SECOND shots
 

Our second generation prototype shooter accuracy is right on the money, 10 for 10. Now programming has to live up to the talents of the mechanical sub-team.
FIRST shots

It works well with both new balls and severely damaged balls. There doesn't seem to be a great deal of difference in the ballistic characteristics of old torn-up balls vs new balls.
This new version shooter doesn't leave a mark on the balls at all, as opposed to the original model that was able to strip the coating off the balls after a hundred shots or so.

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Sweet video and how cool is it to have a dog roaming around while you build robots. looks like a great shooter from ya guys.

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Agreed. Amazing shooter.

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Some of the balls have a few extra teeth marks, but Lady never tires of fetching for us.:)
She's actually a guide dog in training, not that we're shooting blind!

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I've seen several examples of teams getting the softball type launcher working. While they work, they also seam to be quite heavy and are mounted kind of high. Don't forget the CG issue and the ramp factor. If the launcher is mounted low in the robot cg is better but blocking is a problem. Mount it high and blocking is harder, But has any one looked at how unstable a robot can be going up the ramp? The diamond plate is a pain especially if your robot gets a little sideways. I love when opposing team robots tip, hate it when it's our alliance partner. Each day that goes by this game gets a little more interesting.

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NICE launcher. It is amazing how many teams are going after the softball style pitcher this year. Seems like a popular idea.

Question is, who has a complete system yet? One that can pick up, load, and shoot balls.

-Joe

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Gdeaver...

Thanks for the heads-up. Everyone should heed your warning.

Our 2 drum shooter is about 16lbs, and will have a gimble of about 10lbs mounted below it. We'll be putting the remaining weight as low as possible to maintain stability.

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thats basicly what we are doing only we took the concept and turned it on its side. we dont have a goal set up yet but we are in the old middle school and use the basket ball goals... smaller target so we dont make them 100% but its amazing. good job with yours

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Good, accurate shooter. The only thing I don't like is the fact that you can't really go much more rapid fire than that, or so it sounds like by the motors.

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that wasnt rapid???

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The current system has no software support to help ramp the motor back up to shooting speed after a shot. As Mark said in the first message of the thread, now it's time for the programmers to do their magic.

We're targeting a minimum of 10 balls in about 7 seconds, which allows an autonomous with 3 seconds of driving, the rest for shooting.

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Nice mechanism. :)

Where were your safety glasses? :confused:

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I'd like to see another video when you can maintain a steady RPM after shooting. I think that shooter is going to be beastly if you can use it right.

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Very impressive. Quite possibly the most elegant and smooth shooter I've seen yet. Its a pretty good standard to have set =)

Kevin

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Great job guys!

I really like how you used those tiny wheels but still achieved a great amount af acuracy. Now I'd like to see how you guys are planning on aiming that sharpshooter.

Mike C.

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Thanks...

The shooter will be mounted to a rotary table (allowing rotational motion both horizontally and vertically), and aimed via the camera. Balls will be loaded into the shooter via a pneumatic cylinder.

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I don't think this robot will be considered a rapid firing machine comparitively. But definatly the makes of a nice sharpshooter.

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As soon as Mark fine tunes the software to re-ramp up the RPM's after each shot we hope to greatly increase rate of fire.

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Full recovery last night under software control took about 1/3 second per ball launched. That means it's capable of 10 balls in under 4 seconds (if we can hand load them that fast).

Back over to Mechanical Engineering ;)

Mea Culpa. With safety glasses. :o

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just a few questions, one how long does it take to start up from nothing, second how much battery comsumption is there, and last a mixture of the two questions, would it be benifitial to quit in the defence, or does it take to long to get up to speed, I can just see how that is going to be a big battery consumtion, then you add the pnumatics, which will take a bunch if it will be feeding only one ball at a time, and then your drivetrain, and the movement of this and last a ball colection of some sort. I see how it is an amazing prototype but your battery will run short I assume every match.

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Where are people coming from with this "OMG everyone's battery is gonna die midmatch!!1!!"? Our 2005 robot, which ran something to the effect of 6 motors, a full pneumatics system and it lasted a good 12 minutes. While this year we'll be running more motors, I still don't see how a good fully charged battery could possibly die mid-match.

While I'm not assosciated with the team that built this launcher, ours reaches top speed in under 3 seconds.

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I agree, as long as the batteries are fully charged teams should have no problem lasting at least a match (and easily 5 minutes). The problem arises when teams do not adequately charge their batteries or do not have enough batteries. :(

It ramps up in 6+ seconds without feedback, about a second with feedback.

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have you measured / calculated you muzzle velocity yet?
looks to be about 10-12 m/s

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It should be, it was designed to shoot balls at 12m/s. It has not been measured with a speed gun, but it shoots approx. the max distance it should be able to.

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Very good estimate. How did you "see" that???

A couple design criteria where:
1. Design to a 13m/s wheel speed, as there will be losses.
2. Design based upon 1/2 max motor speed to accomodate any battery issues, allow for an extra pulse to get back up to speed after a shot, and so we can have some room in case point one above was not concervative enough.

Upon testing, we shot a ball 35' at 30 degrees (with no spin on the ball). Based on this, we're pretty confident that we're at 12m/s, as this was FIRST's indirect measure.

Since then, we've lessened the top drum speed to generate a back spin, giving us much better control at the same type of distance.

In order to get a final number, we'll be looking at a buying a speed gun (which I'll use with the baseball team I coach in the off-FIRST-season).

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sorry but finally i found you again, i was trying to figure out which team it was who made that shooter but hey now I know, anyhow my team desperately wants to know how you built that,we hardly have anything, we have replicas but they're hardly working, could you give us schematics of what you did so we could make a similar model. It would help us so much.

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Matt's Solidworks models were just the starting point for this prototype, so they don't match the final product. We're going with a refined version of what you see in the video and that's still being CADed. I didn't take any closeup photos of the gearbox before we revamped it.

The prototype itself is now in a one wheel configuration to test the difference, and the final prototype parts are being made - if we can remember how much Argon flow to use. Our experienced welder is delivering pizza tonight, so we have to order something...

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okay, coolie

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Short of a schematic, here's a quick description:

Gearing
A gear (G1) is mounted to the motor shaft. G1 then meshes with a second gear (G2). G2 is used to increase the speed. A third gear (G3) meshes with G2. G3 = G2, as it is used only used to provide opposing rotation.

Pulley system
A pulley is mounted to each of the shafts that support G2 and G3. Timing belts than drive pulleys attached to shafts which support the drums that shoot the balls. We decided to have a larger pulley diameters on the upper drum shaft to generate a backspin

I hope that helps. I can put together a schematic tomorrow in PPT, if you'd like. Let me know.

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You're probably going faster than 12 m/s in this case, because the FIRST measure excludes air resistance. This is an easy fix however, and it looks to be an impressive shooter. can't wait to see pics of the final 'bot!

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http://forums.usfirst.org/showthread...ght=resistance

To quote the Q&A