Pneumatic Muscles

[daniel12997]

So, I have had robotics on my mind a lot recently, and I was just wondering could you use air pressure and pneumatic tubing to make pneumatic muscles? If so how feasible they would be, and what would be some possible uses for them?

Thanks for any comments
-Daniel

[Joe G.]

I recall FIRST choice having a variant of these available a few years back.



I don't think they saw much use.

[asid61]

"Pneumatic muscle" is just a cylinder right? Contract/extend? A cylinder should act like a pair of- I think the term is complementary? -muscles. And pneumatics have a lot of uses.
How many compressors can we have on a bot?

[NWalker]

As far as a contract-extend pneumatic cylinder goes, we (1619) used a few this year to make a hinging claw to pick up the ball. What would happen is the claw would open, swing forward, scoop up the ball, close, and retract back up with the ball. I am new to the team this year, so I don't know the details of placement and such, but that was the basic premise.

[BBray_T1296]

Originally Posted by asid61

"Pneumatic muscle" is just a cylinder right? Contract/extend? A cylinder should act like a pair of- I think the term is complementary? -muscles. And pneumatics have a lot of uses.
How many compressors can we have on a bot?

Definitely one compressor (obligatory we-dont-know-next-year's-rules-for-certain) See 2014 4.10 R79

On a technicality, muscles only "retract" and relax, offering little/no force in the "pushing" or extension direction. It takes a pair of muscles pulling on opposite sides of a joint to fully operate the joint.
A double acting, and to an extent, a single acting cylinder offers force in both the extending and retracting directions.

If you are referring to something similar to what Joe posted, I would make the point that there is (in FRC applications) very very little that that device could do that a standard cylinder could not.

By simply looking at the picture,
It seems lighter due to its not steel construction, and more lenient in handling non-coaxial forces.

[FrankJ]

While the function is similar, a pneumatic muscle is different than a cylinder. FRC has been very restrictive on the list of the components allowed in the past. The tubing allowed would not make a good muscle since it doesn't contract that much with the allowed pressure. There was the First choice part a couple of years ago.

[evand4567]

We have a pneumatic muscle, and I have to say, I can't think of a single use for it that a cylinder wouldn't do 10x better in FRC. It has a very short and weak retract rate, and compared to a cylinder, takes a lot more effort to mount as the fittings are on either end. Additionally, the activation time is significantly longer than a piston. It is much simpler to just get a cylinder, and given the throw of the muscle, a cylinder of that size is likely lighter.

[Kevin Thorp]

A pneumatic muscle is good in tension. Like the muscles in your body it cannot "push". You need a spring, gravity or a 2nd muscle to pull in the opposite direction. They are very durable and have no sliding seals to leak. Traditional cylinders are somewhat delicate, especially long stroke cylinders in the extended position. Pneumatic muscles don't have much stroke (only 25% of it's overall length) but can pull with a lot of force. For example a 20mm diameter actuator can lift 230 lbs at 60 psi. A 20mm traditional cylinder can only lift about 29 lbs.

They aren't simple rubber tubes. Then have diagonal tensile members that can't stretch. So when the diameter of the rubber sleeve increases due to increased air pressure, the length must shrink. Check out this cool Festo humanoid video.

[chrisfl]

Team 1699 has one lying around the shop. I have been bugging mentors for the past year or 2 to try and use them. When just messing around I couldn't get the festo ones to work. They are really helpful though. They weight practically nothing compared to regular actuators and are super strong. You can also vary their length. They aren't just fully retracted or fully extended. Im still trying to get these to work.

[Kevin Thorp]

Originally Posted by chrisfl

Team 1699 has one lying around the shop. I have been bugging mentors for the past year or 2 to try and use them. When just messing around I couldn't get the festo ones to work. They are really helpful though. They weight practically nothing compared to regular actuators and are super strong. You can also vary their length. They aren't just fully retracted or fully extended. Im still trying to get these to work.

You wrote "Im still trying to get these to work". What problem are you having?

[chrisfl]

We were having trouble getting them to retract. But that was during build season and was probably some stupid little thing I missed because I was working on 5 other things at the same time. Sadly our team does little to no off season work to get time to play with them some more