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Unread 15-01-2012, 21:01
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skimoose skimoose is offline
Parent/Mentor/Engineer
AKA: Arthur Dutra
FRC #0228 (GUS)
Team Role: Electrical
 
Join Date: Jan 2005
Rookie Year: 2003
Location: Meriden, Connecticut
Posts: 568
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Re: pic: We've got balance, how bout' you?

Quote:
Originally Posted by EricLeifermann View Post
Being secretive about good ways to get 3 robots on a bridge and balance it isn't going to help you in the long run because if you are the only team that can do it your screwed because you need 2 others to do it. So why not share so more teams can think about it and decide if they want to go the same rout? Helping everyone is really helping you this year....
We're not being secretive, we're still working on solutions. Aren't you?

This picture explains an awful lot if you spend the time to analyze it. If we wanted to be secretive we wouldn't have posted a picture at all. There was quite a lot of chatter about whether three long robots could even fit on the ramp. this shows they can, if built with with biased balance points. You can see the margin for error with six wheel drive is 2-3".

Is this simple to do? Absolutely NOT!

Here are things that need to be addressed.

With 2-3" inches to spare this will take a HUGE amount of driver practice. This takes co-ordination amongst all three teams. Like last year's minibot end game if your team doesn't put in the blood, sweat, and tears to figure it out, you won't be rewarded at competitions.

You'll also need to consider the change in your CG as the bridge tips. How can you keep the robot from pitching off the end of the ramp as it descends? Inertia is going to want your robot to keep moving. Do you need some sort of braking system on your drive base? Something else? Suction has already been deemed illegal by the GDC.

With 2-3" of available real estate to move your robots in, is there a better ways to balance the bridge without moving the drive base?

Can robots mutually aid each other on the bridge? Yes. How? Still working on that. What ever the system is, it has to be independent of what other robots do. As shown in the Breakaway and Logomotion games, relying on a universal method of achieving the goal is not realistic. Very few teams adopted a universal suspension system or minibot/deployment system. If you limit your choices for alliance partners to only teams that have universal systems, you'll have few or none. You need a system that is independent of what other teams do and will work with all the strange shapes that FRC robots come in. This is no small feat, but if you can figure it out, you've moved up on my pick list. If I can figure it out, I just moved up everyone's pick list.

Since you can only extend off one side of the robot at a time, I think (at least currently) that you can only mutually aid one other robot. Assuming I can only legally help one of my alliance partners, at least one of my two partners better be able to aid a robot too. If you want to be a valuable addition to an alliance, you should have a way to aid another robot in balancing on the bridge.

Is there a preferred robot shape? I can't say. We've merely shown that what most felt was the least likely combination, long-long-long, can work. You should be able to figure out how the other combinations will vary. Robot frames have a maximum footprint, bumpers are a fixed size, and wheel base lengths can be figured out for 4, 6, 8, & 10 wheel drives. Can a 4 wheel drive robot figure out a way to cantilever two wheels off the bridge? Your team has evaluated the game. You've prioritized what parts of the game are important to you, and your team is designing accordingly. Our priorities might differ from yours so are the decisions we make relative or valid to your goals? I think its pretty obvious that we are looking strongly at the triple ramp and it will have some impact on our design.

Do you need to figure out how to do this? If you want to triple ramp, you'd better do your homework.

Quote:
Originally Posted by JamesCH95 View Post
Care to share some more of those results/conclusions with teams that may not have three extra robots kicking around to do the same experiments?
I just did.

There's no magic to starting the triple ramp. It's pretty straight forward. One starts up the ramp, As One clears the end of the ramp, Two starts up right behind One. They don't need to be bumper to bumper at this point. Once Two has cleared the end of the ramp, Three gets bumper to bumper with Two and the bumper to bumper train takes over. Now it has to become a coordinated, bumper to bumper procession. We're still working on an effective process for the final balance.

You don't always need three robots. one or two 140 pound students should fill in nicely. Obviously the center robot in this operation is kind of along for the ride. Its between two robots and all of its wheels can be in contact with the bridge.

Now if you're one of the end robots, you are earning those points. being cantilevered off the end of the bridge is tricky. If you can position at the high or low end of the ramp, with your 1.5" of real estate to maneuver in, and stay there when then students shift their positions to balance the bridge, and you don't fall off, you've figured out the triple ramp.

What say you oh Car Nack, will the triple ramp be achieved?
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