Pneumatic Shooting System & Doubts

  1. 2 months ago

    I've been building a pneumatic shooting system in which after the ball goes through the intake falls into a "gun barrel" and then the pneumatic actuator pushes it at a high speed and it goes flying.. This pneumatic gun is attached to an arm so by varying the angle and distance from the flag it can shoot...

    After seeing a crap ton of reveal videos I feel a bit doubting of the idea since lots of people are using mechanical catapults or linear punchers or these wheels that at very high speeds will fling the ball... Is my pneumatic gun still a good idea?

    I'm also not quite sure how I could utilize its capabilities when im shooting do I just have to know what are the approximate best angles and distances to shoot from?

  2. Bhargav S.

    Oct 29 Maryland 952C

    I would go with a flywheel, mostly just because if you use pneumatic then you can only use 6 V5 motors, so if you want to use your idea it should be fine, but I think most teams will use flywheels.
    Hope this helps!

  3. I haven't seen any pneumatic shooting systems yet, I don't think. If you can figure out how to get it to actuate quickly enough without using your entire air supply, then go for it! Especially if you only have 4 v5 motors anyway, like a lot of teams do right now.

    Flywheels are a lot harder to build, and would probably pretty much change your entire intake system. So, I'd just say stick with your idea until it's obvious it won't work. Be sure to give us a reveal video though. I'm sure some other teams are waiting to see if a pneumatic puncher is a viable option.

  4. Edited 2 months ago by TitanRey15

    @Bhargav S. @Got a Screw Loose I'm using Vex Legacy Cortex not V5 and it seems that I can have 10 motors is that correct? (Link: https://www.roboticseducation.org/documents/2017/10/vrc-robot-inspection-checklist.pdf ) --> it says 'in the zone' but im pretty sure it applies to this competitiion too

    And what do you mean by "get it to actuate quickly enough without using your entire air supply"???

  5. MannanG

    Oct 29 Collierville, TN 3631X

    If you are using cortex, then pneumatics is a pretty viable option. What he means is the pneumatics are probably going to need a few pistons to be able to make the ball actually launch far or fast enough. This will probably take up a lot of air and you only have as much as you can store in your reservoirs. So, you will need to make the actuations as quick and efficient as possible to minimize air usage.

  6. Another option is to have the cylinders only powered in one direction and elastic for the other. That would conserve air as long as you have the solenoid as close as possible to the cylinders with the pneumatic tubing as short as possible. I'm not sure if you would achieve enough force with a pneumatic linear puncher but you definitely could with a pneumatic catapult.

  7. MannanG

    Oct 29 Collierville, TN 3631X

    I agree, a pneumatic catapult would probably work better than a pneumatic puncher, unless you wanted to make it so the rubber bands is what provides the shooting power. Then, you could do either, and you would be able to use pneumatics for other mechanisms such as an active brake or cap intake as long as you can have enough actuations.

  8. @TitanRey15 And what do you mean by "get it to actuate quickly enough without using your entire air supply"???

    I mean that the more pressure you exert, the more air you use from your tanks. If you turn down your pressure to use less air, it may not be as effective. I’m not sure how large the air reserves are, but they can’t be infinite. I haven’t used pneumatics in Vex, so maybe they’re fine.

    And yes, you’d have 10 motors. But if you make it to end season events, you’ll pretty much need to have V5 to be competitive.

  9. Rieger.samuel26

    Oct 29 The Universe 6356E

    @Got a Screw Loose I’m not sure how large the air reserves are,

    ~50 psi

  10. MannanG

    Oct 29 Collierville, TN 3631X

    @Rieger.samuel26 ~50 psi

    I thought you could charge the reservoirs to 100 psi

  11. @MannanG I thought you could charge the reservoirs to 100 psi

    You can

  12. callen

    Oct 29 Braintree, MA, USA

    @Rieger.samuel26

    @Got a Screw Loose I’m not sure how large the air reserves are,

    ~50 psi

    That's not really an answer, even if you'd said 100 psi. The volume of the reservoir matters as well, not just its pressure. This is why more reservoirs let you do more activations, even if they were set to the same pressure initially. I haven't used VEX pneumatics, either, so I can just quote a few things from the official VEX docs:

    Volume: 5.07 fl oz (150 mL)
    Cylinder Strokes: 45 Strokes from 100 psi to 25 psi

    Stroke: 2 in (5.08 cm) (will matter for striking, but I don't know the mass)
    Maximum Output Force: 12 lb (54 N)

    Go here: https://www.vexrobotics.com/pneumatics.html#Docs_&_Downloads to read more.

