Let's Make Robots!

Nano Sumo (Electronics)


I give you the Nano Sumo bot, a collaborative project between myself and Gary. View Gary's post on Mechanics here

I think this bot "is" many things. Smallest robot using the Arduino bootloader ? Smallest robot with a microcontroller on LMR? Best use of Solarbotics Planetary Gear Boxes? 

At the heart of the Nano Sumo is my custom designed micro-controller. It uses a Atmega-328 with a Arduino bootloader programmed into it via the on board ICSP socket. It also has a FTDI programming port for programming it with the Arduino IDE. It measures 21mm x 23mm and has 3 analog inputs, 2 PWM outputs, and 4 I/Os. The PCBs were made by Seedstudio. The Eagle files are available for download here.




The pin layout is designed to mate perfectly with the Sparkfun 1A Dual Motor Driver. The outputs of the Nano’s micro-controller board plug directly into the inputs of the motor controller. This allows for the control of 2 motors with PWM for speed control and breaking. The only other needed connection is a wire providing power to the motor controller.


The power source is provided by a single 50mAh 20C li-poly battery. this provides the system with 4.2v when fully charged and can supply up to 1A. A female connector was added on the end to mate with a male connector on the bottom of the micro-controller and on the charger.



A charger had to be built for this battery. The charger i built uses a Maxim 1555 Li-poly charger IC. It has a LED status light to show that the battery is charging. The charging is powered by a 4 AA battery pack so there is no need to be near a wall outlet to charge. The circuit was completely built on a Sparkfun breakout board (seen as the red PCB in the picture)



There are 2 sensors on the Nano sumo robot. One is an analog reflectance sensor and the other is a digital obstacle detector. The analog sensor is your common line sensor that can sense black and white. This sensor is used to stay in the sumo ring, because if you leave the ring, you lose. The obstacle detector is a very tiny digital sensor that gives either a 1 (no obstacle detected) or 0 (obstacle detected) reading. This is a surface mount sensor that does not come assembled. I soldered it together with no problems, but it was not easy. The sensor has a range of 6 inches, which is just about right for this class of sumo. 


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Or, failing that, what would be an adequate drop=in replacement for this type of project? Something with similar specs and pinout to a 328?

mostly something surface mount. You could go with a non arduino compatible AVR or PIC. But good luck finding the chip i used for sale :P.

A success in many different ways.  Collaboration, execution, craftsmanship, and documentation all excellent.

Very impressed with the final product, and had an instant vision of SWARMING !!!!!

Imagine more of the little bots with a IR receiver and a top mounted webcam & IR Transmitter attached to a computer.  The little guys would dance around making rotating circles and rotating squares, spirals, and all sorts of dances, pictures and patterns and even spell LMR ... 

For the webcam & OpenCV to work better they should have little directional hats under there IR rxs.  Then, the resolution of the spelling might have to wait until you guys are making 100 per day :D

Would look very cool though.

Greatly appreciate the comment, and very much like the picture editing :). I could see many of these doing a synchronized dance, they could open up for robotic olympics :)

If you put little covers over the two sides and the back, each with a different color (e.g., red, green, blue), then they could move in formation to make different pictures depending which way they were facing. ; j

BTW, I love the video of your nano pushing little paper opponents out of your practice ring. Have you tried him out against dummy opponents that are closer to the maximum weight for a nano sumo? I

Haha! This is amazing! Love it! It is even more cool than I thougth! :D

Very impressive work on both yours and garys side. I love it!

Now I have a couple of questions. For the smd parts(cap, resonator, resistors), did you just source those from digikey or a warehouse similar?

For the atmega, was there a reason why you didn't just use the paste and do the reflow on that at the same time?

Did you have a fine point time on the iron?

Did you follow a tutorial on doing the reflow, like for instance, how did you get the times for the oven temps?

Again, very impressive work....PM!

Thanks for the comment.

The smd parts came from digikey

I reflowed some atmegas on some of the boards and they didnt work, i found out some of the boards had problems and i was down to 2 atmegas, these were given to me by someone because you couldnt buy these anywhere. Basically i did not want to screw up the last 2 i had so to eliminate another variable, i took the time to hand solder it. I think reflowing them would have  been fine but i didnt want to take that chance. 

Its just the normal tip that comes on a soldering station iron. Conical ?

I was following this for the most part http://www.openhardware.net/Misc_Stuff/ToasterSMD/

Thanks for the info, I'd been unsure of going to smd but you seemed to be able to pull it off pretty well.

Btw, have you tried to remove the other atmegs from boards that failed? I've seen some vids on youtube where people have done this to upgrade to a higher end proc where the source was included for the original.