3 robots designs I hope to see this season

[JesseK]

Really, if you so wholeheartedly believe you will get away with blinding the opponents with a 84" blanket, go ahead. Just don't come crying to CD when you don't get to compete.

[EricH]

Originally Posted by LafondaOnFire

Well if you start 60 inches tall or less and have no appendages outside the perimeter of the frame would it still be an issue with R01?

Oops, I should have checked. [R08], see line A in the blue box. This is intended to interfere with vision, so it's a violation.

Then you throw in [G07]...

[Thermal]

Originally Posted by farmersvilleRob

You can shoot from anywhere and make it every time with math
And we did until we weighed pros and cons with prototyping and mathematical analysis. Balancing will be a huge challenge considering its worth a lot of points (relatively) and the boards are pretty small for 3 bots. Also, collecting off the ground doesn't necessarily mean something that runs along the ground. Gripping on the holes is considered grappling as well if suction cups are, so I would avoid even touching them. Draw a spreadsheet to find the needed acceleration and muzzle velocity for even 20 feet away. It's some rather big numbers for that 11.2 oz ball. You can block an alley easy if you just rolled over there in the last half minute "collecting basketballs". And when threading the needle, I would rather have my robot thread a needle than a driver. Like a sewing machine versus a hand sewer. Though the hand stitching may look prettier, the sewing machine proves a better more precise, versatile, dependable stitch.

I'm pretty curious as to these "rather large" numbers you're coming up with, because right now you're making it sound like my tape measure was actually measuring in centimeters when I fired a ball 20ft on saturday with some rough cut plywood, poor bushings, a very skewed chain run, and 2 fisher price motors powering a single traction wheel.....

I believe after your first regional, you'll appreciate what BJC and artdutra are saying a little bit more. No offense, but they have a combined 14 years of FIRST experience. If you think 20ft is hard with a poof ball, you should of seen the teams doing it with a 12lb track ball in 2008....

[farmersvilleRob]

Originally Posted by Thermal

I'm pretty curious as to these "rather large" numbers you're coming up with, because right now you're making it sound like my tape measure was actually measuring in centimeters when I fired a ball 20ft on saturday with some rough cut plywood, poor bushings, a very skewed chain run, and 2 fisher price motors powering a single traction wheel.....

I believe after your first regional, you'll appreciate what BJC and artdutra are saying a little bit more. No offense, but they have a combined 14 years of FIRST experience. If you think 20ft is hard with a poof ball, you should of seen the teams doing it with a 12lb track ball in 2008....

The math from my team's calculations says a 20 foot shot requires a ball to be traveling at 30.008 ft per sec. and up to 60 feet it's 49.004 ft per second.

[Thermal]

Originally Posted by farmersvilleRob

The math from my team's calculations says a 20 foot shot requires a ball to be traveling at 30.008 ft per sec. and up to 60 feet it's 49.004 ft per second.

And what makes 30fps hard to reach? Your robot already travels at 12-15 and it weighs 135lb...

[farmersvilleRob]

Originally Posted by Thermal

And what makes 30fps hard to reach? Your robot already travels at 12-15 and it weighs 135lb...

http://www.youtube.com/watch?v=l8U9u...eature=related

So this is basically a direct drive with 2 CIM motors, the chunkiest of the chunky, and at the maximum distance angle (45 degrees) he is hitting 23 feet. That's far enough to also cause more problems. (note the editing might not have been for just collecting the ball). And it doesn't seem to include the ball after ball wheel slow down either.

Originally Posted by farmersvilleRob

http://www.youtube.com/watch?v=l8U9u...eature=related

So this is basically a direct drive with 2 CIM motors, the chunkiest of the chunky, and at the maximum distance angle (45 degrees) he is hitting 23 feet. That's far enough to also cause more problems. (note the editing might not have been for just collecting the ball). And it doesn't seem to include the ball after ball wheel slow down either.

We did something similar (not saying exact though, team secret ), and now have balls shooting out about 58-60 feet. No gearing, 100% legal.

[Alex.q]

Originally Posted by farmersvilleRob

You can shoot from anywhere and make it every time with math
And we did until we weighed pros and cons with prototyping and mathematical analysis. Balancing will be a huge challenge considering its worth a lot of points (relatively) and the boards are pretty small for 3 bots. Also, collecting off the ground doesn't necessarily mean something that runs along the ground. Gripping on the holes is considered grappling as well if suction cups are, so I would avoid even touching them. Draw a spreadsheet to find the needed acceleration and muzzle velocity for even 20 feet away. It's some rather big numbers for that 11.2 oz ball. You can block an alley easy if you just rolled over there in the last half minute "collecting basketballs". And when threading the needle, I would rather have my robot thread a needle than a driver. Like a sewing machine versus a hand sewer. Though the hand stitching may look prettier, the sewing machine proves a better more precise, versatile, dependable stitch.