  13. steven1233f

    Oct 29 Crown Point, IN 1233F

    No

  14. @Bhargav S. @callen @MannanG @Carlinh @Got a Screw Loose

    After talking to my robotics coach he said that if there is no leakage in my pneumatics I wouldn't realistically run out of psi during a 2 minute match even with like 50 shots.. remember I have 1 actuator on an arm that punches the ball and because the arm can change angle i can hit the flags of course\

    Also he started talking about power-weight ratio how does that factor and what is that?

  15. OscarMNOVA12

    Oct 30 Event Partner, V5 Beta Tester Northern VA and Pittsburgh MASON, 12, 22172

    I've run numerous lifts and other mechanisms with 2 reservoirs at 100 psi, without leakage you really shouldn't have too much of an issue with running out of air.

  16. Edited 2 months ago by Got a Screw Loose

    So, it looks feasible. Right?
    With ~50 shots, you should probably be good to toggle all 8 high flags about 6 times, with a couple of shots to spare. That seems to be more than enough.
    The only problem I can see is getting the pneumatic puncher to connect correctly and with enough kinetic energy to transfer to the ball. There’s a pretty confusing physics talk from a few years back about punchers. Pretty much their conclusion was to have the striker’s mass just barely more LESS than that of a ball. Also, you don’t want the ball to rest directly against the puncher in the drawn back position.

    Practical sense tells me this souldn’t work, but it all seems to work out fine, if you can figure out the striker.

    I’d love to see this work. It’ll be a big validation of pneumatic cannons.

    Edit: For Accuracy. I always get the puncher’s mass backwards. Thanks, @callen

  17. @Got a Screw Loose All three of my school's teams are working on this pneumatic type of system.. we'll tell you how it goes and it seems this pneumatic puncher talk is a little more complicated than "just hit the center of the ball" so I'll look into that and all and I'll be sure to contact you if I have questions about that whole part of the science here and there..

  18. callen

    Oct 30 Braintree, MA, USA

    @Got a Screw Loose The only problem I can see is getting the pneumatic puncher to connect correctly and with enough kinetic energy to transfer to the ball. There’s a pretty confusing physics talk from a few years back about punchers. Pretty much their conclusion was to have the striker’s mass just barely more than that of a ball.

    Actually, that's incorrect. You want the striker's mass to be just a little less than the ball's mass. The ratio should match the ratio of kinetic energy conserved. So, for example, if 90% of the kinetic energy is conserved in the collision, then you want the striker to have 90% of the mass of the ball. Practically, however, this can be difficult to accomplish.

    @Got a Screw Loose Also, you don’t want the ball to rest directly against the puncher in the drawn back position.

    Correct. That would accelerate the striker and the ball together, acting more like a slingshot. The problem is that, assuming the striker has roughly the mass of the ball, only roughly half of the energy will actually go into the ball.

  19. @callen Actually, that's incorrect. You want the striker's mass to be just a little less than the ball's mass. The ratio should match the ratio of kinetic energy conserved. So, for example, if 90% of the kinetic energy is conserved in the collision, then you want the striker to have 90% of the mass of the ball. Practically, however, this can be difficult to accomplish.
    Correct. That would accelerate the striker and the ball together, acting more like a slingshot. The problem is that, assuming the striker has roughly the mass of the ball, only roughly half of the energy will actually go into the ball.

    Thanks for the correction. I’ve made the edit in my post. My bad. I always get the whole mass thing backwards.
    The energy transfer is the difficult thing with any puncher, as stated. If only half of the energy (very rough assumption) goes into the ball, you’ll need twice the energy to be stored behind the punch.

  20. callen

    Oct 30 Braintree, MA, USA

    @Got a Screw Loose The energy transfer is the difficult thing with any puncher, as stated. If only half of the energy (very rough assumption) goes into the ball, you’ll need twice the energy to be stored behind the punch.

    With a typical puncher you'll get much more than 50%. That 50% was an estimate if it's not really punching, just pushing as it itself speeds up.

  21. Newer ›
 

or Sign Up to reply!