Inconsistant Shooting

[NOV8R]

After the scrimmage this past weekend I noticed when we got our balls back they were no longer air tight. You could squeeze them and hear air escaping. Back in 2006 I noticed the same thing. There was a muzzle velocity measurement during inspection in 2006. The results on this test depended on the balls they used. Balls that were no longer air tight shot at slower muzzle velocities. In 2006 we shot a lot of balls so it was easy to adjust your aim for this. With fewer balls this year it's going to be harder to do.

[tomy]

My team had a very accurate shooter. We can shoot in the same spot many many many times. The only bad thing that messes us up is when balls get squishy. What we are going to do is change the set speed as the games go on. So if our setting at the start of the games is .60 for close range we might change it to .65 with flatter balls.

[Ether]

Originally Posted by tomy

My team had a very accurate shooter.

Wheel or catapult?

[tomy]

wheel

sitting and not moving we shot 5 balls and they all hit in the same sppot + or - 4 inches

want a vid?

we are working on video tracking now

[Ether]

Originally Posted by tomy

wheel

want a vid?

No, just more detail

axles: bottom only or top and bottom?

if bottom only, what's your chute made of?

if top and bottom, is top powered separately?

how many wheels on each axle?

wheel size, motor, and gear ratio?

PID or no?

What's the max wheel speed you are using?

What's the motor voltage (or current) at that speed?

What the launch angle and is it variable?

...stuff like that

[DampRobot]

We found that how the balls were fed in significantly effected the concistancy of the shooter. In prototyping we found that wheeled shooters generally are much more sentitie than the design that we ended up using, a belted shooter.

Try to eliminate as many variables as possible before concluding the shooter is at fault.

[jwfoss]

We found that our accuracy increased greatly when we properly fed the balls into the shooter, directly on their center. (We have a dual wheel single axle shooter with a hood). PID control was the final step, and now we are very confindent in our repeatability.

Remember that the speed the ball enters the shooter has just as much effect as the speed of the shooter wheels themselves.

[Ether]

Originally Posted by jwfoss

Remember that the speed the ball enters the shooter has just as much effect as the speed of the shooter wheels themselves.

So if you double the incoming speed of the ball, the exit velocity will double?

[tomy]

Originally Posted by jwfoss

Remember that the speed the ball enters the shooter has just as much effect as the speed of the shooter wheels themselves.

that is not a problem for us cause our ball goes into the shooter at a consistent speed

feeder

feeder we switch to pvc and sprayed with truck bed liner

shooter

two wheels powered by two cims directly with a lazy susan to change the direction