Team 1107B 2011 Gateway Season 1 reveal

Congratulations at how well you guys did at the tournament, and very nice robot! I’m jealous of your single 4-bar start of your lift – I really wish we could do the same with ours! (Maybe even without the 6-bar, just 4-bar … oh well.) But your curved intake seems to still preform very well, and it definitely looks like it would do great in Skills. (Programming Skills, especially, with your awesome Autonomous, you’ll have a pretty competitive Programming Skills run before too long, I’m sure.)

Again, congratulations, and good luck in your future tournaments! See you at the World Championship? :wink:


thanks Jordan for your kind words!
been keeping an eye on your robot too!
guess well see each other at worlds!

Sweet! 3 years strong. ;D Looking forward to seeing your robot progress until then!


Another question is that how did you guys manage to make a 5:1 lift without any back drive, when many teams make their 7:1 and still back drives?

It looks like from the picture, that they used rubber bands. Rubber bands/elastic tubing is the best way to prevent back driving and would most likely solve your problem of back driving (if you have that problem).

Oh, okay, haha. Thank you! and yes we do have a back driving problem! =P hopefully rubber bands will fix this problem.

Rubber bands will also increase the speed of your lift because there is less of a load on the motor now. Elastics/Rubber bands are basically an uncontrollable motor haha.

yeah, Drbayer pretty much summed it up
we once added an elastic too many and it was easier driving the arm UP rather than down :stuck_out_tongue:

thats a good thing is it not? my first robot this season (if you can remember it) with the one 269 on each side of the lift had that problem… you had to kinda mush it down to keep it down at the start and hope it didnt pop up

yeah, but i think the “best” combination will be when its perpendicular to the ground with only tension (unhooked motors)
that way the energy required to lift up the the same as pushing down 50/50
its much better than say 30/70

Which programing does your team use? EasyC or RobotC?
Why does your team prefer it?

In theory, it is possible to have a perfectly balanced arm (constant mass) at all positions.
It takes an caroid shape cam (although an off-center mounted sprocket is close),
to trade energy in the rubber-band-spring for mgH potential energy in the position of the arm. When the energy tradeoff matches, the force can also be made to match.
In all the robots I’ve seen locally and at two world competitions, I’ve never noticed it done perfectly. With a good Notebook write up, it seems like a good candidate for Think award.

For a non-constant mass arm, such as gateway, where generally you are pickup cargo at the ground level, and lifting it high, you’d want to balance the arm including the usual amount of cargo. This also means an empty arm will be easier to lift than to drop down.

In other robot applications, you can use stuff like constant force springs and gas pistons to take load off DC motors, but in Vex, you’re pretty much limited to rubber bands and surgical tubing.

we use easyC because thats what we began with a few years ago and we are now very familiar with it and can code quickly with it.

hmm, do you have some sort of illustration of what you are describing?
im assuming its some complicated thing with elastics, but i could be wrong

I love your autonomous routine. Very amusing to watch your friend run around to catch the robot.

yep :smiley:
autonomous is now a “sport”
you should see our 1 min routine (posting soon), at one time, i actually have to RACE the robot across the field :wink:

Does anybody want to keep a count of how many times our autonomous routine is referenced in a Q&A thread?

Also, stay tuned for possible coming update (maybe next week?).

welll it would be really nice to know if what you have been doing is legal or not…

Good use of the polycarbonate.

Spring Arm perfectly balanced comments:

I started a new thread for this discussion, with a picture of a simple arm.

This shows the simplest example of an arm with elastic balance at one point.
Next step is to show the modifications necessary to get good balance at all points.