To deadweight or not

[Caleb Sykes]

Our robot is nearing completion, and although I am only approximating, I think our final weight will be no greater than 90 pounds. Even if I am off by 10 or 15 pounds, my question still stands: Should we add some deadweight to the robot to get up to 120 pounds?

We will absolutely be be doing our own testing soon to determine what is optimal for us, but I am curious to know what the community's opinions on this issue are. I think that this year will see many more robots that are underweight than in previous years, so I think that this could be a good topic of discussion.

In my opinion, this will be the year where many matches will be decided by pushing contests. Even with the wide open field, I don't see top speeds of greater than 12 fps gaining you anything. In addition, the argument of "we're going to be so fast/maneuverable that we don't need pushing power" does not hold as much weight (haha) this year since few robots will be exclusively offensive. Therefore, I would be very much in support of my team adding weight right up to 119.9 lbs.

[Whippet]

We're currently planning to ballast our mecum drive so the weight will be evenly distributed among the wheels.

[IndySam]

Speed kills. So many teams bragged about their defense last year but none of them stopped our light fast robot.
If I get there first I win no matter how well you can push me around. Keep pushing we'll be gone.

[GUI]

Keep in mind you don't have to be able to win a pushing contest to defend successfully. You do, however, have to be where you want to be when you want to be there. With how open this year's field is, you don't have the luxury of field elements helping you block the other bot.

[Gregor]

Originally Posted by IndySam

Speed kills. So many teams bragged about their defense last year but none of them stopped our light fast robot.
If I get there first I win no matter how well you can push me around. Keep pushing we'll be gone.

I liked to think of your robot last year, in the nicest way possible, as the squirrel on caffeine. It was so fast, I was impressed your drivers were able to control it. Was there any software used to help with controlling at high speeds?

[DampRobot]

Originally Posted by IndySam

Speed kills. So many teams bragged about their defense last year but none of them stopped our light fast robot.
If I get there first I win no matter how well you can push me around. Keep pushing we'll be gone.

This. Maneuverability far trumps "pushing power" in my mind. You'll be surprised by how fast a robot can jump to speed at 90lbs versus at 120, and what a difference it'll make in gameplay.

Keep in mind, if you think defense is just a contest of who can push more, you're doing it wrong.

[Woolly]

Originally Posted by inkling16

Our robot is nearing completion, and although I am only approximating, I think our final weight will be no greater than 90 pounds. Even if I am off by 10 or 15 pounds, my question still stands: Should we add some deadweight to the robot to get up to 120 pounds?

We will absolutely be be doing our own testing soon to determine what is optimal for us, but I am curious to know what the community's opinions on this issue are. I think that this year will see many more robots that are underweight than in previous years, so I think that this could be a good topic of discussion.

In my opinion, this will be the year where many matches will be decided by pushing contests. Even with the wide open field, I don't see top speeds of greater than 12 fps gaining you anything. In addition, the argument of "we're going to be so fast/maneuverable that we don't need pushing power" does not hold as much weight (haha) this year since few robots will be exclusively offensive. Therefore, I would be very much in support of my team adding weight right up to 119.9 lbs.

I would add a little ballast if necessary to get the drive train to run smoother/straighter. Otherwise any added weight should be functional, whether it be added mechanisms for defense that you can easily remove, or LEDs that are aesthetic and/or sends signals to you alliance partner. (Ex. making your ground pickup light up when ready to recieve the ball)
Granted you can justify a bit of frame reinforcement for the same reason you can justify adding more weight in the first place.

[TheMadCADer]

If you're offensive, even if you "win" a pushing match, you still lose. Time is everything in FRC. Anybody can get three Assists and score the ball, but if it takes 2:20 to do that you won't win many matches.

Making sure you can't easily be pinned or pushed sideways is, however, a very worthwhile endeavor.

[JamesCH95]

A lot of things depend on what drivetrain you have... can you provide details?

A few things to think about:

Your acceleration rate with, and without, added mass.

Are you going to make your robot much more likely to stall its drive motors if you get into a pushing match? I would MUCH rather spin wheels on carpet than stall 4-6 CIMs. Handy reference chart here.

There are many different styles of defense, including just 'being in the way and making them push you sideways to get by' and what I like to call 'kinetic defense' wherein you simply repeatedly ram the other robot, throwing them off course and disrupting whatever task they're doing. Serious pushing force isn't always required for effective defense.

Making the weight easily removable so that you can be a 'heavyweight' for matches were you expect to play a lot of defense, and a 'lightweight' where you expect to play mostly offense might be the best of both worlds.

You could invest that weight into simple mechanisms to add functionality. Brakes, for instance. More durable and stickier wheels, a passive catching structure or something else to easily get the ball from the in-bounder, or a goal-tending mechanism come to mind.

[Jibri Wright]

Originally Posted by JamesCH95

Making the weight easily removable so that you can be a 'heavyweight' for matches were you expect to play a lot of defense, and a 'lightweight' where you expect to play mostly offense might be the best of both worlds.

Correct me if I'm wrong, but wouldn't you have to get re-inspected every time you changed the weight of the robot, even if it is pre-planned?

[tkell274]

I think you should add some weight to your base if at all possible for two reasons.

1. This year robots will be taking A LOT of abuse and any structural help you can provide is key and

2. You want to keep your center of gravity as low as possible.

And to play devils advocate, speed has been great in past years when all you had to do was get to a safe zone as quick as you could and score from there. This year there is no such safe zone anywhere on the field so yes you might be able to maneuver around a heavier bot, but unless you can score on the fly then the second a pushing bot catches up to you they can slam you and mess up your shot. So having a heavier bot or at least a really solid one with a low center of gravity will be more beneficial than a quick bot this year for the case of scoring in the high goal/catching the ball.

[IndySam]

Originally Posted by Gregor

I liked to think of your robot last year, in the nicest way possible, as the squirrel on caffeine. It was so fast, I was impressed your drivers were able to control it. Was there any software used to help with controlling at high speeds?

Nope that was all Nick. Best driver I ever had.

[Arpan]

We've got the same issue. Does not deadweighting really improve the speed of the bot by that much?

[JamesCH95]

Originally Posted by Jibri Wright

Correct me if I'm wrong, but wouldn't you have to get re-inspected every time you changed the weight of the robot, even if it is pre-planned?

See [R5]

The ROBOT weight may not exceed 120 lbs. When determining weight, the basic ROBOT structure and all elements of all additional MECHANISMS that might be used in different configurations of the ROBOT shall be weighed together.

And more importantly, [T8]

At the time of Inspection, the ROBOT must be presented with all MECHANISMS (including all COMPONENTS of each MECHANISM), configurations, and decorations that will be used on the ROBOT during the entire competition event. It is acceptable, however, for a ROBOT to play MATCHES with a subset of the MECHANISMS that were present during Inspection. Only MECHANISMS that were present during the Inspection may be added, removed or reconfigured between MATCHES. If MECHANISMS are changed between MATCHES, the reconfigured ROBOT must still meet all Inspection criteria.

So, presuming you got inspected with all the weights attached, and all possible mechanisms attached/present, you could remove any of the weights at any time with no issues.

[Jibri Wright]

Ok cool thanks