Blue nitrile tread field damage

It also can happen if you slam it into a surface rather than slowly approaching then applying throttle since the impact can help break static friction.

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Technically yes, plaction wheels are just the plastic wheels, but they are intended to be used with some sort of tread, and blue nitrile is the most popular/prevalent form. If you search plaction wheel on AndyMark the first result is plaction wheels with blue nitrile tread.

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Depending on the drive it’s reasonably likely it’ll just stall and heat up the motors. That’s where the brushless motors make a big difference.

WPILib can’t ship vendor-dependent code.

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The tendency to use smaller wheels may also be involved. Anecdotally, burn through does seem to be a more frequent thing these days. Another theory is that high torque drive trains are now much more widely adopted than in the past, so there’s more opportunity.

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The first time one of my robots burned through the carpet that I know of was in 2003 (literally my first event as a mentor). We were using 2 Bosch drill motors in the drill transmissions and and pneumatic wheelchair wheels on that robot.

So if you think this is a new or recent motor power problem, it is not. It has been around for a long time.

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Thanks for your comment. We have been doing this a long time. We do have floor protection. We use some very thick and durable floor tarps designed to protect gym floors. They have served us well for 9 years and generally prevent burn through to the wood. We have had lots of holes in carpets and scuff marks on the tarps over the years.

The big change this year is the power being applied to the high friction nitrile treads and the increased power of the falcon motors. The speed of the burn through is unlike previous years. Combine that with the relative inexperience of the drivers (pretty much everyone is new this year!), inexperience of the programmers, the position of the robots on the field (pressing against the hub), and we had more problems in one event than we would typically have in an entire year.

So we are switching to underlayment based on these changes.

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This makes sense. I think PSAs and penalties during quals to teams that repeatedly damage the carpet would probably go a long way.

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This is a great solution. The issue is we have a whole lot of new programmers on FRC teams. So unless there is very clear copy/paste example code for them to follow, this remains just an idea. Many teams are rebuilding their talent this year and have just figured out how if statements work.

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Yea - IMO the hard part isn’t the code, someone can solve that with a library. The harder part is knowing, in any particular robot, what that green curve’s shape looks like. That’ll havea big impact on what software solution you pick, and where you set your thresholds.

Identifying the shape of that curve, accurately enough to prevent field damage is… probably above my paygrade.

it is also possible to see this happen real time

i watched the field get damaged in clack real time from drive stations when i was playing defense vs swerve drive teams so refs can call it out mid match

you could see when the ground went from dark of the carpet colour to bright of the basketball court field

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I bet a robot-against-a-wall test with a slow voltage ramp and current measurements would do it. Perhaps an eventual SysId feature?

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The real solution: lunacy wheels!

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Or have the programmers limit the power applied to the motors to 10 or less…

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The more I have played with the drivetrain simulators over the years, the more convinced I have become that many drivetrains are geared too high. I know the argument about gearing high is that you get better acceleration at the expense of top speed, but when you actually look at what the simulators tell you, the acceleration for most of these high gear ratios is traction limited (i.e. there is enough torque to cause the wheels to slip). We tried going with an 8:1 gear ratio (to 4 inch wheels with one NEO motor per wheel) for the first comp in 2020 versus our previous standard of 6:1 and the performance definitely suffered. But, relevant to this discussion, the 8:1 gear ratio would also result in wheel slip at the motor stall torque. We could even get wheel slip at max motor power at relatively slow speeds. So, ultimately, this gearing does not really help your acceleration.

Our standard gearing of 6:1 results in much less tendency for wheel slip. Reducing this gear ratio further to 5:1 or so would ensure that we could not slip the wheels at stall torque (assuming that the load is evenly distributed) with very little loss of acceleration.

If I chose a gear ratio that results in a traction limited design, I would be able to spin the wheels with just about any motor and wheel combination.

Brushless motors have probably made the situation worse. A drivetrain design that was stall torque limited with CIMs or MiniCIMs could easily be wheel slip limited with NEOs or Falcons. If teams who have adopted these motors used their “tried and true” gear ratios, they could have easily stepped into a realm where field damage was possible without actually realizing it.

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One of the ways we strive to recognize and inspire good science around these parts is through the clarity and accuracy of our technical communication.

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This did happen during week 1, specifically during glacier peak (unsure about clack). Id assume with the above email being sent to all PNW lead mentors it will have more strict penalties, and teams would be warned during the drivers meeting.

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Clearly, there are some who are too young to understand these movie references…

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This one goes to eleven

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This one goes to eleven.

EDIT: Sniped!

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Hey there, fellow Gen-Xer

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