Philosophies on design reuse

[jvriezen]

Numerous times the topic of re-using something fabricated from a previous year (we often have had a non-functional robot by the next build season and reuse COTS components) there is always a student who says something like

"Why can't we just re-use the bumper fabric with our team numbers already on them, how will 'they' know ?"

I then proceed to explain to them (or get them to realize) that 'they' are (in part) the judges and inspectors at the competition and did they notice that one of their mentors is a Lead Robot inspector and two other mentors are Inspectors?

Its hard to get the notion across that there really is no 'they' and 'us'-- we are all part of the big FRC family.

[ajlapp]

In all seriousness, even if you had a part that did not change at all there are endless ways you could change the design so it's not being reused. You could change the CAM file that generates the G-code to run the machine. You could make trivial dimension changes. You could issue a new drawing revision for some minor callout. You could change radii used on pockets/edges. The list goes on and on.

It's really a silly rule because FIRST is unwilling and probably more importantly unable to outline what qualifies as changing the design enough for them to be OK with it. It's also silly because anything you would re-use exactly as it was from the year before/offseason/etc is most likely a completely trivial part that would gain you no competitive advantage by designing up front.

The rule quite obviously exists to prevent you from designing an entire system of your robot before kickoff and then implementing it immediately, but you really can't design a system that can be used wholesale with no changes, because you have no idea what it needs to do.

Exactly.

[s1900ahon]

Originally Posted by BigJ

I would argue that CAD designs "made public" should also count as COTS.

I agree with your assertion in principle simply because it is consistent, but let's be honest, posting software for others to use is much more beneficial to others than posting a mechanical CAD design.

The software may be used by almost anyone; even if it is posted for a language/environment your team does not use. Algorithms and data structures can be translated. Moreover, even if the software runs on a platform other than the cRIO, the platform is very likely available to you (*).

The benefit to other teams if you post your CAD files is predicated on the other teams having access to the same manufacturing facilities as yours. A design of a custom chassis that requires access to a laser cutter, a turret punch, and a CNC brake does not help most other teams. In fact, I'd go as far as to say that posting the CAD design largely benefits the team posting the design since they'd be able to re-use it and others with similar capabilities would do their own thing.

-Scott

(*) If the software runs on a device that is a custom circuit, the rules
that the custom circuit must be fabricated during the build season (assuming the Gerbers, schematics, and other files were posted to make them COTS too). The lead times for affordable PCB manufacture and assembly make this difficult, and that practicality leads implementation towards COTS computing platforms such as the Raspberry PI, BeagleBone, Arduino, etc.

[BigJ]

Originally Posted by s1900ahon

I agree with your assertion in principle simply because it is consistent, but let's be honest, posting software for others to use is much more beneficial to others than posting a mechanical CAD design.

The software may be used by almost anyone; even if it is posted for a language/environment your team does not use. Algorithms and data structures can be translated. Moreover, even if the software runs on a platform other than the cRIO, the platform is very likely available to you (*).

The benefit to other teams if you post your CAD files is predicated on the other teams having access to the same manufacturing facilities as yours. A design of a custom chassis that requires access to a laser cutter, a turret punch, and a CNC brake does not help most other teams. In fact, I'd go as far as to say that posting the CAD design largely benefits the team posting the design since they'd be able to re-use it and others with similar capabilities would do their own thing.

-Scott

(*) If the software runs on a device that is a custom circuit, the rules
that the custom circuit must be fabricated during the build season (assuming the Gerbers, schematics, and other files were posted to make them COTS too). The lead times for affordable PCB manufacture and assembly make this difficult, and that practicality leads implementation towards COTS computing platforms such as the Raspberry PI, BeagleBone, Arduino, etc.

I agree. But in accordance with your statement, having, say, 254's codebase doesn't really help me directly unless I configure a system exactly like theirs with the same sensors, etc. However, it does give me something entertaining to look at and which to draw ideas from for the next season, much like openly distributed CAD designs

I will concede that replicating a sensor setup is a bit easier than replciating an entire machine shop for any team that wished to go the carbon copy route, although I don't know why any team would.

[s1900ahon]

Originally Posted by BigJ

I agree...<snip>... However, it does give me something entertaining to look at and which to draw ideas from for the next season, much like openly distributed CAD designs

Agreed. I learn quite a bit each year from the mechanical pics, posts, and designs shared by others (my degree is in EE with a minor in CS).

And while I "ooh" and "ah" as I look through the latest 148 design each year, I know that the sharing of their SolidWorks files won't affect my team as directly as someone who posts software.

But, this is the nature of the beast. That being said, I believe that sharing a design file, regardless of the contents, should allow the contents to be considered COTS. It is just consistent and simple, despite my view of the difference in global utility.

[Jon Stratis]

This is a bit of a tough area to come up with a hard "Rule" on - there's an entire spectrum of what many would consider "reuse", and no obvious gap that would separate acceptable from non-acceptable.

First, lets cover the obvious - If you build something before the season starts, you can't use it. Period. End of story (in 2012, at least... we need to wait a few days to make sure things haven't changed for this year!). All parts on the robot must have actually been built this season.

Now, what about the not-so-obvious? Let me give you some examples.

