Two robots face off and try to throw each other off of a table! It'll make more sense after you watch the video...

If you enjoy this project, then check out my books: Rubber Band Engineer and Duct Tape Engineer. || More engineering projects || Everything I make

More footage from actual student-built JudoBots:

Updated version from my book Rubber Band Engineer

I call them JudoBots because of the way they seem to throw and grapple with each other during combat.

Although designed for children in grades 4-6, I think just about anyone can have fun with this. Even parents can't resist trying it out!

The bots are assembled from four components built separate from one another: the base, the stand, the arm, and the hydraulic system. The hydraulic system uses plastic syringes as pistons and water as the hydraulic fluid.

Step 1: Materials, Tools, and Design Criteria

    Please message me to report broken links. All of these materials are used in my other Instructables for kids, so your purchases can be used across multiple projects.

    JudoBot Criteria

    1. The base of each JudoBot must fit within a 10-inch square. This is to prevent students from building sprawling robots that cannot be flipped.
    2. Material limitation: craft sticks (50), craft cubes (10), cubes with holes (10), syringes (4), adhesive bumpers (10), decorative woodcraft/extra woodcraft (5), everything else within reason.

    Material limitations are in place to promote resourcefulness and to reduce cost. Also, clever students can no longer pile hundreds of sticks onto their bot in order to make it too heavy to move.

    You may choose to use other materials. This is what I use because I need to streamline my materials to fit with the other projects in my program, as well as keep the cost per project low.

    <p>I think this is a great project. I'm following some other STEM teachers in my district and having my 5th graders build them in teams. I just can't seem to find a glue that holds the cubes to the syringes. I've tried wood, tacky, hot, and super. Any ideas?</p><p>Thanks!</p>
    Wow, that one looks great!<br><br>I use hot glue. Apply plenty of it to the top of the syringe, then repeatedly press the cube onto the glue and lift it off. When the glue is tacky but still hot, press the cube on and keep it there.<br><br>The goal is to smear hot glue all over the surface of the syringe. If you simply glue the cube onto the syringe with just a little glue, it won't bond well to the plastic.
    <p>i love you bonelli</p>
    <p>hey bonelli</p>
    <p>hey bonelli</p>
    <p>awesome project we have to battle soon :)</p>
    <p><a href="http://youtu.be/0CDJBT_bAoo" rel="nofollow">http://youtu.be/0CDJBT_bAoo</a> Thank you so much. I had a lot of fun doing this</p>
    Very cool! Thanks for sharing your awesome design and for including a video!
    Cool.<br> Very cool.<br> Had to make some...<br> <br> Will video the battle ... &quot;There can be only one&quot;.<br> <br> Thanks for the ideas.<br> <br> C<br> <br> <div> <iframe frameborder="0" height="315" src="//www.youtube.com/embed/GoymH-bHy6Y" width="420"></iframe><br> <br> &nbsp;</div>
    Fantastic project! My students built these in my physical science class and it was their favorite!
    yo you know the whole pressure thing yay that is what works the thing what ever it is you know wat evs
    Judobot Tournament! cant wait fir the thrill of the amazing tounament <br>
    what types of judobots can be made? like creative ones?
    Idea: create a team event after the battles......a pass the parcel sort of thing.....vid the results. For a team vid
    This is a awesome machine ! <br>I build mine this afternoon in 45 minutes, and it works great. I showed my students (5/6 class) your video this morning and they where fascinated. This will be our next Project to do. I can't wait to see what the kids will construct! <br>Thanks for this good idea!
    Very cool - let me know how it turns out, and maybe post some photos
    Hey thanks for the awesome project, we just used it for our kids program at our hackerspace. http://acemonstertoys.org/node/119 We had about 25 kids building them and it turned out fantastic!
    Wow, that's great! Thanks for sharing that with me :)))
    and it is awsome
    Hi there! I just wanted to say thanks for the wonderful idea! I adapted the syringe concept and made a catapult which won first prize! Thanks!
    Wow, that's awesome! What contest did you win first prize in?
    Well it wasn't really a contest we were supposed to build a mechanical toy in Physics.
    these are really really cool i made something similar in technology class but we made claws and used them to pick up ping pong balls in this little game of who can pick up 5 balls faster.
    Great project! I recently used this in my high school physics class. The students really enjoyed it. A couple of groups added a third syringe to make the arm lengthen. I even had one student make his robot walk.
    Amazing! Thanks for sharing that with me. Do you have any photos or video of your student's designs?
    Very very cool. It's genius to use syringes as both the cylinders and pump. Simple and functional. Reminds me of building backhoes and dozers with my pneumatic Lego cylinders. If I don't place in the Play contest I hope you're the one that beats me.
    Thanks, but I got the syringe idea from <a href="https://www.instructables.com/id/Hydraulic-robot-made-of-cardboard-and-scotch-duct-/" rel="nofollow">hydraulic robot arms</a> that I found on Youtube and this site.
    This is so cool and a great fun way to teach kids so much. I am highly impressed.
    Wonderful! :-)
    Just built my first one and it's pretty cool. My students are getting excited to try them out.
    That is awesome!! I'd be thrilled if you could post some photos or video of the project in action.<br><br>I am planning an update for this project, but I'd like you to here it first:<br><br>Use masking tape to secure the piston that actuates the pivot, not cable ties. Students requesting for help tends to bottleneck at this step, so using tape is much easier to attach and readjust (and it's just as effective).<br><br>I just finished conducting this project with about 30 4th-5th grade students. Take your time with each step, especially the testing/redesigning phase. Many robots perform less than impressively at first and require some additions and adjustments. Be sure to bring unassembled components for the students to refer to. Have fun!
    Great Idea!!! <br><br>How long does the typical build take?
    Each one takes about 1.5 hours from start to finish
    A fantastic way to cover the curriculum, involve the students in &quot;doing&quot; and also allow them to have a lot of fun. They soon learn if their design is viable. Proof of concept is the competition. It either wins or loses. Some real- world learning! Wish I'd thought of it!
    VERY well done! my students all want to build it!<br>-stu
    this has earned you a subscriber. the idea of challenging young kids to think an build is also great.
    Very cool. It would be interesting to create a computer interface for these. Maybe a 2 motor setup where one motor selects which plunger to operate and the other actuates the chosen plunger.<br><br>PS I thought Sumo was the sport where the winner gets his opponent to step outside of the ring. Is Judo like that too?
    Yes, it is more like sumo in some ways, but sumobots are already established as small bots with wheels that try to push each other out of a ring, like this: http://www.youtube.com/watch?v=YpqmBEG349I&amp;feature=related
    This is really cool! Being a judo player, the title of this instantly interested me. I've seen similar things on Youtube before, good job.
    That would be awesome to play!!!!!!
    Gosh, that's brilliant!

    About This Instructable




    Bio: I'm a writer, maker, and educator. For free lesson plans and teaching materials, and for assistance with any of my projects, check out LanceMakes ...
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