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Biomechanics of Pouched StructureStudies

Mechanics of hydraulic skeleton Development of flexible system Development of flexible system Control of mechanism of autonomous distributed systems

Please click the research themes for detail descriptions.

Pouched structure filled with fluid is often observed in creatures such as earthworm and sea anemone and so on. The structure is called hydraulic skeleton that transforms the body by changing inner pressure. As the body is innately flexible, notable new features that conventional mechanical systems do not have will be realized using hydraulic skeleton. We are also interested in motion mechanism of organs with pouched structures such as intestine and heart.

We approach these themes as "biomechanics of 腔" using a Kanji character denoting pouched structure.


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Mechanics of hydraulic skeleton
Computer simulation provides useful information about design of hydraulic skeleton although the numerical analysis is not easy. Predicting large deformation requires nonlinear analysis. Recently, with the development of computer technology, it has become possible to calculate deformation with nonlinear finite element analysis (FEA). With the capability of numerical analysis proposed flexible mechanism can be designed with quantitative estimation. The motion picture shows dynamic states of a hydraulic skeleton.


    Angle=40      Angle=90       Angle=140

【Literature】
Daisuke Maruyama, Hitoshi Kimura, Michihiko Koseki and Norio Inou:
Driving force and structural strength evaluation of a flexible mechanical system with a hydrostatic skeleton,  
Journal of Zhejiang University-SCIENCE A, Applied Physics Engineering, pp.255-262 (2010)  
 
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Development of flexible system
Mechanical system consists of stiff materials such as metals and hard plastics in general. For instance, it is difficult to grasp fragile object using such systems. This study proposes new flexible mechanical systems with hydraulic skeleton driving mechanism.

#Flexible robotic arm
Figure shows prototype flexible robotic arm. In this system, hydraulic skeleton (flexible bag) can be used as actuator and structural part by controlling its inner pressure. If the inner pressure is kept high, the bag becomes stiff and it can be used as a link (structural part). It works as actuator by controlling inner pressure (it is fixed at the joint of the arm). Serial multi-link robotic arm becomes heavy in general, however, this system is extremely lightweight because it consists of flexible bags and driven by air pressure. The arm can be fold and it becomes very small for transportation or storage.


#Hermetically sealed flexible mobile robot "MOLOOP"
The robot "MOLOOP" has double looped structure.
Figure illustrates the structure of MOLOOP. It can pass through narrow spaces (normal robot diameter = 420mm, space = 300mm) as shown in the motion picture.


#Flexible ciliary actuator
Ciliary movement is widely found in animals. Versatile applications are expected using flexible ciliary actuator sheet. Prototype actuator sheet can transport objects and it can move itself (Figure and the motion picture).




【Literature】
Hitoshi Kimura, Takuya Matsuzaki, Mokutaro Kataoka, Norio Inou:
Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags:
A Proposal of Dual Structural Actuator,

The Scientific World Journal, 2013, Article ID 128916, 10 pages, (2013)

Mokutaro Kataoka, Hitoshi Kimura, Norio Inou:
Hermetically-Sealed Flexible Mobile Robot "MOLOOP" for Narrow Terrain Exploration-Improvement of Flexible Bags with Fibrous Material-,
The 39th Annual Conference of the IEEE Industrial Electronics Society(IECON 2013), (USB flash memory), pp.4154-4159, Austria Center Vienna, November, 10-13 (2013)

Hitoshi Kimura, Mokutaro Kataoka, Shotaro Suzuki, Daisuke Akimoto, Norio Inou: A Flexible Robotic Arm with Hydraulic Skeleton,
Journal of Advanced Mechanical Design, Systems, and Manufacturing, Vol.6, No.7, pp.1107-1120 (2012)
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Biomechanics of digestive and circulative organs
Peristalsis is observed in gastrointestinal tract, which is a movement to transport inner contents by a sequential intestinal contraction. We analyzed the transport performance of small intestines considering muscular property of the intestinal wall. The optimal interval of contractions was found in this study.
     
The calculated flow rate by two constrictions moving with same speed. It keeps same profile.

     
Relationship between the flow rate and the interval of constrictions.
there exists an optimal interval which maximizes the flow rate for each viscosity.

【Literature】
Norio Inou and Yoji Umetani:
Small Intestinal Movements In Vivo and the Neuro-Mechanical Control Mechanisms, Proceedings of International Symposium on Autonomous Decentralized Systems (ISADS93), Kawasaki, Japan, pp.407-413 (1993)

Yoji Umetani and Norio Inou:
Biomechanical Study of Peristalsis -Modeling and Analysis of Intestinal Movements-,
Transactions of the Society of Instrument and Control Engineers, Vol.22, pp.1081-1086 (1986) (in Japanese)
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Control of mechanism of autonomous distributed systems
Peristaltic movement is controlled by intestinal nervous system. The nervous system is almost same structure along the intestine, but the structure has not yet been cleared. We assumed it as a neural network and demonstrated the validity by mechanical models. The figure shows the presumed neural network and the motion picture is the demonstration. We also demonstrated peristaltic transport of fluid modifying the neural network.

min_1

     Presumed neural network            Peristaltic movement
                                 solid contents transporting


【Literature】
Y.Umetani, N.Inou:
Neurodynamical Simulation of Peristaltic Movement,
Simulation in Engineering Sciences, North-Holland, pp.179-184 (1983)
Y.Umetani and N.Inou:
Biomechanical Study of Peristalsis -Simulation of Peristalsis in Case of Fluid Contents-, Journal of Robotics and Mechatronics, Vol.6, No.1, pp.104-108 (1994)