Hello, so I have got another question on my mind. How good is it to do the robot without the belly pan which we were supposed to put the electronic stuff
Like a lot of things in engineering, it depends. Bellypans do a bit more than just electronics mounting. Can you build a robot without a bellypan? Sure. But there’s some risks to be aware of.
Bellypan purpose #1: Adds strength to the frame of the robot. Specifically, it helps keep the frame square, and to a lesser extent stops it from warping quite as much. You’ll need to replace that functionality somehow, probably in the superstructure.
Bellypan purpose #2: Electronics mounting. Much easier to work around, as you can put the electronics pretty much anywhere on the robot. (There are some places to NOT put them… like right on the Frame Perimeter with no protection.)
Bellypan purpose #3: Protect the inside of the robot from field obstacles. Not an issue this year, but sometimes it can be.
May I ask why you’re thinking about running without a bellypan?
So actually one of our mentors thinks that we should lower the Weight of the robot and one of the idea that He was mostly thinking was to remove the bellypan and I wanted to get some advice about wether we should remove it or not
If the robot is structurally sound, you can switch the belly pan to plastic (and make it smaller). That will save on weight.
How much does your robot weigh? One of the nice things about the belly pan weight is it’s nice and low - it’s better to look high up on the robot for weight loss first, so you can keep your center of gravity low and avoid tipping over!
We knew we were going to be fine on weight, but didn’t realize just how good until we weighed on Saturday. With nearly everything on (missing some electronics and a few fasteners), we were at 97 lbs… with a battery in the robot! We’ll probably end up adding weight to balance our center of gravity for climbing
As mentioned above, this depends on the structural integrity of your chassis. If you are running the AM14U chassis, you can use churros between the side panels and no bellypan, but then your electronics will raise the COG of the bot.
I think that there are two questions that you have to ask yourself:
- Where can I put the battery? - from my point of view, it should be as low as possible to keep the robot from bouncing around and potentially falling over.
- Can I set up the roboRIO in a way that I can use the gyro properly?
If you can figure these two out, you are good to go.
The reason people use structural belly pans is because they serve a handy dual function - the pan can provide rigid structure to a robot chassis and serve as a place to put electronics. These two separate tasks can definitely be accomplished with separate mechanisms, though - this is what most FRC teams did for many years. Structure for a standard tube or kit chassis can be accomplished using gussets and / or cross bracing.
For electronics, some teams would make a box or panel that could hold the electronics in a removable fashion. Others would just kind of mount elections to any available flat surface on the robot. Sometimes flat surfaces would be created for this purpose, maybe vertically if need be. Lots of different options here.
We’re not having a belly pan this year…since the Cargo is pretty hard to drive over…and our electronics has no reason to be that low in the robot. We’re making a plywood electronics board about 4 inches above the top of the KoP chassis. It should be pretty easy to get to the electronics this year, again.
But the layout of our robot is quite different from most robot designs I’ve seen this year. Our ball handling “stuff” is not in the middle of the robot, its on the sides and above and in front.
This this this, a thousand times this.
If belly pan thickness is reasonable and it’s providing structure - bellypan should be… (spitballing .080" Aluminum for a flat sheet and maybe .100 for polycarb):
Find weight elsewhere to take out if you can. You can nickel and dime yourself out of overweight by:
- Be sure to use the correct wall thickness of tube for the application (also saves manufacturing time if you decide you need to cross it out with lightening holes)
- Reducing number of bearings by replacing with plastic and bronze bushings (see the durable intake thread for ideas on this)
- Replace fasteners that are not coming out over the season with rivets, be careful with how you do this on the kit chassis itself. Aluminum threaded fasteners are handy too, especially high up, just not as strong. And to a lesser extent, depending on application, zip ties, 3M vhb, and plastic threaded fasteners.
- Careful, organized wiring - (robot inspectors will thank you for the clean wire runs), that wire weight really adds up
- I hate to resort to this one, but motor weight can really add up. Sometimes it is nice to through a lot of power at a problem, but correctly sizing motors is important for other reasons too (i.e. tight control loops - there is no need for a falcon on a swerve azimuth)