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Similar to Isb2015 presentation - Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring Joint Angles
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Isb2015 presentation - Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring Joint Angles
- 1. Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring Joint Angles Satoshi Makita*1, Momoko Maeda*2, Yuki Kawafuchi*3, Ryota Nawata*4 *1 Sasebo College, National Institute of Technology *2 Imasen Engineering Corporation *3 Yaskawa Electric Corporation *4 Aichi University of Education Acknowledgment: Travel grant by Nakatani Foundation stretching
- 2. Background • Using Muscle-Tendon complexes as springs in sports • Elasticity: Applying larger forces • Dynamics: Speeding up motion • Flexibility: Absorbing impact contacts • Focusing on hands, such as overhead pass in volleyball • Receiving the ball by hands • Control (timing, velocity, height, etc.) Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 2/10
- 3. The objective of our research To estimate elastic and dynamic properties of fingers from the viewpoint of muscle-tendon complexes • Elastic Property: Fingertip force • Dynamic Property: Joint angular velocity Both accord to joint angles -> Evaluation of playing performances Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 3/10
- 4. Related Works: Two typical analyses of viscoelasticity of MTC A) Measuring isolated MTC • NOT appropriate to analyze human motion in sports B) Observing by using ultrasonography • NOT suitable to observe upper limbs in QUICK movement Difficulty of observing behaviors of MTC in sports activities Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 4/10
- 5. Related Works: Using Motion-Capture Two concerns A) Expensive costs to introduce B) Difficulty of tracking both fingers and whole body in same time • Occlusions • Resolution (different length of limbs) Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 5/10
- 6. Our measurement method (based on a simplified hypothesis) An MTC of a finger can stretch during dorsiflexion by pushing the fingertip with external forces Using Data Gloves • Joint angle • Fingertip force Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles External force Extensor digitorum Contract Flexor digitorum Extend 6/10
- 7. Procedure of basic measurement Measuring set of fingertip force and joint angle 1. Push the fingertip toward dorsiflextion 2. Stretch the finger MTC to a limitation angle step by step 3. Reduce the force in the similar way Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 7/10
- 8. Procedure of basic measurement Measuring angular velocity 1. Set the finger in a certain dorsiflextion angle 2. Remove the external load instantly 3. While unloading processes, reduce the load from the limitation, and set a certain angle Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 8/10
- 9. Results: Elasticity and dynamics of finger Fingertip force and angular velocity of released motion are exponentially proportional to joint angle Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 9/10
- 10. Discussion / Conclusion • Exponential trend in elasticity and dynamics of fingers measured as fingertip force and angular velocity of finger motion corresponding to joint angle • Similar to the tendon characters in previous works • A hysteresis between “loading” and “unloading” • Any loss of elastic energy (tendon shortening) have occur • Caused by a difference of muscle behavior Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 10/10
- 11. Ongoing works • Analyze overhead pass motion by data gloves • Requirement to consider stretch reflex • Investigate the unknown hysteresis by ultrasonography • Observation of difference of behaviors between loading and unloading term Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 11/10
- 12. Extra slides Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 12/10
- 13. Conclusion • Estimating elastic and dynamic properties of MTC of finger by measuring joint angle • Based on a simplified hypothesis, relationship between joint angle and MTC stretching • Measuring fingertip force and angular velocity of finger motion corresponding to joint angle • Both can be approximated by exponential curve Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 13/10
- 14. Results: Dynamics of finger Angular velocity is also exponentially proportional to joint angle Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 14/10
- 15. Approximation of Elasticity 𝐹𝑡𝑖𝑝 = 𝑎𝑒 𝑏𝜃 𝑀𝑃 + 𝑐 ∆𝑥 𝑀𝑇𝐶 = 𝑟 𝑀𝑃∆𝜃 𝑀𝑃 𝑑 𝑀𝑃 ≈ 𝑐𝑜𝑛𝑠𝑡 𝑟 𝑀𝑃 𝐹 𝑀𝑇𝐶 = 𝑙𝐹𝑡𝑖𝑝 (Torque equilibrium) Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 𝑭 𝐦𝐭𝐜 𝑭𝐭𝐢𝐩 𝜽 𝒓 Muscle Center of joint rotation dorsiflexion 15/10
- 16. Approximation of Dynamics 𝐹 𝑀𝑇𝐶 = 𝑙 𝑟 𝑀𝑃 𝑎𝑒 𝑏 𝑟 𝑀𝑃 𝑥 𝑀𝑃 + 𝑙 𝑟 𝑀𝑃 𝑐 = 𝑎′ 𝑒 𝑏′ 𝑥 𝑀𝑃 + 𝑐′ 𝐸𝑒 = 0 𝑥 𝑎 𝐹𝑡𝑖𝑝 𝑑𝑥 𝑀𝑇𝐶 ⇒ 𝐸 𝑘 + 𝐸𝑙𝑜𝑠𝑠 = 𝑚 𝑚𝑡𝑐 2 𝑥 𝑀𝑇𝐶 2 + 𝐸𝑙𝑜𝑠𝑠 Energy transduction 𝜃 = 𝐴𝑒 𝐵𝜃 + 𝐶𝜃 + 𝐷 Estimation of Elastic and Dynamic Properties of a Finger Attributed to Muscle-Tendon Complex by Measuring joint angles 16/10
Editor's Notes
- In various sports, muscle-tendon complexes (or MTCs) play an important role for us to do superior performances. The MTCs, especially the tendons behave as springs in vivo and accumulate elastic energy during stretching. As a result, We can apply larger forces, speed up motions with high velocity and absorb impact contacts such as landing, catching a ball and so on. Let us focus on hands such as overhead pass in volleyball. We receive a ball by hands and absorb its impact. After that we have to control the ball to release in suitable timing and velocity and to reach it the suitable height. In this motion, we can use the MTC of fingers dexterously for good performances.
