• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.648-651
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• 2004

Biped robot has better mobility than other mobile robot, but it is hard to maintain balance during walking. In order to maintain balance, stability analysis is a key point for a biped robot. The zero moment point analysis has been used most in stability analysis. In this paper, we propose different method of stability analysis using wrench system. It is possible to generate a wrench system by applying a force along an axis in space and simultaneously applying a moment about the same axis. Wrench system is equivalent to a force and moment applied along the same axis. We compare the result of wrench system analysis with that of zero moment analysis in biped robot stability using simulation program.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.373-378
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• 2013

Impact wrench has a sophisticated structure to implement various pre-designed mechanisms with specific functions. In the structure of impact wrench, the gear box has an important role to generate impacting force of anvil from actuating torque. Since, it requires to design systematically the gear box for accurate mechanism of operation and transferring motions. In this paper, a methodology of dynamic analysis, which is useful to design mechanical system, is proposed and applied to impact wrench, sequentially. At first, the way to perform dynamic analysis for design, which is progressed from component to assembled system, is introduced. Secondly, the proposed methodology is applied to designing impact wrench. Eventually, the results of parameter study with proposed methodology are applied to actual design for design optimization. And optimized-design is evaluated in the view of accurate operation and structural stability.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.298-301
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• 1990

This paper presents technologies to improve the control of an impact wrench. Impact wrench is a tool which is held by the electro-mechanical manipulator and used to fasten and loosen the bolts for remote maintenance of equipment in hostile environment. Vision system was developed to measure the distance and improve the positioning of the impact wrench. The vision system used two laser beams with a CCTV camera. Also, a torque adjusting method was developed to limit the fastening torque.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.6
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• pp.553-560
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• 2022

This study investigates improvement of torsional strength of special wrench for K-series self-propelled howitzer power-pack maintenance. In order to maintain the power-pack, special wrench is one of the essential tools for assembling/disassemblimg the engine and transmission. However, failures(plastic deformation, fracture phenomenon and etc.) have been frequently reported even though special wrench was used within recommended standard torque range. Therefore, in this study, finite element analysis using ABAQUS was performed and modification of design parameters have been proposed. Prototypes based on the proposed parameters were manufactured and torsional experiment(torque about 130 % of recommend maximum torque) validated the newly proposed design parameters. Special wrench based on this study is applied to mass production and currently used for the maintenance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.2
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• pp.88-97
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• 2012

The muscle strengths in various postures are still used in the workplace, although mechanization and automation have been continuously accomplished. The aim of this study is to measure the maximum muscle strength and analyze the muscle fatigue during the various wrench jobs which are one of the upper limbs related works. Four hundreds and eighty five college students (243 males and 242 females) participated in this study. Twelve muscle strengths which are using for pulling, pushing, lifting and lowering the wrench with various postures are measured. For every moment, the muscle strengths for both hands were measured. In each measurement, five seconds averaged value and peak value were collected. The averaged value of preferred hand and non-preferred hand was compared. Also, the averaged value of opposite movement was compared through t-test. The fatigue of agonist for each movement was analyzed using EMG analysis. The result of this study can provide some basic information not only in designing the tools in work but also in selection, training and management of workers.

• Transactions of Materials Processing
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• v.21 no.8
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• pp.493-498
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• 2012

A wheel nut wrench is one of the hand tools used to loosen and tighten lug nuts on automobile wheels and it has generally a solid-type geometry for commercial vehicles. However, the solid-type wheel nut wrenches manufactured by hot forging processes exhibit several drawbacks such as heavy weight and rough surface finish. Thus, many efforts have been devoted to change the part geometry and improve the manufacturing process. For this purpose, the weight of the final product can be reduced drastically using a hollow tube as the initial stock, which can be manufactured by the more economical manufacturing process of cold forging. In this study, the cold forging of a hollow-type wheel nut wrench for commercial vehicles was designed based on the results of fundamental experiments and CAE analyses using the commercial finite element code DEFORM-3D. In addition, cold forging experiments were conducted on a special-purpose forming machine for hollow wheel nut wrenches in order to validate the designed process sequence. As results, it was found that the final products with a weight reduction of 39% and better surface appearance can be manufactured without any defect with the newly designed cold forging process.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.635-640
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• 2000

