Hello! One of my team members had an interesting idea and I’m making this post to refine the idea and see if anyone has used this before.
A few weeks ago, my school ran a camp for early season practice. My team used pneumatics for indexing discs into a flywheel. Because this was a very poorly optimized robot, we didn’t get many actuations out of the cylinder. (See below for data) In summary, the conversation turned to how to increase pneumatic air capacity.
One of my teammates suggested using a large amount of pneumatic tubing connected to the air reservoirs to increase the total air capacity. We tested this using the robot we already had and simply counted the number of times the cylinder could push forward and back, completing the motion against gravity in the timing specified in our code before it automatically retracts. We used an unused 100 foot spool of cable with one end capped joined with our reservoirs with a T fitting. The other end of the spool was plugged.
With two air reservoirs pumped to 105.5 psi, the cylinder completely actuated 57 times in each direction.
With the same reservoirs and 100 feet of tubing pumped to 104 psi, the cylinder completely actuated 78 times in each direction.
With the added air space of the tubing we had a 37% increase in the effective use of the cylinders.
From that we can find that 100 feet of cable has more than 2/3 the air storage capacity of an air reservoir. Interestingly, it we calculate the internal volume of 100 feet of tubing (2.5mm internal diameter) we find that it is almost identical to that of the air reservoir at 149.61 cubic centimeters.
Does anyone use this already? It seems like it could be significantly beneficial in the game. Putting a few hundred feet of tubing on your robot could be unwieldy but it is very flexible in how it is positioned. As you can see in the above pictures, the robot we tested this on used X-drive. If we had rewound the pneumatic tubing slightly smaller it would have easily fit inside the Drivetrain in the unused space behind the intakes and above the ground. If you really want to fit a lot in you could stuff lots of tubing in various dead spaces in the robot.
From a rules standpoint, I don’t see why this would be illegal but I easily could have missed something. I’m not aware of any rules that specify how you have to use pneumatic components that would forbid this.
Unfortunately, this isn’t significantly cheaper than buying reservoirs directly. 100 feet of cable from Robosource costs $40 at the time of writing and a reservoir costs around $50 from SMC.
Lastly, I should note some caveats of this test: This was by no means a scientific trial, just a proof of concept. We only did one trial and the condition at which we ended the test was somewhat poorly defined.