Author Topic: Air muscle aka McKibben Muscle???  (Read 4075 times)

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Offline illwill101485Topic starter

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Air muscle aka McKibben Muscle???
« on: May 16, 2007, 01:33:20 AM »
I'm starting to design a robot using the air muscle. I'm trying to come up with possible problem with design.
Air muscles have a 400:1 power/weight ratio. down side to using them is air supply. they run using 1-6 bar of pressure or 0-80 psi.
I've seen some video on youtube, alot specs, some projects from Shadow and Fresto (both amazing designs).



Fresto design, was planned on using to make huminoid tele comtrolled robots.-
http://video.google.com/videoplay?docid=-8299074891028031301&q=air+muscle


http://www.shadowrobot.com/airmuscles/videos.shtml

any idea are welcome

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Re: Air muscle aka McKibben Muscle???
« Reply #1 on: May 18, 2007, 07:55:08 AM »
Id say simple motors are easier, stronger, more efficient, etc . . .

search the forum for 'muscle', a few other posts comment about them :P

Offline illwill101485Topic starter

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Re: Air muscle aka McKibben Muscle???
« Reply #2 on: May 18, 2007, 11:31:20 PM »
I think its a cheap efficiant mechanism, not to mention light weight. Only thing i will say is a downside is size. I think a robot combining both would be pretty interesting.
Now considering that i'm still pretty new at this i may be wrong(most likely), but could tell why you think that?

Offline illwill101485Topic starter

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Re: Air muscle aka McKibben Muscle???
« Reply #3 on: May 18, 2007, 11:52:25 PM »
"Air Muscle is an actuator that works very similarly to a human muscle—it contracts by thickening. Inside the black pouch is a balloon. High pressure air pumped through the tube inflates the balloon causing the muscle to shorten by as much as 40%.

Air Muscles can provide substantial pulling force for their small size; they can exert force 400 times their weight. Typical DC motors or pneumatic actuators can exert about 16 times their weight. The largest of the standard Air Muscles is 11 inches long, weights less than 3 ounces, and can lift 154 pounds!

Air Muscles work when twisted, bent around corners, or under water. It even has a similar power profile to a human muscle: the force exerted decreases as it contracts, just like the strength of your biceps is maximum when your arm is extended and decreases as your arm is bent.

The Air Muscle consists of a rubber tube covered in tough plastic netting which shortens in a scissor action when pulled out like a human muscle when inflated with compressed air at low pressure.

 Weight: 10 ~ 80 g (0.022 ~ 0.18 lb)
  Diameter: 6 ~ 30 mm (0.24 ~ 1.18 in)
  Length (Fully stretched): 150 ~ 300 mm (5.9 ~ 11.8 in)
  Output (Pull force): 30 ~ 350 N (6.6 ~ 77 lbf), normal
70 ~ 700 N (15 ~ 150 lbf), Max.
  Max. inflated pressure : 2 bar (30 psi), unloaded
4 bar (60 psi), loaded

 
 

 
 
Pros and Cons   
 
 
 
  • Pros:
  - Light weight (10 ~ 100 g) 
  - Low component cost 
  - Smooth in operation 
  - Flexible in alignment 
  - High power-to-weight ratio, up to 400:1 
  - Self-Damped 
  - Compliant 
  • Cons:
  - Limited size availability 
  - Long term reliability and maintenance cost unknown 

 
"-http://www.efunda.com/sponsors/inventables/AirMuscle/AirMuscle_Intro.cfm

Offline Ro-Bot-X

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Re: Air muscle aka McKibben Muscle???
« Reply #4 on: May 19, 2007, 04:44:27 AM »
I think the biggest downside of the air muscle is the actuators for air flow control. I mean the valves. Are there electrical valves? Are they like digital (on/off) or analog (adjustable flow)? Or you will need a motor to turn on/off a mechanical valve?
Check out the uBotino robot controller!

Offline dunk

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Re: Air muscle aka McKibben Muscle???
« Reply #5 on: May 19, 2007, 04:56:18 AM »
Quote
  • Pros:
  - Light weight (10 ~ 100 g)
  - Low component cost
  - Smooth in operation
  - Flexible in alignment
  - High power-to-weight ratio, up to 400:1
  - Self-Damped
  - Compliant
  • Cons:
  - Limited size availability
  - Long term reliability and maintenance cost unknown
so nowhere in this list did you take into account an air or compressed air tanks compressor to power the muscles.

Quote
Air muscles have a 400:1 power/weight ratio.
i seriously doubt that after you have taken into account the weight of an air reservoir and/or compressor.

for tethered projects (ie, projects that do not need to carry the compressor around) i agree that air muscles might be a reasonable solution.

dunk.

 


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