I have been thinking about how difficult it might be for some teams to line themselves up with a goal to shoot while others are defending. Pushing seems like it will be a big role in the game, much like last year.
The difference?
Well last year upon a force applied by another robot, the slippery surface and low contact point caused your robot to slide.
This year, the bumper zone is much higher, we are playing on carpet, and more than half the teams will have high traction wheels.
I wonder how the gameplay will change when teams figure out that they can push a team sideways so that instead of sliding, the moment causes the opponent to tip sideways. You could argue that the contact is legal, since it is within the bumper zone, and it may be legal as long as the opponent does not flip. But at what point is incidental contact limited, and which flips are a little more than unintentional.
I am talking on flat ground here, not the bump. Now, the robots are pretty heavy, so it will require a considerable amount of force to flip them. But have any teams considered this? Tested the force required to flip a robot pushing at that height? Designed their wheel base and style of wheel around this?
You are pushing another robot and see that it is starting to tip over and you don’t back off. The robot tips over, your fault? You had the chance to back off but didn’t but your contact was within the bumper zone.
Is it the other teams fault for building a tipsy robot?
In Rack 'n Roll I saw this happen many times and never saw it called a penalty. But then again bumpers were not mandatory.
That is exactly what I am getting at… This is going to be 2005 all over again, except this time I think the refs are going to be prepared to make the tough calls.
I think a lot of this depends on the design of the robot. If your robot is designed to fill the maximum volume specs, odds are your CG is going to be fairly high, and you’re going to be more easily tipped - it might be possible to be tipped from a single, full speed, bumper-bumper hit.
On the other hand, if your robot is short, and your CG is low… it’s going to take a LOT to tip your robot. The other team would need to be pretty blatant about it, most likely resulting in them pushing in you while the side of your robot is already elevated quite a bit. I would hope something that blatant would be seen as non legal contact, since it would be bumper-frame (or other components) before the robot tipped.
The whole issue with tipping is CG. Keep your CG low enough and in the right place, and you have nothing to worry about.
Obviously each situation will need to be evaluated on it’s own, but if you are on flat ground and the tipping action takes long enough that you should have been able to see what was happening, then yes I believe a red card is in order.
Is it the other teams fault for building a tipsy robot?
The problem is that the tipping moment is created by bumper contact if you built a robot that isn’t tipsy. If the CoG of your robot is less than 13" tall, bumper-to-bumper contact will create a rotational moment. The lower your CoG is, the larger the moment (although you do have to be tipped up further before going over).
And if a robot tips while you’re pushing it, back off, no matter what caused the tip. Back in 2004, my team had a robot that was rather tipsy on flat ground. Early in our first event, a team got to us on flat ground and pushed us over. They’d have gotten away with it if they’d let us get up (we’d fallen so that we could have). But as soon as our arm started coming over to get us upright, they came back and knocked us onto our side, then shoved us into the ball corral. They got penalized big-time.
If the refs aren’t sure whether the tip was intentional, and you back off and stay backed off long enough for the tipped team to get back upright, probably nothing will happen. But if you keep harassing the downed robot, you’ll get penalized for violations of the grace period and/or intentional tipping.
Strictly speaking, from a rules perspective, intent has no bearing on the refs decision.
<G37> Permitted ROBOT to ROBOT Contact - Breakaway is a highly interactive game. Robust construction of ROBOTS will be very important in this high-speed competition. ROBOTS should be designed to withstand the contact that will occur during the MATCH. Appropriate contact is allowed under the following guidelines for which no PENALTY will be assigned:
a. High speed accidental collisions may occur during the MATCH and are an expected part of the game. b. Incidental contact, both inside and outside the BUMPER ZONE, is to be expected and is generally acceptable.
<G38> Prohibited ROBOT to ROBOT Contact - Except as permitted in Rule <G37>, contact is prohibited under the following conditions:
a. Aggressive or intentional contact outside of the BUMPER ZONE. Violation: PENALTY; plus a RED CARD if the offense is particularly egregious or if it results in substantial damage to another ROBOT.
Emphasis mine.
Incidential does not mean accidental.
in⋅ci⋅den⋅tal /ˌɪnsɪˈdɛntl/ Show Spelled Pronunciation [in-si-den-tl]
–adjective 1. happening or likely to happen in an unplanned or subordinate conjunction with something else.
In other words, if your aim was simply to inhibit scoring or robot movement (ie, defense), but not to tip, tipping as a result of contact would be incidental. Even if you had the power to prevent the tip and you didn’t (thus making it no longer accidental).
However, it would have to be pretty clear that it was not your sole aim as to not violate <G36>.
<G36> ROBOT to ROBOT Interaction - Strategies aimed solely at the destruction, damage, tipping over, or entanglement of ROBOTS are not in the spirit of the FRC and are not allowed. Violation: YELLOW CARD
Whether or not refs will call it this way remains to be seen, but that’s what a strict reading of the rules tells me.
I smiled at the reference to 2005-like game play. Ahh, how I would’ve loved to been around in those days.
Realistically though, I’m going to train our drivers so that if they see someone start to tip they back off, so that the call “should” never have to be made. And inversely, I’m going to tell them if our machine starts to tip, then it’s time to back off.
I would expect defensive contact similar to 2006. Pushing and shoving to throw off your aim during shots is intended to be part of the game. Robots **WILL **definitely tip or flip on the bumps, and that is part of the unique design challenge that they gave us this year.
If your robot can be tipped over by being pushed on level ground however that is just poor design in my opinion. You should know going into the game this is part of it. I can’t even imagine what a robot capable of getting tipped over by level ground pushing would be like in this game because it would have to have a high center of gravity that is near the edge of the robot. thereby making it impractical to drive over the bumps and too tall to go thru the tunnel.
With no arms to push high on a robot with how does some one tip in this game in a level ground pushing match?
Robot to robot interaction will be within the bumper-zones of the robots, which is 10" off of the floor. With high traction wheels teams will be able to create more traction (thrust) then their weight. Thus the pushing can create rotational movement fairly easily.
If your CG is below your bumpers it shouldn’t be easy to tip a robot. Tipping with arms was usually 2-3 feet off the ground, not 13 inches where the centerline of the bumper is.
I can guarantee that if a team has any sort of traction wheels (i.e. no HDPE, omni, or mecanums) and with the center of the bumpers being ~13" high that the robot can flip on flat ground no matter how low the cg is. Especially if the robot is in motion and shifting its momentum in different directions.
Keep in mind, however… if the robot is designed to go over a bump, that means it can also be tipped at least 45 degrees before gravity will do the work to flip it over. That’s a pretty big tip, and for a vast majority of robots, that will require prolonged contact and pushing outside of the bumper zone. The only caveat to this is, of course, if your CG is not properly centered in the robot. If it’s significantly to one side, you’ll be easier to tip.
