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Hydraulic JudoBots

Hydraulic JudoBots
This is the Holy Grail among the students in my extracurricular engineering class. The project involves constructing a robot that uses a simple hydraulic system to power a lifting arm and a pivot. Two robots face off and try to throw each other off of a table! It'll make more sense after you watch the video...
 


More footage from actual student-built JudoBots:
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 parent's 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.

The cost per bot is about $4.00 and it will take up to 2 hours to complete, but you'll definitely need to schedule more time for some epic battles!

This project has been submitted for both the Teacher Contest and the Toy Challenge 2. I believe that JudoBots are a great project for both education and play in equal measure. 

Learning Objective
By operating a JudoBot, students will experientially comprehend the basic principles of hydraulics. Building and testing Judobots offers students the opportunity to evaluate materials based upon density, rigidity, and mass. Using the JudoBots in battle gives students hands-on knowledge of how to utilize hydraulics to effectively apply leverage to manipulate a mass. When the project is finished, students will walk away with a new appreciation of applied engineering (and an awesome new toy!)

Update Feb. 2012: After recently conducting this project with about 30 kids, I redesigned many aspects of the JudoBot. Attaching the hydraulics, which once was the most difficult step for some students, is now much easier. All of the photos and instructions are new - enjoy!
 
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Step 1Materials, tools, and design criteria

Materials, tools, and design criteria
 

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.

*The cubes pictured are actually from Bazic, but they have recently discontinued this product. Although the cubes depicted have holes drilled on all sides, this is not necessary. I chose to use Bazic's cubes in this 'Ible because they are colorful, which helps illustrate the design. The product I linked is my current substitute, but please let me know if you find something better
**My usual supplier, TeacherGeek.com, seems to no longer offer bulk purchases of 10ml syringes. You'll need to shop around for 10ml HSW Soft-Ject luer syringes. 
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24 comments
Apr 11, 2012. 12:58 AMBindi 3000 says:
and it is awsome
Apr 9, 2012. 6:33 AMmicraman says:
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!
Apr 10, 2012. 3:21 AMmicraman says:
Well it wasn't really a contest we were supposed to build a mechanical toy in Physics.
Mar 26, 2012. 10:05 AManibioman says:
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.
Mar 11, 2012. 1:11 PMcarladee says:
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.
Feb 26, 2012. 5:44 PMNightHawkInLight says:
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.
Feb 27, 2012. 7:43 AMbiochemtronics says:
This is so cool and a great fun way to teach kids so much. I am highly impressed.
Feb 10, 2012. 3:20 AMiPD says:
Wonderful! :-)
Feb 2, 2012. 11:51 AMjetringer says:
Just built my first one and it's pretty cool. My students are getting excited to try them out.
Jan 29, 2012. 8:57 PMI_am_Canadian says:
Fantastic!
Jan 29, 2012. 12:56 PMgmtanner says:
Great Idea!!!

How long does the typical build take?
Jan 27, 2012. 1:52 PMtechnologyguy says:
A fantastic way to cover the curriculum, involve the students in "doing" 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!
Jan 24, 2012. 1:15 PMstumitch says:
VERY well done! my students all want to build it!
-stu
Jan 20, 2012. 8:45 PMZeroSight says:
this has earned you a subscriber. the idea of challenging young kids to think an build is also great.
Jan 20, 2012. 4:51 AMmacrumpton says:
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.

PS I thought Sumo was the sport where the winner gets his opponent to step outside of the ring. Is Judo like that too?
Jan 19, 2012. 4:19 PMfozzy13 says:
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.
Jan 19, 2012. 3:29 PMAron313 says:
That would be awesome to play!!!!!!
Jan 19, 2012. 2:29 PMKiteman says:
Gosh, that's brilliant!

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Author:WYE_Lance(Workshop for Young Engineers)
I'll continue to update my Instructables as design improvements come my way, so let me hear your thoughts on what you see