Advice On Problem Anticipation

[Daniel Krastev]

Hi,

I made this thread in order to hold a public gathering to discuss problems that may happen during the competition, and ways we can solve them.

For instance,

1) What happens when you open the robot at regionals, and you find a supporting frame damaged? What would the suggested, most efficient solution be?
-Can you use a hammer, or a mallet in order to straighten out the metal?
-Do you have to replace the whole piece? ,etc.

2) If you have a shooting mechanism, what happens if the motor/servo on it gets damaged? How would you be able to replace the motor if it is in a hard to reach spot?
-Do you have to take everything apart in order to replace it?

3) What happens if you know a screw fell off, but you cannot find the exact place it belonged to in the first place?

Keep up the questions, and try to suggest answers so that we be well prepared during regionals.

Thanks!

[EricH]

I may have some answers...

1) Depends on what the piece is and how it's attached. If it's welded, hammer. If bolted, replace. These are the most likely items.

2) If a motor is hard to reach, you might consider redesigning before the end of build. That's a little late now, but keep it in mind. Your best bet is to have a removable shield.

3) Firefly effect. Somebody dropped that one weeks ago... Which reminds me, how full are the bowls of hardware at the end of the events this year? About like normal?

[Daniel Krastev]

Thanks for the answer. Do you think you can give me more advice on any common problems? Thanks.

[Jeffy]

One of our biggest things this year was- "How do you tighten that belt/chain?"

Another- How can we replace the foam on a roller?

Just a piece of advice- There is no problem that cannot be solved. Don't get frustrated, everyones robot breaks at times.

[EricH]

Originally Posted by Daniel Krastev

Thanks for the answer. Do you think you can give me more advice on any common problems? Thanks.

Murphy's Law is in effect. Plan accordingly.

In all seriousness, you can expect to take a pounding. Stuff will be damaged. You'll want to evaluate what happens if something breaks as a what-if: What if our drivetrain throws a chain? What do we need to fix that? What if our shooter breaks? What do we need to fix that?

Make sure your PS knows the rules pertaining to penalties very, very well; if you saw the discussions from the aftermath of Week 1, more penalties came from there than from anywhere else.

[Killraine]

If it were still build season, I would say that you need to design everything knowing how you will fix it when it breaks.

At this point, I would recommend getting your pit team together and running through your robot top to bottom looking for possible places to expect problems. This can help to save time in the pits and ensure you don't put a non-functioning robot on the playing field.

On a related note, a pre-match checklist is another great idea to make sure you do your best. Questions like "Is our battery fully charged?" and "Did we reconnect the Linksys after we loaded the new programming?" can be lifesavers.

In the end, something unexpected will happen and the best you can do is have as many tools, spare parts, and raw materials available to your team to be able to address them when they come up. As in all things, knowledge is power and preparation is your best friend when it comes to these issues.

[MrForbes]

If you're having wierd behavior problems with the robot, first thing to do is check battery voltage! If you put in a freshly charged battery, and it still shows voltage dropping strangely, tighten all the connections in the main battery circuit (those big fat black and red wires that connect the battery to the main breaker, and the PD panel). Be very careful not to overtighten the nuts on the PD.

Have spare parts, including motors, transmissions, chain master links, bolts, nuts, screws, rivets, etc. in whatever sizes were used on the robot. Also have some extra hardware, such as some longer bolts and stuff, and extra structural material like aluminum angle, sheet lexan, etc. to implement last minute design changes.

After you've been thru a few seasons, you will have learned a LOT about how NOT to design and build robots! but every year new things will cause problems, and increase your knowlege.

Most important thing is to remember that every team there will help you, if asked!

[Vikesrock]

Originally Posted by Daniel Krastev

Thanks for the answer. Do you think you can give me more advice on any common problems? Thanks.

Here's my opinion. Each FRC robot is unique, and each has a large number of parts. Other than control system issues the problems that teams experience with their specific robots are usually widely varying and the solutions to any common problems likely depend on the specific design.

My advice would be to identify any parts of your robot that you think you may have trouble with and determine how you would work on/fix that part. I also recommend that you bring a variety of tools and materials to work on problems that you did not foresee.

