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Video: Getting Started with Sumo Robots
Introduction
RoboChallenge Sumo was adapted from robotic sumo rules that are used in international events for robotics hobbyists. Like Tug O'War, designing sumo robots requires mechanical skill and knowledge of structures, but it also requires more sophisticated programming, as well as more advanced strategy than Tug O'War. Sumo tournaments can be extremely exciting events.
(Note: in our current rules the board should be BLACK not white)
In international robot sumo, there are several different categories that are distinguished by size and mass. The smallest of these are 25g and 2.5cm X 2.5cm. These are Nano sumos. There are micro sumos that are 100 g. But the most popular sizes are mini sumo (500g and 10cm X 10cm) and full size (mega) sumo, 3kg, 20cm X 20cm. In international robot sumo, the designs can be extremely complex, can cost thousands of dollars, and are designed by top-notch engineers.
For RoboChallenge Sumo, we have rules that allow students to build larger robots that enable builders to use LEGOs or other educational robotics systems to create interesting designs. Our robots are limited to 30cm x 30cm size, and 1kg (1000g) mass. Our robots can be built with low cost LEGO robot materials, which are usable by kids of all ages.
(Note: in our current rules the board should be BLACK not white)
Note for Teachers: Sumo is appropriate for students of all ages K-12. You will need to have access to robotics materials such as LEGO Mindstorms, Mindstorms NXT, or another robotics format, such as VEX. The information on this web page and the video offer tips and recommendations assuming that LEGO materials are being used, but Sumo need not be limited only to LEGO materials. The time required to build and program Sumo bots could be as short as a few hours for older, experienced students, or a few weeks for younger kids, depending also on how often students are able to work on their projects. For the youngest students it may be necessary for them to copy specific templates to program their robots.
Materials and Resources Required:
- LEGO Mindstorms, Mindstorms NXT, or other Robotics materials
- Computers and programming software (often included with robotics materials)
- Flat surface
- Sumo Board (A circular black board with a white border).
- stopwatch
Instructional Information
- Grade Level/Age: K-16 (8th grade science standards make nice connections)
- Curriculum Standards Applied: Science, Mathematics, Technology
- The Engineering Design Process (see the resources at the bottom of the page)
- Evaluation: An instructor can use the Robotics Project Rubric at the bottom of this page
This tutorial, and the accompanying video, cover the following main topics (click on a topic to go to that section)
Sumo Rules
Two Sumo Robots attempt to push each other off of a circular board. The Board is black with a white border. Robots can use a variety of designs, programs, and sensors. There is no perfect Sumo bot.
Basic Rules
- Maximum mass: 1kilogram (1000 grams)
- Robot must be safe
- The robot must wait 5 seconds before moving
- The robot loses the round if it falls out or is knocked out of the ring
- For more detailed rules, see the RoboChallenge Rules Page.
Running Matches and Tournaments
It's easy to set up a match between two Sumo robots. Running a competition with several robots can require a little more preparation, but is also not terribly difficult. 90% of the time, the winner in a Sumo match is very easy to determine; one robot will be pushed out of the ring. Only rarely do you need to use the rules governing ties or awkward situations.
In each match, a robot must win 2 out of 3 rounds. Ties can occur, and if necessary, tiebreaker rounds can be held. See the Rules page for more information.
Space
Sumo can be run in a variety of situations. Nearly any room can be used, as long as there is a flat surface like a floor or large table. Sumo competitions can also be run outdoors, but some robots may experience problems due to the brightness of sunlight. If an event is to be run outdoors, it is important for the robots to be programmed and designed to operate in bright light. Some tips on this can be found in the Building section of this page. To make Sumo a nice spectator event, it is useful to have seating and bleachers or an elevated stage. College lecture halls work nicely.
Basic Supplies
To run a match, at a minimum, the following supplies are necessary: a sumo board, a stopwatch, and a flat surface. If there are many robots, it is helpful to have more than one Sumo board.
To check to see that the robot meets the mass and size requirements, it is useful to have a ruler and a balance, especially an electronic balance that is capable of measuring more than 1 kg.
Elimination Chart
A Sumo tournament can be a simple match between two friendly robots, or a massive event with dozens of robots from several schools. Categories by age can be established for larger groups if necessary, though in our experience with RoboChallenge, we have seen the robots of very young elementary students compete very well against those built by high school and college students.
