Building Robots at School

March 30, 2011

Tethered Mini Sumo Robots

For years now I have been building tethered mini-sumo robots with my junior secondary students.  The robots are a fun way to discuss traction, torque, power, gear ratios, and a raft of other important engineering concepts that all actually come into play in a final competition.  The video on this page represents one of my earlier classes to build the robots, and since then we’ve added a few more rules to make the final projects look a bit better.  For instance I now ban exposed batteries and weights, and limit tape to being used for electrical insulation only.  I also use a piece of welding rod to support the tether wire, as you can see in the very slick looking robot with the rounded front in the video.  We’ve also upgraded to cast polyurethane tires, which give much better coefficients of friction than these store-bought tires do.  The key rule for all mini-sumo robots is that they have to measure less than 100mm long and 100mm wide in their starting position and weigh less than 500g.  To ensure a fair competition in my class, all students start out using a Tamiya Dual Motor Gearbox or a Twin Motor Gearbox.  For more details on where I source materials, and how I implement the project, check out my Tethered Mini Sumo lesson plans and Mini Sumo Design Tips

In the event the video does not show up, try this link: http://www.youtube.com/dtengineering#p/a/u/0/QPaa4Ea8TOo

Mini Sumos can be a lot of fun… give them a try!

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September 22, 2008

Intro to Ortho: The Three-View Lego Drawing

Filed under: mini sumo,robots,teaching,Tech Ed — dtengineering @ 6:09 pm

For several years now I have taught a course called “Robotics and Flight 10”.  The students in the class are grade nine and grade ten students, and for the majority of them it is their first “real” tech studies class.  The two cornerstone projects of the course are building tethered mini-sumo robots and tethered electric airplanes.

It didn’t take long to realize, however, that the students had great ideas on how to design their robots, but that they had a real problem getting those ideas out of their head in a way that I could understand.  It wasn’t their problem… it was just that they didn’t know how to DRAW!

So I needed something simple, but fun to start the kids learning the basics of orthographic and isometric projections.  I wanted to have something that would challenge the wide variety of skills and abilities that students have, and I wanted to do it with a realatively low investment of time and money.

So what we do is give the kids some Lego blocks.  I show them how to set up their paper on their drafting board, and point out that while the T-square does look like a “T”, the square actually looks like a triangle.  Then I get them to use the drawing tools to draw a border and title block.

Once they can do that they take two pieces of lego (just the bricks… not the fancy stuff) and I show them how to set up an orthographic drawing.  We don’t draw the “bumps” on top or the “holes” on the bottom of the bricks, nor do we draw the “seams” where two pieces come together.  We just assume that the lego has fused together in to one solid piece.  We pay special attention to the difference between construction line weight and object line weight, aligning the views, and the correct way to rotate the lego between top, front, and side projections.  Since all drawings are done at full scale, the students can take measurements directly off the Lego.  I generally refuse to mark a drawing unless it is pretty close to perfect, so most kids get 5/5 on this drawing… although some of them end up going back to fix or re-do it more than once.

Once they get the first drawing done, the next task is to do a slightly more complex drawing, with three pieces of Lego.  I make a point of advising them that just putting three pieces together to form a “bigger box” is not acceptable… they need some corners and variety in there.

Once they have finished the three-piece drawing, I talk to them about hidden lines, because for the third drawing they have to build a five-piece Lego structure and draw it with hidden lines.  By the time they finish this, they are usually getting a pretty good idea of how to draw a simple orthographic projection.  So it is time to give them something more challenging….

  1. This is where they do the “Stump the Teacher” drawing.  The rules are:
  2. You can use as many lego pieces as you want, and make it as challenging as you want.
  3. When you bring it to me for marking, if I can see one error, I send it back… and don’t tell you where the error is (or how many errors there are!).
  4. You can bring it to me three times… if, on the third trip, there are still errors then you have to start over with something simpler.  You have stumped yourself!
  5. When you submit a perfectly drawn piece it will be marked as: 
  • Basic complexity (same as the five piece lego drawing)          2/5
  • Some challenge                                                                3/5
  • Challenging! (the drawing in the photo fits this category)       4/5
  • This is CRAZY… it hurts MY brain!                                      5/5

If, however, I either give up on finding an error, OR I make a mistake in my marking (I have to show them where the errors are on their third and final trip and have been known to very occasionally see an error where there isn’t one) then they get a bonus mark of 6/5 and get to claim the rare and coveted title of having “Stumped the Teacher”.

This is followed up by a few classes doing something similar but with isometric drawings, and then we get in to designing the robots.  Although introducing the drawings this way takes about ten classes, it is perhaps not surprising that the quality of design drawings… and robots… has increased significantly since I started doing this introductory unit with the kids.  If you have an interesting idea for introducing technical drawing to students, perhaps you will leave a comment describing it or linking to a description of it?

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