[DFTF] The Classic Blunder...

FIRST General Forum
1

This is part of a series of posts called Drinking From The Firehose on getting Dr Joe back up to speed on All Things FIRST.

Today’s topic:
The Classic Blunder…

No, *(http://www.imdb.com/title/tt0093779/quotes) No, my blunder was even more classic:

I designed a robot that SOME team could finish in less than 45 days, just not MY team.

As the picture above implies, I have been trying to make up for it by working myself to death for the last 3+ weeks, thinking I could set things aright by din of effort.

It has worked to some degree. Our chassis was looking awesome when I turned out the lights in The Box* this morning and headed to my day job. With more hard work between now and Tuesday Midnight, we will have a pretty amazing chassis, one that no rookie team has any business building: We’ll cross the barrier with ease, we should be able to balance a Box of Rock on the Coopertition Bridge, we may even be able to help pull off a 3 robot balance after lunch on Saturday. It has other features as well that I won’t go into (hint: we’ve named it, The Rook)… …this sounds like a list of positives, but actually it works equally well as a list of negatives. You see… … I am out of gas, we’re almost out of time, and we’ve got nothing to handle balls… …at all.

We’ve got weight for it. We’ve got space for it. We even have a reasonable concept or two we’ve sketched on various napkins over the last few weeks. What we don’t have is TIME.

I can hear myself saying the words to my Rookies: "It doesn’t matter what Cheesy Poofs can build in 45 days, or Thunder Chickens, or Swamp Thing, or Miss Daisy, or WildStang, or CHAOS, or Beatty, or Buzz, or Pink, or ANYONE ELSE can build in 45 days…

…it only matters what WE can build… …in 45 days… …because that is the only option available to us."
I said it. I believed it. I meant it. I just didn’t do it…

and there are only 106 hours left…

Joe J.

  • Where else would you expect a team named Schrodinger’s Cat to work?*
2

Don’t forget about that 30lbs withholding allowance. Try building a way to mount your ball handling mechanism in the time from now until stop build day. then, while waiting for competition, try to figure out how you’re going to score. If it has to be a stationary dumper that requires you to be a fender scoring bot, then that’s not a bad thing. just make sure you can get balls to place on your robot where an end effector can be used, and build it before you bag the robot. It sounds tough and it definitely will be, but what else do you have to lose?

3

Always remember, that 30 pounds withholding is huge. In 2009, we withheld our entire turret. In 2010, our lift system. In 2011, our minibot deployment system.

This year, I think we may get lucky and be able to bag an entire robot (for the first time since 2008).

Use that withholding allowance to your advantage.

4

A big fuss has been made about making 3 point shots from across the arena, but no one has really talked about ‘stealing’ opponents missed shots. An agile, low CG robot that isn’t slowed by the bump, and can quickly acquire missed shots from the opponents zone and ferry them across the field to friendly robots could provide a much more effective defens that a high traction box on wheels…

With the materials you have on hand, how hard would it be to create a minimalistic ball acquisition and storage system (a la 1902 in 2006)?

5

Joe,
What makes you think we’re finished building? We have a proto that moved onto the bridge last night. We think we see a light at the end of the tunnel but it could be that fatigue is putting up spots before our eyes. I will know more by tomorrow night I hope!

The reality here is you can prototype between stop build and your regional. Plan on what you can bring to manufacture and work like crazy on the practice day. I bet everyone of those teams you mentioned has taken their robot apart on the the practice day at least once having figured out that some parts won’t work the way the game is played or the functionality is not needed due to a different strategy.

6

If we’re both at champs you should come check out what we’re running in that regard, its nuts

7

Fellow Rookie,

We just got our powder coated parts back from the paint shop today, and we have all weekend to build. We do have a practice robot mostly finished, but we too have a bunch of work to do.

Keep in mind that you can walk in to the event with 30 pounds of custom parts.

Have a great weekend,
Andy

8

This being my 12 year of FRC, I’ve noticed the competition change in little ways here and there, but the withholding allowance has been one of the most major changes in FRC these past 5 years. The days of crating your robot by Monday night, so that FedEx could pick it up at some point Tuesday morning - are gone. (I almost miss those days) Now we can (and many teams do) build 3/4 of a robot in 6 weeks and then spend another 3-4 weeks building/perfecting the other 1/4 (often some very important component).

So as others have already mentioned, use the 30 lb withholding to your advantage and I’ll be at the door checking your weight (at least in spirit).

PS: Everyone else - if you bring your bumpers into the competition unbagged, it counts towards your witholding allowance!!

Other blunders to watch out for…

  1. Loose chain may work for a little while, but it will fall off at the worst possible time. Find ways to properly align and tension chain.
  2. Loose electrical connections may work for a little while, but will work loose at the worst possible time. Find ways to secure, crimp, and attach wiring.
  3. Fasteners like screws, bolts, and nuts MUST be locked down using locknuts, threadlock, lock washers, etc. This year with many fast spinning wheels to shoot balls, things will tend to work themselves loose!
9

Yeah, the 30lbs is HUGE! We added enough length to our arm to use the 3rd row in between regionals last year. Concentrate on the drive train and the gatherer, fix the shooter and bring it to the regional. You’ll sacrifice most of Thursday but it is better than nothing.

10

The withholding allowance is definitely a possibility for you to get some extra functionality on the robot. Just don’t succumb to the follow-on to your Classic Blunder, building all practice day and missing inspection and practice. You know how important driving practice on a real field is, especially for your rookie drivers. You already made the mistake of designing a robot your rookies couldn’t finish in 45 days. Don’t double down and design and build a secondary system that your rookies can’t install, wire, and program in 4-6 hours. I’d vote for a simple ball collection and transport system. Even better if you can work out your mount-points beforehand and get those installed on your chassis before you bag it.

