pneumatics or motors?

In this year’s game you can either. My team’s inexperienced with pneumatics and more experienced with using motors. But using pneumatics this year seems more beneficial.
What are the pros and cons of each for this year’s game?

For your ball shooting mechanism?

Using pneumatics vs motors in what aspect? We need more detail before we can comment.

Agreed. While I wouldn’t use pneumatics for certain applications (like driving my drivetrain), I would definitely use them over motors in other applications (such as linear movement).

Don’t be lulled into false hope with the number of available motors. Add too many or have several running at the same time can cause you to draw the battery down to critical levels. Remember that the Crio will automatically disable all outputs when the battery voltage falls to 5.5 volts. It will generally reboot if the battery voltage falls to 4.5 volts for a short time. You are being given more motors to choose from for your particular design. Use them wisely.

ahh sorry guys. My bad. What I mean: pneumatics or motors for shooting?

Depends on your design. In my opinion, based off of tons of research, pneumatic rams would need reloading, and would have not as much power as motor powered shooters. For shooting basketballs, just use motors.

I didn’t see a possible way to use pneumatics to shoot consistently. You have to have a huge amount of force just to get the ball to move. My team tried it with a tennis ball earlier in the year to test the idea of shooting anything using pneumatics, and it barely made it 10 feet. That was with all the air pressure they wanted to use. They didn’t have a tank restriction and didn’t use just 60 working psi. It was unimpressive. I could be wrong, and there could be a genius way to use them. But right now using a baseball pitching design seems to be the only viable option to keep a consistent shot while it being reasonable in the sense that you can do it more than once.

I just don’t see any way that you can flow enough air to move a piston fast enough to launch a ball any impressive distance. For close up action that may work fine, but the maximum valve port diameter restrictions in the rule book just seem too restrictive to do anything worth while.

Don’t underestimate what’s possible with pneumatics. Watch the robot in the lower right in the following video kick soccer balls pneumatically. http://www.youtube.com/watch?feature=player_detailpage&v=Q_X4ua4VhtI#t=160s

That was fully pneumatic? Wow, I always figured it was surgical tubing/etc. Care to elaborate? That was (albeit entirely characteristically) an amazing machine.

Using a pneumatic cylinder to push balls directly will be disappointing, given the equipment legal on an FRC robot.

In Breakaway, many teams kicked the soccer ball using latex tubing to power the kicking 'leg, and then used a cylinder to reset the ‘leg’. A latch held the ‘leg’ in place until the driver decided to kick again.

In Aim High, the more successful robots used a spinning wheel, like a baseball pitching machine uses, to launch balls. A well-designed mechanism was extraordinarily repeatable, but that is difficult to actually do, since the wheel wants to slow down as its momentum gets put into the ball.

Don’t be afraid of pneumatics, but please read the rules very carefully to make sure your robot uses ALL of the safety equipment properly. This includes the 120 PSI relief valve*, the pressure release valve, the pressure switch**, the primary regulator, both pressure gauges, and the cRio and a Spike to control the compressor.

*This is supplied uncalibrated, be sure to calibrate it before use
** This is wired to a digital input of the digital sidecar. That signal is used by the cRio to control the Spike relay controlling the compressor.

There are some details in this thread http://www.chiefdelphi.com/media/photos/35118

If you want to see pneumatic shooting at its best, check this out:

close up CAD rendering of the robot:
http://www.teamtitanium.org/images/09botfull.jpg

I got to see this robot up close when it was in use for Lunacy, it was a really beautiful job!

In Aim High, pretty much any team that did throw balls used a motorized wheel, like the aforementioned pitching wheel. It did have the tendency of slowing down the wheel, but if you give it a second or two to ramp back up to speed, I think it’ll still be faster than drawing back a pneumatic cylinder to reload.

If you want to use pneumatics, my suggestion would be to use a “catapult” type arm to throw the ball, and place the pneumatic cylinder between the fulcrum and the load of the arm. Think how a hammer works driving a nail… the fulcrum is the butt of the handle, the arm swinging it is the arm (located up more on the handle), and the load is the head driving the nail with a lot of speed.

Neither of you are thinking outside the box :wink:

Take a 12" cylindar. lock it 1/2 way (mechanical lock like a fence latch). pressurize the cylindar. release the lock and see how fast the cylindar reacts and how far you shoot the ball.

oh, I’d put a hard stop on the rod so you dont damage the cylindars end cap :wink:

I dont think that will work very well Daniel… We tried something like that on the 1st day, and the output port limits the speed at which the cilinder will react… Very unimpressive… Now if you could open one side with a huge port, that would be a different ball game…

Check to see if quick release valves are legal in this game. We used one on a single cylinder in Breakaway and could shoot well over 30’ if we had a good angle.

In Breakaway, we scored from the far end of the field in autonomous and during the matches using a pre-pressurized, gate-latched pneumatic cylinder, and lots of surgical tubing to assist with kicking the soccer balls.

The cylinder re-tensioned the surgical tubing, was latched in the closed position, pressurized to 60psi (a force of ~180lbs), and another much smaller cylinder released the gate latch. Tremendous forces and speeds! That design helped our alliance win the 2010 Colorado Regional. With 120psi on the air cylinder our kick tests on soccer balls have gone about 55’.

If we wanted to kick a short shot, like if we were on offense, then we fire the solenoid to kick, and then immediately reverse it. We actually had good distance control, depending on how long of a delay we used between the extend and retract we had decent control of the stroke.

That’s exactly what our team did (servo release instead of pneumatic). Except our balls would go about 10 feet. Probably just “rookie mistakes”

In 2008 we had a 2-stage pneumatic launcher that would throw the ball clear over the bars through direct actuation (no mechanical advantage or spring assist), something we were told was impossible. The trick? **Use multiple 1/2"-3/4" pistons, each with its own solenoid valve. ** Those pistons will respond VERY quickly.