Mini 11

It is the pink robot in the video below:
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Robot Challenge 2011:
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Akir4 is the name of the mini sumo-robot I built in 2011 and is my third mini-sumo. sw_vanster_liten.jpg
This time compared to the first two mini sumo-robots the robot was first designed in a CAD program. This approached is great since you have to solve all design issues from start compared to having a general idea in your head and solving each issue as you go. To build it without a detailed CAD drawing often means that you run in to problems which you haven’t taken into account and have to redo your design or even start from scratch. On the other hand, making a detailed CAD drawing will take a lot of time especially when you take into account every screw and screw hole and use exact measurements from the parts you are going to use.


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Motors: 4x Pololu Micro Metal Gear HP 50:1 (HP=High Power=important!)
Servo for scoop: MG995 (eBay)
Proximity sensors front: 4 x Sharp GP2Y0D340K, 2 Sharp GP2Y0A21YK
Proximity sensors rear: 3 x Sharp GP2Y0D340K
Proximity sensors sides: 4 x Sharp GP2Y0D340K
White Edge detection: 6 x ITR8307
Accelerometer 3 axis: MMA7341L
Wheels: 4 x custom made with casted tires (See description below)
Battery: LiPo 3cell custom made from three single cell 600mAh(eBay).
Milling parts
The parts was then produced using a CNC mill, the CAD drawings was converted into machine instructions (g-code) using CAMBAM. The parts that were milled were the motor mounts, wheels, and all part for the scoop.
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Casting tires
The tires of the wheels are made of polyurethane. Vitalij Rodnov over at Baltic Robot Sumo have written an excellent guide of the casting technique.


The two big PCBs was designed in Eagle and thereafter ordered for production. The clearances were to small as well as the vias to many to produce it in our lab. The PCB for the scoop however was produced in our lab. img_3600_2_small.jpg
Microcontroller master (top board): ATmega324
Microcontroller slave (bottom board): ATmega168
Voltage regulator (Switched from 11.1V to 5V): LM2576T
Motor controllers (h-bridges): 2 x MC33887
Bluetooth module (external, plugs in on the side): RN-41

Assembled robot.

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Protective layer of polycarbonate and painted pink.

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The robot as it looks after have running some competitions.

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Gold Swedish Championship 2011
Gold Swedish Championship 2012

31 thoughts on “Mini 11

  1. Hi there very nice blog!! Guy .. Beautiful .. Wonderful ..
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  2. hey, could you give me an idea of how your movable scoop functions?
    is it a servo, a quick-release with a solenoid, or something else?

    also i think i will use ultrasonic sensors instead of IR, mainly because of cost, but also i’ve read that they’re more reliable. what made you choose IR?

    thanks! nice robot.

  3. Hi,
    I’m pretty new to building robots in general and even newer at sumobots. This is one of the first times I’ve looked at multi uC robots and PCB based robotics. so my question is what is the purpose of the PCB? and how that was designed and or the way to build one and design one?

  4. Hi,

    Great mechanical construction !! I have a question about the motors wiring. They are wiring in serial or in parallel ?? thanks in advance

  5. Hello Again! :))

    I was in a shopping spree in pololu’s website, and i bought four “50:1 Micro gearbox (HP 620rpm), 4 Solar Botics wheels + rims (RW2i) and some necessaries (Sharp IR, etc..). I was just wondering, most of my metal gearbox motors burn within a year of competition.

    How’s your gearhead motors doing? Are two, 2cell LiPo batteries enough to spin the gearheads without burning the brushes easily? I’m a bit cautious with these since these gboxs where shipped to a distant place, going to the Philippines.


    • Welcome back Ascas.

      I run my motors in parallel on 3 cell lipo. This gives extra power but will shorten the lifetime quite a lot.

      Do you have any link to the competitions in the Philippines, or link to the robot you are building?

