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    Rob's Tinkercad Classroom: Automata

    Rob Morrill
    Published on - November 11, 2021 by Rob Morrill

    Teachers & Parents, Inspiration

    "Automata" often refers to cam or crank-driven mechanical projects. This one invites students to transform the spinning rotational motion of a micro servo motor to create spinning and/or an up and down motion in a different plane by using cam mechanisms.

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    From measuring and drawing, cutting and gluing, planning and engineering, to coding and creating meaningful art, this project has something for everyone. 

    What goes on top?

    When I did this project with sixth graders, my only requirement for what was animated on top was that it be meaningful to the student and that they be able to explain the meaning in their online learner's journal entry. One can also imagine course-specific animations for projects that integrate with history, science, literature, language, etc. 

    IMG_20211102_110725__01 IMG_20211102_110725

    This student's project reflected her concern about the Earth and the impact of the climate crisis. When the Earth spins, we get alternating visions of two possible futures.

    IMG_20211109_092538_2 IMG_20211102_120412

    This dragon took flight through a layer of clouds.

    This spinning piece was designed in Codeblocks and 3D printed.

    What you’ll need:

    • Cardboard
    • Cutting tools
    • A hot glue gun
    • A ruler
    • A paper straw
    • A bamboo stick or skewer
    • A continuous micro servo 
    • Masking tape
    • Male to alligator clip wires
    • A Micro:bit, Circuit Playground Express, or other microcontroller of choice

    3D printed elements are not strictly necessary, but they make things much easier, and they also allow kids the opportunity to design functional parts and animated art.

    A drill and 15/64” drill bit is very handy for making the hole for the straw, and it lets students practice drilling.

    If you or someone in your network has access to a laser cutter, it's easy to knock out many circles of several sizes from recycled cardboard in a short time. However, hand cutting works fine as well.

    IMG_20211102_103038_2

    Make the frame

    I suggest making frames out of four pieces of cardboard--two that are 70x170 millimeters and two that 70x100. I found this a good opportunity to review the metric system with my sixth graders, and also to practice ruler use skills, including how to draw a rectangle. We also cut little triangles to act as gusset braces in the corners. 

    This video is not only a reminder about the metric system, but also a guide on how to make basic shapes for cutting out. 

    Next, we used a 15/64” drill bit to make a hole for the straw. This gave students a chance to use a drill in a safe way, some for the first time. The straw is an important element because it acts as a bearing that guides the bamboo rod along its path. Cut the straw to about 1/3, but don’t glue it in yet. 

    Pro tip: Even with good precautions, glue gun burns and minor cuts are likely to happen once in a while. (Fun fact: I'm typing this with a bandaged finger that was attacked by a chef's knife during last night's dinner prep.) Make sure students know in advance what to do if they get injured. Do your research on treatments and have some supplies on hand.

    To make the box frame, I gave my students exact measurements that we all adhered to. However, for the little servo stand, I challenged them to use their own engineering decisions to build the structure. My only stipulation was that it had to get the servo 5-6 cm up.

    For a spinning motion, the cardboard cam (yellow piece below) should be slightly off-center from under the straw. For and up and down motion, the cardboard cam will be centered under the straw. 

    IMG_20211102_122637This frame is set up for an up and down cam motion. The rotating part of the servo is under the straw, and the servo "horn" is glued to the yellow cardboard cam off-center to create an eccentric vertical path.

    Be sure to have students wrap the servo in two layers of masking tape before hot gluing. This will make separating the servo from the project for later reuse much easier. Each servo comes with several white horn attachments, and if they can’t be separated from the hot glue, then it’s not too much of a tragedy. Also, there's usually no need to screw the servo horns in.

    IMG_20211102_084306 IMG_20211102_084328

    Here, the servo's white "horn" is glued off-center on the cardboard cam wheel. This will create an up and down motion for the bamboo stick rod. The 3D printed cam follower acts as a guide to keep the rod aligned. 

    This servo's horn is glued in the center of the cardboard cam. It will spin under the white 3D printed cam follower. It's slightly off-center from the rod and straw, so it will create a spinning motion for the bamboo rod.

    Both of these 3D printed cam followers offer a neat design challenge to students. How big does the opening have to be for the bamboo sticks you have? How thick should they be? How wide and deep should the opening for the one on the left be? Etc. 

    Screen Shot 2021-11-04 at 4.36.56 PM3D printed cam followers like these are really useful while also providing students with meaningful chances to measure, plan, design, print, and test. 

     

    ezgif.com-gif-maker (3)-1Here we can see the two main types of motion that these cam setups provide. 

     

    Get coding and testing

    Once you have the basic setup, it's time to test and fine-tune the mechanism's motion before hot gluing the straw in place to guide the bamboo rod. Tinkercad's Circuits environment lets you simulate the wiring of all kinds of components, including micro:bits and servos. Then you can code in blocks and/or Python.  MakeCode is another great choice, and I'll provide some resources below for both environments.

     

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    In either coding environment, to wire the servo to the micro:bit, connect the brown/black wire to the "GND" (ground/earth) pin, the red wire to the "3V" pin, and the orange signal wire to the "0" pin. The colors of the alligator wires don't matter; we just need them to connect to the proper wires coming out of the servo. 

    In Circuits, students can actually connect simulated wires, which is great practice for the real deal. Circuits also opens doors to other devices, like the Arduino. This video is a getting-started intro for the micro:bit.

     

     

    In MakeCode, we'll first make things easier by adding a library of specific MakeCode blocks for servo motors. To do that:

    First, scroll all the way down in the blocks toolbox to "Advanced" and then "Extensions." Screen Shot 2021-11-02 at 9.21.19 AM
    Next, click on the servo extension. Screen Shot 2021-11-02 at 9.21.37 AM
    Finally, you'll see that a new category of blocks for servos has been added. Be sure to only use the "Continuous" servo blocks.  Screen Shot 2021-11-02 at 9.22.18 AM

    For the coding piece, we used simple button presses to control the servo during testing. The "show icon" blocks help visually confirm what piece of code is running:

    Screen Shot 2021-11-02 at 8.52.22 AM

    The micro:bit has more interesting inputs than button presses though. Here, when the light-sensitive LEDs get covered, the servo activates.

    Screen Shot 2021-11-02 at 8.50.01 AM

    The micro:bit's accelerometer is another great input choice. Here, when the micro:bit is rolled more than 35 degrees to either the left or right, it initiates servo motion. 

    Screen Shot 2021-11-02 at 8.46.48 AM

    Here's an example of a Codeblocks project for a piece to adorn the rod.

    Screen Shot 2021-11-02 at 9.18.19 AM

    Take it further

    My students have a learner's journal in the form of a website, so they were asked to write a reflection explaining the significance of their project and sharing some of the highlights of what they learned. They also included a short video of their project in motion. 

    Students can also be challenged to make projects that interrelate, like plants and animals from an ecosystem or characters from history or literature. Or, how about pushing the boundaries of what motion the code causes? Another idea: what other kinds of motion can you create with hinges or different cam styles--moving arms or legs? Blinking eyes? Finally, I did a similar project a few years ago in which 7th graders animated characters and scenes from books their 1st grade friends were reading in library time. Adding the element of an authentic audience really raised the stakes in a fun way.

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    That's it! I hope your projects get set in motion soon. Please share what you make @morrill_rob. Find the complete list of Rob's Tinkercad Classroom articles here