We wondering how team’s have dealt with field obstacles in the past when using Swerve Drive.?
We have seen “Swank Drive” from 1533 https://youtu.be/-bItWi9Jc0w
and “Twerve Drive” from 4143 https://youtu.be/a9x06bqDGrw.
Any other examples of how to deal with obstacles when using swerve?
We have our swerve drive test platform working well on flat ground, but trying to think ahead if we have to deal with obstacles.
This is probably not what you were thinking, but this year’s HAB could be considered to be an example of a possible field obstacle. There were some clever ways that swerve drive bots tackled this obstacle. One of the other swerve teams here in NC, 2640 - HOTBOTZ, mounted their rear two swerve modules to legs and were able to climb to level 3 HAB by extending those legs along with a 3rd pogo leg in the middle of their bot. You can see it in action here (they are the hot pink bot on the blue alliance) A system like that could be used to navigate large field obstacles. I saw other swerve bots this year that did other clever things by moving their wheels around to accomplish their climb.
For smaller or more random field obstacles - SWANK!
At 2:03 and 2:22 in this video you can see Bomb Squad crossing over the barrier in 2012 with a swerve drive. It looks like they just put angled guards around the swerve modules.
Edit: for reference, the barrier was 4" tall.
If you want to do swerve with large obstacles, larger wheels are going to help the most. The other main thing you will need to do is make sure you have enough ground clearance with the frame and a large enough attack angle with the wheels. I like the “twerve” drive, but not the amount of complexity it adds.
It appears from video that Bomb Squad was always oriented a specific way when crossing the barrier. Does anyone recall if the guards/shields for the swerve drive rotated or where they fixed?
At 2:12 you can see the module rotating behind the angled gaurd which is fixed relative to the chassis.
We have swerve this year and had no issue navigating Hab 1 or going off hab 2 without anything added. We simply had a smooth bellypan but I don’t think we ever got close to getting stuck.
Old eyes on small phone is not s good combo
Fixed jives with my memory. Also jives with the way that 16’s controls used to be set up resulting in them driving less like most swerves and more in large sweeping arcs unless in a specific crab mode.
Pretty sure they were fixed. 1717 did something similar with a skid that popped out from under the chassis on one side: https://www.youtube.com/watch?v=rM80DE3dBZk
Several teams without swerve also used wedges to pop the front of the robot up over the bump so they could drive over.
2910 had a pair of aluminum rollers in the middle of their chassis in 2018 to keep them from being able to get high-centered on the platform if they were sideways on the corner. Something like dead axle omni wheels in a strategic location can help prevent the chassis from bottoming out.
Another non-swerve example, but something to keep in mind, is to always ask if you need to have the capability to go over the obstacle. In 2004 (going WAAAY back) there was a big platform in the middle. Some teams articulated their drive base or used big wheels, other teams (like254 and 67) just avoided going on the platform entirely and did everything from the ground.
They also did this in 2016 and there were all sort of obstacles there.
Watching videos from 2010 and 2016, it looks like swerve bots were able to cross obstacles by making sure they had a wheel alignment which was perpendicular to the obstacles.
Were there problems with damaged swerve mechanisms in those years. We weren’t around back then
Your gonna have to ask someone who’s actually done it, because I don’t know. I would assume that the angled guards usually take most of the force so the swerve doesn’t have to. Jumping the robot using the guards would most likely wreck a module depending on where the guards are from the floor and wheel though.
The swerve modules themselves (from the attachment to the chassis to the wheel) are generally pretty robust. We were using a COTS swerve (Team 221 Revolution design) in 2016 and it had no issues. In fact, we still use that robot for demos and beat it up pretty hard and the modules still work great.
I believe our current in house design is even more robust given the large diameter module bearing and the lower height above the floor between the plane of the bearing and the wheel contact patch. We had no issues driving off the HAB2 this year and landing with the full weight of the robot after dropping and it seems like the other swerve designs out there had similar results.
3419 built a swerve drive using 8” pneumatic wheels for Stronghold. As far as I know, we were the only team that did this - there certainly weren’t a lot. It worked great, though:
We all still hope for the return of Pneumaswerve one day.
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