For those unaware of the new 2016 product rollouts, both AndyMark and VexPro put out new products this past week. Among AndyMark’s newest offers are a new line of HiGrip wheels with varying hardness (50A and 60A respectively). AndyMark’s Nick Lawrence does a great job of explaining each wheel’s costs and benefits in his post in the new products thread: Link
The “old” white HiGrip wheels have lasted many teams an entire season worth of matches, mine included. I wanted to get other team’s thoughts on having wheels that can be worn out after a day or even a single match, but offer enhanced “dynamic robot response” and traction. In other words, having a wheel for every occasion?
Would your team run the white wheels all season and disregard the others all together?
Would you run the white wheels in normal matches and have a black or a blue set ready for special situations?
Would you run black wheels and switch them out every day?
Or are you a team that is filthy loaded and will switch out your blue wheels every match?
Thoughts in implications for robot design and strategy?
I think it will depend on the game. If, for some reason, we are put into a situation where the task we need to do completely changes between matches (Oh God, I hope not), then there could be a possibility. But other than that…I can’t see us swapping out wheels with different tread.
You must spread some Reputation around before giving it to Michael Corsetto again.
Truly, I wouldn’t trust something with that much of a change. How would drivers practice? Do we need a PracticeQualsRobot and a PracticeElimsRobot? Not to mention the changeout time at the event - I’d rather use that ‘lunch break’ (ha) to strategize and work with my new alliance than to change out wheels.
Would it not just make it easier? I know I have heard of some teams that have practice robots that are slightly worse then their competition bots so that when they use their competition bots they have an easier time driving.
I heard on a Gamesense stream 118 does something similar to that.
When you practice driving a robot, you can get pretty good at adapting to “non ideal” but consistent things.
Maybe you have an intake mechanism where the “worse wheel” offers a little more slip and it takes a game piece longer to make it through the intake. If the driver is used to intake, pause, shoot, you might throw off the timing with a new wheel. Maybe it matters, maybe not.
Are there instances where it could be safe and beneficial? Sure, but I just think the feedback is that sometimes a better technical solution (more grippy wheel) might not be preferential to a more consistent experience for the driver.
From a conditioning standpoint this might be true but to make a change in functionality like that over the course of a lunch break, when the driver’s have been competing with that robot the way it’s been all day(s), it seems like it might throw off some coordination and timing.
To clarify, what kind of non-drive mechanisms would you consider using the wheels for? Shooters, intakes? Else?
I would never want to rely on a part that only lasts a match or two, as this implies that there is a good chance that the part behaves differently at the end of the match than at the beginning.
I also definitely would not want a different part on the robot in playoffs vs. in qualification matches. At most, we get a couple dozen matches per year - barely enough time to optimize the robot and drive team around one configuration, and definitely not enough time to optimize several.
IMO, intakes and conveyance systems will be the best place for the Black and Blue wheels (think Banebots replacement). There are already plenty of other proven options for drive wheels that offer both high traction and high durability.
Make what “easier”? I assume you mean make acquiring/manipulating the game piece “easier”?
How will increased “grip” on the game piece effect it’s intake velocity/momentum? How will that impact the rest of your system and control loops? What other mechanisms could be impacted by this change?
Just as a mental exercise, spend some time pondering the impact of changing out the intake wheels on a 2015 118 robot. How does that effect the rest of system?
Things to think about.
-Mike
Edit: lots of smarter people are also faster at posting than me.
We’re definitely closer to the top of that list; exactly where will be decided sometime after we figure out our game strategy. The softer/grippier tires are more likely to make an appearance as an intake or shooter of game pieces than pushing the robot around.
It seems that doing an 8-wheel drive with harder wheels in the center and gripper wheels on the corners might prove a good engineering trade off in a number of situations.
I can attest that when designing intake systems, you want to have as little variability as possible. Changing one variable can drastically change the function of the mechanism and make its exact working unpredictable. Which is very dangerous.
I would aim to use the same wheels in all matches regardless. If I were to consider using the black wheels (unlikely that it would be cost effective to use the blue ones in a drive train application), I would make sure a design criteria be to swap in new wheels in 6 minutes, including bumper removal and replacement. If that’s not achievable, I would probably go for white wheels instead.
Based on past experience, I personally would avoid using the 6" wheels at almost any cost. In 2013, we saw many of these fail under conditions which we would expect a wheel to just work. Most notably when Team 20 broke 1 in our first match at IRI which was the likely cause of critical drive gearbox damage, rendering us that team that couldn’t move at IRI for 6 matches. We discovered there to be voids in the molded polycarbonate spokes which allowed the wheel to rip itself in half.
The 2014 and 2015 Kitbot used the white 4" wheels. Based on not witnessing many failures in either of these years (especially with the heavy defense in 2014), I would be much more at ease with using these wheels. Anecdotally, they have proven to be more robust.
Should a design call for larger than 4" wheels, I am not sure what direction I would suggest. Banebots doesn’t carry colsons larger than 5", and VexPro has limited options above 4" (some traction treaded wheels are available). Maybe the AM 8" pneumatic wheels would be a desirable choice.
After how those wheels reacted to the extremes of the 2013 game the am-0940 was redesigned to have beefier ribs and some thicknesses were increased. This took care of the void problems you’re mentioning.
It could get expensive to use them every match… which is why some of the racing sports limit teams to the number of tires they use in a season. However you can purchase various durometers of Urethane at resin supply shops, so there is no reason you couldn’t design your own wheels, or a mold for the AM wheels, and re-cast your own tires when needed.
In fact I’m off to cast some mini-sumo robot tires right now…
Awesome, glad to hear it! I redact my statement in this case from “avoid at almost any cost” to “proceed attentively”.
I suppose we just haven’t seen many teams use 6" HiGrips recently since the kitbot switched to 4", there was little reason to go bigger in 2014, and holonomic was common in 2015.
Side note, the level of customer service and continuous improvement from AndyMark and other FIRST suppliers in response to customer concerns is amazing. Thank you!
I really want to test out the different durometers of wheels on the gamepiece before making any judgements. This year could be an intake-heavy game, whereas 2014 might be a game where your intake is used only several times per match.