It’s not the case shown in their photo, but my team is using this case for our OPi5 for now while we wait for a more permanent mounting solution for the robot.
MID-WEEK UPDATE, WEEK 2
One of the things that I like about this game is that it provides a significant engineering design challenge that asks questions that weren’t already answered, at least within the experience of our current students (and many mentors). Unlike the most recent games, I’m seeing a great diversity of possible solutions being developed and tested. Is the “meta” going to be angled elevators? Elevators on a pivot? “Pink” arms? Four-bar linkages? The answer is not clear, and these and many other ideas seem like viable approaches to solving the game. This makes me happy
1339’S DESIGN DECISIONS
A reminder: we are building two competition-ready robots (A and B) using the same geometry and superstructure, but materials from different companies.
- Drive Base: Swerve. Though driving at full speed over the Charging Station makes large pneumatic wheels sound like fun, we think the advantages of a durable swerve drive outweigh other considerations. Robot B is running the new REV Max Swerve modules, while Robot A is running on the SDS MK4i modules that we tested extensively since last April.
Superstructure: Crane (Elevator on a Pivot). We initially looked to inspiration from construction cranes and robots built for the 2013 BEST Robotics game. Ri3D team Cranberry Alarm created a single-stage elevator robot that got a lot of things right, and our design is going to be an upgraded version of their design. We are using two-stage Thrifty Elevators with no carriage and an attachment for the intake on the end of the second stage. The FRC robots that ours may have a lot in common with include the 2016 robot from team 330 (one of my favorite robots ever).
Intake: Pasta Roller. We think that horizontal rollers will be an effective way of intaking both game objects from either the floor or the shelf. Everybot made a very effective design that ours was paralleling, so ours is likely to look similar to theirs in many ways. We will have an additional opening at the bottom of the intake for bringing in cones from the floor. We also plan on running our intake on omni wheels in front of our bumpers when on the ground level. Our rollers will once again be polycarbonate tubes covered in medical wrap, as this has a great combination of grippiness on game pieces, ease of replacement (and inexpensive!), and coming in a variety of colors. We are currently planning on using 2" rollers and perhaps combining them with some VIW’s (Vectored Intake Wheels) on one or two axles. VIW’s are great at centering cubes (good for a full-width intake) but bad at initiating the intake process (they aren’t sticky enough). Here are some short videos showing some of our testing with VIW’s to illustrate.
- Pneumatics: Yes. Keeping center of mass as low as possible is going to mean many tradeoffs. We will be changing the angle of our intake using pneumatics rather than motors to reduce wire runs and overall weight. It has been since 2019 that we have run a pneumatic system on a competition robot, so for many of our students this will be their first foray into experience.
OTHER RELEVANT STUFF
Covid hit our team this week, with several key students and mentors kept away from school and meetings, which has impacted our progress. A snow day yesterday also hurt our productivity. We are continuing to work on our theming (a big part of AngelBotics) and the KISS concert shirt is looking great. We had a lot of fun being filmed for FIRST Updates Now on Tuesday, looking forward to seeing it on YouTube soon.
https://youtu.be/BzaJbbK-jfo 1339 AngelBotics has some very unique intake prototypes to display along with how they are approaching AprilTags and their awesome KISS themed branding.
What has been the inter-roller spacing in the gifs for the cone pinchers, and have you noticed a significant drop in adherence while using VIW’s compared to Rubber (or silicone) rollers?
Spacing has ranged between 2-4" on all of our effective cone prototypes. I would probably make our high-fidelity prototype with 3" gap spacing. There is a definite difference between round rollers and VIW rollers; the VIW’s have a harder time grabbing the cone to begin with, and they are jittery when holding it. We coat our round rollers with medical tape, which is roughly as sticky as silicone but less than the 35a wheels from AndyMark. Hope this answers your question, happy to respond again if it doesn’t.
I know we all get excited about robotics and sometimes just want to see a prototype work, but safety needs to come first. I’ve seen a bunch of prototyping videos this season with no safety
glasses/side shields in sight. but id especially like to point out that there are two hands in a pinch zone what looks like ~.5" away from a spinning shaft, im sure you can imagine what could happen. And in the top video we see someone’s hand almost get sucked into the rollers. I don’t want to shame anyone, I love the prototypes but please remember safety. All it takes is a split second around all the fun things we get to use every year with our robots and things can turn unfun… Rolling up sleeves around rapidly spinning tools and shafts, safety glasses, and clamps. All these things seem like an inconvenience sometimes when we really just want to get things done but taking a minute to do them can make sure that we all get to keep having our fun with robots every year.
We’re thinking about doing a very similar elevator on a pivot. How are you planning to make sure that it can take the forces of getting hit while you’re ground intaking?
