Friday, 26 February 2016

Ozobot gets a LEGO Chariot

Ozobot is a tiny programmable robot for kids. My kids have been using Ozobot with LEGO, you can find out more in our LEGO Ozobot town article. Of course, one of the problems they wanted to solve was transporting a LEGO figure.

Ozobot isn't designed to pull a heavy load so we had to come up with something that would put as little stress on the mini robot as possible. If you try this project then make sure you keep the load light.

We all had a go at coming up with a solution and to my surprise I was the one that found something that worked well (with a bit of help from the boys.)

Ozobot with LEGO Chariot

Here's the chariot in action. You can just pop it over a moving Ozobot or put them down together. Or you can have Ozobot pick up its chariot automatically as you'll see later. 

Making a LEGO Chariot

LEGO Chariot Parts

LEGO chariot parts

To make a LEGO chariot for Ozobot you will need:

  • Three thin 1x6 LEGO pieces
  • One thin 1x4 LEGO piece (we used one that's flat on top)
  • One thin 2x3 (or 2x4) LEGO piece
  • A LEGO wheel base with tires attached
  • A regular 1x2 LEGO brick
  • 1 4cm LEGO Technic rod as a support for picking up the trailer automatically (see below)

Top Part

The top of the chariot needs to go partially over the Ozobot. Create a trapezoid shape using the long thing LEGO pieces.


Add the 2x3 (or 2x4) thin LEGO piece to your wheel base. Add the 1x2 LEGO brick to the part that sticks out.

Join together

Now attach the parts as shown:

You now have a LEGO chariot which you can use on its own or with a LEGO figure on top. 

The trailer happily follows Ozobot around our Ozobot grid tape board. If Ozobot changes direction then the chariot will slowly adjust to the new direction. 

The chariot also makes Ozobot much more effective at triggering dominoes. Without the chariot Ozobot tends to just push them along rather than over. 

Automatically attaching and dropping the trailer

When playing with Ozobot and its chariot we found that we could arrange for Ozobot to pick up its chariot automatically. There are some points on the board that aren't accessible with the chariot on so we wanted to make sure that we could automatically drop the chariot on reaching these areas. 

Attaching the trailer

We used a 4cm LEGO Technic rod to prop up the chariot over the path. Angle the rod so that it is in Ozobot's path and make sure the chariot is positioned so that it can drop onto Ozobot.

When Ozobot comes along it pushes the rod out of the way and the chariot drops into place. As Ozobot drives away, the trailer follows along.

Angle the rod so Ozobot can easily knock it out of the way

Dropping the trailer

A LEGO brick at the side of the path will stop the trailer while allowing Ozobot to continue on its journey. Just place the LEGO brick so that one tire will run into it. 

Once the trailer has been dropped the kids pick it up and set it up again (we haven't figured out how to automate that part!)

Ozobot Chariot in Action

In this video Ozobot picks up its chariot and then stops at the harbour where there's time to load or unload (see the Ozoblockly post for the code.) After the harbour, Ozobot continues to the next action spot where it does some demolition work (and a light show to show off!) and then it drops the trailer to continue round the board to areas where the trailer doesn't fit.

Adding a mini chariot to Ozobot adds to the feeling that Ozobot is a robot on the LEGO minifigure scale which has jobs to do in the LEGO town. 

Read next: Ozobot review

More from Tech Age Kids:


Jennifer Leban said...

I love this! I just tested it out on one of my classroom Ozobots and I found that it worked best if I took the rubbery "cover" off first. But it was so cool, and I can't wait to show off this trick to my students! Awesome!

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