By Cameron Loyd and Jonathan Spalten
It’s been several long years since RoboWrestling has gone to competition, but the time has finally come. We’ll be presenting a high level overview of their robot, Kirbi, and covering Kirbii’s debut at Robogames 2023.
The RoboWrestling team was created to compete in autonomous sumo competitions, a specific brand of combat robotics in which small but mighty bots compete to push each other out of a metal ring, called a dohyo. For RoboJackets members who haven’t had a chance to watch a robot sumo match, it’s an intense race of speed and precision, and we recommend viewing the short video below for an overview. This year, RoboWrestling will be traveling to California to compete in the autonomous sumo division at RoboGames. This is the first year that sumo is back in the US after RoboGames 2019 was canceled, so this is an exciting opportunity for the team to experience a real competition environment!
The work over the past years on Kirbii has been subjected to highs and lows. The lack of competition over the past few years has stunted parts of the design process as well as knowledge transfer from previous team members. Despite the setbacks, the team has been working hard and is excited for competition. On the mechanical side, the goal was to make the robot as robust as possible. Sumo robots are subjected to strict size and weight restrictions, so the focus is on developing a competitive advantage while keeping in mind physical tradeoffs. The mechanical subteam prioritized a good blade, the key part of the robot that leverages up the opponent off the ring, and an arrangement of strong magnets on the bottom of the robot. Since the dohyo is made of steel, the array of magnets give Kirbii an effective weight of over 300 pounds, though the robot’s real mass is only 3 kg. The goal with Kirbii’s mechanical design is to drive the blade underneath opposing robots to reduce their hold on the field and drive them out of the ring. Likewise, the higher Kirbii’s effective weight is, the harder it will be for opponents to leverage the robot off of the field. The mechanical team has also built their own dohyo, which has enabled the team to test-drive their robots and gain more experience before competition.
The electrical subteam has also made several improvements to Kirbii’s design. The new electrical configuration uses one motor controller for both motors, as opposed to the previous design which had two separate motor controllers. The single Sabretooth motor controller has improved specifications like higher continuous amperage and consolidated control signals, which will help with robot operation and simplify the circuitry. Like its predecessors, Kirbii also uses a pair of distance sensors to find its opponent on the ring. The two sensors are multiplexed together before connecting to the teensy microcontroller. Overall, the mechanical and electrical foundations of Kirbii are solid and ready to compete.
The software team is responsible for the strategy that Kirbii employs at competition. With such quick match times and consistent environmental surroundings, simplicity is king. The team opted for a hunt-and-seek strategy, affectionately known as slammy whammy. The algorithm uses data from the distance sensors to determine the opponent’s location. Then, there’s a threshold for action defined by a minimum distance to the opponent plus agreement from the multiple distance sensors on the opponent’s location. Once this threshold is met, Kirbii launches its attack by going full speed to plow the opposing robot off the field.
The competition at RoboGames 2023 was small compared to previous years. There were a total of 3 robots present, including RoboJackets. Kirbii was able to win its first match against Turtlebot, a new competitor that did not employ magnets to increase its effective weight on the ring.
The other robot present was against the Kimauánisso Robotics Team from Brazil. They are tough competitors and consistently place high in any competition they attend. While Kirbii did lose to them to get second place, Kirbii did not go down without a fight and did get into pushing matches that led to a point reset.
The main goal of this competition was to get as many team members on RoboWrestling experience in the competition environment. Although this was a smaller competition, the team hopes to be able to qualify for the All Japan Robot SumoTournament this December as the United States’ representative now that international teams are able to compete for the first time in four years. RoboJackets consistently attended this competition before the COVID pandemic. The team at RoboGames was a total of 12 members. Jason Katz, RW PM and now Vice President, emphasized:
As of now, there are no current members in RW who have been to comp, because our first year as an official team was 2020. Our last comp before [in 2019] everyone was on the way out graduating. … If we go to Japan, we’re not going to be able to bring 12 people, but we want the team to know what it’s like.
RoboWrestling as a whole is going through a rebuilding period after a long period of not being able to attend competition, first because of RoboGames’ cancellation, and then because of travel restrictions from the pandemic preventing international competition. Notably, Kirbii was designed before the current team started in RoboWrestling. To help with this transition, the team is considering going to smaller weight classes like 500 g to enable faster iteration, as 500 g sumo robots can be produced using exclusively 3D printed materials and do not use magnets on their wooden arena. In the future, the team hopes to use the 500 g robots as an experience for new members to find their footing, much like BattleBot’s 3lb program, while having more experienced members work on the larger bots. The team hopes this will allow them to bring more robots (and therefore, members) to RoboGames while still being able to compete at the highest level of competition in Japan.