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Posted: Thu Mar 27, 2014 9:54 pm
by JonCard
I had this idea for a squid robot for running underwater. I'm not sure about much so far, but I think it's going to have two pairs of chambers, 1 pair along the axis and 1 pair with one in the middle and the other in a bulbous forhead to "dump" air when the middle needs to deflate. Maybe 4 chambers along the axis is smarter, no one accuses me of being smart. :) This will allow any two consecutive chambers along the axis to inflate, pushing water backwards.

I have started to play with it in SolidWorks, before the idea completely leaves my head, and I am hoping for some some feedback. Am I correct that the orientation of the ribbing in the chambers is really important? The drawings attached will try to push the expansion fore-and-aft, not in towards the center, right? I started it this way, figured I was doing it wrong, and decided to stop for feedback.

I'm not sure how I'm going to make this. I figure I can try to make the inner hull as one piece and the outer hull in two different parts, and then cast the chambers in wax. The wax surrounding chambers would have to be assemble-able (word?) around the inner hull, and then put the outer hull around them. I might need some support pieces between the inner hull and the wax that won't melt out and will stay cast in the silicone. The exhaust valve will probably have to be rigid, so that might make for something.

What do you think?

Re: Squid

Posted: Sat Mar 29, 2014 3:32 am
by JonCard
Here's my latest incarnation of this nutty idea. The tubes into the 4 chambers will be connected to double-action pneumatic cylinders, driven from the shaft by a camshaft so the two pistons are 90 degrees out of phase with each other. The camshaft driven by a motor. Hopefully, this will turn into a squid-like, jet-propelled submersible engine. For basically no feasible use whatsoever, as far as I can tell.

Re: Squid

Posted: Mon Mar 31, 2014 2:51 pm
by Gianteye
Howdy. I think these soft bots have some really interesting applications in underwater ROV's. One of the difficulties is regulating buoyancy. There's actually a thread on the OpenROV forum here about trying to power a soft gripper with water vs air pressure.

In general ribbed chambers will expand things perpendicular to them. However, placement is really important. If they're close to any surface, that surface will end up distorting a lot more than any other area the bubble covers. I think ribbed chambers tucked deep into the body of a silicone bot will end up stretching out the bot laterally, but it's an experiment I haven't tried yet.

One of the engineering problems you'll likely run into is how to make sure the thing moves in one direction versus another. If I've got it right, and you're intending to have this thing move forward by lengthening and then contracting rapidly, it seems like it would be difficult to make sure it moves forward. Chances are the amount of water the fore and aft would displace would be so close to one another and the friction they experience would be so similar that net forward motion would be minimal and the force would deflect into spinning.