What Is A Sumo Bot?

This project was inspired by the competition style of sumo robotics of which an example can be found here. Two bots are placed in a black ring with a white border with the objective being to autonomously knock the other bot out of the ring. This is why it makes a good project when it comes to the use of sensors.

In this instructable, I will guide you on how to create a mini sumo bot of your own. It is a great project to pass some time or to even start a robotics event of your own. It is compact, full of learning opportunities and very fun to play with.

Supplies

Bill Of Materials

Green PLA
2x SG90 Continuous Servos
HC-SR04 Ultrasonic Sensor
Infrared Sensor
2m Red Jumper Wire
2x M4 Bolts
2x M4 Hex Nuts
1x Lithium Ion Battery 3.7V 3600 mAh
1x Li-Ion 18650 Battery Holder
TP4056 Li-Ion Charging Module
5V DC-DC Boost Converter
Arduino Nano
Small Breadboard
Blue Tack
2x Wheels
2x M3 Small Screws (For Servos)
1x SPDT Switch

Helpful Equipment

3D Printer
Dremel Kit
Hot Glue Gun
Computer

Step 1: 3D Printing the Chassis

First, download the attached file and open it up using the software FlashPrint or another 3D printer software. Save this file onto an SD card and insert into the 3D printer. After setting up the printer, loading the filament and heating the extruders, print the design.

SumoWD2final.gx
Download

Step 2: Sanding Down the Chassis (Refinement)

Once the chassis has been printed, the supports will need to be removed. Using a chisel or bevel, these can be pried off with ease. A file can also be used to smoothout and cleanup rough edges. Although take care so as not to destroy the chassis or hurt your fingers.

Step 3: Putting the Wheels and Servos Together

For this step, the servo must be combined with the wheel securely in order to ensure that it doesn't fall off during competition. This joint can be accomplished by screwing the two parts together which makes for a strong joint.

Step 4: Attaching the Servos to the Chasis

Once the wheels have been attached to the servos, the can now be fitted to the chassis permanently. The best way to do this I found was to use a hot glue gun as its strong enough to hold the servos to the chassis, but it also allows for any changes to be made to the positioning of the servos if ever necessary.

Make sure the servos are aligned properly and in the correct orientation when fitting them to the chassis!

Step 5: Adding the Front Roller Ball

This step is pretty straight forward as the two holes for the screws have already been shaped out. Just line up the roller ball with the chassis and secure the two components together using M4screws and hexnuts.

Additional hex nuts can be placed in between the roller ball and the chassis acting as spacers to reduce the downward sloped angle of the sumo bot.

Step 6: Adding the Breadboard and Sensors

First, secure the infrared sensor to the front of the bot using hot glue while making sure the sensor is able to clearly scan the ground below it. Next, secure the ultrasonic sensor to the necessary holes at the front of the bot as can be seen in the photos above.

Finally, add in the breadboard with the Arduino nano on it to the center of the bot and secure it using blue tack so that it is easy to remove in times of troubleshooting and repair.

Step 7: Creating the Battery Management Circuit and Adding It to the Chasis

The Lithium ion battery should be connected in parallel with both the TP-4056 Li-Ion charging module and the 3V-5V step up booster. Make sure to connect jumper wires to terminals of the correct polarity during this process.

When soldering remember to take care by staying aware, working in a well ventilated area and by wearing eye protection.

A switch should be placed on the positive output of the 5Vboost converter in order to allow for the bot to turn on and off. The output of the DC-DC converter goes directly to the Arduino Nano's power input.

Step 8: Code, Arduino Nano and Circuitry

First of all, in order to program the Arduino Nano, you will need to download the Arduino IDE and the necessary drivers for the Nano. After doing this you should be able to upload the code linked below by connecting your computer to the nano via a USB to Micro-USB cord.

Next, using the diagram above, connect each of the necessary components and sensors to the Nano.

The 2 Servos should be connected to pins 9 and 10.
The infrared sensor should be connected to an analog pin (this sensor is not included in the code as it competition specific only - should be added by the user)
The HC-SR04 ultrasonic sensor should have its echo pin connected to pin 5 and its trig pin connected to pin 4.

Once this is done, test out the bot and make any adjustments necessary.