16-01-2008 23:48

Woody1458

Re: pic: 2008 FIRST team 1001

First off Ill start off with what I like. I'm glad someone is actually realizing the scale of things when making their robot (the ball is bigger then their robot). However, I am wondering where your manipulator is, and if you are just trying to be a speed robot this is an awful drivetrain to do it with. Being on all Omnis people will be able to push you around with nothing you can do about it. Also as far as speed you only get 50% of your output twards speed, the rest of the power goes towards the wheels pulling away from each other. But ambitious none the less and good luck!

17-01-2008 07:58

Qbranch

Re: pic: 2008 FIRST team 1001

Well, thats true, IF you want one of the flat sides of the robot to be the front. There's nothing saying you can't pick a corner and have that be the 'front' of the robot when driving.

True, however with a small (1 square foot or so) robot on a omnidirectional drive train of some sort, I doubt many robots will be doing much catching up with you. Remember, the absolute maximum intermittent duty horsepower four 2.5" CIMs working together can produce is 1.8hp at the shaft. This means, if you have a 120lb robot and you want to travel at 15 ft/sec, it'll take you 0.42 seconds to reach that speed. Now, if your robot weighs, say, 30lbs (beleivable for what is essentially a square with motors, transmissions, wheels, and all things required for the FRC controller + drives), and we accelerate to 15 ft/sec with the same energy input, we reach the speed in just 0.11 seconds. True, both of these robot assume perfect traction, a battery that never dips below 12vdc, and a victor drive that can drive the motors to their maximum Wo state (about 67 amps), however the point is still made: little robot, accelerates and makes turns MUCH faster than any other robot could hope to.

But, yes, if you got into a pushing match you'd surely lose... not than anyone could get you in one anyhow.

Sparky 1001: *chuckle* nice picture. I'm not sure what your team really is building... but if you are going towards building the smallest FRC drivetrain robot you can, more power (or acceleration? ) to you. But uh... I think just using vex might get a little outclassed.

sooo... what are you all actually building? I'm curious now!

-q

17-01-2008 13:59

Woody1458

Re: pic: 2008 FIRST team 1001

even if a corner is your front you only get 50% of your possible power (two motors are idling) this drive train is good for a game like last year when maneuverability > speed/power but this year when the path of traffic is linear, i think its the wrong time for this design.

17-01-2008 14:34

lukevanoort

Re: pic: 2008 FIRST team 1001

You actually get more than 50% speed... do the trig on the vectors and you will find something surprising.

17-01-2008 19:56

Sparky 1001

Re: pic: 2008 FIRST team 1001

this is not our "real" robot...we are almost done getting the stuff we need & then we will make it...

I did a bit of testing to see if Omni Weels would help this year. I think I will be able to move in & around other robots a lot faster...we r not sure on the speed yet but it can sure hall

is there anyone else that has ever tried this before?...I was trying to find some other team that might be able to insight me on it but I had no luck...

once u get the feel for the drive it's really not that hard.

o btw we will have bumper that will be able to help push the ball...

~Daniel Solomon~

23-01-2008 13:12

LieAfterLie

Re: pic: 2008 FIRST team 1001

You get 70.7107% of normal drive power going forward, backward or sideways, and 50% going diagonally. And people are not going to be doing much pushing if you can just go sideways and get around them. I think manueverability is important for a speed bot here, it lets you get around obstacles very easily. And pushing is disallowed for the most part anyways, except for 'warning taps.' FIRST made sure this game could not be played defensively, at least not by blocking and pushing other robots, unlike last year where it was a suggested strategy.

24-01-2008 17:46

libertyrobotics

Re: pic: 2008 FIRST team 1001

Take a look at our omni-directional drive system. In the video it is only doing a third of what it's capable of. The first half is on ceramic tile and then the second half shows the capabilities on carpet. Our programmer estimates the top speed to reach 15ft/s.

http://www.liberty.k12.mo.us/hs/libe...ive%20test.wmv