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Topic: large drum-bot (Read 775 times) previous topic - next topic

rich_brighton

nice 1 guys and thanks a lot cr0sh specifically!

i will be starting this in the next couple months now that it seems possible (just about!).

cheers!

DVDdoug

Pneumatic actuators are probably the most economical solution, especially if you already have a compressor.  But, they can be clunky/noisy, and difficult to "control".   You can control the speed to some extent by regulating air pressure, but otherwise it's just "move" and "move back".    I imagine you could use some feedback to get servo-like control, but I don't think there's anything like that available off-the-shelf.

I don't know if it's still done the same way, but "100 years ago" when I worked for the company, the characters/robots at Chuck E. Cheese were pneumatically operated.  If there's a Chuck E. Cheese near you, you might check it out.  (If they still have those animated characters, and if they are still pneumatically operated, you should be able to hear the actuators activating,)

GoForSmoke

If it's just a regular beat you want then a camshaft on a motor can drive the motions. Using pull against springs, fishing line as ligaments attached close to joint pivots -- you can get very fast moves from short pulls. If you need to vary the beat then really strong solenoids to pull the strings would work. That or find cheap clutches for the cams! I move my arm 30 cm, my muscles change length much less than 30 cm. With this you have the power of constant turning motor and flywheel.

I've seen balloon like sacks used as robot muscles long ago. Each balloon uninflated had two 'ends' tied to two arm sections and a valved hose near one end. When the balloon was given air, it shortened the length between the tied lines and the arm moved but it wasn't anything like industrial with the amount of spring. OTOH for your robot if the arm down to hit the drum position is a bit 'deep', it won't drive the stick through the drum but just hit a little harder. That would be more expensive, maybe but could also run off 1 compressor (and many valves) and have the power stored in the air tank. The cool part is you would see his muscles move even under clothes. Just remember that arm movement starts with the upper torso.

I find it harder to express logic in English than in Code.
Sometimes an example says more than many times as many words.

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