Don't Underestimate Hatch Panel Placement Difficulty

I’m hearing very little discussion about how difficult it will actually be to accurately place Hatch Panels. I would equate the challenge to scoring gears on the spring in 2017… but you have slightly more margin for error and a way worse field of view.

If you can, open up the field CAD and look at the Cargo Ship Bays and Rocket from the driver station perspective. You don’t have a direct line of sight to your scoring objective, and even more significant, you have to deal with depth perception challenges when lining up to score.

If you didn’t catch it in the manual, there are small pegs that extend out from the side of the Cargo Ship to divide the Cargo Pods. These pegs (if I did my math right which is a dubious proposition) are 20.25" apart. That leaves you with 5/8" to work with on either side of the Hatch Panel when you’re placing it.

I strongly recommend that teams factor this into their initial strategic goals and are aware of the challenges. I think FIRST made a really great call by effectively forcing teams to have cameras on their robots… I have a feeling you’ll need them even after the Sandstorm is over. The best teams in the world will have semi-autonomous scoring during teleop.


You might also want to build a very basic mockup of a hatch, with a ramp for a ball, and see how accurately the panel must be placed, to keep that ball from rolling out.

it’s interesting.

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Thanks for the warning @Ryan_Swanson I knew it was tight on the cargo ship… now verified.
Accuracy of placement of the primary game piece (cargo does ot score without it) will be critical and I can see this in first few weeks producing very low scoring games.

How useful would an alignment system using the reflective tape be? Seemed like an extreme emphasis on that during kickoff.


I suspect the best systems will use both the white alignment tape on the floor, using look-down sensors for the approach, and the retroreflective tape up close. Anyone else thinking front traction and rear omnis to simplify the maneuver?


I bet you tried this already… how hard was it?

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Based on watch the “Deeper Space” video, it looks to me like there is a fair bit more space the 5/8" on each side. Can someone confirm the sizes?


Yes. Some of the members of our team wish to return to mecanum (which we made work wonders in 2017, definitely our best performance to date by far), but the other drive train we’re considering is what we did in 2014 with omnis in the rear.

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Based off the Solidworks model - looks more like you have ~1" on either side of the 19" HATCH PANEL


Does anyone know what material the POST (small pegs) on either side of the bays is made? (is it ferrous)

It’s not mentioned.

Here’s the only mentions of the posts in the manual (page 22)

pretty sure its an 1/2" aluminum spacer from mcmaster, looking through some of the field videos will probably provide insight.

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Why would you place the Omnis in the rear per say? Would front Omnis not accomplish the same thing? Or is it dependent on where your bot’s center of mass is in relation to the center wheel?

Team-build version uses 3/4" long hex bolts and nuts.

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Where you place the omnis depends on where you want your center of rotation to be. By placing them in the rear, the CR moves forwards, often to between the front wheels. This allows you to turn, in this case, around whatever you’re carrying. Align, spin, slap, run away. If you place the omnis in the front, the CR moves to the rear, so you have to be pretty precise as a slight move adjusts the position of the carried item quite a bit.


From the video they look like pretty standard bolts, which might allow using a magnetic alignment device (unless they were aluminum bolts for some reason), which would be pretty cool; however, they are not present on rocket, so it is not a generalizable idea.

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Another difference from gears in 2017 is that you need to place the hatches close to parallel to the face of the ships to get both sides of the velcro attached. In 2017 lots of gears were placed on pegs from various off angles, drive trains and manipulators will need to account for this.


So are you recommending Omni wheels in the rear, if anywhere?

Mecanum in the front Omni in the back do it and your cool.
(if you are curious and if I recall correctly doing this makes your turning point change with your speed been a while and could be wrong.)

You don’t need the field CAD, there’s a folder of pictures(the WPI picture folder) of the field on the official field page that provide views from each driverstation