• Journal of Drive and Control
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• v.20 no.1
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• pp.41-47
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• 2023

The aim of this study was to develop a method for installing strain gauges on moving, lubricating oil-filled, and sealed parts, such as drive shafts of equipment, including construction machinery. A measuring device was constructed using an embedded CPU and an IoT sensor to measure the strain of the strain gauge, which allowed for the measurement of axial torque and axial force, and subsequent analysis. To verify the performance of the developed device, the axial torque and axial force of the forklift were measured during operation using a strain gauge attached to the inside of the drive shaft. This study confirmed the possibility of measuring and analyzing the strain of a moving part, such as the inside of a drive shaft, which is sealed and filled with hydraulic oil.

• Structural Engineering and Mechanics
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• v.54 no.4
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• pp.771-792
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• 2015

In the paper we study dynamic response of a finite, simply supported Timoshenko beam subject to a moving continuously distributed forces. Three problems have been considered. The dynamic response of the Timoshenko beam under a uniform distributed load moving with a constant velocity v has been considered as the first problem. Obtained solutions allow to find the response of the beam under the interval of the finite length a uniformly distributed moving load. Part of the solutions are presented in a closed form instead of an infinite series. As the second problem the steady-state vibrations of the beam under uniformly distributed mass $m_1$ moving with the constant velocity has been considered. The vibrations of the beam caused by the interval of the finite length randomly distributed load moving with constant velocity is considered as the last problem. It is assumed that load process is space-time stationary stochastic process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1925-1930
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• 2010

For high-speed/high-accuracy position control of a gantry-moving-type linear motor, we propose a nonlinear adaptive controller including a synchronization algorithm. Linear motors are easily affected by force ripple, friction, and parameter variations because there is no mechanical transmission to reduce the effects of model uncertainties and external disturbances. Synchronization error is also caused by skew motion, model uncertainties, and force disturbance on each axis. Nonlinear effects such as friction and ripple force are estimated and compensated for. The synchronization algorithm is used to reduce the synchronous error of the two side pillars. The performance of the controller is evaluated via computer simulations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.794-798
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• 2002

This paper deals with a moving coil type linear motor for fast access of the miniature ODD. This slim-line motor is composed of the mover supported by guide mechanism, the coil wound into it, and the yoke attached to the permanent magnet for stator. The driving force is generated by the PM of the stator and the current in the coils of the mover. Magnetic circuit analysis and Finite Element Method are applied to estimate the thrust force at air gap. In order to compare the force characteristics between two methods, various experiment results are applied to verify on a prototype. Also the flexible modes of the motor are predicted through the FEM and the structural components are modified to locate this on high frequency region.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.50-57
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• 2016

Refrigerator glass shelves are manufactured by Insert Injection Molding. The current process of injection of glass into the mold induces movement of the core, on urethane springs. Defects in the product can result from too low a force being transmitted from the springs. To solve this problem, the force on the moving core and the injection molding pressure were subjected to numerical analysis. Based on this, the number of urethane springs as well as their hardness was changed to improve the situation. The number of springs was changed from 6 to 4. The diameter of the springs was increased from ${\emptyset}75$ to ${\emptyset}100$, and the hardness was increased from 70 (shore A) to 90 (shore A). These improvements caused the force on the molding core to increase by approximately 65,442 N. The proportion of defects decreased by 66%.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.19-24
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• 2008

We propose a new miniature air-bearing stage with a moving-magnet slotless linear motor. This stage was developed to achieve the precise positioning required for submicron-level machining and miniaturization by introducing air bearings and a linear motor sufficient for mesoscale precision machine tools. The linear motor contained two permanent magnets and was designed to generate a preload force for the vertical air bearings and a thrust force for the stage movement. The characteristics of the air bearings, which used porous pads, were analyzed with numerical methods, and a magnetic circuit model was derived for the linear motor to calculate the required preload and thrust forces. A prototype of a single-axis miniature stage with dimensions of $120\;(W)\;{\times}\;120\;(L)\;{\times}\;50\;(H)\;mm$ was designed and fabricated, and its performance was examined, including its vertical stiffness, load capacity, thrust force, and positioning resolution.

• International Journal of Control, Automation, and Systems
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• v.2 no.2
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• pp.171-181
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• 2004

An autonomous navigation algorithm for marine vehicles is proposed in this paper using fuzzy logic under COLREG guidelines. The VFF (Virtual Force Field) method, which is widely used in the field of mobile robotics, is modified for application to the autonomous navigation of marine vehicles. This Modified Virtual Force Field (MVFF) method can be used in either track-keeping or collision avoidance modes. Moreover, the operator can select a track-keeping pattern mode in the proposed algorithm. The collision avoidance algorithm has the ability to handle static and/or moving obstacles. The fuzzy expert rules are designed deliberately under COLREG guidelines. An extensive simulation study is used to verify the proposed method.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1227-1233
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• 2011

An effective method of obstacle avoidance for omni-directional mobile robots is proposed to avoid moving obstacles in dynamic environments. Our method uses the concept of circle lists which represent the trajectories of robot and obstacles. This method predicts not only collision position but also collision time, and hence it enables the robot avoiding the most urgent collision first. In order to avoid obstacles, our method uses artificial repulsive force and contraction force. Simulation results show that the robot could avoid obstacles effectively.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.460-465
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• 2000

In this study, a durability estimation system of turning centers is developed to systematically evaluate the effects of structural specification and testing condition on the durability. All loads such as weights, inertia forces, cutting force and so on, are automatically transferred from the upper elements to the lower elements by the force flow which can be derived from the structural code of turning center. And the external loads applying to the moving and rolling elements are determined by using the equilibrium conditions of force and moment. Especially, the durability of turning center is estimated based on the lifes of moving and rolling elements under the required testing condition.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.10
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• pp.73-80
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• 1998

Recently, we have developed a linear brushless DC motor(LBLDCM) with high speed and precise position control performance to apply it to the semiconductor assembly and inspection machinery. It is composed of double side alignment by two armature-stator pairs and each pair is consist of a moving armature with 8 poles by 3 phase coils and a stator with rare earth permanent magnet (Nd-Fe-B) arrays. Through the thrust force analysis on a simplified and whole model of the suggested LBLDCM by an Electromagnetic FEM solver, skew angle of magnet arrays to reduce the thrust force ripple and the winding conditions of the armature is designed. From experimental results, the user's requirements was satisfied and we confirmed distinctly that the repeatable accuracy less than a micron of the linear motion can be obtained at high speed by the developed LBLDCM. This is owing to directly drive the work without the gear train.