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

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.8
• /
• pp.164-170
• /
• 2004

The skin movement artifacts are referred to as the relative motion of skin with respect to the motion of underlying bones. This is of great importance in joint biomechanics or internal kinematics of human body. This paper describes a novel experiment that measures the skin movement of a hand based on MR(magnetic resonance) images in conjunction with surface modeling techniques. The proposed approach consists of 3 phases: (1) MR scanning of a hand with surface makers, (2) 3D reconstruction from the MR images, and (3) registration of the 3D models. The MR images of the hand are captured by 3 different postures. And the surface makers which are attached to the skin are employed to trace the skin motion. After reconstruction of 3D models from the scanned MR images, the global registration is applied to the 3D models based on the particular bone shape of different postures. The results of registration are then used to trace the skin movement by measuring the positions of the surface markers.

• Journal of the Korea Computer Graphics Society
• /
• v.29 no.5
• /
• pp.11-20
• /
• 2023

In this paper, we propose a novel deep learning-based motion reconstruction approach that facilitates the generation of full-body motions, including finger motions, while also enabling the online adjustment of motion generation delays. The proposed method combines the Vive Tracker with a deep learning method to achieve more accurate motion reconstruction while effectively mitigating foot skating issues through the use of an Inverse Kinematics (IK) solver. The proposed method utilizes a trained AutoEncoder to reconstruct character body motions using tracker data in real-time while offering the flexibility to adjust motion generation delays as needed. To generate hand motions suitable for the reconstructed body motion, we employ a Fully Connected Network (FCN). By combining the reconstructed body motion from the AutoEncoder with the hand motions generated by the FCN, we can generate full-body motions of characters that include hand movements. In order to alleviate foot skating issues in motions generated by deep learning-based methods, we use an IK solver. By setting the trackers located near the character's feet as end-effectors for the IK solver, our method precisely controls and corrects the character's foot movements, thereby enhancing the overall accuracy of the generated motions. Through experiments, we validate the accuracy of motion generation in the proposed deep learning-based motion reconstruction scheme, as well as the ability to adjust latency based on user input. Additionally, we assess the correction performance by comparing motions with the IK solver applied to those without it, focusing particularly on how it addresses the foot skating issue in the generated full-body motions.

• Journal of Industrial Technology
• /
• v.21 no.B
• /
• pp.265-272
• /
• 2001

The human arm is modeled by three rigid bodies(the upper arm, the forearm and the hand)with seven degree of freedom(three in the shoulder, two in the elbow and two in the wrist). The objective of this work is to present a method to determine the three-dimensional kinematics of the human elbow joint using a magnetic tracking device. Euler angle were used to determine the elbow flexion-extension, and the pronation-supination. The elbow motion for the various driving conditions is measured through the driving test using a simulator. Discomfort levels of elbow joint motions were obtained as discomfort functions, which were based on subjects' perceived discomfort level estimated by magnitude estimation. The results showed that the discomfort posture of elbow joint motions occurred in the driving motion.

• 제어로봇시스템학회:학술대회논문집
• /
• 2002.10a
• /
• pp.77.5-77
• /
• 2002

A mechanical device was developed for assisting the grasping function of a person whose fingers suffered cervical injury and thus are unable to grasp. This device is composed of a mechanical glove put on the user's hand and a muscle sensor to measure the activity of his or her muscle. The mechanical glove consists of a finger frame, a base and an air cylinder mounted on the base. With the kinematics carefully designed, the finger frame can achieve the grasping motion under the actuation of the air cylinder. For controlling this motion, an innovative sensor was developed to detect the user's motion intention. The sensor measures the change of the muscle stiffness...

• International Journal of Control, Automation, and Systems
• /
• v.6 no.4
• /
• pp.607-612
• /
• 2008

This paper proposes a robot visual servo approach based on image appearance and a wavelet function neural network. The inputs of the wavelet neural network are changes of image features or the elements of image appearance vector, and the outputs are changes of robot joint angles. Image appearance vector is calculated by using eigen subspace transform algorithm. The proposed approach does not need a priori knowledge of the robot kinematics, hand-eye geometry and camera models. The experiment results on a real robot system show that the proposed method is practical and simple.