Even if you are jsut collecting balls, I believe contact in the alley is a 9pt penalty. Fairly substatial.

[Katie_UPS]

I wanna one-up the half court shooter. I wanna see a robot that can line up in front of the feeder station and pitch-machine top hoop goals consistently. I'm not well-versed on motor math, so I have no idea how feasible this is, but its something I'd like to see.

[Djur]

Originally Posted by Katie_UPS

I wanna one-up the half court shooter. I wanna see a robot that can line up in front of the feeder station and pitch-machine top hoop goals consistently. I'm not well-versed on motor math, so I have no idea how feasible this is, but its something I'd like to see.

Seconded!

[artdutra04]

Originally Posted by farmersvilleRob

On the three shot robot, there is absolutely no way to load 3 balls at a time, and shoot all three with a spitting bot or any bot for that matter. The balls simply are too heavy.

The motors available in the kit of parts this year have a combined power output of over 3,000 Watts. There is easily enough power to do this.

Originally Posted by farmersvilleRob

If I were the other team and saw someone balancing, i would simply take a 3 point foul and touch the bridge to make it "not supporting all robots) instead of have a team score 10-20 points off a chassis bot basically.

If you interfere with the act of the opposing alliance balancing their bridge, you get a Red Card and their bridge counts as balanced. (G25)

[farmersvilleRob]

Originally Posted by artdutra04

The motors available in the kit of parts this year have a combined power output of over 3,000 Watts. There is easily enough power to do this.

If you interfere with the act of the opposing alliance balancing their bridge, you get a Red Card and their bridge counts as balanced. (G25)

3000 watts, but that's combined. You can't mismatch motors and think there will not be binding (for arm robots) or miss matched speeds and spin up times (pitching machine). Also that battery would drain so fast! lol

I would go for the consistency and simplicity and reliability and easy repairs that one arm offers whether it be any type.

[artdutra04]

Originally Posted by farmersvilleRob

3000 watts, but that's combined. You can't mismatch motors and think there will not be binding (for arm robots) or miss matched speeds and spin up times (pitching machine). Also that battery would drain so fast! lol

You can use a different power motors in the same mechanism easily without any problems, as long as you match the free speed to within a few percent of each other. For example, if Motor A is 10,000 rpm and motor B is 5,000 rpm and you want to use them in the same gearbox, simply gear down Motor A 2:1 before you interface it with Motor B.

[farmersvilleRob]

Originally Posted by artdutra04

You can use a different power motors in the same mechanism easily without any problems, as long as you match the free speed to within a few percent of each other. For example, if Motor A is 10,000 rpm and motor B is 5,000 rpm and you want to use them in the same gearbox, simply gear down Motor A 2:1 before you interface it with Motor B.

But if you geared down one motor, when applying the ball to the system, one motor has more torque that gives more resistance to the ball's inertia. But at the same time, the other motor takes the same resistance to the ball's inertia, but has less torque than the geared down motor so it slows down more and gives the ball an odd trajectory and speed and backspin.

[apalrd]

Originally Posted by farmersvilleRob

But if you geared down one motor, when applying the ball to the system, one motor has more torque that gives more resistance to the ball's inertia. But at the same time, the other motor takes the same resistance to the ball's inertia, but has less torque than the geared down motor so it slows down more and gives the ball an odd trajectory and speed and backspin.

FALSE.

If you mix two motors in a given system, and gear them appropriately, they will share the load.

Why?

Say I have a CIM (free speed say 5000rpm for this simplified example, with a torque of 1 units) and a FP (free speed say 20000rpm for this simplified example, with a torque of 0.2 units)

I gear the FP down 4:1 before mixing it with the CIM. The free speeds now match, but the FP only has an equiv. torque of 0.8 - the sum of the stall torques of the two motors geared together is now 1.8 units

When I apply a load to this system, the motors will slow down because there is a load. Say I apply a torque of 0.9 - half of our stall 1.8. Assuming everything is perfectly linear, the motors will slow down to half speed. Because they are geared together, they HAVE TO RUN AT THE SAME (relative) SPEED. Since, at a given speed, each contributes a different amount of power, the power they contribute is approximately correct, the sum of their power output is equal to the load, and given the power output of the motors, the larger motors will contribute more power than the smaller motors. - In this example, the CIM would contribute 0.5 torque units and the FP would contribute 0.4 after gearing (the FP sees 0.1).

You can effectively gear motors relative to one another and add their (geared) torques without much issue, and design the system as if it was a single super motor. To make things even better, most of the motors in the KOP come in pairs, and you can have up to 4 CIM or BB's, so you don't often need to mix motors of different types.

(as a side note, BJC and I wrote up some TI-84 equations/graphs for throwing a ball, and it wasn't as bad as you make it sound, balancing the ramp isn't very hard for a single human-driven robot, and if you are ever in the opposing alley it's a penalty under [G28], even if you were collecting balls)