I didnt see a thread for this (correct me if there is one), but anyway, what teams are having a drive base that will traverse the bump that is at mid-field? (As a normal occurrence anyway!)
My team is definitely, so how about yours?
imo, a no brainer since we can’t throw the balls onto the scoring side until the last 30 seconds.
Yep. Not being able to cross the hump in 2010 didn’t hurt us at FLR, but this year just plain isn’t 2010… Zone management will be a big deal!
My input here, is it really necesary to cross the bump? Especially when it may be faster for one to cross the bridge and also safer? Think about it, Bridge= no blocking, (if so fouls will be incurred) Bump=block crazy, I expect to see many robots stuck or prevented from crossing the bump due to just a little defense, anyone else see my point? Crossing the bridge seems like the way to go, and it makes the intake design much more simplistic. It could even be faster… Please confirm that my reasons for not going over the bump are logical…
It really is more of a pillar
I thinking going over the bump is a good thing to have in your design, even if you plan of using the bridge. If you came off the bridge in a match wouldn’t it be bad to be stuck there the rest of the match?
Well, as our team is finding out, it’s a bit more difficult than they though to tip the bridge. If this statement is true, I’m not sure. But we’re fairly certain we’ll be traversing the barrier and saving the bridges for endgame.
What if every robot on your alliance is a bridge-only robot? Nasty traffic jam, that. What if an alliance partner (or opponent) falls and blocks the bridge?
I personally know several teams that are going bridge only this year. I wouldn’t recommend it.
Occupy Chief Delphi… I am the 4 Percent!
Yes! 80.00%
No! 16.00%
No… but I wish we were! 4.00%
To the teams who are going over the bump: do you have a long or short base drive train. Our decision process went something like this:
-We need more than 12" to pick up an 8" ball easily, so we need a long base.
-A 4WD with 120lb on it, even with a short wheel base is pretty hard to turn, so we need a 6WD.
-A 6WD in short configuration would likely tip going over the barrier, so we need to go over the bridge.
Where in this process do others disagree, or come to a different conclusion?
We’ve designed our robot around our strategies, and our strategies will only involve going to the other side maybe once or twice per round maximum, sometimes none at all. Because of this, we designed to use the bridge instead of the bump.
My team is ready to cross the bump… technically?http://www.youtube.com/watch?v=dD8OUCOpnRo
Here’s what we came up with:
-We need more than 12" to pick up an 8" ball easily, so we need a ball-intake appendage that extends out of the front of our robot.
-A 4WD mecanum with 120lb on it turns on a dime but can be kept from the key, bridge, and alley, so we need an octocanum with preposterous torque.
-A 4WD octocanum in long configuration needs only passive mechanism help to make it over the barrier, so why not do that?
Are we right? Are you? I’m sure experience will tell us! :eek:
My thoughts EXACTLY!!! if you can do it well and consistently, then why bother with the bump, and make sure before the match, if you send a team across, MAKE SURE they can do it without failing… I feel the perfomance boos gained by not adapting for the bump allows for a better performing (and better scoring) robot.
Given two robots, identical in all aspects but one–one of them can cross the bump and the bridge and the other one can only cross the bridge. Which robot is better? The one that can cross the bridge, obviously.
However!
Crossing the bump is a tricky engineering proposition, and not all teams have the time to figure out how to do it. So what you need to weigh is whether or not crossing the bump is important enough to merit your engineering time. For teams with a lot of resources, the answer is yes! For teams with few resources, the answer may be no.
So let’s do some bump analysis.
Q1) Do you need to be able to go on the bridge to win?
A1) Yes.
Q2) Is the bump as important as the bridge?
A2) Maybe! Let’s see.
Q3) How much is balancing the bridge worth?
A3) Balancing the bridge is worth ten points.
Q4) How much is crossing the bump worth?
A4) Crossing the bump is not directly worth any points. It is worth as many points as you can score in the time you save crossing the bump vs. the bridge.
Q5) How much time do you save crossing the bump versus the bridge?
A5) Probably no less than two seconds and no more than five seconds per crossing (one way).
Q6) How many times per match do you need to cross midfield?
A6) Run some simulations and figure it out! Our simulations told us that scoring is fastest when you maximize efficiency, which is done by minimizing travel time, which is done by not crossing midfield. This means that two out of three robots in an alliance should only have to cross midfield once per match at most. Your simulations may tell you something different.
