So, my friend and I are in the process of building a robot that, at least for the prototype, launches projectiles into baskets and trash cans with precision (eventually, we want to get it to launch projectiles at any point within any 3D space by mapping and other environmental information). So, right now, we're thinking of launch mechanisms. They need to be precise with their "launching speed" so that we can predict the trajectory of the projectile (as much as possible). With some easy to get materials, we thought of 1) something like a miniaturized pitching machine, and 2) a setup that preset a platform on springs to a compressed position and a sudden release.
There's another idea that's much more wild and fun that we hope to get to work, at least once - some kind of explosion that set off the projectile. So far, we've thought of somehow making an internal-combustion type of build that, at least in our minds, involved two pipes :one held a piston that would compress a gasoline air mixture that internal-combustion engines used and some kind of spark plug would combust the mixture and cause the piston to quickly drop. The piston is connected to a rod which through a series of gears and whatnot would be connected to a platform in the other pipe which would quickly explode upward and would set the projectile going.
Now, this is no long term thing, but it would be awesome to see something like that work once. We're no experts on materials, so the important question becomes can we get the materials to make such a build? Is there something else you could suggest that involved some kind of explosion?
So, my friend and I are in the process of building a robot that, at least for the prototype, launches projectiles into baskets and trash cans with precision (eventually, we want to get it to launch projectiles at any point within any 3D space by mapping and other environmental information). So, right now, we're thinking of launch mechanisms. They need to be precise with their "launching speed" so that we can predict the trajectory of the projectile (as much as possible). With some easy to get materials, we thought of 1) something like a miniaturized pitching machine, and 2) a setup that preset a platform on springs to a compressed position and a sudden release.
There's another idea that's much more wild and fun that we hope to get to work, at least once - some kind of explosion that set off the projectile. So far, we've thought of somehow making an internal-combustion type of build that, at least in our minds, involved two pipes :one held a piston that would compress a gasoline air mixture that internal-combustion engines used and some kind of spark plug would combust the mixture and cause the piston to quickly drop. The piston is connected to a rod which through a series of gears and whatnot would be connected to a platform in the other pipe which would quickly explode upward and would set the projectile going.
Now, this is no long term thing, but it would be awesome to see something like that work once. We're no experts on materials, so the important question becomes can we get the materials to make such a build? Is there something else you could suggest that involved some kind of explosion?
Maybe less flammable methods:
Diet Coke & Mentos?
Vinegar & Baking soda?
CO2 cartridges?
Recombined H & O from electrolyzed H2O?
Ok. Super face palm right now to myself. Completely forgot that an explosion was just fast expansion of gas. So, any sort of reaction that can cause gas expansion would be appropriate.
Yes. Some explosions just have more oomph behind them.
Google "potato gun"
Explosion is the hardest way to pull off repeatably - either you're making a gun (in violation of various laws an regulations, no doubt - beyond scope of this forum), or you're making a spud-gun style device; those depend however on the mixing of the fuel and air in the combustion chamber (as in, put fuel + air into chamber, press fire, nothing happens. Wait 30 seconds for the gasses to mix, press fire again and it goes). I always found that no matter how carefully I tried to control my process, results were not even reliable in making it fire 100% of the time, let alone with predictable power.
If taking inspiration from spud-guns, use compressed gas, such as from a CO2 tank - these are available on all different scales, from 8g to carbonate a single serving of water, to tanks you need a cart to move around. This can also be easily metered, by monitoring pressure and temperature.
This will be a generally challenging project both in terms of software and mechanics, no matter what you use to fling/shoot the projectile.
Perhaps a less messy method would be to install a compressor (hack one of the car tyre ones) and a mall pneumatic reservoir. Use the compressor to charge up the reservoir then a solenoid valve to instantaneously release the pressure. You could get some serious thrust on a projectile from this.
see the height achieved here from a small 8v compressor.
*** edit more appropriate video
Stages from start to end
- compressor
- check valve
- short section of rigid tubing (make shift pressure vessel - ideally with a pressure sensor for feedback to arduino)
- solenoid valve (your trigger)
- short section of rigid tubing (projectile should fit within or sit around it)
Bonuses of this method being it is reusable and adjustable (just vary stored pressure)
Do not cross-post. Threads merged.
You might use the parts from a paint ball gun for the trigger/gas release mechanism. The gas pressure might be regulated by an adjustable pressure regulator operated by a servo.
@zoomkat, just what I was thinking! You could take the paintball gun and put the CO2 tank on the end of a valve that is controlled by a servo. You would need a pressure sensor on the output side of the valve, and possibly on the input as well. The trigger could be pulled by a solenoid or servo.