FRC 95 The Grasshoppers 2020 Build Thread

We are trying a live stream of our ‘Working Demo’ at the Montshire Museum of Science today.

4 Likes

Is the onshape directory available for export?

I think so. It’s linked in the first post.

Slow but steady progress.

We have merged the power cell module and the chassis and started getting more programming sorted out.

Feels like we have growing pains with this every year. This time ensuring that APIs, Firmware, and other things were all synced up were speed bumps.

With driving around we quickly found an issue with one of our transmissions. Our new-and-improved chassis design meat that we could remove the transmission with 5 bolts and we left the wheels/chain completely untouched.

Very happy we worked this out!

Unhappy to find this:

Broken shifter coupling. We replaced it and then it happened again… anyone see this before? We’ve never had these fail on a robot in years of using them.

Today we had a working demo at The Montshire Museum of Science, which is a kids museum with a lot of fun interactive exhibits. We did a quick demo and talked to a lot of kids and parents. Also good to practice setting up our pit, working without our shop, and MAKING A LIST OF EVERYTHING WE FORGOT. It was a very productive exercise. The museum is only 5 min from our build space so it was a good exercise with a low penalty of failure.

Tasks to look forward to:
-Finish wiring up power cell sensors. We’ve created an arrangement of 4x IR sensors that can tell if PCs are in our singulator, space them properly in the indexer, and stop them from entering the shooter prematurely. I’ll do a more detailed write-up on this setup this week.
-Driving PC acquisition. We’re a few small programming steps away from collecting PCs with a moving chassis.
-Testing the climber. We broke some of the climber parts in unrelated testing and need to replace them before we test the climber.

The awful weather and flu season has hit us and our sponsor hard, so we are a little delayed on getting some parts. Hopefully we get them early this week to continue assembly.

Thanks for sticking with us everyone.

13 Likes

Browsing your OnShape, I see what I assume are pumps for locking the robot to the floor.

VERY cool to see! I think this technology will make a big difference in performance of many teams this season. You just won’t be able to perform the same at a high level of play without it.

29 Likes

Wait. What?

13 Likes

9 Likes

Yup. This has been a skunkworks project for the season. We didn’t hide it (models were in OnShape since we started CAD on it) and we foreshadowed it:

But didn’t advertise it either. We have made substantial progress in improving the efficiency in the Aramabot pumps and making a skirt that can seal to the carpet. We’re capable of creating around 0.3-0.5psi of negative pressure under a chassis. There is a lot of testing left to do, but we’re excited for the promise it shows.

We are currently waiting on a Q&A to determine the legality of such a mechanism though.

12 Likes

Even at only 0.3psi, with the approximate contact area you have in your CAD you should be getting an extra ~130 lbs of downforce. That’s huge! A full robot’s extra weight. If it’s ruled legal by the GDC, you should be able to stop just about anywhere to shoot without worrying about defense.

6 Likes

Are those the 2 Cim ball shifters? We are using those this year and will look out for that!

They are. I’m not sure what’s going on because one has been fine while the other has broken twice. I’m going to take it apart and thoroughly check it at our next meeting. I suspect an assembly issue.

okay this is a epic gamer move. Good job to you guys thinking out of the box! ever think about having grip pads come down and lift you up a bit rather than vacuums sucking you down?

5 Likes

I’d assume for this to work you would need an unpocketed bellypan or some other way of sealing the bottom of the robot. Correct?

I would be interested to see some testing results from a system like this.

Prior knowledge of other robots doing things similar to this have yielded inconsistent results. See Chomp in battlebots. Their vacuum holders never worked well, but again, the forces they had to deal with were somewhat more than what we do. I’ll be interested to see how it works out.

Just wait for when defense is a more viable strategy at the Colorado Regional, due to lower air pressure.

:stuck_out_tongue:

In all serious though, this is a game changer at the top level of play if it’s ruled legal. Lighter robots can now be the best of both worlds, and absolute chonkers like this robot become immovable at the press of a button. Defending against a robot like this could be very very difficult. In a game like 2020, it isn’t such a monumental advantage, but last year the ability to “lock down” would have changed a lot of how defense was played, and even the viability of defense against certain teams.

I don’t think it’s a “must have” but it could certainly be a “very nice to have” in the realm of swerve drive.

7 Likes

Thanks!

Been there, done that, won the award :upside_down_face: (2014):

We have used this setup in several other robots as well. It’s our current fallback plan. However, we can theoretically drive with the ground effects system engaged…

Correct. We have a solid 3/16in PETG bellypan right now for that reason.

This is a snapshot of our best results (6 different spots on carpet):

Results from an early iteration:
image

We are looking forward to testing it on a moving chassis with our final-version skirt, which is looking good.

10 Likes

image

51 Likes

Are those values on the right pressure achieved?

If so, did you time how long it took to achieve that pressure as well?

2 Likes

Yes, pressure in psi.

We did not record time to reach pressure.

I guess suction is the new meta. Suction climb last year suction drive this year.

3 Likes