Monday, 22 August 2016

Battle Bots or Robot Wars at Home - Building The Robot Base

My kids are crazy about Robot Wars (like Battle Bots in the US.) Okay I admit it, I got them into it. But they love the show. As soon as they found out about it they were keen to create their own battling robots.

Controlled vs Programmed

We decided to go with Robot Wars style human control of robots rather than programmatic control. We do lots of stuff with programmable robots so we thought it would be good for the kids to learn some practical robot driving skills with this project. 

Choosing a Robot Base

We've got lots of robots! But most of them are expensive and somewhat delicate and we're not keen to put them into battle. We do have a pair of Attacknid robots but while they are great for battling, the work has rather been done for you. So we set about finding a cheap robot that we could use as the base for our battle bots.

We're not looking for competition style Sumo robots yet. Just something small and inexpensive that allows the kids to get to grips with designing a battling robot. We went with these DoIt Wifi Robot Cars from Banggood. We were happy to wait a while for delivery as we wouldn't have time for the project until the summer holidays anyway.

Just recently, Wifi-based microprocessors have got much cheaper with the introduction of the ESPP 8266. A Wifi-based robot makes it easy to connect to the robot and write a browser-based controller. We won't look at custom code in this article, but it was a consideration for the future.

Building our Wifi Robots

The robots arrived packaged in bubble wrap and in cardboard boxes. The kits include parts that aren't necessary for building the basic robot but might be used in other configurations. You also get encoding wheels but no sensors to make use of them. 

Assembling the robots was pretty straightforward, just a few nuts and bolts to hold the components on to the acrylic base. We used cable ties to attach the main board as that seemed less fiddly.

Connecting the Electronics

Our kit didn't include any instructions for connecting the electronics. Some of it was obvious and the rest we figured out through trial and error.

We ended up with the following configuration:

  • A-: Left motor black lead
  • A+: Left motor red lead
  • B-: Right motor red lead
  • B+: Right motor black lead
  • VIN: Battery red lead
  • GND: Battery black lead

My kids, aged 8 and 9, were able to do much of the assembly but we needed to check the wires were firmly connected as getting them into the screw connectors was a bit fiddly.

(You can see some LEGO add-ons in the photo, more on that in the next post.)

Controlling the Cars with the DoItCar App

The cars can be controlled via an app called DoItCar. You turn a car on and then connect your devices Wifi to the car. If you have multiple cars and devices them turn them on one at a time and make a note of their names. 

Once connected to Wifi, run the DoItCar app and choose Local Connection (hide the keyboard to see this option.) Then you get simple controls which allow you to turn the car left and right, move forwards and backwards and to pause. 

We used the app successfully on a Kindle Fire HD (via the Google Play Store) and on a Google Nexus tablet. 

The app connects easily and reliably, and the controls work, but the interface isn't quite what we want for battling and at some point we'll want to control weapons. We'll be looking at replacing this with a custom controller. 

But for now we've got the basics of our battling robots.

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