End of Year Course Reflections, what we learned

Curriculum
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Not sure where to post this, but FYI here goes.

We just completed our first semester implementing XRP robots in our high school robotics course.

Sad Abstract:
-The implentation of XRP robots in the robotics course was very successful and going forward we will be using this platform.
-Much was learned about the robots and teaching with them this first semester.

We do a semester robotics course where students learn soldering, construction, 3D printing Laser cutting, programming microcontrollers, sensors, servos, then use the skills to scratch build a robot for an end of course competition.

We switched to the XRP robot and this eliminated some of the kids experience with real world systems ( ie, designing for real world systems is complicated)
The big however is that the kids spent a lot more of their time writing more advanced code. While this didn’t change for the kids who were already naturally good at this, it did move more of the kids from the lower tiers of understanding to the “Got this” level.

For that reason alone I am going forward with XRP robots for the course. There are many other reasons including the XRP platform is something a person without a robotics background can move into where 100% scratch built requires a teacher with a much wider skill set.

So, what did I learn.

  1. Tires:
    We use the robots on a linoleum floor The rubber on the O-rings became shiny and cracked probably being inexpensive and having a lot of used rubber in the mix. Also when they became dusty their traction was low and inconsistant.
    We solved this by sanding the surface on the O-rings with sandpaper and cleaning them with alcohol before each test and each match.
    Higher quality O-rings of a different compound are on the list for next year.

Chassis:
The chassis didn’t have enough weight over the drive wheels. If a student put weight over the front casters for an effector when the robot stopped and the weight came off the rear wheels they would work inconsistently.

I had the kids 3D print a peg that could snap into the side rails allowing steel washers to be stacked near the wheels for more weight. this worked well but in retrospect, it makes turning the robots over quite the production with the washers being unloaded each time. I will require the kids design a ballast peg that allows the washers to be secured mechanically

Batteries:
We need to use rechargeable batteries which because I am cheap are nmih which means the voltage is low. It works but pid especially with block code is poor.
We added an additional battery to give us a true 6v.
I am planning on using two 18650 cells.
If we ever print the chassis’ ourselves, I will modify the cad file to accept some kind of 18650 cell holder that has the batteries on the top of the robot.

Chassis:
The design of the robot works pretty well to get at the stuff on top but flipping robots over to work on the underside is a very common activity. For instance inspecting and cleaning the wheels if running on linoleum. We 3D printed special clip on stands to make the robots invert able. This worked to guarantee the robots not getting damaged while doing this procedure. A chassis that had flat feet built in would make servicing the robot (especially to change batteries) easier and safer on the delicate wires on the top.

electronics:
The on / off switch is very delicate relative to the nature of high school freshmen, but we had no trouble with that. The switches are tiny and kind of hard to locate, but we also had good results with kids not breaking anything and being able to operate things easily.
We had one board die, I thought it had to be the pico so I pulled it and soldered on a new pico.but it turned out to be the main board, or maybe I got the board two hot when doing the rework. I did use eutectic lead solder which is the lowest melting solder in the shop.

All and all it was a very fruitful semester and the kids learned a lot and had a great competition. The XRP was brought in to allow the kids to spend more time programming and testing and it certainly lived up to that goal.
I will be incorporating them into the class going forward.

The drawbacks, cost of robots and replacement parts, (one XRP robot costs more than 10 scratch built class room robots of a similar size and function and more monolithic hardware (ie, the board does a lot where before each item was discreet and could be plumbed up to whatever with some Dupont cables in a matter of seconds.

The next item on the agenda for XRP robots is adding relays. Should be simple enough and worst case it could be a fet board which Sparkfun might even be making. I have not had a lot of time to keep up with XRP bots recently.

3 Likes
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Thanks for this reflection on you students’ and your experiences with the XRP platform. The contrasts with prior experiences are particularly helpful. The feedback on parts quality, e. g. o-ring tires, is useful. The plan going forward seems promising.
Thank you!

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Thank you for this! Your feedback has been extremely valuable as I plan for my XRP-based six-week summer offering for high school students. In another post you wrote:

" 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."

Did you add the micro extensions and magnetic adapters to your XRPs? What was your experience with whatever approach you took. If you DID add the adapters and extensions, can you share your source? (There were too many options and I don’t know how to choose)

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Glad you got something out of the reflections.

We did add a usb micro to usbc female cable. Here is a amazon link to it.

link

The thinking was, usbc is a pretty robust connection, we have tons of C cables, and unlike micro they plug in both ways.

They are not super high quality, and we just hot glued them in place on a little platform a student made for something else.

One could certainly 3d print a nice little holder for the USBC female end.

I am ordering some of
this one

which I will try next year.

Good luck with your summer course, I’m sure the kids will love it!

2 Likes
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Also, we never did the magnetic connectors because the USB C is so robust.

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Thanks again! I start next week and while I’m not new to PBL or robotics, this will be my first time offering a structured learning experience based on Python. I will try to provide meaningful weekly feedback on my experience in case it might be helpful for anyone else considering doing something similar.

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That is very generous of you. I often have that intention for instance recently I was walnut shell blasting out the intakes valves on my VW jetta ( a common task on some modern cars ) Anyway, I film the first 5 min then just give up and do the job because the camera work and thinkin about documentation is harder than the actual work!

We did a lot of work with AI (specifically copilot) this semester for the intro kids and it was VERY interesting indeed. I think the best was having them try and write pong.

Of course right now were are at the phase where we are banning AI work (my school “blocks” generative AI) but I am old enough to remember calculator bans, graphing calculator bans, search enging bans, etc. It’s always the same argument “well, yeah of course calculators are not cheating, but search engines are different, kids will be able to just look stuff up”

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Would you be willing to share your curriculum for your summer program? I’ve been looking for something like that for training our new students.
Good luck with the program!

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Also, just to make sure people are aware. There is this summer guide available https://experientialrobotics.org/mountainmayhem/

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Thank you for that information. I am not doing a summer program but for someone looking to do one, that really looks helpful. I will look it over more carefully when I have a chance.

KWOL