rotational motion and a tilting table. Three experiments were conducted to test rotational motion, postural changes, and falling and lying. The results confirmed that the PCDSM could effectively detect postural changes, movement patterns, and falls or non-falls.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.898-902
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• 2006

The motion of a system composed of a plate, constant springs and varying dampers is considered when the system is subject to harmonic force. Letting the frequencies of harmonic force and damper variation ${\Large f}_1\;and\;{\Large f}_2$ respectively, the displacement at the center of the plate has the strongest component at frequency ${\Large f}_1$. The angular displacement of the plate has strong components at ${\Large f}_1-{\Large f}_2$ and the natural frequency of the rotational mode of the system. If these two frequencies coincide, the plate oscillates with almost single frequency and a large amplitude. Part of these simulation results are proved analytically.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.82-88
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• 1997

In this paper, the development of a precision CNC lathe prototype for mirror surface machining is presented. To obtain high precision machining accuracy, a hydrostatically supported precision spindle and a sliding guideway with turcite pad are adopted as the motion elements. The machining accuracy of the prototype machine, and the motional accuracy of its motion elements are tested and evaluated to confirm the validity of the application of these elements on the prototype. The hydrostatic spindle shows 0.09 .mu. m of rotational accuracy and the guideway shows about 0.8 .mu. m/170mm of horizontal straightness. The sur- face roughness of cupper and aluminium cylinder machined by the prototype machine with diamond tool are 0.07 .mu. m and 0.10 .mu. m Rmax respectively. From these results, it is verified that the prototype lathe is avail- able for high precision machining.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1723-1728
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• 2005

This article describes the fuzzy control of the 3-dimensional motion of the container cranes used in dockside container terminals. The container is suspended by four flexible cables via spreader, and due to the disturbances such as the wind and acceleration of cranes, the container undergoes translational(sway) and rotational position errors. And due to the uncertainty of weight and rotational inertia, accurate position control of container crane is difficult to realize. This paper, based on the analysis of 3-dimensional dynamics of container moving systems, describes the design of the fuzzy controller, which does not require the computation time to optimize the distribution of cable tension. The developed controller is shown effective in controlling the container position in the presence of gust and parameter uncertainties.

• Journal of Magnetics
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• v.3 no.2
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• pp.41-43
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• 1998

The frequency spectra of complex permeability have been measured as a function of ac field amplitude in the annealed amorphous $Fe_{83}Zr_7B_8Cu_2 $ ribbons. The longitudinal permeability results from the rotational magnetization at small fields, $h_o$<5 mOe in as-quenched samples. However, at the further increase of ho, the wall motion begins to be involved in the low frequency region. The permeability from the wall motion drastically decreases in the annealed sample, while that from the rotational magnetization increases up to annealing temperature of 50$0^{\circ}C$ and then drops there after.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.6
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• pp.584-590
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• 1984

This study is to develop a program, with which the motion of the system can be simulated in view of kinematics and dynamics, and then evaluate functional capabilities of many robots in order to select the most suitable one for any given working conditions. According to the theory of Denavit & Hartenberg, rectangular coordinate is set at each joint in the robot of six joints, as this one is the major concern, and transformation matrices are derived between any two coordinates. The necessary displacement of each joint for executing a given a work is obtained from the position and posture transformation and the in-stantaneous velocity of the joint is got from given velocity distribution of the path. The necessary torque of each joint is finally calculated by Newton-Euler Method. This simulation program is applied to a robot with six rotational joints, Rotational angle and torque to time which has a given motion trajectory are figured and also torque to r.p.m.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.115-120
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• 2001

A gyroscope is a rotating body possessing one axis of symmetry and whose rotation about the symmetry axis is relatively large compared with the rotation about any other axis. Tuning fork is this type of structure that various modem gyro-sensors are based on. In this paper, dynamic behavior of a cantilevered beam subjected ta a base rotation with respect to the eccentric axis that is parallel to the beam axis is analyzed. The final equations of motion in terms of generalized coordinates can be solved with numerical scheme with various values of angular velocities and angular accelerations of the rotating axis. In contrast to the case of rotating cantilever beam like helicopter blade, the rotational motion with respect to the beam axis has effect to decrease the stiffness of the beam and has unstable region depending on the magnitude of the rotational angular velocity and angular acceleration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.9 s.114
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• pp.958-963
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• 2006

The motion of a system composed of a plate, constant springs and varying dampers is considered when the system is subject to harmonic force. Letting the frequencies of harmonic force and damper variation $f_1\;and\;f_2$, respectively, the displacement at the center of the plate has the strongest component at frequency $f_1$. The angular displacement of the plate has strong components at $f_1-f_2$ and the natural frequency of the rotational mode of the system. If these two frequencies coincide, the plate oscillates with almost single frequency and a large amplitude. These results can be applied to development of a moment shaker with low frequencies.