- Therefore the objective of our research is to estimate elastic and dynamic properties of fingers to evaluate playing performances of overhead pass in volleyball theoretically. From the viewpoint of muscle-tendon complexes, these properties can be analyzed by stretching length and resultant tension. These two parameters can be approximated by joint angle and fingertip force with a hypothesis addressed later.
- To analyze viscoelasticity of MTC, there are two typical methods. One is measuring isolated MTC by some mechanical ways such as tensile strength tests. Of course, it is not appropriate to analyze human motion in sports because the properties can change whether the tendon is in vivo or in vitro. Another way is observing by ultrasonography, which is widely accepted in biomechanics researches, especially focusing on lower limbs. However, I think it is not always suitable to observe upper limbs in sports because we do various quick motions and movement.
- To observe quick motions in sports activities, we usually use Motion Capture system. Although it is a very proper approach, there are two concerns written the slide. One, Motion capture system takes expensive costs to introduce to your labs. Second, tracking both fingers and whole body in same time is not easy because a lot of occlusion can occur in sports motion, and there is a problem of resolution of markers attached to the body
- Under consideration of the above methods, we propose a measurement method based on a simplified hypothesis of MTC stretching: an MTC of a finger can stretch during dorsiflexion by pushing the finger with external forces like that. With the hypothesis, we can estimate the lengthening of the MTC from joint angle changing, and also elastic resultant force from fingertip force. These two parameters can be easily measured by data gloves.
- First we investigate the elasticity of finger MTC, which can be described as a relationship between joint angle and fingertip force. In our procedure, first we fix a hand on the measurement equipment. While we push up the fingertip toward dorsiflexion, each set of joint angle and fingertip force is recorded. Then we define two terms: loading and unloading. Loading denotes the direction the fingertip is pushed up, and unloading denotes the opposite direction after the fingertip reached a limitation angle.
- In a similar way, we record each set of joint angle and angular velocity of released finger motion. After we set the finger in a certain dorsiflexion angle, we release the finger. In the unloading process, once we push up the finger at the limitation angle and reduce the load to set a certain angle.
- Here are measurement results to show exponentially changing of resultant fingertip force and angular velocity of released motion according to joint angle. From the figures, we can see that both the fingertip force and angular velocity are exponentially proportional to joint angle. This exponential trend of resultant force is similar to the character of isolated tendon reported by previous studies, but we can see a large hysteresis here.
- From the results, our measurement method is reasonable to analyze human hand motion in sports on the viewpoint of muscle-tendon complex because the resultant trends of elastic and dynamic properties of MTC are similar to that of tendon reported in some previous works. In addition, a hysteresis which maybe caused by any loss of elastic energy was observed between loading and unloading processes.
- Now we prepare to analyze overhead pass motion by data gloves. And also we tackle to investigate the unknown hysteresis by ultrasonography in the same way as many previous works.
- I summarize my talk. In this research, we aim to analyze human hand motion in sports with easy and cheap way, and propose a method to estimate elastic and dynamic properties of muscle-tendon complex of finger. The method based on a simplified hypothesis gave reasonable results of estimated properties, which show exponential trends.
- This is a result to show the dynamics of finger related to its joint angle. The angular velocity of released finger also have an exponential trend.