It is impossible... ...until there is no other way...

This is sort of a general life lesson thread. So… take a break from the discussions of this or that rule or which refs missed what call, put up your feet and think of an example from your own life.

One of the most important lessons that FIRST keeps teaching me over and over is that in so many parts of our lives, we KNOW something is impossible so we just don’t really give a solution our full concentration.

For example, this past weekend our robot needed a bit more torque in high gear. We had enough in low, but high gear was a bit dicey turning with our grippy wheels. But… I had decided to go direct drive to one of our wheels with an (excellent I might add) AndyMark Super Shifter. So… …there was nothing to be done…

Skip to the first practice match of our most recent regional. I asked our driver to try going over the bump at a 45 degree angle rather than taking it on straight on. The robot really went over nicely but when we got back to the pits, I saw that we’d bent the output axle of the AndyMark (the robot designers fault, not the Super Shifter – hitting the ground at an oblique angle on one wheel kind of put a hit to our drive wheel that I hadn’t fully thought out). But… …there was nothing to be done…

Skip to the first match of the finals. We had a great run in the seeding matches and by a combination of skill and good fortune we were #4 Seed. As we got ready for the first Qtr Final match, and we went through our preflight check, the right gearbox was not working well in low gear – pulling way too much current. Bad luck but at least we still had high gear and besides… …there was nothing to be done…

We got slaughtered in our first match because of our toxic combination of poor turning in high and our inability to go into low (well that plus the other team played well). I was certain we were going to get slaughtered again if we didn’t do SOMETHING.

Then it hit me. The stress on the gearbox probably just skewed the gearbox shafts just enough to cause a bind in one of the gear pairs. There was no reason to think that they wouldn’t re-align if I loosened a few bolts wacked the case and tightened them again. A hectic bit of wrench work later and we were ready to roll.

We lost a close 2nd Qtr Final match and exited the tourney. But at least we went out swinging.

It was on the way home from the competition that it REALLY hit me.

I was thinking about “after glow” competitions and our teams chances of doing well at them. The horror of not having enough torque in high gear and the possibility that my poor design choices could cause us to freeze up at random moments in a match hit me full force. Now I HAD to fix those darn gearbox problems.

And suddenly, I thought of a simple fix that I could have implemented at the regional had I not KNOWN that a fix was impossible. With an hour of work once we have our robot back, we’ll have our chassis running better than ever and immune to these two scourges.

This story got a bit longer than I wanted, but I think that it is a typical story not just in FIRST circles but many many parts of our lives.

I can think of 10’s of examples from FIRST alone where things were IMPOSSIBLE until I just HAD to figure out a way to make them possible.

How many of you have had similar lessons taught to you by FIRST?

Do tell.

Joe J.

So this year I just KNEW that our robot would be over weight. It always is. But after 5 weeks… The only thing I could still come up with was drilling holes. We needed everything to much. About 2 hours after getting it out of the bag, it hit me. Within 30 seconds I designed the kicker to work with 2 pistons instead of 3. We weighed ourselves, 2 pounds over. :eek: A lot less than I expected. Pulled off a piston, 119! Something that I just KNEW would be impossible, was fixed by simply looking at it with a fresh mind.

Another thing I would say is in the design. Does anyone else have times when they sit there for hours thinking about something and how to fix this one little problem, and then someone walks in and tells you the solution? I know that has happened to me many times. I am always shocked at how simple an impossible solution is.

-Rion

You have brought up two great tools for engineers. A fresh mind and fresh eyes. It is possible to work on a problem too hard. Take a break. Work on some other aspect of the project, or just get some sleep. The engineering mind seems to have a background task that is working on problems without the conscious mind knowing about it. I kept a pad and pencil by my bed to write down solutions that would come to me in my sleep. Often going back to a problem a few hours or day later somehow makes the problem easier. Fresh eyes come in two parts. Often just articulating the problem seems to generate the solution. I don’t know how many times I would be halfway through explaining a problem when I’d say “Never mind, I know what to do”. Or when I was done, the other engineer would say “Can’t you just …”
Somewhat on the same topic, 40+ years ago my first engineering boss told me that “Most great inventions come from people that are too dumb to know that it can’t be done”.

