getting there first isnt everything,

unless you are 100mS too late and end up inverted

ask Code Red!

http://www.chiefdelphi.com/forums/pi...gle&picid=4722

PS: thats us with the blue lightning striking the wall, 578

I disconcur.
 

First of all, in my opinion literally impossible and "pushing the laws of physics" basically means it can't be done, but like I said that was my opinion. Secondly, our robot weighs approx. 129 lbs (depends on elevation and scale), we sacrificed accuracy to a certain extent, but we're always within a few inches either way at the top of the ramp. Third, I don't see how a 180 degree turn isn't faster than a V. Although you are converting all your momentum from one direction to another, you constantly have momentum in a 180, which gives you a consistently higher speed (you have to stop in a V, not a 180). Add this to the fact that unless you make a very wide V, you cover less distance in a 180 and the 180 is definitely the faster option.

It seems to me that our V shapped path has worked well. Not only are we very consistant with hitting the bins but we are able to "aim" the bot acording to it's origional position. We've also found that our bot will pick up it's front two wheels when turning do to the drastic change in speed.

That is a good point. Someone suggested we make our arms longer so we can take them all but, this is why we didn't make our arms longer. Our robot goes up the ramp and we take out the 5 stacks of bins in the middle in about 5 seconds. That gives us a good share of them, but leaves some to fall on the other side.

We changed our robot location and our autonomous program, and our long arm is now getting to the stack at about 1.5 seconds. (It turns out that we hit the stack faster one way than the other since the motor is slower in reverse.) We also knock the bins down much faster, hitting the whole stack at once (except the last column).

As to what happens when a bot hits the bins from the other side at 2.6 seconds right after our arm, hm...I don't know, but I hope we make it to the finals to compete against Team 16 and find out. And then there is Team 71's arm hitting the stack in 2 seconds, last video I saw. What happens if our arm is competing against theirs. Hope to see that "quick draw" contest also.

Of course, there are a number of other teams who get to the top at around 3 seconds, so...it should be an interesting weekend at the Nationals.

We look forward to seeing you all there.

no no no if you hit the wall accurately in 3 seconds you do not HAVE to be running blind.....we have sensor inputs that makes us accurate every time in 3 seconds. plz stop by our pit I'll explain it....it is actually pretty simple.

we use dead reckoning, but we also have front wheel steering, so we powerslide

Fastest bot guranteed
 

Hey all of you guys look at this. I am from team 314 you guys are boasting about your speed well think of this you don't have to go up the hill to hit the stack. We sit in place launch an arm out like a baby gate and sweep over the stacks. we hit 5 of the seven stacks every time. The cool thing about it is robots have tried running into us, but it doesn't affect us like team 71. we start our robot in low gear and drive in reverse as it is sweeping then drive forward and reel it in. And the amazing thing is we hit the stack in 2sec> so stop being cocky if you want you can see us at the ford sweet repeat and the kettering kickoff and we will put you in your place!

if you run a 180° arc to get to the ramp, then most robots (if they use tank steering) must have the motors on one side running backwards to make the bot turn that fast

but if you do a V turn you can use all motors full speed in one direction, make a very small turn, then use all motors full speed in the other direction. the end result is you get faster acelleration because your motors are working together, instead of fighting each other during that long turn.

BTW - momentum wont carry you through a turn - try it with a toy car sometime- turn the front wheels and give it a push - it wont go all the way around a circle from momentum alone.

The laws of physics remain intact - if you start out in one direction and end up going in the other, then somehow you had to overcome all the kinetic energy from the first, and add enough to accelerate in the other direction. All that energy had to come from the battery, and with the 120A breaker, you have about 2HP to work with. To get to the wall in less than 3 seconds you need to have your wheels pulling more than 1g of acceleration - not impossible, but it takes a great deal of careful design to pull it off.

BTW - the fastest possible way would be to have your BOT leapfrog over the edge of the ramp and hit the wall- it would take the same amount of energy to get from the starting point, to the wall, and you would be taking the shortest possible path (a straight line).

The wally arms are cool - but I have not seen one yet that does anything but knock part of the wall over, leaving the bins still on the ramp. If a bot is coming the other way with a plow, they are going to push the fallen boxes over the ramp and into their scoring zone - you dont get any points for knocking the wall over.

you need to push them into the scoring zone to get points, and if your bot is still in the starting box at T=15, you have a lot of catching up to do to get to your side of the field.

Re: Fastest bot guranteed
 

I find it amusing that your apperently superior robot was unable to qualify for nationals

Actually I just reviewed a video of our "wally arm" and even with a robot coming the other way, we still got 10 of the bins into our scoring zone with about 10 more on the ramp. True, the robot coming the other way in this case didn't have a big plow. We will have to see if robots at the nationals can catch the bins and push them back over the top during autonomous.

Also we don't stay in our starting box. We stow our arm and head for the ramp.

V turn is does not necessarily faster then a 180 arc. For a V turn you have to accelerate the motor, decelerate motor, turn, then accelerate the motor in the opposite direction. We tried it initially on our tank drive bot and it took about a second longer.

We have a decently fast bot for a internal stacker (If we went much faster we would probably tip :D ). In our main auto mode (we have like 5) we take bout 5 secs to hit the bins and take out all but one or two three-stacks.

A better way to make the turn is with some sort of steering other than tank, so u can go full forward with both sides the whole way. Whether it is front wheel steering, swerve or crab drive steering, the turn will involve less wheel slippage and more power than tank. Some robots can pull off a slide (with casters perhaps) and that works very well too.

stopping the motors and accelerating the motors is nothing compaired to accelerating the whole robot - try it with your wheels off the ground. the motors (and wheels) have very little mass compaired to the rest of the Bot.

If nothing else, this years auton mode sure has been a great format for the physics of motion, energy, power...

Not necessarily...
 

You would be surprised how much energy is stored in the motor armature when it is spinning at 20,000 RPM.

I * Omega^2 terms can get to be a significant fraction of the total energy of a system.

Just my two cents...

Joe J.

hey man why are you trying to put us down?
we didn't go to nationals because we ran out of money.
We went to four regional and we are going to two off season tournaments one of which we set up.
So like i said come to the ford sweet repeat in Rochester hills, MI
or to the Kettering kickoff in our home town flint, MI.

And get put in your place!