Adding sensors to my 3pi to make a sumo bot


I got a 3pi for Christmas and have had a play and have some code that makes it stay inside a ring. I want to be able to add some proximity sensors to the front so if it detects something I can move towards it with an aim to push it out of the circle.

Has anyone done this and can you recommend sensors to use? There are many types (Light and Sound) and sensitivities available and I can’t decide which is best (read easiest) to use.

I have a m3pi expansion board but have not added an mbed controller yet so I am limited ot how many ports I have available.

Thanks for reading

Hello, Dave.

You can see the available pins in the “Pin Assignment Table Sorted by Function” in the Pin Assignment Tables section of the 3pi user’s guide. Which type of pins you use (digital or analog) will depend on the sensor you choose.

However, we do not recommend using the 3pi Robot for sumo competitions. If you are looking for a sumo robot, you might consider something like our Zumo Robot.


Thanks Derrill,

Why wouldn’t you recommend it for a competition, is it just that it’s not designed to be bashed around?
To be honest I was only going to have a “friendly” match with a friend who also recently got a 3pi.
I have thought of protecting the 3pi around the pcb as I don’t want any impacts damaging it.


As you already speculated, the 3pi is not intended or designed to take impacts like those in a sumo competition, so I strongly recommend not using it like this. The 3pi chassis is basically just the exposed PCB, so components can easily be knocked off. The Zumo I mentioned in my last post has a plastic chassis, and most of the components are better protected from impacts.