Excellent points, Joel and big props for pointing that out! I would add to tuck in those hoodie strings and tie back long hair too if you’re going to be anywhere near operating tools / mechanisms.
Thanks to those of you who used our GIFs to remind us all to maintain safe practices in the midst of the excitement of build season. It doesn’t feel great to serve as the bad example but you’re right, we need to make sure we aren’t risking health for the sake of getting robots done.
BEGINNING OF WEEK 3 UPDATE
KILL YOUR DARLINGS
One of the things we hear frequently in FRC is that engineering is an iterative process, and that ownership of ideas needs to be held loosely in order for progress to be made. Sometimes this truism needs to be applied in ways that are, well, hard. In 2016 we had decided as a team to create a custom tank-tread driven robot, in large part because when it came time to make the choice one student was so invested in the idea that tears flowed, and we voted with him out of sympathy. Less than two weeks before Bag & Tag we had completed the drive base and discovered that it would not be competitive, and we quickly came up with a new design that used wheels. It was a hard lesson; the last week of build season was panicked and painful, and our robot was much worse than it could have been had we not been so focused on the drive train. I couldn’t find photos of the tank tread but here’s the revised robot:
This year we pushed that difficult decision earlier. At the end of week 1, our team unanimously chose to design a “crane” style robot in the mode of Cranberry Alarm’s Ri3D team. Late last week we were getting signals that this design might have problems with competitiveness.
- In order to hold game pieces within the frame, it would have a high center of gravity.
- To have a low CoG, we would need to have our intake continuously outside the perimeter, exposing it to hard hits and potential penalties.
- The pivoting elevator has a long moment arm and a joint that, with a hard hit, could suffer severe and debilitating damage.
- The exposed cable (the thing that made it a “crane”) has a long history of entanglement with extended arms
We considered a number of other options for moving the elevator up and down, including a capstan, a curved rack-and-pinion, and a large sprocket, but in the end we decided that the trade-offs weren’t worth it. In order to meet our team goals in terms of competitiveness and simplicity, we needed to abandon the idea and go with something else.
LISTEN TO ADVICE, SEEK HELP
Being part of the Open Alliance is both give and take. We greatly appreciate all the folks who have posted their designs, answered our questions, and given us frank advice on whether we ought to keep the course or change direction. I’d especially like to thank @Nick.kremer, @cadandcookies, @AllenGregoryIV, @nuclearnerd, @BJC, and @Andrew_Schreiber for their really helpful criticisms and insights.
We have decided that a fixed, tilted elevator will be the most effective way to play the game for us. This requires that we push back our Gantt Chart milestone by a week for our superstructure CAD but it’s worth it (we think). A tilted elevator gives us access to every level of the scoring zones, allows us to pick up game pieces off the floor or from the tray, holds game pieces within the frame perimeter while traveling, and gives us the lowest CoG for going over the Charging Station at speed.
Our “A” drive base is wired and driving. We have printed the bump-out swarf protection design for our MK4i modules that you can find here if you want to print your own. They fit nicely and look good.
The “B” drive base is also nearly electrically complete and should be driving tomorrow. The “B” code team has accessed REV’s swerve code and is working through it.
The “C” robot is going to be a slightly modified REV Starter robot. Today the team learned how to do chain-in-tube WCD drive, and tomorrow they will be ready to finish assembly of the frame and wheels.
I realize that this will come across as brown nosing to some, but I need to say that it wouldn’t be possible for us to take on this much if we hadn’t been able to rely on the REV ION line. It’s making a huge difference for us as a team. This is probably our biggest technical leap since 2013, and it’s very much thanks to great products from Thrifty Bot, Swerve Drive Specialties, Cross The Road, and especially REV. Thanks y’all.
Our team captain Ethan and lead programmer Dresden have created our first team PCB to address our need for additional sensor access this year. I’ll let Ethan describe it for you:
“It’s a RoboRIO MXP expansion board. With a I2C multiplexer (tca9548a) that allows use of multiple I2C sensors with the same address. Specifically 4pin JST PH REV I2C compatible with REV Color Sensorv3 and REV 2m Distance Sensor. It uses the MXP’s I2C port which does not crash In comparison to the main bus. In addition it breaks out the MXP’s DIO ports in to 4 pin JST PH for REV magnetic limit switch’s and 6 pin JST PH for REV through bore encoders. Allowing them to be plugged straight in with JST PH which is a more durable connection than through a converter and the traditional DIO ports.”
Amazing that we can have these in hand in just a few days. If anyone else is interested in getting one let us know!
Thanks again, everyone. This community is what helps us get better, and we appreciate all of you so much.
