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Unread 04-09-2011, 10:18 PM
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Here's the problem with the minibot

I just returned from the Michigan State championship, and here are my thoughts on the minibot. First the good:
  • This is the best endgame in the nine years I've been involved with FIRST (In my opinion.)
  • It was a very difficult "challenge" that many teams succeeded in meeting.

...and now the bad:

Keep in mind that in many cases the outcome of a match was based on the minibot.
  • Assuming that the switches at the top of the pole were flawless in every match ever played, there was a clearer problem. when did the minibot deploy? Did they go early? did they cross the plane? I know that there was a referee at each pole trying to keep a close eye on this; however, this is flawed when your talking tenths and hundredths of seconds (which we are.)
    .
  • My team spent over $1,500 on parts for the minibot.

    After a mentor asked Direct drive minibot output diameter, JVN writes,
    "Obviously after the first 2 weeks of competition the secrets are all out.
    If you're going to use a design that is "heavily inspired" from one you saw on the field, at least take the time to iterate the design and figure out the details yourself.
    You can make this into a positive design experience for your team with some methodical experimentation...
    "

    He's right! but short sighted, considering not every team can trash $30 motors chasing the right shaft size.

    Even though minibots themselves are cheap enough ($200 or so). developing a competitive minibot takes money. I feel to really compete in the minibot race you had to pay another fee to the LEGO corporation. My team gladly paid and used "methodical experimentation" to developed a 1.4 second minibot.
    .
  • The race was the problem! Most every team in FIRST could have successfully developed a simple "slow" minibot with accurate deployment. I feel many teams have become discouraged and ran out of resources competing in the minibot arms race. If teams were allowed to focus on consistency instead of speed, I would have expected see beautiful latching mechanisms and really explored the limits of the Tetrix systems. What the race gave us, was stripped down motors with batteries and magnets attached to them, all in spite of the tetrix's capabilities. Innovation was was focused on how to misuse the tetrix system, not using it for what it was designed to do. (I hope the FTC teams that lent out their kits, hadn't expected much back)


My Solution:
I like the days that if you could get on a ramp or climb a pole you received the points. the minibot race could have been a flat rate challenge. you make it to the top, you receive the points.
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Unread 04-13-2011, 08:02 PM
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Re: Here's the problem with the minibot

This Post took 4 days to Show up, Strange.
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Unread 04-13-2011, 08:50 PM
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Re: Here's the problem with the minibot

I agree with all the things you said that you think is bad. I do not find anything good about it though. However I like your solution.

Our team is a little bit more thrifty. We only spent $1335 on the minibot. That is a ridiculous amount of money spent. Quite a bit was "wasted" early on when we thought we need the Tetrix Motor Controller, additional Lego Mindstorm touch sensors, big wheels and Tetrix motor mounts etc. Then more money was wasted to find the "legal" switch.

Many teams spent more money on the minibot than other teams spent on their whole robot. That is just wrong for FIRST to design an end game like that which in most cases determine the winner of the match. Less resourceful teams and less established teams have a big disadvantage. Rookie teams already have to overcome a lot of obstacles, both financially and technical know-how. This is just not fair. And it is not a good way to welcome new teams or try to retain them when it is so hard for them to compete with some success.
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Unread 04-13-2011, 08:56 PM
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Re: Here's the problem with the minibot

Point-wise, it's just too valuable in my opinion.
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Unread 04-13-2011, 09:02 PM
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Re: Here's the problem with the minibot

Nevertheless, good points all. The extreme premium placed on finishing first in the minibot race is driving everyone towards a very small number of designs. A flat rate for minibots would definitely leave room for different designs and reduce the numbers of "heavily inspired" designs. Bonus points if you can tweak your flat rate endgame to encourage usage of the NXT brain and sensors to encourage actual partnership with FTC teams, since they're more likely to know how to accomplish the task. My proposal:
Slightly fancier towers with multiple scoring zones marked along the length.
15 pts for triggering the tower.
10 pts for stopping the minibot in the correct, randomly determined scoring zone.

Depending on the difficulty you're aiming for, the random zone could be told to teams at the start of the match, told to the robot through the fms, or indicated on the pole via lights, an electromagnet placed inside the pipe, or something else.
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Unread 04-13-2011, 09:06 PM
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Re: Here's the problem with the minibot

I also think the rules were a bit restrictive. Sure, there was variation in what the minibots looked like, but once you get down to the 1-2 second minibots, there wasn't much variation. Yes, cutting out restrictions bring up safety issues and how teams can simply out-buy other teams but it also invites teams to make the best of what they have availiable to them.
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Unread 04-13-2011, 09:10 PM
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Re: Here's the problem with the minibot

I agree. The endgame is absolutely awesome this year. It flows with the game and it leaves people sitting on the edge of their seats. It's just what an endgame should be.

Team 573 has two minibots this year. Our first minibot was developed during weeks two and three of build season. It was made mainly of Tetrix parts and it vertically clamped to the pole with the help of a trip lever and surgical tubing. It wasn't the lightest(4.5lbs) and it wasn't the fastest(4 second climb), but it was sufficient for our first competition. Our deployment system was basically a cradle on drawer slides pushed by a lead screw. We headed to Waterford and we were finally able to do some real testing with our minibot and deployment system. I can say that our minibot was the reason for our success at Waterford. It climbed the pole 14/16 times, and even though it was slow, it earned us a ton of points. I believe that this is what FIRST intended with the minibot portion of the game.