Back in 2006, our team’s rookie year, I remember walking onto our construction compound on the Sunday before ship, happy that our robot was working and in need of few touch-ups. When I got there, I was informed by the members who were already there that our robot had been weighed for the first time.

“You’re joking right? 40 pounds?” :eek:

After pulling the battery off the bot we still had another 30 pounds to shave. Two days before ship, this is what our robot looked like: http://www.chiefdelphi.com/media/photos/23078

Two days, thousands of holes, and a few removed components later, we had this: http://www.chiefdelphi.com/media/photos/23240

I sure thought that shaving 20% of our robot’s weight in 48 hours was impossible, but our team came together calmly and strongly, and we got it done. Though we had to sacrifice some components (namely, 4wd became 2wd), we still had a solid robot which did the job we designed it to do.

You cannot believe how shocked we all were when we ended up WINNING the 2006 UC David Regional competition. After some experience in Arizona with exploding rollers and bent frame members, we managed to pull together and succeed in our second event. Not only that, but we were the 3rd picking alliance! And it was through our team unity (and a VERY lengthy scouting meeting) that we selected two machines which perfectly complemented our robot. To this day, that will always be my favorite FIRST experience. Simply put, the adversity that we had to overcome throughout the season paid off more than I could have ever imagined. Just remember that even the impossible is simply another challenge waiting to be overcome!

I had a similar experience when working on autonomous code in 2008. We had the robot running laps around the practice field just fine, using encoders for distance and a gyro for turns. We had SuperShifters on the robot. Our turn loop wasn’t very well-tuned, so we had to turn corners in first gear while going forward in second gear.

So the robot would go across the field in second gear, shift to first, turn left 90 degrees, traverse the field (still in first) turn left 90 degrees, shift to second, go across the field…etc until time ran out.

The problem is, the second turn would always overshoot by 10-20 degrees. We had no idea why this was occurring. We looked through the code and verified that the code being called for the first turn was exactly the same as the code being called for the second turn. Both turns took place in first gear, both were 90 degrees using the same feedback loop, and both were followed immediately by a straight section. We spent hours working on this, but couldn’t figure out why the turns should be any different.

Then, we asked a mechanical mentor to watch autonomous run. He immediately understood the problem: “you’re shifting into second gear immediately after that second turn. It takes about a half-revolution for the gears to engage after a shift.”

Swapping the position of two lines of code, to stop the motors before shifting gears, solved the problem.

I can’t resist… We so thought we had you guys beat that year at Davis. Lesson learned… always hot glue pwm cables in so that don’t wiggle out. (And outback treads can result in massive amounts of current draw that will eventually melt wires)

Back to the topic… This year we spent several weeks building a complex springloaded kicker mechanism (which kinda worked) only to abandon it in favor of a kicker driven by a toughbox that we put together in just one day. So incredibly simple, I wished we could have some of that time back. There are some very elegant solutions to problems, but way to often the best solution is just a simple one.

I have two, both of which are fresh in my mind from last weekend.

Sometime Friday afternoon my Driver Begins to complain about the left side of the drive, he says it feels “Funny”. We get the robot off the field and look at the drive, and nothing appeared to be wrong, I turned it by hand and there was no binding, no noise, and it just felt okay. So, I told him we’ll worry about it if it becomes serious. Three or Four Matches go by and we notice our Autonomous Mode is drifting hard towards the side in question, and it almost looks like there’s some sort of mechanical problem with the drive, and each time I spin it and it feels okay, so I’m stumped and just tell him to Drive through it, which he did very well. Fast forward to Lunch Break before Eliminations, when one of the other mentors tells us that one of the PWMs to the left side of the drive was unplugged… We plugged it in and it worked perfect.

