• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.123-128
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• 1998

This paper describes the evaluation of a force-reflecting interface with ultrasonic motors(USMs). The force-reflecting interface allows a human to feel object within virtual environment. To effectively display the mechanical impedance of the human hand we need a haptic device with specific characteristics, such as low inertia, almost zero friction and very high stiffness. USMs have attracted considerable attention as the actuator satisfied these conditions. USMs combine features such as high driving torque at low rotational speed, high holding torque and fast response therefore we studied two degree of freedom force-reflecting haptic system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.188-200
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• 2005

Control of a multi-fingered robotic hand is usually based on the theoretical analysis for kinematics and dynamics of fingers and of object. However, the implementation of such analyses to robotic hands is difficult because of errors and uncertainties in the real situations. This article presents the control method for estimating the kinematic constraint of an unknown object by active sensing. The experimental system has a two-fingered robotic hand suspended vertically for manipulation in the vertical plane. The fingers with three degrees-of-freedom are driven by wires directly connected to voice-coil motors without reduction gears. The fingers are equipped with three-axis force sensors and with dynamic tactile sensors that detect slippage between the fingertip surfaces and the object. In order to make an accurate estimation for the kinematic constraint of the unknown object, i.e. the constraint direction and the constraint center, four kinds of the active sensing and feedback control algorithm were developed: two position-based algorithms and two force-based algorithms. Furthermore, the compound and effective algorithm was also developed by combining two algorithms. Force sensors are mainly used to adapt errors and uncertainties encountered during the constraint estimation. Several experimental results involving the motion of lifting a finger off an unknown object are presented.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.122-128
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• 2009

In this paper, we present a design and an evaluation of a hand-held ball based haptic interface, named "TouchBall." Using a trackball mechanism, the device provides flexibility in terms of directional degrees of freedom. It also has an advantage of a direct transfer of force feedback through frictional touch (with high sensitivity), thus requiring only relatively small amount of inertia. This leads to a compact hand-held design appropriate for mobile and 3D interactive applications. The device is evaluated for the detection thresholds for directions of the force feedback and the perceived amount of directional force. The refined directionality information should combine with other modalities with less sensory conflict, enriching the user experience for a given application.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.393-399
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• 2023

Upper limb amputees wear an upper limb prosthesis for both aesthetic purposes and functional necessity, and in particular, in the case of amputee with both hands, it is essential to wear a myoelectric prosthetic hand capable of gripping action. The prosthetic hand operated by the EMG signal of the remaining muscles is a public insurance benefit item of the Industrial Accident Compensation Insurance, and test method standards are needed to be developed for the safety of the user and the effectiveness of the product performance. In this study, we developed systems for measuring the gripping force of myoelectric hand prosthesis by a load cell and for durability test of the prosthesis over repeated use with a proximity sensor, and propose a test method standard. Since the international test method standard has not yet been established, it is expected that Korea will be able to play a leading role in this standardization field in the future.

• Physical Therapy Korea
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• v.14 no.4
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• pp.91-98
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• 2007

In this study, 1,933 Korean male and female subjects ranging in age from 10 to 82 were selected to investigate the various statistics about hand dominance and employment characteristics of preferred hand in handling diverse products and facilities. The statistics show that 5.6% are left-handed and 7.6% are ambidextrous. The average left-hander has a strong tendency to use his or her left hand more often when taking a forceful action than one that requires accuracy. On the contrary, the average ambidextrous or right-handed person generally uses his or her right hand more with action that requires accuracy than force. Derived from such results, the conclusion is that depending on which hand is the dominant one, people seem to use their hands differently when they handle objects and is a point that should be considered in designing hand control devices.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.858-863
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• 2004

In this study, the new prosthetic hand which can perform sensory feedback is developed. Although the continuous development of current prosthetic hands, they have some drawbacks. The drawbacks are the low grasping capabilities, the lack of sensory information given to the user, and so on. Despite the improvement of the function of fingers, the sensory information problem still remains undeveloped. By using differential gear and underactuated mechanical design, it can be solved with the minimum additional weight. And it will be applied to all of the prosthetic hands.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.455-458
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• 1988

In this paper, a grasping force control of robot hand is presented with consideration of workpiece dynamics. It is difficult to control a manipulator without the knowledge of Its dynamics, because its handling with unknown workpiece may bring about overshoots and vibrations. Then it is necessary to adjust control gains according to the handling workpieces in order to achieve good control performances. The authors propose a new control strategy which uses adaptive observer and VSS (${\underline{V}}ariable$ ${\underline{S}}tructure$ ${\underline{S}}ystem$) controller to subdue these overshoots and vibrations. Some simulations of the proposed method are carried out for a grasping system to control the grasping force to various workpieces, whose dynamics cannot be known in advance.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.119-122
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• 2001

This paper discusses the peg-in-hole task of chamferless parts using force/moment/vision sensors. The directional error occurring during the task are categorized into two cases according to the degree of initial errors, And different Mechanical analysis has been accomplished for each cases. This paper proposes an algorithm which enables to reduce intial directional error using digital Images acquired from hand-eyed vision sensor, And to continue the task even with the large directional error by adjusting the error using digital image processing. The effectiveness of the algorithm has been demonstrated through experimentation using 5-axis robot equipped with a developed controller force/moment sensor and color digital camera on its hand.

• Safety and Health at Work
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• v.6 no.1
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• pp.9-17
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• 2015

The human hand is a complex structure that performs various functions for activities of daily living and occupations. This paper presents a literature review on the methodologies used to evaluate hand functions from a biomechanics standpoint, including anthropometry, kinematics, kinetics, and electromyography (EMG). Anthropometry describes the dimensions and measurements of the hand. Kinematics includes hand movements and the range of motion of finger joints. Kinetics includes hand models for tendon and joint force analysis. EMG is used on hand muscles associated with hand functions and with signal-processing technology.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.313-318
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• 2001

A haptic hand controller operated by the user's hand can receive information on position and orientation of the hand and display force and moment generated in the virtual environment to the hand. This paper presents a design method for KU-HHC, 6 DOF Korea University-haptic hand controller, which allows separation of workspace from linkage mechanism in consideration of the efficient user operation. First, the 3 DOF mechanism in which all the actuators are mounted on the fixed base is developed by combining a 5-bar linkage and gimbal mechanism. Then, the 6 DOF HHC is designed by connecting the two 3 DOF devices through a handle. This paper presents the forward and inverse kinematics for this device and Jacobian analysis. Improvement of the kinematic characteristics using performance index is also discussed. The hand controller KU-HHC based on this design concept and kinematic analysis was manufactured and shows excellent performance.