After scouting more competitions, we realized that our reliable minibot wouldn't be able to compete at later competitions, so we built a new one. It's the standard minibot design now - it has a lexan chassis, two motors direct driving a single shaft, a battery, and two limit switches. We did some slight modification to our deployment, but it worked well on our pole in the room and at the Michigan State Championship, where were finally able to use it. Our new minibot can beat many minibots up the pole. Now our problem is our deployment system. We are fearing that we won't be competitive in the minibot race due to our deployment. We noticed very quickly that our lead screw deployment system took as much time to get the minibot to the pole as it did for the minibot to climb.

FIRST's challenge was to build a minibot that can be deployed to a pole and successfully climb it, and either minibot did just what it was built to do. Both minibots and our deployment were reliable as well.

On the other hand, changing the race to just making it to the top would drastically change the game. It would devalue the minibots and it would add more value to the tube hanging. Also, changing the endgame would eliminate all of the iteration and tweaking that we and many other teams have done. I guess the real question is what is more important, being competitive, or completing the challenge?
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Unread 04-13-2011, 09:11 PM
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Re: Here's the problem with the minibot

If I calculate correctly, We've spent about $750 for 6, ~1 second, minibots.

The biggest problem was we ruined around 4 or 5 motors in the process, but the minibots are about $100 worth of parts each.

(BTW if anyone would like to burrow we've only got 1 potential burrower so far, that leaves 4 more up for grabs! If interested there's a thread in this subforum named 931 Minibots)
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Unread 04-13-2011, 09:23 PM
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Re: Here's the problem with the minibot

I agree with all of the points about the end game.

However, I disagree about the necessary cost of development.

Sometime around week 2 Richard posted results of a dynomometer test of the Tetrix motors with the gearboxes removed. Using those test results it took us about 15 minutes of calculations to come up with the correct shaft size. The only motors we smoked were due to bad switch placement.

While I'm sure the above story sounds like "look how smart we are", that's not the point of sharing it. Engineering is about using calculations to come to a solution, and coming to the solution as cheaply as possible.

Message to the students: math and physics save a lot of money!!! Pay attention in school - this is why your teachers are torturing you with this stuff.
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Unread 04-13-2011, 09:32 PM
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Re: Here's the problem with the minibot

Anyone else feel like this was an attempt to push FTC parts? I mean, just thinking skeptically, the whole cost thing then makes sense. /cynic

Also, I think it's a great endgame idea, just a little to restrictive.
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Unread 04-13-2011, 09:48 PM
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Re: Here's the problem with the minibot

Quote:
Originally Posted by Team 288 View Post
The biggest problem was we ruined around 4 or 5 motors in the process, but the minibots are about $100 worth of parts each.
The motors are $30 and the Batteries cost $50. The starting point is $110.
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Unread 04-13-2011, 10:07 PM
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Re: Here's the problem with the minibot

All told, we smoked 10 tetrix motors *so far*. We used the dyno data to put together the correct shaft sizes. A couple of our motors smoked when the switch failed to work, a couple more when the modified trannies on our 2 second bot weren't perfect and locked up. Several broke tabs during minibot suicides, and the rest were destroyed by eager students learning about motor torque curves.

I'm proud that we have not copied a single thing. Design and build is 100% ours. I did not enjoy the cost, and the regular calls of "order more motors". In one case we smoked a motor because our grenade pin got knocked out and the bot ran through the entire 2 minute match. I will not cry when this minibot madness is over.
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Unread 04-13-2011, 10:33 PM
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Re: Here's the problem with the minibot

I feel like this years end game decides more matches than most of the actual tube scoring. In the past two regionals I've attended (Boilermaker and Midwest) it seemed that matches we won due to the fact that some teams had effective minibots and some didn't. At boilermaker we were in an alliance with a team who only had a drive train and a minibot vs a fully functioning robot who was proficient at scoring tubes. Due to mechanical issues only 2 robots worked in that round, our alliances minibot robot and the opposing alliances scoring giant. The minibot robot went to the tower and stopped until the end game where it deployed the minibot and the other team spent the entire match scoring tubes. In the end we tied 30-30. So robot wise our alliance didn't exert much effort or work but still managed to tie with an alliance who was scoring constantly. I just feel like the reward of the race is a little high in comparison to the actual scoring of tunes
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Unread 04-13-2011, 10:34 PM
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Re: Here's the problem with the minibot

I like the idea that Stephen proposed about a flat rate challenge. You made it, you get the points. Last year, you hang, you get the points. Two years ago, scoring a supercell is 15 points no matter when you scored it. Three years ago the big ball on the overpass score the bonus points no matter when you scored it. I don't think it is any less exciting. It eliminates all the problems with deploying too early, crossing the plane etc.

For those who have been around longer, were there a game in past years with end game that gives more points to the alliance that did it first?

It seems to go against FIRST values. We should celebrate when a robot can do a certain task. We don't build battlebots. We don't try to beat the other guy directly. We should try to use the robot we designed to score as many points as possible and use strategy as an alliance to win.
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Unread 04-13-2011, 11:04 PM
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Re: Here's the problem with the minibot

Uhhh, FIRST's challenge is about building robots that perform better than everyone else's robots, not just building robots that can perform a task *at all*.

....and while we don't have a 1.4 second minibot, we have a 1.8 second minibot, and with the FIRST Choice program we spent a total of about $80, $60 of which was on spare motors we didn't need.

Would it have cost us a lot more to optimize out that extra half-second? Perhaps. Perhaps not, if we fused things properly so we weren't smoking the inductors in the motors during our experimentation.

A lot of sound and fury, methinks, has accompanied the poor, maligned minibot this year.
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