The breakout board looks awesome, what is the process for getting one? We are weighing our options
Hello, I have an update regarding the Burkout Board. We have made final revisions and ordered five built units, as well as the requisite parts. We expect them in a couple of weeks and are planning to build, test and then use three of them. If these are actually good (the hand-wired prototype works great) we can order more for teams. Give us a month I guess? Thanks for your interest!
Yesterday I spent most of the meeting time with eight students helping a fellow Denver teacher clean up the storage space for her classrooms. While we were gone some of the team members enjoyed a little down time. Here are the results:
“I have no catch phrase”. Nice. This all made me smile this morning.
Great to see the students having fun. They have a good sense of humor.
Next up: the basketball team visits and attempts to assemble a robot.
EARLY WEEK FOUR UPDATE
THREE ROBOTS IS HARD
My apologies for the lack of in-depth posts over the last week. We have been working so hard that I’m afraid I have personally violated our team motto (“Robotics Is A Fourth Place Activity”) multiple times, including a few rather late nights. I am sure that everyone can relate to how difficult it can be to balance everything at this time of the year. For us, we have taken on the additional work of making three competition-viable robots, each with their own design elements, component choices, and tradeoffs. We did this for several good reasons (which I have previously written about) and it’s going relatively well but it is hard to do. I’m very thankful for all the other adults who are assisting this year, as we would be SOL without their help and guidance.
We have a fairly detailed plan for working on all three robots at once. Our tools are found here:
We crafted this several weeks before kickoff and have referred to it frequently to check in on our progress relative to where we thought we might end up. We are planning to compete in Week 2 (St. Louis) and Week 4 (Colorado) with our A robot (now named Heart of Chrome because we spent so much time polishing all the aluminum for it). Here’s a photo of the tubes:
We are then planning on taking the B robot (now Starchild) to a Week 6 competition. We are really hoping to get into Green Country in Tulsa OK, but are looking at either SVR or Alabama as alternatives. For this reason, we are focusing our programming and drive practice on the Heart of Chrome base. Today the programmers completed characterization of the SDS MK4i modules and got pose estimation running using the Orange Pi 5 and this camera. Programming leads are feeling the FOMO with not having a Limelight 3 but we’re deep in the sunk cost fallacy, and anyway they’re all sold out, right?
Starchild, meantime, is the focus of our manufacturing efforts. We have assembled most of the structure, shown here, and will have the elevator assembled and attached tomorrow. The goal is for B to be mechanically complete by Saturday with the exception of the intake, which is still going through CAD optimization.
Carter is a 9th grader who has extraordinary CAD skills and has taken command of our Prusa farm. Because we are trying to package four intake rollers tightly, we couldn’t use the typical 2" vectored intake wheels (VIWs) and he has designed a 1.125" VIW that he has begun printing. Tomorrow we will test six of these on our intake prototype. Y’all are of course welcome to the CAD if you want to try these yourselves.
Our ninth graders have had a blast building their own robot, a slightly modded REV Starter. Melissa (Drive Team captain for Robot B and a 10th grader) pointed out that she wishes that she and her classmates had had such an experience last year, as most of what she learned was in the more intimidating environment of the older students. I agree with her, and I think we will keep this as a plan for future seasons. Currently Mister Speed has it’s electrical panel and drive train complete.
Robots should have handles. We picked these up from old laptop carts that were being scrapped by our school, but Mentor Garrett pointed out that McMaster-Carr sells a very similar product. We are being very active in incorporating these into the design, and you should also add something to your robot to make it safer to carry.
Thanks! I’m gonna go home and eat. Have a great evening.
Seriously, these are nice. I didn’t think a VIW could work at this size but I’m ready to be proven wrong. Y’all should try them.
Penny for scale.
I wanted to share with you video of our team in action today. So much going on. When FRC works it really works.
You guys are awesome. Crazy (in a good way), but awesome. Looking forward to seeing you all at the scrimmage in a few weeks. Keep up the good work!
Small update on our third Python prototype robot, “Mr Speed”.
The drive train was recently completed and this evening we were able to set the CAN IDs for our Rev SparkMax controllers and Power Distribution Hub. We ran out of time with the actual roboRIO programming this evening but were able to mock up the necessary script to complete the installation during our next meeting. Wanted to share our code and terminal recording as we’re happy to get here after a generous tutorial from team 3200 Raptacon.
Here’s the gist: rioSetup.sh · GitHub
and here’s the terminal recording: Angelbotics Robot.py roboRIO Installation Script Test - asciinema
…stay tuned for more updates
These 1.125" mecanum wheels look great! Correct me if I’m wrong, but it looks to me like you printed the 2 halves and the rollers separately and then assembled them. If that’s the case, how did you connect the halves once the wheel is assembled to prevent it from falling back apart? Thanks for the insight and the resource!
They were glued with medium CA