![Measurement procedure
● Relationship between joint angle and fingertip force
1) Fix a subject’s hand on the measurement bed, and lift up the
finger as high as possible by his/her own muscular strength.
2) Push up the fingertip until the MP joint shifts a certain angle,
and measure the angle and fingertip force by a goniometer and a
force sensor respectively.
3) After the limitation angle, we bring the finger down and simi-
larly measure the two parameters until the initial angle.
release
loading
Initial angle
unloadingLimitation
angleUnloading
Loading
● Relationship between joint angle and angular ve-
locity of released finger
1) Once we lift the finger up at a certain angle by
pushing its fingertip, the applied force is instantly
removed to release the finger. The angular veloci-
ty can be estimated from several time-shift imag-
es captured by a high speed camera.
2) In the unloading process, we lift the finger up to
the limitation angle once and bring it down to a
certain angle, and release it.
Measurement results
● Relationship between joint angle and fingertip
force
● Exponential curve in loading process is similar to
tendons behavior reported in previous works
● Large hysteresis may be caused by any loss of mus-
● Relationship between joint angle and angular veloci-
ty of released finger
● Similar hysteresis occurs
1
10
0 20 40 60 80 100
Appliedexternalforce[N]
Joint angle [deg]
Loading
apprx-loading
unloading
1
10
100
0 20 40 60 80 100
AngularvelocityofMPjoint[rad/s]
Angle of MP joint [deg]
loading
apprx-loading
unloading
Ongoing Works
● Measuring joint angle by using data gloves for sports motion analysis
● Investigating behavior of muscle when the hysteresis occurs by using ultrasonography
Acknowledgment: This work was supported by JSPS KAKENHI Grant #15K12663](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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A Mechanical Model of Elasticity Attributed to Flexor Digitorum - Icam2015 presentation poster
- 1. A Mechanical Model of Elasticity Attributed to Flexor Digitorum * S. Makita*1 , M. Maeda*2 , Y. Kawafuchi*3 , R. Nawata*4 *1 NIT Sasebo College, *2 Imasen Engineering Corp., *3 Yaskawa Electric Corp., *4 Aichi Univ. of Education Keywords Biomechanics, Muscle-tendon complex, Human hand, Elastic force and energy Abstract ● Muscle-tendon complexes (MTC) contributes to hu- mans dynamic motion in sports. ● A tendon is seldom stretched by usual muscular strength but can be stretched by any applied external forces. ● A hypothesis of biomechanics of human hands is pro- posed to estimate the elasticity of flexor digitorum ● Measurement results show that the elastic and dy- namic properties of MTC can be approximated by our derived expression. External force Extensor digitorum Contract Flexor digitorum Extend Motivation ● To investigate contribution of muscular properties of human hands to sports activities, e.g. volleyball ● Easy way to measure and estimate, without any expensive equipment ● Easy to understand its contribution for non-professional people to coach the sport Our proposal Estimate elasticity of MTC by measuring joint angles of fingers ● Measuring relationship between joint angle and exerted fingertip force ● Similarly joint angle and angular velocity of released fin- ger Major two approaches to muscle- tendon complexes 1. Measuring viscoelasticity of anatomically-isolated tendons in mechanical way ● Accurate analysis of mechanical properties ● Impossible use in sports 2. Using ultrasonography or MRI to observe MTC in vivo ● Feasible analysis of interaction between muscle and tendon in body movement ● Difficult to observe in sports activities including quick movements because of lack of portability ● Not always intuitive for non-professional people to apply its knowledge to coaching Sports analysis using Motion Capture ● Too expensive to casual use ● Difficulty observe both whole body and fingers motion in same time because of resolution Flexor digitorum Rotation center of joint dorsiflextion
- 2. Measurement procedure ● Relationship between joint angle and fingertip force 1) Fix a subject’s hand on the measurement bed, and lift up the finger as high as possible by his/her own muscular strength. 2) Push up the fingertip until the MP joint shifts a certain angle, and measure the angle and fingertip force by a goniometer and a force sensor respectively. 3) After the limitation angle, we bring the finger down and simi- larly measure the two parameters until the initial angle. release loading Initial angle unloadingLimitation angleUnloading Loading ● Relationship between joint angle and angular ve- locity of released finger 1) Once we lift the finger up at a certain angle by pushing its fingertip, the applied force is instantly removed to release the finger. The angular veloci- ty can be estimated from several time-shift imag- es captured by a high speed camera. 2) In the unloading process, we lift the finger up to the limitation angle once and bring it down to a certain angle, and release it. Measurement results ● Relationship between joint angle and fingertip force ● Exponential curve in loading process is similar to tendons behavior reported in previous works ● Large hysteresis may be caused by any loss of mus- ● Relationship between joint angle and angular veloci- ty of released finger ● Similar hysteresis occurs 1 10 0 20 40 60 80 100 Appliedexternalforce[N] Joint angle [deg] Loading apprx-loading unloading 1 10 100 0 20 40 60 80 100 AngularvelocityofMPjoint[rad/s] Angle of MP joint [deg] loading apprx-loading unloading Ongoing Works ● Measuring joint angle by using data gloves for sports motion analysis ● Investigating behavior of muscle when the hysteresis occurs by using ultrasonography Acknowledgment: This work was supported by JSPS KAKENHI Grant #15K12663