My final piece of advice is don't be afraid to ask for help. If you run into an issue or problem you don't know how to fix, many of the veteran teams will be more than willing to lend a hand if you ask.

[Killraine]

Oh and when things do break, PLEASE do not be afraid to go to other teams for help. Put out an announcement in the pits or send a representative over to a veteran team. Most teams will be more than willing to help you as much as they can. Don't be afraid to ask though, we only bite playfully (like puppies.)

[Dick Linn]

One thing we found useful over the years was to have a maintenance and inspection checklist that was followed immediately after every match. Besides the obvious (swap for a fully charged battery ...) it included visual checks for loose or bent components, chain tension/lubrication, alignment and so forth. Sometimes that can prevent problems or give you more time to deal with them before they become critical.

As for replacing parts, we gradually learned to design and build with accessibility in mind from the start. That comes with experience.

[Alexa Stott]

As many people already noted, a pre-match checklist is essential. A few ideas for what should be on there:
1. All electrical connections secure (no lose pwms, wireless bridge plugged in, etc.)
2. Newly charged battery. When in doubt, change it out.
3. ALWAYS test any new code you dump in before you go out for a match. Debugging during a match is never fun.
4. At the NJ Regional, teams were given special instructions on how to properly set up their DS and robots before each match. Follow these: it makes everything move much more quickly.
5. Check that all bolts are properly secured, including those attached to your bumpers. Getting a penalty for leaving excessive parts on the field or extending outside your footprint is silly if they could've been prevented by do a pre-match check.
6. Make sure your payload specialist knows ALL the rules, especially those regarding the super cells/empty cells. They cost alliances a lot of points.
7. Do a "full system check" before you leave the pits to make sure everything is working properly.

That's about all the "generic" things I can think about for now.

[Al Skierkiewicz]

I guess that this is the time to restate my Murphy's Law corollary...
Anything that can go wrong will go wrong,
in the last match on Einstein. Plan for it.
Make things easy to replace, rewire, repair with minimal tools if you don't have a spare. Check everything over twice by two separate people at two separate times before each match. Don't let rookie team members charge your batteries. Use your nose, it is the third most important tool in your toolbox after eyes and ears.
Finally another Murphy wisdom, test it and force it. If it breaks, it needed replacing anyway.

[Tom Line]

These answers are going to vary largely depending on your robot, however, we have a pretty solid system modeled after how we set up spares for Industrial machines.

The only protection you can have against failure is preparation.

End up having spares of all fasteners, bushing, bearings, and other COTS.
Have multiple spares of any item that you deem is likely to break.
Have single spares of any item that might break, but probably won't.
Have single spares of any item that is very hard to make.
Finally, evaluate your robot for any critical components. You absolutely MUST have spares for these, and if any are likely to break, you should have multiple spares.

Evaluate the tools you will need in your pit to fix anything on your robot - including a major structural failure. Spare aluminum tubing in multiple sizes is an absolute must for quick bolt-on fixes and reinforcement.

Have your pit crew train ahead of time - have them sit for an hour with the robot and discuss how to fix and replace every item on it in the best and quickest manner.

[Dad1279]

I've found it nearly impossible to predict failures. We try to keep our robot as modular as possible, and try not to burry fasteners and mechanisms so they are hard to maintain. For example, our elevator & roller assembly is removable with just 4 bolts and a few wires.

Make sub-assemblies easy to maintain. For example, our first rollers had 1/4" bolts threaded into both ends. Changing a roller or a belt would take 10 minutes. Now we have a 1/4" bronze bushing in each roller, riding on a 1/4" rod, with collars. Now to maintain the roller, just pop a collar and pull out the rod.

Read: FRC Suggestions, Rev A - the document formally known as FRC Guidelines, Tips, and Good Practices http://www.usfirst.org/uploadedFiles...%20Rev%20A.pdf

Make bumpers easily removable.

Keep the robot Simple (KISS) and it will be reliable.

Chains will stretch/break-in. Allow for a tensioning system on any chains longer that a few inches.