• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1513-1518
• /
• 1996

A force reflecting hand controller can be used to provide more realistic information to the operator of a teleoperation system such as kinesthetic feedback from a slave robot. In this paper, a new design concept of a force reflecting 6-DOF hand controller utilizing the kinematic structure of a Stewart Platform is presented. Based on the optimal design technique of a Stewart Platform, a force reflecting hand controller has been designed and constructed to verify the technical feasibility of proposed design concept. In order to provide an operator with kinesthetic feedback information, a force mapping algorithm based on a reciprocal product of screws has been introduced. Finally, the technical feasibility of the design concept has been demonstrated through some of experimental results of the device under virtual environment on a real-time graphic system.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.1
• /
• pp.89-96
• /
• 2009

This paper describes the intelligent robot's hand with three finger sensors for a humanoid robot. In order to grasp an unknown object safely, the intelligent robot's hand should measure the mass of the object, and determine the grasping force using the mass, finally control the grasping force using the finger sensors and the controller. In this paper, the intelligent robot's hand for a humanoid robot was developed. First, the six-axis force/moment sensor was manufactured. second, three finger force sensors were designed and fabricated, third, the high-speed controller was manufactured using DSP(digital signal processor), finally, the characteristic test for determining a grasping force and for grasping an unknown object safely It is confirmed that the hand could grasp an unknown object safely.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1545-1548
• /
• 1997

A Force-refecting hand controller can provide the kinesthetic information obtained from a slave manipulator to the operator of a teleoperation system. This thesis presents the desgn and the analysis of a 6-degree-of-freedom force-reflecting hand controller using fivebar parallel mechanism. The goal of this thesis is to construct a superior hand controller that can provide large workspace and good force-reflecting ability. The forward kinematics of the fivebar paprallel mechanism has been calculated in real-time using three pin-joint sensors in addition to six actuator position sensors. A force decomposition approach is used to comput the Jacobin. To analyze the characteristics of the fivebar parallel mechanism, it has been compared with the other three parallel mechanisms in terms with workspace and manipulability measure. The force-reflecting hand controller using the fivebar parallel mechanism has been constructed and tested to verify the feasibility of the design concept.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.10
• /
• pp.964-969
• /
• 2012

Robot hands capable of grasping or handling various objects are important for service robots to effectively aid humans. In particular, controlling a contact force and providing a compliant motion are essential when the hand is in contact with objects. Many dexterous robot hands equipped with force/torque sensors have been developed to perform force control, but they suffer from the complexity of control and high cost. In this paper, a low-cost robot hand based on SEA (Series Elastic Actuator), which is composed of compression spring, stretch sensor, and wire, is proposed. The grasping force can be estimated by measuring the compression length of spring, which would allow the hand to perform force control. A series of experimentations are carried out to verify the performance of force control of the proposed robot hand, and it is shown that it can successfully control the contact force without any additional force/torque sensors.

• Journal of Sensor Science and Technology
• /
• v.21 no.3
• /
• pp.192-197
• /
• 2012

This paper describes the control of the hand fixing system attached to the finger rehabilitation robot for the rehabilitation exercise of patient's fingers. The finger rehabilitation robot is used to exercise the finger rehabilitation, and a patient's hand is safely fixed using the hand fixing system. In this paper, the hand fixing system was controlled with PD gains to fix a palm of the hand, and the characteristic test for the hand fixing system was carried out to sense the fixed hand movement of the front and the rear, that of the left and the right, and that of the upper. It is thought that the hand fixing system could safely fix the hand, and the movement of the fixed hand could be perceived using the five-axis force/moment sensor attached to the hand fixing system.

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.6
• /
• pp.503-509
• /
• 2013

Objective: The purpose of this study is to analyze the individual finger force between dominant hand and non-dominant hand and to investigate an effect of the individual finger on the total grip strength depending on dominant hand and non-dominant hand. Background: Many studies on the ratio of the grip force between dominant hand and non-dominant hand has been researched. While a 10% rule which is a ratio of the grip force between dominant hand and non-dominant hand has been applied in most studies, studies on the rate of the individual finger force between dominant hand and non-dominant hand have been insufficiently researched. Method: The experiment was preceded with 17 subjects (male, mean 25.8 ages). The individual finger force and total grip strength were measured using pliers being able to change the grip span from 45 to 80mm. Results: The difference of total grip strength between dominant hand and non-dominant hand is following 10% rule. However, the difference of individual finger force between dominant hand and non-dominant hand are not same as the difference of total grip strength. Especially in the case of grip span with 50mm, the differences between total grip strength, index finger, middle finger, ring finger, and little finger were $9.87{\pm}14.80%$, $8.95{\pm}37.17%$, $13.71{\pm}28.27%$, $6.77{\pm}24.35%$, $39.29{\pm}42.46%$, respectively, with p=0.018 of statistical significance. Additionally, the results of regression analysis in 50 and 60mm of grip span showed that the difference in ring finger affected the most to the total grip strength; and the effects followed in order of index finger, middle finger, and little finger. Conclusion: Our study suggests that an effect of individual finger and grip span of pliers have to be considered when explaining the difference of the total grip strength between dominant hand and non-dominant hand. Application: This result is expected to be used for designing ergonomic hand tool.

