Re: Team 842's drivetrain for FIRST Stronghold!
 

how much do the wheels move up and down from your pivot? It seems like +/- 4 inches of movement? Maybe they move freely and have no hard top or bottom in their range?

I love it. Its good to see an "out-of-the-box" solution!

Re: Team 842's drivetrain for FIRST Stronghold!
 

There are hard stops for the travel on all of the wheels, and travel can be limited without much trouble. I believe the largest amount of travel for a wheel on the rocker is just under 2". The nature of the rocking mechanism gives the wheels a lot of travel relative to each other without moving the frame very much. (If we lift the front wheel 3" off the ground, the frame only raises about 1.5")

We're intending to show the inspectors that the robot will sit on flat ground with any orientation of the suspension and keep the bumpers within the bumper zones. This should satisfy R22 without question, but we'll also bring our team's best lawyer just in case. :)

Re: Team 842's drivetrain for FIRST Stronghold!
 

Had to do it, school colors....

Re: Team 842's drivetrain for FIRST Stronghold!
 

Thanks for sharing! We have similar ideas going on! (the final product will be very different, but the ideas are similar lol) Hopefully we will have something to show soon too!

Re: Team 842's drivetrain for FIRST Stronghold!
 

Ok, yeah, that was good.

Re: Team 842's drivetrain for FIRST Stronghold!
 

Very cool!
How well does it turn on carpet? Do you have a way to actuate the rocker to simulate a center wheel drop?

Re: Team 842's drivetrain for FIRST Stronghold!
 

We are planning to lock it into a 6wd dropped center configuration with pneumatics, though this hasn't been implemented yet. One benefit of this is that we will be able to adjust how much drop we have on the center wheel to make high gear more manageable to drive.

The suspension design is heavily influenced by team 39's robot from 2010. They locked the suspension into a mecanum setup that year for navigating flat ground. You might even catch a glimpse of that robot in the background of the video at the start of this thread, if you look closely...

Re: Team 842's drivetrain for FIRST Stronghold!
 

Video showcasing more what the drivetrain can do:

https://www.youtube.com/watch?v=cyKq...ature=youtu.be

Re: Team 842's drivetrain for FIRST Stronghold!
 

We are going to put in some faster gears!

Re: Team 842's drivetrain for FIRST Stronghold!
 

Part of me wants to say that's way over-complicated, but it's so smooth and controlled I can't help but love it. There is a definite advantage to reducing the shock load on your electronics.

Re: Team 842's drivetrain for FIRST Stronghold!
 

Beautiful articulation,

but the real stars are the MBS Yellow tires -

Any team that has them will shine!

Re: Team 842's drivetrain for FIRST Stronghold!
 

Great music selection.

This is going to be fun to see in Flagstaff.

Re: Team 842's drivetrain for FIRST Stronghold!
 

Reducing shock to the electronics is a major benefit, but the main reason we went down this path was because of the improved control the driver has going over this terrain. With the straight pneumatic wheels on a KOP chassis, we could have easily came out of the defenses off by +- 45 degrees in either direction, in addition to the massive pitching up and down that occurs on some of them, such as the rock wall. Hopefully the rocking mount for the front wheels will help keep all the wheels on the ground as we breach.

Re: Team 842's drivetrain for FIRST Stronghold!
 

A few questions:

-Each wheel is powered by its own motor and gearbox, correct? It's hard to see the underside but that is my assumption.

-this will be our first year ever traveling to Flagstaff. Is this the level we should expect to see, in terms of design and game savvy, from all the teams there? If so, I am a little bit excited, and a little bit scared. I've heard you guys are vicious as a region.

Re: Team 842's drivetrain for FIRST Stronghold!
 

Here is a peek at the underside of the robot. All three wheels on each side are powered by a 3 CIM Vexpro ball shifting transmission. We are only using two CIMs on each side though. The 3 CIM design has better mounting points than the 2 CIM ball shifter. (In this pic, you'll note that one of our red idler rollers had shattered. It was a low fill 3d printed prototype that we probably shouldn't have used...)

Flagstaff should be a fun event this year! It's the first year a competition will be held at the Walkup Skydome. Some strong local teams, and a few from out of state. 125, 192, and 2122 are all coming to play, and they will probably make our robot look like something built in a garage by amateurs.