• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.244-248
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• 1987

The force/torque sensor for robot is developed. The compliance algorithm for peg-in-hole insertion task using the forec/troque sensor is developed. The system consists of an IBM PC, robot, force/torque sensor, strain meter, A/D board, and interface board. The IBM PC functions as a main processor and the robot controller as a slave processor. The sensor is constructed to measure $T_x$, $T_y$, $F_z$ which are necessary to precisely execute a peg-in-hole insertion task by SCARA type assembly robot. The outputs of sensor are analyzed. On the basis of the analysis, compliance algorithm for peg-in-hole insertion task is developed. Some comments concerning the development of wrist force/torque sensor and compliance algorithm are given.

• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.141-150
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• 2010

The purpose of this study was to analyze the golf swing motion for a soft golf clubs and regular golf club. Soft golf is a newly developed recreational sports for all ages, including the elderly and the beginners of golf. To quantify the effect of using soft golf club, which much lighter club than regular clubs, a motion analysis has been performed using a 3D optoelectric motion tracking system that utilizes active infrared LEDs and near-infrared sensors. The subject performed swing motion using a regular golf club and a soft golf club in turn. The obtained motion capture data was used to build a 3D computer simulation model to obtain left wrist, elbow shoulder and lumbar joint force and torque using inverse and forward dynamics calculations. The joint force and torque during soft golf swing were lower than regular golf swing. The analysis gave better understanding of the effectiveness of the soft golf club.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.682-684
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• 2015

A 12/14 bearingless switched reluctance motor (BLSRM) with hybrid stator poles has been proposed due to the outstanding decoupling characteristics between the torque and suspending force. However, the motor is a two-phase motor. The output torque of the motor has torque dead zone and high torque ripple. Hence, the motor cannot self-start at some rotor positions. To solve the self-starting problems and reduce the torque ripple, a stepped rotor is proposed in this paper. Then, the motor with the stepped rotor is optimally designed. In the new designed motor, the majority parameters are kept the same with those of original motor; only the torque pole arc and rotor pole shape are optimally designed. The characteristics of the redesigned motor, such as inductance, torque and suspending force, are analyzed and compared with those in the original motor. Finally, the effectiveness of the proposed method is verified by the simulation results.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.295-299
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• 2013

This paper presents the new structure of a spindle motor for hard disk drive (HDD). It can produce axial force as well as torque without a pulling plate or a pulling magnet required for the normal operation of a hydrodynamic bearing in rotating-shaft structure. The proposed models have different air gap length along the axial direction by changing the thickness of permanent magnet (PM). One has a single slope and the other has double slopes on the surface of PM. For the design of the proposed models, variables are defined and its effects on the motor performances are investigated by 3-demensional finite element analysis (FEA). The equi-performance curves are investigated for the main characteristics of the spindle motor such as generated torque, axial force and torque ripple ratio. The validity of the proposed models is verified by the feasibility study and performance evaluation.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.327-331
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• 2006

This paper presents the analysis method for the torque characteristic of the 1-phase induction motor considering space harmonics in the air gap. The equivalent circuit method is used, where the circuit constants are obtained by classic theory. In addition, the space harmonic components in air gap magneto motive force are analyzed and added to the equivalent circuit to obtain accurate torque characteristics in low speed regions. Each torque component due to the harmonics is calculated and the total torque characteristic is obtained and compared with the measurement result.

• Journal of Institute of Convergence Technology
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• v.12 no.1
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• pp.7-12
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• 2022

The reduction ratio of the magnetic gear is determined by the ratio of the number of poles between the high-speed permanent magnet layer and the low-speed permanent magnet layer. In general, it is known that the greater the least common multiple of both poles, the smaller the torque ripple called by cogging of the magnetic force generated in the magnetic gear. However, little is known about the effect of the harmonic modulator that filters the magnetic field in the magnetic gear to magnetically couple the high-speed side and the low-speed side except for the number of poles. In this study, torque ripple characteristics according to changes in modulator shape such as opening ratio and tooth thickness are analyzed using a finite element analysis tool.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.878-888
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• 2016

Cogging torque has a negative impact on the operation of permanent magnet machines by increasing torque ripple, speed ripple, acoustic noise and vibration. In this paper Magnet Shifting Method has been used as a tool to reduce the cogging torque in inset Line Start Permanent Magnet Synchronous Motor (LSPMSM). It has been shown that Magnet Shifting Method can effectively eliminate several lower-order harmonics of cogging torque. In order to implement the method, first the expression of cogging torque is studied based on the Fourier analysis. An analytical expression is then introduced based on Permanent Magnet Shifting to reduce cogging torque of LSPMS motors. The method is applied to some existing machine designs and their performances are obtained using Finite Element Analysis (FEA). The effect of magnet shifting on pole mmf (magneto motive force) distribution in air gap is discussed. The side effects of magnet shifting on back-EMF, core losses and torque profile distortion are taken into account in this investigation. Finally the experimental results on two prototypes 24 slot 4 pole inset LSPMS motors have been used to validate the theoretical analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.12
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• pp.156-163
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• 2010

The brushless motor is getting widely applied to the automotive component with the advantage of the high efficiency, high reliability and etc.. Most of the motor applications require the low vibration and acoustic noise. The cogging torque is the one of the main cause of the noise and vibration. The step-skewed rotor is used to reduce the cogging torque. We analyze the characteristics of the step-skewed rotor and non skewed rotor with the same stator by using 2-dimensional FEM. And then we analyze the characteristics variation according to the rotor eccentricity. The prototype is made and tested. As the results, the step-skewed rotor structure reduce the cogging torque and local radial force but it is more sensitive to rotor eccentricity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.4
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• pp.409-416
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• 2007

A momentum type actuator produces force and torque disturbances as well as its designed control torque. These disturbances are ones of the largest disturbance sources inside the spacecraft, which deteriorate the pointing stability of the high precision spacecraft. The measurement and analysis of actuator disturbances are therefore imperative for such a spacecraft, and thus a three dimensional torque measurement table has been developed for that purpose. The data acquired from the measurement table are processed in the frequency domain and displayed in the power spectral density(PSD). Through this process, disturbance model parameters are obtained and used for the attitude stability simulation. The process has been adopted for the disturbance measurement of the reaction wheel, and the validity of measurements and parameter identification procedure is verified.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.753-758
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• 2012

This paper deals with the analysis of vibration and noise sources in a modular-type SPM fractional-slot motor. To reduce cogging torque, torque ripple and unequal radial force, which are the main causes of the electromagnetic vibration, the optimal shape of notch and magnet are designed.