Dodgeball Robots

In an effort to teach our incoming Freshmen the basic skills they will need in build season, our team is going to be building robots that play dodgeball, using the FTC size limits (18 by 18 by 18 inches) and leftover FTC parts. I was just wondering, what would you build if you were making a dodgeball robot?

Are you using dodgeball size balls or something smaller to accommodate the robots (FTC scale seems a bit small for dodgeballs but it might just be me)?

That said, if I were to make a dodgeball robot I would design it as follows:

If FRC size restrictions - make a 2006-esq robot
If FTC size restrictions - make a 2014 FRC-esq robot

Circular robot with 3-sided pickup, swerve drive, and a dual wheeled shooter. Field-centric, of course.
I would have to go for omnidirectional movement using an H-drive, omnis on the corners, mecanum or swerve, because avoiding things in dodgeball while getting balls can benefit from moving sideways.
And yeah, FTC seems kind of small for dogeballs. However, given single-ball possesion rules it should be workable. Think 2008 or 2014.

A really simple, skid-steer robot with a front roller pickup and a flywheel shooter or catapult depending on what you’re more comfortable with.

Team 20 almost always has a team in our school dodgeball tournament, and we’ve discussed several times using the 2012 or 2006 robots to play (they would get out quickly, but it would be a cool demonstration, wouldn’t it?). We never have though.

Are the robots only playing against/with other robots, or humans as well?
Some of GeeTwo’s design features below me might be better sutied for robot-robot dodgeball, and some might be better for robot-human dodgeball.

Without a more specific understanding of the rules (number of balls, minimum separation distance between throwers and dodgers, is catching allowed, size limits due to either rules or mandated materials), I don’t think it’s possible to decide between a robot that dodges based on size, acceleration or rotation.

Unless the rules are set up so that balls are coming in from a known span of directions, a kiwi drive would be on the short list. Swerve would also be worth considering, but given the short reaction times, the time to steer the wheels to the desired direction might be more costly than losing half the acceleration.

If catching is allowed and scored, I might consider building a larger robot with a net mounted on movable poles.

Multiple pickups and launchers would be tempting, but a fast turret or robot rotation is much easier and more reliable, and almost as effective.

Autonomous dodging (and possibly catching) would definitely be on the short list of desired features from the programmers. Presumably using a panoramic camera, it would have to detect a ball quickly “getting larger”, then decide which way to go to get away from it based on its apparent motion left to right. As far as whether to dodge left or right, a quick decision is almost certainly better than the right decision.

Desired features:
-Catching device on the front that can feed into a shooter
-ground intake that can feed into shooter
-flywheel shooter
-Fast Omnidirectional drive, probably H-Drive or swerve drive
-relatively small, but large enough to have a decent sized intake

This sounds like a fun challenge to CAD for actually. What size dodgeballs were you planning on using?

I think I would put a 6 wheels tank drive on supershifters… I like the feel of that drive train… Of you can have many balls in your possession, I’d roam in the beginning of the match to gather the highest number and then I would install the robot, wheels parallel to the middle line. This way, you can move forward and reverse do dodge and you can shoot sideways.

See the 2013 OCCRA game:

If catching is allowed, I’d take my inspiration from the Hoberman Sphere and related products to surround my entire robot with a cylindrical structure that starts off with lots of points facing up and down, then quickly brings both sets of points out and clamps them together to catch an incoming ball no matter what direction it came from. Reverse direction of actuation to catch balls falling from above or gather from the floor.

The shooter would be relegated to a secondary function, only for use in getting rid of caught dodgeballs and attacking opponents unable/unwilling to fall into that trap. Two spinning wheels on a single axle at the front of the elevator (which uses polycord belts, BTW), so that fired dodgeballs travel up and over said shooter wheel before leaving the bot in a forward direction. Not sure if I’d shorten the few catching arms directly in front of the shooter opening, or if I’d stick with closing the catcher whenever I wanted to launch an attack. Either way would be fine, because at that point it’s all up to the driver.

I’d probably go with a side-shooter (shoots perpendicular to the direction of travel) with a limited-rotation turret, a mostly flat net on the shooting side (under the shooter) for catching (drops to small hopper), and an intake on each end also feeding small hopper. 6WD corner omnis. Sensor-wise needs a “camera” to recognize incoming dodgeballs and something to aim the shooter (either another camera or some form of medium-distance rangefinder), also detector for if the shooter is loaded (cameras could feed driver’s station). Depending on degree of autonomy, a ball detection system may be in order as well.

I take the 2006 offerings of 1011 (side shooter) and 836 (low flywheel with a parabolic deflector) as my primary inspiration for this BTW.

If I were to build a robot for a dodgeball-esqe game I would make it a kiwi drive, provided in dodge ball your opponents cannot cross a line. For shooting, I would use a flywheel shooter. I don’t know the size of the balls so I can’t visualize what type of intake it should have. If the dodgeballs are small, I would use an intake similar to 469’s 2012 robot, and if they are large I would use something similar to 1678’s intakes in 2014.