Hardening the xrp for classroom use

Curriculum
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After evaluating the xrp for the last few weeks, 1/1/2024 ~ 2/9/2024…
I am very impressed with the produce. So much so I ordered 10 and am going to use them for our robotics course this spring.

Here’s some things I identified as risks I will be mitigating when switching our robotics course over to xrp robots.

The usb micro plug being plugged in and out many times by students as well as being attached to a potentially moving robot makes this a weak point.
I will be adding a 6" micro extension ($5) to a magnetic disconnect adapter ($8) to each robot to manage that risk.

Flipping the robot to remove the batteries for charging introduced a lot of potential issues with cables getting caught , stressed, unplugged, etc. I am buying some Nmih wall wort chargers and changing the ends to match the battery cable on the XRP. so that the batteries can be charged in situ. ($12 + $.50) The drawback is that the robots need to be stored with access to a bunch or outlets. I have this access but this might not be much of a solution if they have to be locked up between classes.

Not directly robots but swiffer dust mops. Our computer lab is next to our robotics lab which is next to our metals lab which is next to our wood shop, so the floors are perpetually covered in dust. The XRP rubber tires do not like dust. Sweeping the game area then swiffering it worked well. Vacuuming long term would be cheaper so we will be trying that as well.

for the on off switch I am thinking of a remote items as well but if the battery connection which looks quite robust can double for an on off switch rather than the board mounted item we might use that.

I am trying to download the 3d files for the XRP but they are blocked from our school network because of being free software. This might be something to consider if these items are aimed at educators. Could I download it when I get home at 9:00pm tonight after spending another 15hour day at school, sure… will I…no. Putting the 3D files in a education friendly repository like something at the WPI code site (which by deffinition someone would have to have access to to use the robot that might make more sense.

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Hi

Thanks for the feedback!

We also recognize the power connector as a weak link. I often have to remind students to not pull the robot by the USB cable when it gets away. We tried for USBC which would have been a little more robust. But the long-term plan is to get wireless downloading to work. Please let us know how the magnetic connectors work. We used them in a lab at school and had some issues, but it was mostly good.

For the batteries, what I recommend, and what we do at WPI, is to have a shelf with a bunch of chargers and a bin of batteries. We tell students, when your batteries run out, take out your batteries, put them into the charger, and take new ones from the bin.

Swiffer: good idea!

The access problem is why we have XRPCode at wpi.edu. It might be worth rehosting more of our content there as well. Using platforms purpose-built like Printables seemed like a good idea for parts sharing, remixes, and a place where everyone could collaborate on new designs.

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I had the kids cut the little retainer wings off of the black plastic AA battery holders inside the battery storage.

The 3d printed cover seems to do a pretty good job of holding the batteries in on it’s own so fighting batteries into the end slots over those retention “wings” seems like a recipe for kids to apply more force than you would want on a robot with hand made superstructure on the other side.

I also have the students doing the development exploration on this hot glue in the battery holder with a couple of 1cm long glue seams. This makes the battery holder from falling out of the chassis.

I don’t like the idea of turning the robots over again and again to replace batteries.

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I designed a 3D printed foot based on the existing servo holder clip.

It clips on the rail and allows the robot to be safely inverted and placed on the table without straining the wires.

I printed up a couple sets and I have two students testing them right now.

https://drive.google.com/drive/folders/1qGbJhNywhPrq3yM06lZIudz1Pllg0JUh?usp=sharing

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