This paper presents the analysis method of the instantaneous screw axis using line geometry in bump and rebound motion of 5-SS multi-link suspensions. Instantaneous screw axis is based on screw motion, and screw motion of zero pitch can be expressed as $Pl{\ddot{u}}cker$ line coordinates of line geometry instead of screw coordinates. In screw coordinates, twist and wrench are described by components of instantaneous screw axis. For instantaneous motion of wheel assembly, the principle of virtual work with twist and wrench is applied to 5-SS multi-link suspension, and it makes 5 linear equations. Therefore, it is possible to find instantaneous screw axis by solving these equations. This analysis by line geometry demands geometric values only, such as the locations of spherical joints in the case of multi-link suspensions.

• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.33-41
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• 1985

The purpose of this study was to determine the extent of tooth structure crazing when pinhole were drilled in dentin at various distances from the dentionenamel junction, and when pins were inserted by hand wrench and Auto-klutch handpiece. Sixty freshly extracted teeth were embedded in blocks of cold-curing acrylic resin to a level 1mm apical to the cementoenamel junction, the crown of the teeth were removed to a level 1.5mm coronal to the cementoenamel junction. After being sectioned, the cut surface of the teeth were smoothed, and they were divided into 4 groups. Group I : 4 pinholes were drilled with self-threading Minim spiral drill and pins were inserted with hand wrench in fifteen teeth. Group II : 4 pinholes were drilled with self-threading Minim spiral drill and pins were inserted with Auto-klutch handpiece in fifteen teeth. Group III : 4 pinholes were drilled with self-threading Regular spiral drill and pins were inserted with hand wrench in fifteen teeth. Group IV : 4 pinholes were drilled with self-threading Regular spiral drill and pins were inserted with Auto-klutch handpiece in fifteen teeth. The cut surface were then examined microscopically for the presence or absence of craze line. The results were as follows: 1. The self-threading Minim pin groups (Group I & II) produced less craze lines than did the self-threading Regular pin groups (Group III & IV). 2. In the self-threading Minim pin groups, there was more craze lines with hand wrench (Group I) than with Auto-klutch handpiece (Group 11). 3. In the self-threading Regular pin groups, there was more craze lines with hand wrench (Group III) than with Auto-klutch handpiece (Group IV). 4. Placement of the pinhole at 0.0mm from the dentionenamel junction produced more craze lines than placed at 0.5mm, 1.0mm (p<0.05), however there was no statistically significant between the 0.5mm and 1.0mm distance.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.832-837
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• 1991

After many years of proliferation, the nuclear industry is indebted for a formidable consequence, the safe management of spent fuel. Naturally, the high radioactivity involved with such process motivates the development of effective telerobotic systems. Nevertheless, the existing master-slave type of tele manipulators are limited in effectiveness by the human operator's limited sensory and manipulation capabilities. This paper presents the result of a research effort to resolve such problems by assigning the slave manipulator a certain degree of intelligence; sensing and actuation. In the presented system, a perception-action loop is achieved using ultrasonic range sensor and laser distance sensor interfaced with the PUMA 760 industrial robot system, and applied to automating impact wrenching task for unbolting the lid of nuclear spent fuel cask. The perception-action loop performs determination of the cask location, collision avoidance and centering of the impact wrench onto the bolt head. To aid the insertion task and to provide versatility a mounting module consisting of an RCC device and an automatic tool changer is designed and implemented. The performance of the developed system is tested on the model cask and the result is given.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.917-922
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• 2004

As the tasks of robots become more diverse, some complicated tasks have come to require force and position hybrid control. A compliant device can be used to control force and position simultaneously by separating the twist of the robot's end effector from the twist of compliance and freedom by using stiffness mapping of the compliant device. The development of a fuzzy gain scheduling scheme of control for a robot with a compliant device is described in this paper. Fuzzy rules and reasoning are performed on-line to determine the gain of twists based on wrench error and twist error and twist of compliance and twist of freedom ratio. Simulation results demonstrate that better control performance can be achieved in comparison with constant gain control.