• Journal of the Ergonomics Society of Korea
• /
• v.14 no.1
• /
• pp.69-81
• /
• 1995

Few studies on the biomechanical analysis of hand postures and tool handling tasks exist because of the lack of appropriate measurement techniques for hand force. A measurement system for the finger forces and joint angles for the analysis of manual tool handling tasks was developed in this study. The measurement system consists of a force sensing glove made from twelve Force Sensitive Resistors and an angle-measuring glove (Cyberglove$^{TM}$, Virtual technologies) with eighteem joint angle sensors. A biomechanical model of the hand using the data from the measurement system was also developed. Systems of computerized procedures were implemented inte- grating the hand posture measurement system, biomechanical analysis system, and the task analysis system for manual tool handling tasks. The measurement system was useful in providing the hand force data needed for an existing task analysis system used in CTD risk evaluation. It is expected that the hand posture measurement developed in this study will provide an efficient and cost-effective solution to task analysis of manual tool handling tasks.s.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.5
• /
• pp.597-603
• /
• 2011

Objective: The objective of this study was to compare one-hand and two-hands lifting activity in terms of biomechanical stress for the range of lifting heights from 10cm above floor level to knuckle height. Background: Even though two-hands lifting activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lifting tasks using both a one-handed as well as a two-handed lifting technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lifting tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lifting tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 43%, as the workload was increased twice from 7.5kg to 15.0kg. For the right-hand lifting task, these were increased by the average 34%. For the two-hands lifting tasks, these were increased by the average 25%. The lateral shear forces at L5/S1 of one-hand lifting tasks, notwithstanding the half of the workload of two-hands lifting tasks, were very high in the 300~317% of the one of two-hands lifting tasks. The moments at L5/S1 of one-hand lifting tasks were 126~166% of the one of two-hands lifting tasks. Conclusion: It is concluded that the effect of workload for one-hand lifting is greater than two-hands lifting. It can also be concluded that asymmetrical effect of one-hand lifting is much greater than workload effect. Application: The results of this study can be used to provide guidelines of recommended safe weights for tasks involved in one-hand lifting activity.

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.5
• /
• pp.413-420
• /
• 2013

Objective: The objective of this study was to compare one-hand and two-hands lowering activity in terms of biomechanical stress for the range of lowering heights from knuckle height to 10cm above floor level. Background: Even though two-hands lifting/lowering activity of manual materials handling tasks are prevalent at the industrial site, many manual materials handling tasks which require the worker to perform one-hand lifting/lowering are also very common at the industrial site and forestry and farming. Method: Eight male subjects were asked to perform lowering tasks using both a one-handed as well as a two-handed lowering technique. Trunk muscle electromyographic activity was recorded while the subjects performed the lowering tasks. This information was used as input to an EMG-assisted free-dynamic biomechanical model that predicted spinal loading in three dimensions. Results: It was shown that for the left-hand lowering tasks, the values of moment, lateral shear force, A-P shear force, and compressive force were increased by the average 6%, as the workload was increased twice from 7.5kg to 15kg. For the right-hand lowering task, these were increased by the average 17%. For the two-hands lowering tasks, these were increased by the average 14%. Conclusion: Even though the effect of workload on the biomechanical stress for both one-hand and two-hands lowering tasks is not so significant for the workload less than 15kg, it can be claimed that the biomechanical stress for one-hand lowering is greater than for two-hands lowering tasks. Therefore, it can be concluded that asymmetrical lowering posture would give greater influence on the biomechanical stress than the workload effect for one-hand lowering activity. Application: The result of this study may be used to provide guidelines of recommended safe weights for tasks involved in one-hand lowering activity.

• Journal of Sensor Science and Technology
• /
• v.20 no.5
• /
• pp.351-356
• /
• 2011

Stroke patients should exercise for the rehabilitation of their fingers, because they can't use their hand and fingers. Their hand and fingers are fixed on the hand fixing system for rehabilitation exercise of them. But the hands clenched the fist of stroke patients are difficult to fix on it. In order to fix the hands and fingers, their palms are pressed with pressing bars and are controlled by reference force. The fixing system must have a five-axis force/moment sensor to force control. In this paper, the five-axis force/moment sensor was developed for the hand fixing system of finger-rehabilitation exercising system. The structure of the five-axis force/moment sensor was modeled, and designed using finite element method(FEM). And it was fabricated with strain-gages, then, its characteristic test was carried out. As a result, the maximum interference error is less than 2.43 %.