Presentation on theme: "Why we should mimic jellyfish for efficient underwater propulsion."— Presentation transcript:
Why we should mimic jellyfish for efficient underwater propulsion
Cyro – biomimic jellyfish robot
Guns? I thought this was bioE! Why does a gun recoil? How is a submarine propelled?
How does a jellyfish propel itself?
(Naïve?) Propulsion Model j-u Time = t Time = t+ t u M V u+ u M - m V- V
Model v. Experiment Little jellyfish (prolates) Big jellyfish (oblates) Big
Vortex complexes Increase Efficiency
Biomimetic Robot Design Features to replicate? How to do this simply? Bell material properties: buoyancy, elasticity Bell geometry/deformation Muscles/Actuation
Hard body vs. soft-body Finite degrees of freedom (DOF) Infinite degrees of freedom (DOF)
Action and Reaction: SMAs Shape Memory Alloys (SMA) Stress, strain and heating
Crystal structure phase change Temperature induced phase change: Martensite: soft, plastic, easily deformable state Austenite: much harder material, rigid/difficult to deform.
Reaction: Spring steel and elastomer SMA changes length metal does not
3-D printed mold: Integrating actuators
The devil in the details No-flaps Flaps
Computer control: Feedback SMA contracts Changing resistance Monitored by computer Adjusts current flow through SMA
Mimic vs. Nature
Up, up, and away
Small modifications go a long way! Flaps and segments lead to large increased in thrust
References Jellyfish Propulsion Mechanisms S. Colin and J. Costello. Morphology, swimming performance and propulsive mode of six co-occuring hydromedusae. J. Exp Biol. 205 (2002) J. Dabiri et al. Flow patterns generated by oblate medusan jellyfish: field measurements and laboratory analyses. J. Exp Biol. 208 (2005) Bioinspired Jellyfish Robot (Robojelly) A. Villanueva et al. A biomimetic robotic jellyfish (Robojelly) actuated by shape memory alloy composite actuators. Bioinsp. Biomim 6 (2011) A. Villanueva et al. A bio-inspired shape memory alloy composite (BISMAC) actuator. Smart Mater. Struct. 19 (2010)