Q7) What is A5 * A6?
A7) Our team thinks it’s between zero and ten seconds.
Q8) How many points can you score in A7?
A8) Do the math yourself. Our team says no more than 9.
Q9) Is A8 points per match worth the cost of engineering your robot for the bump?
A10) You tell me.
We’d love to be able to cross the bump as an insurance policy in case our analysis was wrong, but our robot is not specifically designed to do it because we have limited engineering resources. It’s a mechanism that we’ll make if we have the time.
You left out in your analysis, how often is the bridge blocked and for how long. Think about all teams following your logic. How much bridge crossing is happening? It is just too dangerous for two bots to attempt to cross one bridge at once. Could it be done? yes, but not safely and quickly…
On day one our team did a little simulation of the game and from that we found that most of the moves our team members made were going across the field to get a ball from the human player in a competitive match (several scores from each alliance). With that being said we played around with whether or not going over the bump was necessary. We thought through it some more and came up with that if we just went over the bridge it would take a few seconds longer to cross but we are limited to 2 bridges: one of which is our own alliance’s shared with 2 robots and a common bridge which is shared with 5 other robots 3 of which would want to stop us. Additionally, what if one of our robots got stuck on either bridge or takes much longer than us to cross then we are now stuck in rush hour traffic at the tolls, and in a game with so few balls what if for some reason we there are several ball in our opponents zone constantly?
Conclusion, crossing the bump while another design challenge will pay off in the long run in that we can move across the field over multiple access points to maximize our ability to play the game. To accomplish this we have angles on the front of our frame that allow us to glide over the bump with a 6wd.
We were also torn between a long and wide drivebase. A wide robot would give us a large gap for pickup and have an easier time fitting on the bridge but comes a the cost of having a high chance of tipping if not designed properly due to the shorter wheel base. A long robot takes away our ability for a large pickup but is safer at going over the bump and fitting in our ball pickup and shooter.
Conclusion, make a long robot with a drop down harvester at full width and is heavily weighted towards one side to fit on the bridge for a triple balance.
Pretty lengthy but this is what our team came up with in the end. The biggest thing is making sure your team can accomplish what you intend to build.
Good luck!
We don’t know if we’re going over the barrier. Hopefully we’ll know in a week or two. But we are going to make the robot so it can attempt it.
The students really wanted to go over the bump, so that is what we are doing even though some of the mentors still think this puts the schedule at risk. Our team has traditionally done track drive which takes more machining, expense, and tweaking, than other drive bases. Last year they had more difficulty (than usual) getting everything done on time. So for practice over the summer they decided to build a demo-bot using regular wheeled kit-bot parts. From that experience they seemed ready to build a normal wheeled robot this year so they could focus more on the other parts of the challange. Than they saw the barrier that seemed to call out for tracks. What to do!
What we came up with is a wheeled robot that still has some track like characteristics. In stead of chains in some places it has timing belts. These belts are supported in such a way as to act enough like a track to hopefully allow the robot to avoid high centering when crossing the barrier. It is not a real track and will not be good enough to use much, but hopefully it will work just enough to navigate the barrier.
If everything works out, and that still seems like a big if right now, we will have a robot that drives around most of the time like a wheeled robot with just a little assistance from the pseudo tracks only when needed. We are using custom wheel mounting plates, but believe the design could ultimately be adapted to a kit of parts frame to allow teams to experiment with track drive without a lot of machining or expense.
The design is lower cost than traditional track drive and requires less machining because it uses the standard Gates timing belts with off the shelf pulleys. But that means you only get part of the advantages of track drive. The students are calling this variation Corvallis Spartan Drive because they do not know if it has ever been tried before. We will need to post some pictures if we ever get it working. Too soon to say if it has any advantage, or will even be competitive, but that is what happens when you try something new.
I know for our team being able to get anywhere on the field rather quickly has always been beneficial to us. This is a lesson we have learned by looking at the robots that you routinely see in the finals at championships. Generally speaking they are able to easily transition from different zones of the field quickly. This allows them to acquire game pieces quickly and score them regardless of where the game pieces are on the field.
Therefore, I think that we will attempt that approach again this year but I can see where robots that can’t transition the barrier are useful. If they are a really good shooting robot they can stay in their scoring zone while other robots on their alliance cross over to the other side to feed them ball.