78B practicing

This is a all girls team and their rookie season.
Here is a video of the bot.

We are from Rhode Island and our first comp is trinity in NH.
Any questions?

Linear slides driving the four bar, very cool :slight_smile:

Reminds me of a Trinity robot back in Gateway. One thing that robot always suffered with was that the 2 sides of sliders would sometimes not be in sync, has that happened with this robot so far?

If you spin the pulleys in opposite directions its not even noticeable. like maybe one side is a 1/8" lower but nothing so bad that it is a concern.

Do you have any closeups on the design? This is very cool and creative - I like it :smiley:

We don’t want to release that because we don’t want to just give away our design.

Nice work girls. Looks like a solid machine!


Looks great. Good job!

It’s awesome how you got it to work! I wanted to do something similar to this for my first design, but I decided to scrap it because space seemed to be an issue for me, and it would just be a big pain to link everything together.

Nice job!

So I have been getting alot of questions of how we did the arm system this year, so I will share some details about it the goods of it, and the bads.

First we call this the elevating four bar, it uses 4 393 motors on high torque and uses the winch and pulley kit. That is its only source of power and movement, we do not power anything else.

So what we did do was connect a rope to the back cross member of the robot, this allows for a hard stop, as the elevator raises up the rope becomes tight forcing the motion to be transferred into the four bar and causing it to raise up.

That’s it guys, nothing to crazy just some rope motors and boom elevating four bar.

Onto the bad’s about this this design will not easily high hang, I don’t say never because someone could make it work. it takes along time to get it 100% right. We spend almost 15 hours just getting it to go up correctly.

The good’s
Our lift when fully raised can lift to 39" which is a lot higher than most teams.
its fast, in the video we released we had been running and stress testing for about four hours before recording that. Math is your best friend and before building we did a lot of math and we leaned that it lift to full height in about 1.4 seconds.
its unique I know everyone loves their six bars, but seriously guys the ones who think of newer things are the ones who will win. We personally will never do the same thing twice.
Center of balance, This is huge for us we wanted to be able to climb that bump with our arm up and we can. Because everything is in the middle we have an amazing center of gravity.

The future for the team and bot.
We plan to go to three tournaments so far and are hoping for more than that.
We have a way to hang with out current design, all I have to say about that is we don’t need to be that high off the ground do we? Only a paper’s thickness right? :stuck_out_tongue:
Big ball grabber, already on

Thanks for all the compliments and we wish all teams luck and futhermore ask for any questions?


If you want to go faster, a true 4-bar arm at 1:3 goes up in under a second. Ours doesn’t reach 39", but I think the top of the table is like 35". You could get it up there if you wanted to. The thing is, you don’t have enough motor power to lift the entire chassis above maybe 2-3". You could low-hang, but not high hang.

t’s a neat idea you’ve got there, using a winch kit. I’m just throwing out another design if you’re interested.