• Journal of the Korea Computer Graphics Society
• /
• v.26 no.3
• /
• pp.9-19
• /
• 2020

With the recent development of various kinds of virtual reality devices, there has been an active research effort to increase the sense of reality by recognizing the physical behavior of users rather than by classical user input methods. Among such devices, the Leap Motion controller recognizes the user's hand gestures and can realistically trace the user's hand in a virtual reality environment. However, manipulating an object in virtual reality using a recognized user's hand often causes the hand to pass through the object, which should not occur in the real world. This study presents a way to build a visual feedback system for enhancing the user's sense of interaction between hands and objects in virtual reality. In virtual reality, the user's hands are examined precisely by using a ray tracing method to see if the virtual object collides with the user's hand, and when any collision occurs, visual feedback is given through the process of reconstructing the user's hand by moving the position of the end of the user's fingers that enter the object through sign distance field and reverse mechanics. This enables realistic interaction in virtual reality in real time.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.2
• /
• pp.227-237
• /
• 2007

The purpose of this study was to examine the effect of precision that kinematics had when short approach shots were taken. In this study, the subjects chosen were 5 skilled and 5 unskilled subjects, who were allowed to shoot 10 rounds of shots at target distances of 1m, 2m, 4m, and 8m. Three dimensional analysis was used as methods to obtain kinematics of each shots. In order to verify the statistical significance of the kinematic factors followed by the results of different skills and target distances, we used the two-way repeated ANOVA. The study was experimented within the level of p<.05. The results obtained were as follows: 1) the difference of shots of the forward and backward variations were larger than those of the left and right variations, the unskilled subjects' shot distances greatly got larger than that of the skilled subjects as the distance of the target increased, 2) not being affected by the target distance variations, the skilled subjects' rate of down-swing was shorter than the back-swing on short approach shots, 3) the skilled subjects' center of body weight tended to move more naturally towards the target when doing the down-swing to finish than that of the unskilled subjects on short approach shots, 4) the skilled subjects' right hand angle of cocking were narrower and tended to be kept much more consistent than that of the unskilled subjects on short approach shots, 5) the unskilled subjects when doing their back-swings, their right hips swayed towards the back, their trunk-flexion angles were shown to be lower than that of the skilled subjects on short approach shots, 6) the skilled subjects`body weight tended to move more naturally towards the left foot when doing the down-swing to finish than that of the unskilled subjects on short approach shots.

• Korean Journal of Applied Biomechanics
• /
• v.14 no.1
• /
• pp.145-160
• /
• 2004

The purposes of this study to provide quantitative data in necessary to advance techniques kinematic analysis of Cucarachas which is an action of Rumba. Then, this study is performed on 5 female players who have won within the third prize at a national athletic meeting. When whole foot reached to floor, Displacement of right-left hip joint (until $E1{\sim}E3$ average moved 15.15cm)is found at right-left direction since the hip joint is turned to right back. On the other side, large displacement is shown because Rumba Cucaracha Movement is expressed by maximum shift of hip joint to right and left direction. Displacement of right hip joint(E3$57.40{\pm}7.46$) is found in front and in rear direction since hip joint is moved in rear and in front to turn the hip joint. It may be stated that this is ideal displacement expressed by movement of whole body with artistic poise and presentation because role of hip joint is very important in technical and artistic side. Angle of right shoulder joint E2($105.44{\pm}9.64$) is got wider. It may be stated that player shifts up and abduct elbow joint to right since center of gravity of player is exceedingly shifted to right in this motion of Cucarachas. On the other hand, since this motion is abducted right elbow and shrunk external abdominal oblique to him center of body to left front of hip joint, the angle becomes narrow. It is shown that angle of knee in right knee joint E4($75.44{\pm}2.61$) is large since right leg and hip joint is turned by foot using reaction of ground and so center of body is shifted to left. Large angle of ankle E4($134.40{\pm}10.50$) in Cucaracha Movement is shown by the action of twist force using narrow part of foot and compression force against ground with adduction speed of arm. The various kinematic analyses associated with motions of dance sport have not been sufficiently peformed so far, and thus a number of research projects for dance sport should be proposed and performed to be continuous.

• Journal of Advanced Navigation Technology
• /
• v.24 no.6
• /
• pp.540-548
• /
• 2020

In this paper, the performances of virtual reference station (VRS) and flächen korrektur parameter (FKP) based Network real time kinematics (RTK) according to baseline length were compared and analyzed. We applied the VRS and FKP corrections for each baseline length obtained from National Geographic Information Institute Network RTK services to an FKP-supported commercial receiver and analyzed the RTK results in the range and position domains. In the case of VRS, RTK performance was degraded due to the spatial error, which increase in proportion of the baseline length. On the other hand, FKP compensates for spatial errors by using the gradients of dispersive and non-dispersive errors, so it showed stable RTK performance compared to VRS even if the baseline length increases up to 130 km. However, in the case of long baseline of 150 km or more, integer ambiguities were incorrectly fixed due to the decrease in the performance of the FKP corrections.