      Best Regards

      • ahm well the pmw(pulse modulation wave) I was thinking to use that in my robot , but Im wrong cause it can lose torque….so Im designing a robot sumo but now my real problem are the motors (pololu gearbox), caus I want to buy 2 with high torque but is low power
        whats the diference after all?I mean the realationship between torque and high power ., what is better?…ahhh I almost forgot it

    • Hello Michael.
      According to the rules for Mini(500g) Sumo the restriction is a 10x10cm base with unlimited height. After the start the robot is allowed to expand in size. In the start when the scoop is up Akir4 is aprox 9.8 x 9.8 cm and the weight is aprox 490g.

      Best Regards

  6. I’m such a huge fan of your bot. How’s the torque going on with your Pololu mini Gbox? Since Mini sumobots in our country have a larger size restriction (15X15cm) should I buy the larger Version of the pololu Minis to increase torque, BTW the speed is almost similar.

    We were also wondering how you combined two ATmega chips to increase pins (l2C). We somehow did it, although the codes are somehow in the prototyping stage.

    We would surely appreciate your help and advice!

    • Hello ASCAS thanks for your nice feedback.

      The torque of the pololu motor is really high. If you buy them make sure to buy the ones called HP(high power). For a bigger robot you might wanna have bigger motors but make sure to compare the rated torque, there are several bigger motors that have less torque than the pololu mini.

      Yes I use I2C to comunicate between the two ATmegas, but I have had some trouble with it. I would rather recommend using SPI or UART.

      Good luck with your robots!

      • I just bought 4 of these wonderful “HP 50:1 pololu gearboxes”. I don’t have a problem finding LiPo batteries, since I have tons of them here.

        Did you connect the same sided motors in series (total consumption of 12v), is that cause of using 3 cell LiPo batteries (11.4V)?

        If my theory serves me right, connecting same sided motors in parallel (6v) while using 3 cell LiPo batteries (11.4v) could easily wear out the brushes. I’m just need to be careful of these brand new babies 😀

        • See my answer above, but yes you are right 11.4 will drastically decrease the motor life but do give it a bit of extra power.

          • Peter, can you help me in launching my site. I have my codes ready, made from scratch 🙂 . I have never tried to buy a domain or host my own site, I usually register to subdomains, I don’t get that much viewers around in free hosting. Could I ask? How do you run your site “ ” Do you pay a monthly bill? Thanks!

            By the way, I’m almost finished with my documentation about my new sumobot. For the mean time my old version is in here . My old one is kinda sluggish :/ so as the competitors 🙂 It includes my videos during the competition and my previous sumo prototype (750/rpm Mini) 😀 Feel free to browse my profile. Thanks for the support by the way!

    • If you can fit that many sensor what would be the logic to fit less?
      In robotics the more information you have about your surroundings the better. With many sensors you for example don’t have to spin to search for you opponent.

      • In the final of your’s video which you’re called eight final round you was losen by a mini sumo. What is the insufficiency of your perfect designed robot to cannot win that robot ? However their robot seem not powerfull to beat your akir4 what makes them powerful what do you think ?
        Thanx for your patiently answers 🙂

    • I have two big pcb’s one in the top and one in the bottom and one uC for each. I have a lot of sensors and it would be hard to fit all sensors on one uC. Now I only need a 4 pin connector to connect them (gnc, vcc i2c clock, i2c data).

  7. Hey Akir4!
    I just came across your website and i had a few questions about your sumobot.
    1. What commands did you use for the sumo when programming it?
    2. What is better, flat plow, curved, or angled?
    3. What are the main points you have to hit on in order to have a sucessful sumo? (eg. bigger wheels = traction etc)

    • 1. I don’t understand your question? it is programmed in C.
      2. I would say that a sharp plow is the best, if you get under your opponent then it doesn’t matter if it is curved or not.
      3. A well tested robot that doesn’t fail or run out of the ring by itself is a great start. Then I would say that speed, good scoope and good sensors are key. Traction and Stealth are also interesting factors.

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