Match 64 was to be our final Qualifying match, and it was with 103, and I’ve been dying to play alongside 103 for years. So the match starts, our Autonomous goes and the robot stops like usual, and then a little bit of smoke starts coming from the robot. A little bit of smoke turns into a lot of smoke, at which point the match is called. I ran onto the field without hesitation and turned the robot off and open the cover as more smoke came out. We began frantically looking for the problem (still on the field) and I see that two of our PWM Cables have shorted together which caused them to burn the insulation off of the wires. Luckily, due to the setup of Philly, our head pit guy (aka Pitmaster) was standing within yelling distance of the field, and I got him to run back to the pits and grab a handful of PWMs. I rewired the bot, in the most quick and nasty fashion I could, and we went on to play the match. We won the match 5 to 3. Most people saw the smoke and figured that our robot was toast, but some quick thinking saved it, and a win.

Heh, this reminds me once again of 2008. We wanted to make the robot maintain a straight heading in autonomous mode. So I added a gyro and a PI loop, which worked very well. So well, in fact, that we decided to use it in teleop as well. It did an excellent job of keeping our four-CIM, six-wheel drive train going in the right direction.

So we went through VCU with this drive system, and for the most part, it worked wonderfully. There was just one problem: our driver kept complaining that the drive was slower than usual. He said it didn’t seem as powerful as it used to be. When asked if he had any difficulty turning, he said no: it just didn’t feel as powerful as before. We figured the motors and bearings were just wearing down and kept playing without any changes. We made it to the quarter-finals, I believe.

Fast-forward to Chesapeake, and we had completely forgotten about the drive train. That is, until we were testing some sort of autonomous routine that required me to print out the actual voltages the PI drive loop was sending to the motors. I instantly knew something was wrong: the software was sending half the power to the right motors that it was sending to the left motors, and yet the robot was driving perfectly straight! We investigated the problem, and found that one of the left motors was completely dead. No one knows how long it hadn’t been working; it was probably dead before ship. It could even have been dead since before we installed it in the robot! The PI loop was so good at keeping the robot straight, it was able to compensate for a dead motor well enough to make the problem virtually invisible. Unless, of course, we tried to push another robot with all four of its motors working.

So we were weighing our robot before re-bagging it. We had built our hanger and upper superstructure separate and easily detachable so that we could keep working on the hanger as part of the withholding allowance.

Anywho, so we had apparently already weighed the upper segment and it had come in at like 44 lbs. We put the bottom half on the scale and it comes back at 80 lbs. So naturally, what with it being only a day or two before competition, everyone is less than happy. There were a bunch of bouncing suggestions, but quite frankly 4 lbs is quite holes to drill.

While everyone is proposing different ideas I went over to the upper section with a few of the other mentors. We figured that it was worth a shot weighing it again, it’d have been a big shame if the robot were torn apart over a mistaken weight. To everyone’s surprise and relief the upper half had managed an impressive dieting program over the past few days. The scale read it in at 36 lbs. We’re still not quite sure how the whole thing happened, but we certainly aren’t complaining.

When it was inspected and weighed at competitions it came in at 120 lbs exact. Gotta love those sort of numbers :slight_smile:

Oh man, your win in that match was amazing. I have been wondering for quite a while now why your robot went up in smoke. I was also surprised to see that the E-Stop button didn’t work (I have this memory of your driver jamming it and yelling at the refs…)

Thanks! I was actually the one who hit the E-Stop (Nick, the driver may have hit it after me - I’m sure it was hit more than once), it’s the first time I’ve ever had the pleasure of doing so since I first got involved back in 2005. In retrospect, hitting the E-Stop was a bit pointless, because the only way to get the smoke to stop was to turn the robot’s power off - but at the time it seemed like the correct action.

I’m still waiting for Pictures of the smoke cloud to surface… :smiley:

looks at title
I cite Clarke’s Three Laws of Prediction (couldn’t resist)

  1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

  2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
  3. Any sufficiently advanced technology is indistinguishable from magic.