Feb 16

K3MOSAB3 (2014)


Hello. When I left the Community for the first half of this year, I missed SprinkleOtter’s SumoBot challenge. I know I’m way too late to actually compete, but I decided to build one anyway. The result is K3MOSAB3 (kee-moh-sah-bee), an EV3 SumoBot with super-intelligent programming and clever mechanisms to bring it to victory. I would like to thank Karl4123 for all of his help and advice that was instrumental in bringing K3MOSAB3 to life. Continue on to “Additional Information” for more.

See a video of K3MOSAB3 here: https://www.youtube.com/watch?v=xvn5osELITs

See K3MOSAB3 battle an NXT clone of itself here: https://www.youtube.com/watch?v=VMIIPn8NoQc



The construction of K3MOSAB3 draws some inspiration from DamonMM2000’s SumoBot. The design of K3MOSAB3 most reminds me of the FLL robots I build: tall wheels, a lot of sensors and tons of stuff jammed into a compact footprint. Motors B+C are EV3 Large motors that directly drive the wheels; no gears. These wheels were chosen because they’re the grippiest LEGO makes and their tall diameter allows K3MOSAB3 to move about swiftly. The rear wheels are HiTechnic Rotacasters, which allow K3MOSAB3 to change directions efficiently. Motors A+D are EV3 Medium motors that run the jack and pivot wheels, respectively (more on that in the next section.) A Gyro sensor is tucked away just ahead of the left rear wheel. A color sensor up front scans the floor, and lastly, the Infrared sensor keeps a lookout for opponents ahead. The entire robot is encased in a rigid frame that protects K3MOSAB3’s internals.

Forklift Evasion


While perusing over other SumoBots, I noticed that so many robots have a forklift of some sort that lifts up its opponents front wheels, rendering it helpless. So, I devised a clever way to prevent K3MOSAB3 from becoming ensnared. The result is my favorite part of K3MOSAB3, the Forklift Evasion system. When the Gyro sensor detects K3MOSAB3’s front being lifted up, it will deploy a rack-and-pinion jack to first lift the front off of the opponent’s forklift. Now, the wheels on K3MOSAB3’s rear bumper will activate, pivoting it around and away front its opponent before dropping back down again. And voila, K3MOSAB3 is free again!

Program: Sumo-K Auto

Full Program

In the main program, the three sensors monitor the environment and choose between various algorithms based on the sensors’ readings. At the start of the program, K3MOSAB3 eliminates Gyro drift by using Karl4123’s wonderful fix. Then, it moves toward the corner, where it waits for its opponent to come by. Until K3MOSAB3 detects its opponent with its IR sensor, it will run the “Searching” algorithm. It will drive forward for 2 seconds, then stop and sweep its sensor 90 degrees to the left and right. If nothing is sighted, it will repeat the process. If K3MOSAB3’s Color sensor detects it starts to drive out of the arena, it will stop, reverse, then turn around. If the Gyro senses the front being lifted, K3MOSAB3 will deploy the “Forklift Evasion” algorithm, as explained above. If the IR sensor detects the opponent (within 28 inches), K3MOSAB3 will deploy the “Opponent Charge” algorithm, where it will charge forward at 100% power until it reaches the end of the mat in an attempt to push its opponent out.



K3MOSAB3 features some of my most in-depth programming, right up there with the Plethora II. What it may lack in brawn, it makes up for in clever gadgets and intelligent programming. And, true to its name, K3MOSAB3 will always find its opponent. (“Kemosabe” means “trusty scout” in Potawatomi.) In conclusion, I am very pleased with K3MOSAB3, although I wish I could have entered SprinkleOtter’s competition. And I would again like to thank Karl4123 for all of his help. Thank you for reading and see you next time

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