Moby construction review?

Over in the VIQ forum is a really great thread around this years game Herobot “Fling” Herobot: Fling Unofficial Thread

Moby is the one for this years VRC game. Has anybody built it to see if there are issues with the build instructions and how well it (doesn’t) play the game?

4 Likes

We built it to prepare for a camp hosted over the summer. There were a few issues from what I can remember.

  • The default user program could not control Moby, we might have needed a VexOS update however

  • Due to the high torque of the mogo lift and oversized channels, many parts could bend if the mogo lift was pushed out of a small range.

  • When lowering the lift the structural support channel between arms could hit the front wheels (major reason why parts could bend)

  • The shaft spacing in the manual was oversized for the lifting arms, resulting in the arms forming a trapezoid, and straining the already weak standoff connection to the support c-channel from either lifting arm, alternative spacing was required.

  • Wheel spacing was loose due to the starter kit not having a large variety of spacers, not a huge issue, but it would be a good idea to add some extra

Those are the biggest ones I can remember

13 Likes

Thanks very much for the update. I’ll make a bigger effort than last year to suggest to roboteers to use the ideas, not the construction.

1 Like

Another thing I was wondering, is what is better, Claw bot or Moby? Last year the crunch it could beat a claw bot, but Moby doesn’t seam to be the best hero bot this year.

What robot is better for Tipping Point?
  • Clawbot
  • Moby

0 voters

1 Like

I mean, mogos are way more valuable than rings, so I’d argue moby is better than a clawbot

Since the mobile goals are worth more, I’d say Moby. But it appears that Moby has some initial issues that need to be fixed. Last year a Crunch could do pretty well with no mods.

But as JVN says, “It’s all about the iterations” so maybe Moby having early issues makes it a better Hero bot, since teams will need to start iterations / design upgrades earlier.

4 Likes

Clawbot is capable of dragging a goal across the field though.

But I would guess it would be hard to get the mogo up on the platform with the clawbot.

Is Moby able to pull the platform down from a balanced position? Given the metal prongs that would be used to do so, I can imagine the platform will become very scratched up over time.

platforms get banged up every game… EPs cry at end of season when at championship game elements look like they went through demolition derby.

9 Likes

Built a Moby yesterday – my build notes:


If you’re building Moby from the Competition Super Kit, there’s a fair bit of cutting required to do so. My cut list:

  • Cut one 1x2x35 c-channel into two 1x2x15 c-channels, with a 5-hole piece left over as scrap.
  • Cut two of the 2x2x25 angles to 20 holes long. The instructions also show the corners cut out of one side of the angle – you don’t need to do this, just cut them to length.
  • Cut two 1x2x35 c-channels to 25 holes long (you need a total of 4 1x2x25 c-channels; the kit comes with the other 2).
  • Cut two 3" shafts from a 12" low strength shaft (you need a total of 6 3" shafts; the kit comes with the other 4).

The omni wheels at the back of the robot just barely clear the two c-channels holding the two halves of the robot together. The clearance is tight enough that after my first pass at screwing the parts together, I had to loosen all the screws and retighten them with the c-channels as far forward as possible (there’s a little bit of play with the screws loose because the holes are a bit bigger than the screws).


In steps 1 and 7, it wasn’t clear to me what holes the bearings needed to go in on the c-channels from the angled projections shown. I ended up getting most of them wrong and having to move them around based on where shafts needed to go in later steps.

Here’s a clearer illustration of where the bearings go:

moby_bearings


As mentioned above, the default drive program will not control Moby if you connect the motors to the specified ports. Worse, it thinks all four motors are part of the drivetrain, so if you start the default drive program and try to turn the robot, bad things will happen to the mobile goal lift.

I wasn’t able to find a listing of which ports are mapped to which controller buttons for the default drive program so I just wrote a quick blocks program to drive the robot:

moby.v5blocks (7.3 KB)


In addition to the mobile goal lift bending itself if you try to push past its range, the c-channel connecting the two halves of the lift can also cut into the motors’ plastic casings when the lift is all the way up – some anti-slip mat zip-tied to the top of the motors for padding would probably be a good idea.

9 Likes