I have been playing around with the idea of using a swerve drive next year. However, my coach doesn’t want to do it because of the extra weight. so, I have two questions: how light can you make a swerve drive and is it worth the extra wieght?
while it depends on the materials that are available to you, it will default be higher than a normal drive setup of the same material. you also gotta ask yourself if the programming is worth it as well. As for the success of it, ask 118 
Forget about weight, you better have have a LOT of resources available to design and build it. After seeing the 118 machine up close, this isn’t something you think up overnight. The weight also is greatly affected by the types of wheels, motors, chain etc that you choose to use. Try to look at the pictures from 111,118, 71 and others to pick up the tricks from each for weight savings and efficient design. Just be ready for the complexity and hope that the playing field is flat if you choose to develop it in the off season!
There’s always a simpler & lighter way to do things…
Its not that swerve drives are “heavy” or “complex,” its that no one has been clever enough to design one that is lighter and less complex. (Although some have gotten pretty darn close)
My advice is to go for it. Who knows? Perhaps with enough work and research you’ll hit on an idea that will revolutionize the swerve as we know it.
Team 16 had a nice chapter on swerves in FIRST Robotics: Behind the Design.
Complexity and resources are the most taxing when doing a Swerve system. However, weight can always be designed around. I have one designed that weighs only 35, and that includes the whole base frame.
Machine resources are the most taxing, as any sufficiently advanced Swerve will need a lot of advanced machining.
I see you are from WI. Are you going to IRI?
If you are seriously thinking about doing swerve in the near future, you should make a point of attending. I know that 71, 111, and 469 will all be their with their different methods of swerve and I know 469 would be happy to share with you anything and everything about ours…
What is IRI and when is it. As for machining we have a company that can bend aluminum into somewhat complex shapes. And we have a guy that is quite impressive on the mill.
Another question, what keeps coaxil swerve drive modules from turning when you are driving them, aren’t the drivetrain motors usually more powerful then the ones that turn the modules?
IRI is an incredible off-season event…
http://www.chiefdelphi.com/forums/showthread.php?t=57360&highlight=469
Even if you aren’t going to compete, everyone who can should go because it’s incredible!!!
Don’t forget 118.
118 will also be able to answer specific details about their coaxial swerve (the only one at IRI that I know of as 71, 111, and 469 each built other versions of swerves). The basic answer to your question is that the force follows the path of least resistance, and for the drive motors, that is spinning the wheels as it only has to overcome rolling resistance (and built in resistance).
if you do a search on ‘torque steer’, you should find some posts addressing this subject. usually, the motors are geared in such a way that while the drive motors are more powerful, the steering motors are outputting more torque. also, the width and diameter of the wheel, along with its CoF come into play as well.
this is one reason (the main one, acutally) that i prefer to mount my drive motors in the modules.
at iri us(1625) will also have our 3speed coaxial swerve drive for you to look at.
the only downside i can think of is weight everything else makes it worth it.
also as far as torque steer goes i had 4 cims each one powering its own module and i just had a set of 2 diagonal modules spun 180deg so the 4 cims cancelled each other out torque steer wise.
Sorry I missed 118… I’m glad I got to see it in person at Nats.
But, as you can see, if you are thinking about doing ANY kind of swerve drive, IRI will be the place to check it out…
So we have done swerve drive for 4 years now on team 118. Every year our swerve drive changes a bit. This year was actually our lightest wheel box yet. It weighed a max of 3 pounds (this is not an exact measurement, but from carrying it this is what it feels like). With the extra weight we made the V6 this year. Otherwise we use to have it so each wheel box gets a CIM motor attached to it. There are many ways to make them it really depends on what you want your robot to look like. If you have any other questions feel free to PM me and I can try to get some pictures or answer any other questions that you have. For us the weight we put into it, it has been extremely helpful in being agile
It would be fun to have a “Swerve off” round at IRI with all the robots swerving all over the place…
that would be amazing. i’d feel sorry if one tank drive d bot ended up in there trying to stop somebody
Maybe some kind of obstacle course designed especially for crabs to swerve through with special challenges to pick stuff up and drop them (tubes since thats the game this year). I think that would be awesome and would test both the styles of crab as well as the skill of the drivers.
\getting farther off topic
we might need to do this on the other side of the gym from the pits or whatevers left from 72 teams.
Even if we can all go to the practice field near the same time and have each other drivers (and others) try the others out to see how different styles and program compare. Might be interesting…
That would be amazing. i was already planning on going around and quizzing other teams drivers as to what there control scheme is. But actually driving the various robots would be even better.