Legality of Downwards-Sloping Ramps
 

There's been lots of discussion of various ramps, and it appears that most, if not all, ramps were accepted by inspectors from regional events to the Championship.

But that doesn't really satisfy me. At any event, possibly questionable or even outright illegal robots are passed and allowed into competition. There's hasn't been a thorough, rules-based discussion of downwards-sloping ramps (including, but not limited to, those of a U shape or those beginning at higher than 30'').

So that's why I've started this thread. The first real question I have about the legality of a downwards-sloping ramp comes from the following rule:

Emphasis mine. It is possible that gravitational potential energy, if utilised before or during deployment, is not legal. Some argue that this usage requires the minibot goes down, and that this is actually a disadvantage. I don't think so.

The minibot is required to go up the pole from the deployment line to the sensor to score. During that period, there's no plausible way to gain an advantage by going down. That's why this is (or should be) legal.

However, going downwards before or during deployment can be an advantage. It provides a kinetic energy that, though directed downwards, can be and was converted into kinetic energy propelling the minibot upwards. Because it is an advantageous use of energy not stemming from the minibot battery, a downwards-sloping ramp should not be legal.

Thoughts?

Re: Legality of Downwards-Sloping Ramps
 

i had this idea as well, say you were to direct drive a wheel with a diameter of something like 1.5 inches, and your mini-bot started 4 feet above the pole, races down a ramp until it reaches the pole, even though it would de-decelerate on the pole, the change in potential energy would be the equivalent of 6 feet of height gain, instead of 10 feet of height gain. the question is, will this be faster than a pure ramp bot.

Re: Legality of Downwards-Sloping Ramps
 

If you look at it that way, then any minibot raised above the surface of the arena has "stored energy" and is therefore illegal, and I think that we can all agree that this is ridiculous and not the way the rules were intended to be read. I don't think there's much of an issue here.

Re: Legality of Downwards-Sloping Ramps
 

Have you even seen a downward sloping ramp pass inspection and compete?

I haven't, I would assume because essentially everyone agrees they are not legal.

Re: Legality of Downwards-Sloping Ramps
 

Specifically, no. However, this entire discussion came out of comments on a facebook video from a team working on a ramp sloping downwards. When the suggestion was given that is may be illegal, they stated "multiple lead inspectors passed it. one here in [state] before we left. and the one in St Louis did too." I'm still not sure if it was an offseason project or for that team's competition robot, but if inspectors WOULD pass them, it's believable that there could be a few.

Re: Legality of Downwards-Sloping Ramps
 

That method is without a doubt illegal. <G19> states "MINIBOTS must remain completely autonomous and move up the POST solely through electric energy provided after the start of DEPLOYMENT by the permitted, unaltered battery and converted to mechanical energy by the permitted unaltered motors. This is quite simple. MINIBOTS must move up the post SOLELY through electric energy provided after the start of DEPLOYMENT. The gravitional energy from the downwards ramp is not electrical energy, is not provided by the motors, and is not an allowed form of gaining energy to move up the post.

Re: Legality of Downwards-Sloping Ramps
 

Guys,
The downward sloping ramp is still manipulated by a minibot using energy stored in it's battery and converted to mechanical energy in the motors. While some will argue that there is an advantage here, I disagree. While it may be true that gravity will accelerate the minibot while traveling down the ramp, the motors will still have to overcome gravity on the way back up a slope and still travel a longer distance to do so. Add to this any increased friction as the minibot transitions from the down side to upside of the ramp and you will see that there is likely a net loss in energy during this time.
As to inspector involvement in this design, we simply inspect on the rules in the robot section not the game rules unless specifically directed by the GDC. The ramp needed to be constructed of allowed materials, exist entirely inside the bumper zone at the start of the match, be safe with no sharp edges, etc. It is the refs on the field who make the determination as to the legal use of such device that passed inspection. I think it is easy to realize that if the minibot deployment occurred within the correct time frame, these ramped designs would add feet to the travel distance encountered by the minibot.

Re: Legality of Downwards-Sloping Ramps
 

There was one at the Championship on the Newton Field. The slope wasn't as crazy as people are talking about in this thread, but it was noticeably sloped.

Re: Legality of Downwards-Sloping Ramps
 

Yes - ours.

There was a discussion in a different thread around week 2 or 3 of regionals on this topic. The consensus seemed to be as long as the minibot stays below the deployment line the entire time it contacts the ramp AND the end of the ramp is higher than the beginning, then there is no net potential energy converted to kinetic energy.

