Bio-inspired robotics and Microorganisms Flashcards
Bio-inspired robotics? Why?
- Reproduce functions and mechanism found in biological system.
- artificial and natural devices often operate with the same environmental constraints.
- bio-inspired robotics –> new tools, biological understandning –> new principles
Biomimetics
- An engineered device that reproduces EXACTLY the target biological system.
Ex. karrborrband (Hook-and-loop fastener)
+ Nature has millions of years of experience
- Exactly copy of Nature is almost always impossible => most “biomimetics” are actually “bioinspired”
Bioinspired
- An engineered device that has borrowed some concept of biology, but has taken some freedom in its implementation
+ Nature’s solution offer a good starting points
- Risk of taking Nature’s example out of context or tweaking it to the point where it becomes meaningless
Biological robots
- An emulation (efterliknande) of a biological system used to better understand the biological system itself
- similar to biomimetics, but the target application is different
+ Allow test hypothesis in conditions impossible or unpractical to test on the actual organism
- Errors in the transfer from biological to artificial system may lead to false scientific claims
The process inherent to biorobotics
- Identify the target behavior
- Model a hypothetical mechanism with the target behavior and verify it
- Implement and “Validate” an Artificial Version of the Model
Two keypoints that affects the quality of a biorob.
- consideration of spatiotemporal scale (descibe changes/impacts on the earth) differences - Natural devices = often several orders of mag. smaller and faster than their robotic counterpart
- An appropriate level of abstraction (avskiljning) - The fundamental building blocks of nature and engineering are different; there is
always some level of abstraction in the transfer
Swimming vs. flying
- inertial and viscous forces are 100-1000 times higher in swimming.
- Re is about 15 times larger than for flying (higher density/viscosity ratio for water).
- Flying speeds are usually higher –> happens at higher Re.
MIcro Areial Vehicles (MAV)
+ rapidity, accessibility, stealthiness (military)
- autonomy, payload limitation, complexity/fragulity
Application: MILITARY, entertainment (toy), search and rescue, inspection
Locomotion
ability/act of a entity to transport or move oneself from place to place
medusoid
mimic the stroke kinematics of jellyfish
Helical Swimming
- inspired by the E.coli
Simplification fo the model:
1. 1D i.e. rotation around helical axis, translation around helical axis
2. tail: slender helix with circular cross-section
3. Head: spherical
4. Flow field of the head and tail do not influence each other - solution for head and tail are calc. separately and added up
step-out frequency
- if the freq of the rotating field is increased above max-freq the ABF CANNOT follow the rotation anymore.
- can be increased by increasing the magnetic torque –> increased the drag on the swimmer, lower u_max
- or increased the volume of the nickel head: u_max COULD also be increased
u_max
- the head must be “proportion” to the tail to get u_max as high as possible
- smaller head with same tail length: faster velocity increase expected to the freq.
Shape parameter
Influence of the head size:
- fluidic point of view (does not contribute to forward propulsion, creates add. drag on the swimmer, decreasing speed) –> SMALL HEAD +
- Magnetic point of view: volume –> magnetic torque can be applied, larger volume –> larger torque, step out freq. increased –> LARGE HEAD +
- tail length: short to minimising drag and weight, long for stability
wall effect
- Higher effect at low Re
- closer to the wall the drag/fluidic resistance is larger –> gives a perpendicular F_drag to the desired forward motion along the helical axis –> drift sidewise
- Similar to the observ. of E-coli –> circular path due to the counterrotation
