Autonomous Sumo Combat Robot with Pneumatic Flipper - How to

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This Sumo Bot was designed, built, programmed and tested over a 12 week period for one of my final year engineering classes. The aim was to design and build a lightweight fully autonomous sumo fighting robot for an in class Sumo Bot competition. The robot was required to push, lift or flip the opponent’s robot out of the arena.

There were two physical restrictions which the sumo robot must abide by. The robot must weight no more than 1000g and is required to fit within a 200mm x 200mm x 300mm (WxLxH) measuring box. Other restrictions included the robot had to be completely autonomous with zero human interaction, must cost under $150 AUD (not including the micro-controller) and the robot must begin each round in the same orientation in which it was place in the measuring box. 

We were given the option for adding a lifting/flipping system to our robots. I knew it would require a lot more work but I couldn't resist the temptation of adding a "weapon" to the bot.

The Arena
The arena was circular with a diameter of 1.54m with a matt black surface and a 2cm wide white line around the perimeter.

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Step 1: Components

Picture of Components
This section contains a list of items required in making the Sumo Combat Robot. It has been split into two parts, the first is a list of items which were purchased and the second is a list of items which were scrounged from previous projects. All purchased items contain a link to the suppliers website.  

Cost Items

2 x Motors 47:1 Metal Gearmotor 25Dx52L mm HP

1 x Motor Controller 10A H-bridge Dual DC Motor Driver Controller / High-power Strong braking

4 x Pulley Hub FingerTech Timing Pulley 26T 

2 x Belt FingerTech Timing Belt 276mm (92T) 

4 x Wheels Dave Brown Lite Flite Wheels 2" 

4 x Line Sensors TCRT5000 Module Line Tracking Photoelectric Sensor

3 x Sonar HC-SR04 ultrasonic sensor distance measuring module

1 x Battery ZIPPY Flightmax 1300mAh 3S1P 15-25C 

2 x Pneumatic Cylinder Air Actuator 25mm  

1 x Tank 100CC Air Cylinder 

1 x Pneumatic Switch Servo Operated Air Retract Actuator (Air up/Down)  

1 x One way valve One Way Air Refill Valve 

1 x Tubing Air retract pipe D3x1.7mm x 1m 

1 x Indicator LED ShiftBrite 

 Non-Cost Items                                                                                    USE
Aluminium Sheet  50cmX50cmX1mm________________________ Chassis
Aluminium L-Section _____________________________________Chassis support
Super Glue____________________________________________Sensor mounting
Tarzan Grip___________________________________________ Wheel to pulley mounting
Pop Rivets____________________________________________ Chassis assembly
Double Sided Tape______________________________________ Insulation, component mounting
Heat Shrink____________________________________________ Insulation
Connecting wires_______________________________________ Interface with components
Power Switch__________________________________________ Main power cut-off
Selection Button_________________________________________ To select between attack/evade modes
Solder_________________________________________________ Component wire connections
ATMega128 Microcontroller ________________________________Sumo robot controller
10 wire IDE Plugs________________________________________ Connect sensors to the microcontroller
Microcontroller power plug_________________________________ Deliver power to the microcontroller
Zip Ties________________________________________________ Hold pneumatics in place and tidy up electronics
Elastic Bands___________________________________________ Support pneumatic cylinder
M3 cap screws_________________________________________ Hold front wheel pins in place
Transistor______________________________________________ Switch motor controller on and off
Resistor_______________________________________________ Limit current to transistor
9g Servo_______________________________________________Control pneumatic switch
Female Crimp Pins_______________________________________ Connect microcontroller to the motor controller
Crimp Pin Housings______________________________________ Insulation over crimp pins
Electrical Tape__________________________________________ Insulation
0.8mm Steel Wire________________________________________ Link servo to the pneumatic switch
6mmX6mm square bar ____________________________________Flipper arm connection
Aluminium Sheet 20x15x3mm_______________________________Flipper arm
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Amazing! One of the few instructables worthy of being on this website! I love it!
kmmarlow (author)  FLIPminoman1 year ago
Thanks mate, I had a lot of fun working on it.
I will be uploading some of the other project I've been working on when i get time.
Please vote for me in the competitions.
Thanks again
jjjohnjoel9 days ago



Motors 47:1 Metal Gearmotor 25Dx52L mm HP


34:1 AND 75:1 MOTOR OF 6 V ...WHICH SHOULD I USE......




ckoufalia6 months ago

nice job i have a question i read somewhere that all sumobots is needen to have an IR kill switch what is this thank you

Sory for my english

kmmarlow (author)  ckoufalia6 months ago

Not exactly sure what they would have meant by an "IR kill switch". Ive used an 433Mhz wireless kill switch before which 'kills' the bot.

I think they was to be able to stop the bot without having to touch it.

thank you a realy helpfull answer

амалов6 months ago

прикольная хреновинка =)

I have been working on mine for a college competition for one of my courses. So far it works great. I wish we could use sonar rather than the IR LEDs and detectors.

kmmarlow (author)  invisiblelight3867 months ago
Nice looking bot! In some cases IR world better than sonar. You could try and convince your lecturer to let you use a laser pointer and the same detector (you'll get pinpoint accuracy and a longer detection distance)

Another thing, if you spend a couple hours polishing up your bot it will make it difficult for the other bots to detect yours. .. Depends how sneeky you want to be.

Good luck in the comp!

I'm going to try and make a spring loaded flipper that would be contact activated. There is one sumobot that is almost invisible to my sensors, and I could use a new tactic.

kmmarlow (author)  invisiblelight3866 months ago

you could easily integrate a contact sensor (micro switch) into a design with any ling of flipper system.