PS. We’ve all been there. Sometimes even after you’ve been working with the same team for a decade. Just make a note to expand your capabilities in the off-season and retract your expectations slightly next year.

11

The OCCRA kids built this bot this past fall. It is a very simple collecing and scoring mechanism that had a high pivot and a set of balls that sucked up and spit them back out in goals up to 60 inches tall. It was a very effective scorer.

Also, if your chassis is as described, it should be good for at least 10 points a match and maybe more. There is a fairly simple method to score 8 points every match as long as your robot is not too tall. 8+10 will win most matches, and I would almost garauntee a spot in elims (though probably not the finals).

12

Just be sure to take lots of close up pictures and measurements (unless everything is already in cad) before you bag it up, so that you can have a plan ready to go for attaching your 30 lbs of magic components. We also brought our entire minibot deployment last year – the MB was a key element to our success at the regional.

13

Added Emphasis here.

The 30lb withholding allowance does not apply to unmodified COTS parts. This means that you can with hold in excess of 30lbs of your robot assuming that you only have 30lbs of fabricated/custom/modified COTS parts (Andy’s had me thinking about this for a bit). Not sure what you’re looking into withholding, but depending on how it’s built and how much is COTS you could withhold darn near half your robot - or at least I know that we could.

14

Joe, your situation is not unique to being a rookie team. On 968 one year, we shipped nothing more than a completed base, which we had not even driven. In 2008, the year we made it to Enstein, we did not ship it to its first event with a working ball mechanism. In fact, we had the last parts of the ball mechanism shipped to the hotel in San Diego, where they arrived at 9:00 AM on Thursday morning. Talk about cutting it close. There’s a lot that can be done very quickly if you have a solid plan and the dedication and tools to implement it.

Currently, in 696’s 12th year, we just now completed the base and bridge/bump crossing mechanism. It has not been driven yet. It looks stellar, but none of it is done or tested.

You’re not alone.

15

I’m seconding what everyone else has said - 30lbs is enough to do a lot.

In 2010 we got to our regional, and our kicking mechanism… didn’t work at all. It was a nightmare, and dangerous. So between the regional and Champs we completely redesigned the kicker from scratch, in a single unit that we could bolt into our chassis and plug in, and be done.

It’s definitely do-able!

The fact that what you have done is solid is fantastic. Better to have one thing completely finished than two things half finished, correct?

16

I have a question for all the people talking about the 30 pounds and how great it is. How can a robot truly be competitive if the electrical team doesn’t have time to test their wiring, the software team doesn’t have time to test autonomous routines, and the drivers don’t have time to practice? I’ve seen this type of thing occur many times at work, and it always delays projects. Mechanical engineers sometimes think the deadline for the project is their deadline and don’t leave any time for integration and debug.

Say you have a hypothetical team with very few resources, so they can only go to one regional and they can’t afford to build two robots. Let’s say the mechanical part of the team decides the shooter doesn’t need to be completed prior to bag-and-tag. They build a prototype shooter, but they never put it on a robot. The plan is to work on the shooter for a few weeks and attach it at the regional. It won’t go onto a robot until practice day, and the team will miss much of the practice session working on the build.

System integration is the hardest part of engineering. In the real world the game balls have different densities, so your precisely controlled mechanical system is not so precise. In the real world things rarely work the first time and you have to study the problem to decide if it is mechanical, electrical, or software. This is why teams should be doing system integration throughout the season. Don’t wait until the end to test the system or you may quickly run out of time.

I don’t believe a team with low resources can decide to just finish 30 pounds of the robot after bag-and-tag and truly be successful (OK, a low percentage will). These types of teams need to finish early giving the electrical team time to work out wiring issues, the software team time to test code and write autonomous modes, and the entire team time to make an objective decision about the drivers. You can build the most perfect mechanical system in the world, but without electronics, software, and drivers it will just sit there. Yes, we couldn’t do it without the mechanical team either.

**Remember there are 3 robots on every alliance. **Many alliances will likely pick one defender/feeder robot, and many will look for a good balancer. You don’t have to have a way to score balls. Make a basic feeder before bag-and-tag. Give your drivers plenty of time to practice. If you show yourself to be a great defender that doesn’t get penalties at the regional, you will likely get picked.

17

I don’t think anyone here is advising this as a primary strategy. It is a backup when in desperate straits and running out of time.

18

Then why not take the Apollo 13 approach? “Let’s look at this thing from a… um, from a standpoint of status. What do we got on the spacecraft that’s good?” Find a strategy that will work for the robot you have.

Sacrificing the practice time on Thursday for a high risk addition is rarely going to work in the scenario I described. There are three robots on every alliance.

19

Hehe, it is sort of a relief knowing that the rookie teams from the likes of Andy Baker, Aren Hill, and Dr. Joe all still have a bunch of work to do.

Wish we were close to being as far as you are Andy. As for Aren’s bot - I can’t even imagine us being close to where we are if we were building what he made, I think right now we’re pretty close to where Dr. Joe is.

That said, Dr. Joe, if you guys need anything machined or fabricated let some of the guys in the area know (I’m sure Brandon Holley would be willing to help out).

20

Let’s say there’s 3 potential subsystems, a drivetrain and two scoring mechanisms. The drivetrain and one scoring mechanism are completed. Are you suggesting that they do not work on a second scoring mechanism? I’m of the opinion that it couldn’t hurt and if it doesn’t work at the competition, as you’ve suggested is very likely, they can just take it off. Yes, they may sacrifice practice time, but if the addition does work, it could double their point output. A team that expects to win in qualification can’t rely on playing defence because they will have matches paired with robots that can’t score.

Yes, it is a high-risk situation. But it’s also high-reward and it seems most people in this thread support taking the chance.