In 2008 we used an elevator. That elevator was held together using small plates with bearings on either side. The plate got bolted to one section of the elevator, and the bearings would then ride up and down the next section. It worked out well for us, and in 2011 we did almost exactly the same thing. I say almost, because the elevators were quite different. For the part that matters here, 2008 used 1x2 box tubing, 2011 used 1x1 box tubing. So, our plates were 1" smaller in 2011. Reuse of a design concept? Yes. Reuse of a design? No. There were differences (although the difference is minimal), and there was no CAD or specific design tolerances - we just built it and eyeballed where the holes should be each time.

How about another example... in 3 of the past 6 years we've used a 6 wheel, drop center design. Every time we used KoP wheels in the middle, with Omni wheels on the corners. They were all chained together, and chains run up to the gearbox included in the KoP for that particular year. We ended up with something that was virtually identical each year. Reuse of a design concept? Definitely. Reuse of a design? Technically, no. There was no specific design we reused. It was built with the KoP chassis and parts given to us (except for the omni wheels), which meant that things naturally turned out pretty similar. There are only so many ways to chain together a pair of wheels!

One last example. This year, you want to use CIMple boxes instead of the provided ToughBox Mini's. So, you pull them off last year's robot and stick them on. Reuse of a concept? Not really. Reuse of a design? Again, not really... However, the CIMple boxes, if I remember right, come unassembled. So, reusing them in this way is technically illegal, as they aren't in their COTS condition (you would have to disassemble them and reassemble for it to be legal). For my team, we often reuse gear boxes from one year to the next (especially BaneBots ones). While you can approach it and think "taking them apart and putting them back together to meet the technical definition of the rule sucks", it's much better to think "We should take them apart, clean them, and understand what sort of wear goes on during the season. do we need to replace any gears? What happened to the grease that was in the gearbox, and why does it look nasty now?". It turns into a learning experience where the students not only get the same experience they would if purchased new, but additional experience they wouldn't have gotten otherwise.


For me personally, I draw the line for my team by asking the question "what did you learn doing that?" If you can say the students learned something the first time it was built (off-season or previous year) that wasn't learned re-building it, then you have a problem. Many times, if we want to "reuse" a previous design, we'll look at it, figure out the good and the bad, and look for ways to improve it.

This off-season, our team built 2 arms that work in different ways on 2 vex robots we threw together (we've never built an arm before). If we decide to build a robot with an arm once the game is released, you can bet those two arms will be front and center to aid in our design, and we might end up with something that looks pretty similar to one or the other.

[IKE]

Originally Posted by ToddF

For the first time, our team has managed to do some serious development work during the off-season. We have debated internally about how best to utilize what we have learned while staying both within the letter and the spirit of the design reuse rules. ....

ToddF,
I concur with others on congratulations on doing some off-season work to make your team better.
While the rule seems pretty clear cut, some of the blue box examples make it otherwise.
Also keep in mind that FIRST sponsors BETA Test teams to test the software. Some things they learn will get rolled out to other teams, but not every detail.

I think the strong feelings that differ on this topic may stem from a difference between Academia and Corporate world. In academia, if you use someone else’s thoughts to explain a position without referencing it, then you are plagiarizing. This position puts an interesting emphasis on original work.
Often on engineering projects, you are requested to use "Lessons Learned", re-use internal designs that have been validated, or attempt "Commonality".

When these two cultures read the same rule, they have slightly different interpretations. I would almost guarantee you that at certain regionals, if you did a big sales pitch in the pits about "commonality", "design libraries", and using TDS (Toyota Development System) principles of reusing reliable designs you could likely win a Quality of Industrial Design award. Winning awards doesn't make it right, but it does speak to the disconnect of some views on this subject, and what industry professionals (often the biggest chunk of Judges) would love for students to be able to bring to the table.

One of my favorite students to go through our program was obsessed with originality his first two years. He designed some really neat but fairly impractical designs. We talked to him about benchmarking and paying attention to good design details. Having Form follow Useful Function (most of his early designs were more about unique Form to create novel function). The stuff he churns out now is really impressive. On the surface it may look like something you have seen before, but the details are really impressive.

Per "apalard's" post about re-using, to my knowledge, the closest we came to re-using a major system was the chassis project of 2010 and our competition chassis of 2011. They were really close but arguably different in many, many, many aspects. That being said, our 2006, 2007, 2008 chassis were all 6x6 sheet metal designs with dead axles and shiftable transmissions. The architectures were similar (especial 2007 and 2008) but all the design details were different.

Ultimately, your team will have to figure out where their comfort is.

Oh, and I would recommend not doing a swerve drive for the first time during the build season. FYSS (First Year Swerve Syndrome) is a well documented condition that has the symptoms of early delusions of grandeur followed by countless headaches, sleeplessness, depression, irritability, and in some cases I have seen it be fatal (to a team).

[tim-tim]

You should always be able to make the design better.

We view the off-season as a research and development period. We gain a lot in the proof of concept categories. Almost none of our work would be competiton worthy, for reasons such as material selection, manufacturing techniques, weight, etc.

Look at your concepts/designs and improve them. You and your team probably learned a lot from the experience of the off-season; now put those lessons learned to work.

[BigJ]

I'm not entirely sure why it hasn't yet, but designs should really move over the the software reuse rules with the caveat that no physical fabrication used on the competition robot is done prior to kickoff.

The software reuse rules are (generally) that you may reuse your software/algorithms as long as they are openly available to others.

(Offtopic: I think you intended to edit your original post but made a new topic instead )