If you used a microswitch on the front of the flipper which activates it when touched.

Good luck defeating that pesky opponent :)

M3RCIL3SS8 months ago
Hey what code did u use, please help, if u could give the code that would be cool
it will be powered by arduino
kmmarlow (author)  M3RCIL3SS8 months ago
Hi, The code i wrote was for implementation on a atmega 128 AVR micro-controller so it will not be very helpful for the arduino.

Step 12 of the I'ble has some flowcharts which accurately outline my method used for the AI and the logic for the Flipper control.

Hope that helps.
Message me if you need assistance with any specifics.
makesomeso8 months ago
i like your instructable very much and its cool. nice work. this is one of my favorite instructable.
aaron012710 months ago
Hey loved your ineluctable. My schools is entered in bots IQ. (battle bots) and we are doing a wedge design with a pneumatic flipper on the front like yours. I was wondering if you could give me some insight on how to do a good flipper.The bots can weigh up to 20 pounds. we are only allowed 8 cubic feet of at 150 PSI. Thanks and hope to hear from you soon.
kmmarlow (author)  aaron01279 months ago
Thanks, (Also sorry for the really late reply) For a ~10kg robot 150PSI is Heaps. Its more about the mechanical design of the flipper and the pneumatic ram itself than the pressure of the tank. (howerer all work together in making a good flipper)
Tool such as this can help you get an idea of the 'full bore piston diameter' you require to achieve the force you need to lift an opponent. the larger the ' full bore piston diameter' the more force the piston will output, however increasing its size will also slow the flipping speed and use more compressed gas per flip.

The flipper should be as close to the ground as possible and when activated flip high enough or hard enough to roll the opposition over.

The basic principle of levers need to be considered "most flipping mechanisms will be "Third-order Levers". A good resource is

Another option is to use a four bar linkage such as Which lifts and pushes into to the opponent at the same time.

3D Computed aided design software such as google sketchup or SolidWorks are great for quickly looking at different flipper designs. Also lego technic is a valuable prototyping tool.

Any more questions just let me know.
Best of luck in the competition, and trust me, you will learn HEAPS for competing.

That's an awsome robot you got there!
kmmarlow (author)  gunnlaugursig11 months ago
Thanks it was great fun building it!!
dcruz1311 months ago
Awesome project! this gave me a lot of ideas for my final year project, where I'm planning to build a sumo robot using fuzzy logic on its operative mode.

As I'm new on prototiping, wich softwares do you suggest to schematics simulation?
Did you used some simulation software for the robot, like "testing" its behavior like reallife?
kmmarlow (author)  dcruz1311 months ago
Basically this bot is a purely reactive robot. So all of the testing (simulations) were done one the fly.
However other programs i know of which can simulate robots are Microsoft Robotics Studio and Matlab, there are heaps of others out there. plus heaps of peer reviewed papers on fuzzy control.
Good luck mate, and most of all, have fun!
goodiesohhi11 months ago
Don't you usually need manual control in combat robotics?
kmmarlow (author)  goodiesohhi11 months ago
Depends which comp you go in. This was made for a fully autonomous combat comp. Some also allow a combination of both, or only manual control.
Yep. I just need the materials.
I know right.... same.
What if you ground down some parts i.e. the flipper or saw blades?
kmmarlow (author)  Inventors Unite1 year ago
The issue with isnt the weight of the saw blade itself, its the weight of the motor required and probably the fly wheel which will undoubtedly be needed.
If weight wasnt a problem then it would be very simple to add in a saw blade. Thinking of building a bot?
Is it possible to add saw blades that come out the bottom?
kmmarlow (author)  Inventors Unite1 year ago
Anythings possible, however keeping it with the flipper and adding in a saw blade would put it over weight.
darkbain1 year ago
I love this Instructable. I've never seen the mini pneumatics before and now I'm all excited. Might have to get a set just for kicks. Thanks for posting. Also Grats :).
kmmarlow (author)  darkbain1 year ago
Thanks mate.
Yeah the mini pneumatics are awesome to play with. I have a spare set waiting for my next bot build.
Treknology1 year ago
At last! I'm delighted to see battle bots whose goal is simply to win, not total destruction.

One doesn't really comprehend the miniaturization until the PC-PSU comes into play (kudos to that designer for "cheap and replaceable").

You've done an excellent job of fitting what is really complex by i'ble standards into only 12 steps.
kmmarlow (author)  Treknology1 year ago
Thank you, I was trying to organise everything in the i'ble so it flows and is simple to understand for a novice but include enough info for a more experienced person.

Thanks again
That was really great! I thought that "shorter" bot near the end was going to take you, but yours pulled through. Well done!
kmmarlow (author)  KryptoCleric1 year ago
Yeah I know :) ! You could imagine how I felt in that last round, super nervous.
webby01211 year ago
Wow, this is awsome! Is this robot under 1.362kg?
kmmarlow (author)  webby01211 year ago
Yep sure is, Its final weight came in at 999.4g (0.9994kg)
It had to be under 1kg
xMSIx1 year ago
Robot Wars!
kmmarlow (author)  xMSIx1 year ago
You better believe it!!
chuckyd1 year ago
IT's good to see someone building a robot instead of building a remote controlled toy and calling it a robot.
kmmarlow (author)  chuckyd1 year ago
Agreed, Fully Autonomous things can also be much more fun to build. Mainly because of the challenges in implementing the autonomy.
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