Our ramp starts out downward, but the minibot does not gain any energy from the downward slope since the end of the ramp is higher than the start of the ramp (i.e. there's a net loss of potential energy by the time the minibot leaves the ramp). Furthermore, the minibot stays below the deployment line the entire time it is touching the ramp.

Why do we do it? Becuase the Tetrix motors inhale audibly and we're trying to unload them as much as possible during acceleration.

Re: Legality of Downwards-Sloping Ramps
 

I have seen 2. Teams 51 and 340.

I actually walked over to my good friends on 340 on Wednesday afternoon, and questioned it's legality. They had a level one ready in case it didn't pass.

-Nick

Re: Legality of Downwards-Sloping Ramps
 

What if the motor is pushing the minibot down a slope? One could argue that the minibot is being solely driven by the motor, and that gravity is only providing a force to pull it down, like it normally does. If all else fails, just ask the judges to turn off the gravity! :D

Re: Legality of Downwards-Sloping Ramps
 

I agree with what Al says, but I have a few questions.

To those of us who are still scratching our heads about this, perhaps the questions should focus on what has been Deployed, and when Deploying ends.

If the Host bot is not supposed to impart any pole-climbing help to the mini-bot after the mini-bot is deployed (and if starting the mini-bot motors is one way to know that deployment is ended?), then a ramp that is part of the host-bot deployment mechanism(s) would seem to violate that rule; regardless of whether the mini-bot pays the universe back on the upward climb after reaching the bottom of the ramp.

If the mini-bots include both the parts that climb to the tops of the poles and the ramps that are left at the bottom of the pole, that might make a difference; but my instinct is that the ramps are parts of the host-bots, not part of the mini-bots

If the device that gets deployed (the mini-bot) is supposed to only use battery power and not begin with any other stored energy, then a ramp that is not part of the host-bot would seem to be a violation of the rules governing mini-bot construction and behavior (but maybe not).

If you can't spin up a flywheel during deployment and carry that angular momentum into the race, I don't see why you should be allowed to drive down a hill and carry that angular and linear momentum into the race.

On the other hand, if when the race begins you want to start off of the pole and then drive along a track to reach the pole, and if the time spent driving on that track is part of your total race time, and if you are allowed to race along things that are not the pole (such as a track you bring and keep below the line), then I can understand that a ramp would be legal.

I admit that I have not (re)studied every deployment, etc. rule before writing this; but I do hope that a careful examination of what it means to be deployed, and of when the state of "being deployed" ends for a mini-bot, will help clear this up. There are plenty of gurus who can cite the precise rules that apply. I'm just trying to think through how many of those rules need to be examined.

Blake

Re: Legality of Downwards-Sloping Ramps
 

Blake - what your looking for is the official definition of DEPLOYMENT, found in Section 1.6:
The act of deployment starts when the minibot breaks the plane of the tower. Pretty straight forward - it hasn't started when the minibot is still within your robot, or when it's fallen off and is sitting in the middle of the arena. It's only when it's actually over the tower.

The act of deployment ends when the hostbot is no longer in contact with the minibot. Again, pretty straight forward - if you're still pushing the minibot towards the pole, you haven't finished deploying yet. It's only when the minibot is on the pole and moving (hopefully) away from your robot that it's deployed.

Re: Legality of Downwards-Sloping Ramps
 

Who said you can't use a fly wheel. Provided that the energy stored was generated by A) tetrix motors on the minibot or B) a change in position of a mass that is part of the minibot, or the entire minibot, as a result of gravity only (it is ridiculous to say that you can't use gravity on your minibot to gain an advantage, then making your minibot lighter would be declared illegal as well) then a flywheel would be perfectly legal from what I can tell.

Re: Legality of Downwards-Sloping Ramps
 

The rulebook

<G19> MINIBOTS must remain completely autonomous and move up the POST solely through electric energy provided after the start of DEPLOYMENT by the permitted, unaltered battery and converted to mechanical energy by the permitted unaltered motors (and associated, appropriate circuitry). <G19> means that HOSTBOTS are not allowed to launch the MINIBOT up the pole at the TARGET, or otherwise contribute to the vertical movement of the MINIBOT. Energy for vertical movement may not be stored in the MINIBOT before DEPLOYMENT (except that which is contained within the battery and excluding incidental kinetic energy stored in the motors or wheels, but NOT, for example, in a flywheel).