scholarly journals A Three-dimensional Finger Motion Measurement System of a Thumb and an Index Finger Without a Calibration Process

Sensors ◽  
2020 ◽  
Vol 20 (3) ◽  
pp. 756 ◽  
Author(s):  
Yeongyu Park ◽  
Joonbum Bae
Keyword(s):  
Index Finger ◽  
Three Dimensional ◽  
Length Change ◽  
Measuring Method ◽  
Finger Joint ◽  
Joint Angles ◽  
Calibration Process ◽  
Hand Motion ◽  
Wearable Systems ◽  
Cmc Joint

Various wearable systems have been investigated to measure hand motion, but some challenges remain. Many systems require a calibration process to map sensor signals to actual finger joint angles by the principle of measuring the length change of the finger, or bending sensors. Also, few studies have investigated how to measure thumb motion accurately using the wearable systems. This paper proposes an exoskeleton system with linear Hall sensors to measure three-dimensional hand motion without a calibration process. The calibration process is avoided by measuring finger joint angles through an absolute rotation measurement. A new wearing method with lower parts underneath the hand joints and rubber bands is proposed to fix the structure to the hand and adapt it for various hand sizes. As the thumb has a complex biomechanical feature at carpometacarpal (CMC) joint, a new measuring method of the CMC joint is proposed to directly calculate the orientation of the metacarpal. The prototype of the thumb and index finger was manufactured, and the performance was verified experimentally by using an optical motion capture system.

Development of a Visual Monitoring System for Deformation Measuring of Welded Members and its Application

2008 ◽  
Vol 580-582 ◽  
pp. 557-560 ◽  
Author(s):  
J.G. Han ◽  
Kyong Ho Chang ◽  
Gab Chul Jang ◽  
K.K. Hong ◽  
Sam Deok Cho ◽  
...  
Keyword(s):  
Monitoring System ◽  
Three Dimensional ◽  
Measuring Method ◽  
Welding Residual Stress ◽  
Measuring System ◽  
Visual Monitoring ◽  
Test Error ◽  
Steel Members ◽  
Loading Tests ◽  
Visual Monitoring System

Recently, in the loading tests for steel members, the deformation value is measured by calculating a distance of both cross-heads. This measuring method encounters a test error due to various environmental factors, such as initial slip, etc.. Especially, in the case of welded members, the non-uniform deformation behavior in welded joints is observed because of the effect of welding residual stress and weld metal. This is mainly responsible for a test error and a loss of the reliability for used test instruments. Therefore, to improve the accuracy and the applicability of measuring system, it is necessary to employ a visual monitoring system which can accurately measure the local and overall deformation of welded members. In this paper, to accurately measure a deformation of welded members, a visual monitoring system (VMS) was developed by using three-dimensional digital photogrammetry. The VMS was applied to the loading tests of a welded member. The accuracy and the applicability of VMS was verified by comparing to the deformation value measured by a test instrument (MTS-810). The characteristics of the behavior near a welded joint were investigated by using VMS.

scholarly journals A Finger Grip Force Sensor with an Open-Pad Structure for Glove-Type Assistive Devices

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 4 ◽  
Author(s):  
Junghoon Park ◽  
Pilwon Heo ◽  
Jung Kim ◽  
Youngjin Na
Keyword(s):  
Degrees Of Freedom ◽  
Grip Force ◽  
Force Sensor ◽  
Assistive Devices ◽  
Finger Joint ◽  
Assistive Device ◽  
Force Estimation ◽  
Joint Angles ◽  
Fingertip Force ◽  
Grasping Force

This paper presents a fingertip grip force sensor based on custom capacitive sensors for glove-type assistive devices with an open-pad structure. The design of the sensor allows using human tactile sensations during grasping and manipulating an object. The proposed sensor can be attached on both sides of the fingertip and measure the force caused by the expansion of the fingertip tissue when a grasping force is applied to the fingertip. The number of measurable degrees of freedom (DoFs) are the two DoFs (flexion and adduction) for the thumb and one DoF (flexion) for the index and middle fingers. The proposed sensor allows the combination with a glove-type assistive device to measure the fingertip force. Calibration was performed for each finger joint angle because the variations in the expansion of the fingertip tissue depend on the joint angles. The root mean square error (RMSE) for fingertip force estimation ranged from 3.75% to 9.71% after calibration, regardless of the finger joint angles or finger posture.

Kinematic determinants of performance parameters during golf swing

2019 ◽  
Vol 233 (5) ◽  
pp. 554-561 ◽  
Author(s):  
Batbayar Khuyagbaatar ◽  
Tserenchimed Purevsuren ◽  
Yoon Hyuk Kim
Keyword(s):  
External Rotation ◽  
Three Dimensional ◽  
Left Knee ◽  
Performance Parameters ◽  
Joint Angles ◽  
Lower Trunk ◽  
Left Elbow ◽  
Posterior Tilt ◽  
Shoulder External Rotation ◽  
Measures Of Performance

In golf, the trunk and pelvis kinematic variables are often related to measures of performance due to the highly complex and multi-joint movements involved in swings. However, it is unclear how specific body segments or joints contributed to the golf performance parameters. Therefore, the purpose of this study was to identify the key joints, including those of the upper and lower trunk, that are associated with golf performance parameters, such as X-Factor and pelvis motion. A motion capture system was used to obtain three-dimensional kinematics of golf swings performed by 10 low handicap male golfers. Based on regression analysis, right knee adduction, right shoulder external rotation and left elbow extension in ball address to top of the backswing and left knee adduction and lower trunk right bending with left rotation in top of the backswing to end of follow-through were presented as predictor variables for the X-Factor. For pelvis movement, a greater number of joint angles were associated with pelvis posterior tilt during backswing and pelvis motion to target with right rotation during downswing/follow-through. This study provides fundamental details of the movement mechanisms of major joints, as well as their relationships with performance parameters. Such understanding can be combined with training to improve the golfing skill and prevent possible injuries.

Three dimensional profile measuring method based on coupled Dammann gratings

2015 ◽  
Author(s):  
Shaoqing Wang ◽  
Changhe Zhou ◽  
Shengbin Wei ◽  
Kun Liu ◽  
Xin Fan
Keyword(s):  
Three Dimensional ◽  
Measuring Method
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