A Mechanical Model of Elasticity Attributed to Flexor Digitorum - Icam2015 presentation poster
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This document proposes a mechanical model to estimate the elasticity of the flexor digitorum muscle-tendon complex (MTC) in the human hand. It describes measuring the relationship between joint angle and fingertip force applied during loading and unloading of the finger. The results show an exponential curve for loading and hysteresis between loading and unloading, consistent with tendon behavior. It also measures the relationship between joint angle and angular velocity when the finger is released, again showing hysteresis. This simple model allows estimating the elastic properties of the MTC without expensive equipment, providing insight into hand function and application to sports coaching.
![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