And furthermore - This is a premature optimization for 99.9%[1] of teams, the development effort and resources needed to see performance gains from this would be better spent on iterating manipulators, driver practice, or software development.
Are there benefits yes, but to paint it as “the future of FRC drives” like it is some inevitability is marketing crap designed to sell gearboxes/motors.
[1] Yes, I mean there’s maybe 3 teams that are at the point where the 775Pro drive compared to a CIM drive is the remaining performance gains for them.
Andrew, there’s a lot of teams for whom switching to a 775pro drivetrain is as simple as buying a different gearbox, setting a current limit on the Talon SRXs they were going to use anyway, and making a little more room for electronics on the robot. That’s not a lot of development time or resources.
I never said there would be. I just left a team in the situation I just described, and joined another team in that situation too. I wouldn’t recommend a 775pro drivetrain to either of them, because I don’t see much, if any, benefit. But the claim that the cost of development is a major reason to avoid a 775pro drivetrain is simply a bad argument. Mostly because of the gearboxes AM just released.
Through offering a COTS solution for 775pro gearboxes, AndyMark is significantly reducing the required development necessary for teams to implement a 775pro drivetrain. As AndyMark and others use the products, they will inevitably develop resources that will help to further lower the barrier to entry. It’s not hard to imagine a point in time when the barrier to entry is low enough that a majority of teams can successfully pull off a 775pro drivetrain.
I imagine that the same basic thing happened when mecanum drives were used for FRC. At first it would’ve required a crazy amount of time and effort to pull off (for a questionable competitive advantage at best), but as more resources were developed, it quickly became one of the most popular drivetrain options for FRC.
I’m a believer that 775pro drivetrains will become fairly common in the coming years. I would definitely not reccomend it for my team until the resources have expanded, but down the road it’s something we’ll look into.
Edit: This isn’t to say that the benefits of 775pro drivtrains have been definitively proven, but on the surface at least saving weight and having a similar performance looks appealing.
I have been an engineer for a long time, and cannot recall any situation in which a proposed improvement turned out to be as easy as it first appeared.
The best example of an all-775Pro drive train that I saw this year was PWNAGE (2451). They put a heck of a lot of work into it, and into the rest of their robot.
The best example of an all-MiniCIM drive train that I saw this year was Blackhawk (3310). They put a heck of a lot of work into the rest of their robot. The drivetrain is ‘just’ good execution based on fundamentals and COTS components that were well understood, by them if not by many other teams.
It is hard to say that one of those robots is a lot better than the other, but is is clear that Blackhawk had more time to focus on scoring.
Can anyone who competed with/against both of these teams comment on their relative quickness? From what I saw they are both darn quick.
This quote is really all most teams need to know. I’ve seen 11 years worth of CIM drivetrains. That’s 22 regional competitions, 6 champs, and countless off-season competitions. I’ve never seen a CIM motor burn out. I have, however, witnessed 775’s, 550’s, FP, and those stupid minibot motors burn out. What do they have in common? All are air-cooled motors. In fact, I’ve seen air-cooled motors burn out every single year. One year, my team even smoked on live TV for a local morning show!
The benefit of smaller packaging and an extra 5 lbs isn’t nearly worth the risk. The drive train is one of the 2 absolutely critical parts of a robot, the other being the control system. With those two items functional, your robot is just a paperweight sitting on the field.
I won’t go so far as to say my team would not pick another team with a 775 drive… but there would be some serious discussions with that team about their drivetrain and the design process that went into it before we did.
First of all, let me say that I will be very surprised if 3946 does a 775 drive train in 2018, though that has more to do with machining and time constraints than the fairly easily mitigated risks of low thermal mass. With the advent of COTS 775 drive-tough gearboxes, I certainly see 775 drives assuming an increasing proportion of FRC drive market share, though I doubt the CIM drive train will go away as long as CIMs continue to be manufactured and legal.
Here’s a quantifiable benefit no one has mentioned yet - cooling the motors off. If you’re in back-to-back eliminations and need to cool your motors down, with [mini-]CIMs you’re down to methods which are slow, ineffective, risky, dangerous, or some combination. (I’m referring to cooling the rotor, not the case.) Swapping all the motors may be your best bet, but how many teams can do that between finals matches? With a 775 drivetrain, you can put the robot on blocks, give the motors 12 volts, and blow the heat right out.
357 brought the [strike] Joker [/strike] Jester Drive into FRC in, I’m fairly certain 2005 but I know it was at least 2006 as they are in the 2006 Behind the Design book (on the cover in fact, but there’s a whole section on the process). When they did this they had to mold their own rollers and machine their own wheels. Yes, the investment was incredibly high. A few years later (my memory is telling me 2007 time frame, I know they were COTS in 2008 but I can’t recall if they were in 2007 and 357’s profile in the 2007 book has their custom wheels/rollers again) AM started producing them and selling them. They were viewed as an alternative to swerve or kiwi. Nobody was selling it as “the future of drivetrains” merely as an option to achieve a specific type of motion. They then sold like hotcakes and people decided they were “best period drivetrain period ever period” [1].
However, the comparison to mecanum or even omni wheel development and democratization is tenuous at best in my opinion due to the fact that omnis and mecanums were drastic rethinking of how drivetrains could move whereas the 775Pro drives are, at best, incremental improvements [2] that come with an additional cost (in terms of risk) that is severely being downplayed by a manufacturer with the potential perceived intent [3] of selling more units of a new product line.
So no, I’m not objecting to 775Pro drives [4] I’m objecting to a representative of a manufacturer hocking their own products as some revolutionary thing when it’s an incremental improvement at best and the effort spent there could be better spent by the overwhelming majority of teams.
And before someone asks why I didn’t complain when Paul said that MiniCims were better for drive applications - he caveated the crap out of it AND he had data. Nathan here has literally his opinion and is presenting it as fact. When an individual does that I get irked [5] but when a representative of a company does it I get disturbed. I’ve always felt that AndyMark has the best interests of teams at heart. I want to keep thinking that. But statements like I objected to make that VERY hard.
[1] these people being, of course, idiots who don’t understand design tradeoffs and that there cannot be one drive to rule them all.
[2] I’m not even sold on this
[3] i.e. someone could read it as
[4] I’ll probably be involved in running one… again
[5] Unless it’s Ether. Dude’s opinions are pretty much evidence and his evidence is an unchangeable law of the universe.
Everything else is more or less accurate. I believe they ran these in 2005 for the first time. 2006 are the ones everyone remembers because of the Behind the Design book & they were absolutely massive - mainly because they made a wheelchair that used the same wheels for a separate project. https://www.chiefdelphi.com/media/photos/25712
One last thing to note - 357 stopped using mecanums in 2014 two years before the team disbanded. There was some ‘we basically brought these into FRC so we have to keep using them’ but eventually that wore off and they didn’t see the benefits in continuing to make the wheels when they could buy a set for much less time, effort & money. Once everyone can do something the cool factor wears off a bit.
Sure, the motors that get far hotter might cool down sooner than the motors that don’t likely need to be cooled down at all… Unsure what the benefit is here?
I agree with the first part. The extra benefit there is that it’s the CIMs which are more likely to get hot when running on a high duty cycle. They have greater thermal mass, but terrible dissipation.
The few teams gearing their CIMs fast enough to run into this have found methods to cool between matches and/or are looking at running 6 MiniCIMs to reduce the initial heat dissipation.
I’ll take less temperature rise over “better” cooling any day.
3310 was pretty fast. The couple of times we tried to block them out as an alliance, they zoomed by. The one time we tried to race them to their gear, it was moot because there was another gear close by anyways.