Tournaments can be run single elimination style for large groups, or for 7 or fewer robots, a round-robin style approach can be used. It is important to place robots randomly in a single elimination tournament. A whiteboard is useful for making sure everyone can see how the tournament is progressing, to avoid mistakes in match-ups, and to add to the level of excitement as the tournament proceeds.
Handling Difficult Situations
The following are some of the things that can come up in a Sumo event that may require the judges to intervene. These situations are dealt with for the most part in the rules, but is important to know that these situations can arise from time to time.
Tangled, Stuck or Dancing Robots- Sometimes the Sumo round isn't going anywhere because the robots are stuck, immobile, or they are moving in a circular manner that will not allow either robot to win. In RoboChallenge, we separate robots after a few seconds, and start the round again. Whatever time elapsed is subtracted, and the round continues until 1 minute has passed. This avoids long, boring situations, and helps reduce the occurance of ties.
Both Robots fall out at the same time- When both robots fall out, the one that falls out first loses. But in the case where both robots leave the board at about the same time, the judge should determine which robot caused the event. The robot that was the aggressor should be the winner. If it is not clear which robot was the pusher and which was pushed, call the round a tie.
False Start- Sometimes the robot operator doesn't hit the botton correctly, or otherwise causes the robot to malfunction. If this is noticed before the 5 seconds of wait time have passed, start the round over again to give them another chance.
No Show- Sometimes a competitor is not around because of other events or activities. If you can, skip that matchup and come back to it, in the spirit of enabling maximum participation. But don't allow a missing competitor to delay a match. Declare a forfeit, and move on.
No program or incorrect program- Sometimes programs get changed or lost on the day of a tournament. If you can, allow them to reprogram the bot before the event begins. It perfectly fine and encouraged for a robot to have more than one program, in case one doesn't work, it can use another. A robot that cannot be reprogrammed in reasonable time should withdraw.
Interference- It's important to keep people and competitors from touching or bumping the table, or touching the robots during the rounds. A competitor who interferes with the round loses the round. If a spectator interferes, the round should be done over. In sumo, where ultrasonic sensors may be used, it's very important for people to not be close to the competing robots.
Robot falls off table- If the competition is being done on tables, competitors and judges should attempt to catch a robot that tumbles off the side to avoid excessive damage.
Robot cannot be repaired quickly- The judges should make an effort to allow a few minutes for repairs to take place between rounds if necessary, but should use judgement to prevent delays. If a robot is beyond repair, a competitor should concede the match.
Adult Intervention- Generally, our events are kid-centered, though it's entirely possible that such an event could have adult competitors as well. Consequently, it should be students, not adults, designing, programming, operating, and repairing the robots. Younger kids may require more adult assistance, but Junior High and High School students should be doing almost all of the work themselves. If judges need to, they may ask adults not to repair students' robots or otherwise interfere with the tournament.
Building Easy Sumo Bots
Sumo robots are usually wheeled robots, usually with four wheels, powered by two motors. Sometimes, they use tractor treads. They can be built to use ultrasonic sensors to find their opponent, or light sensors to "bounce" from one side of the board to another. Here are some ideas for building some very basic Sumo Bots.
RCX Sumo Bot
Here a few examples of basic Sumo bots that can be built and programmed with Mindstorms RCX (The Robotics Invention System). One easy way is to use the instructions included with the Mindstorms Robotics Invention System 2.0 to build the basic driving base with 4 wheels. To improve the traction, you can try adding weight to the robot. This robot will need a light sensor mounted to the front, pointing downward
If you do not have these instructions, or have a different version, the instruction booklet can be downloaded from LEGO. Got to LEGO's building instructions download page, and do a search for the brand "Mindstorms" or enter 3804 into the quick finder.
Link to LEGO's Building Instructions Page: http://us.service.lego.com/en-US/BuildingInstructions/default.aspx
After you've started with a robot such as this, you can experiment with gears, wheels, and mass to build other basic "box" like designs. Think also about how your design distributes weight so that it doesn't tip or fall over, and so that the wheels have maximum traction.
For Sumos, it is important to consider that your robot will push and be pushed. Some sumos have scoops or walls on the front and/or back for pushing, and they may have some kind of structure to prevent other robots from getting under them or hitting them from the side.
Here are a few more examples of Sumos built with RCX LEGO's. Some are based on the basic robot above. To see more, see the links at the bottom of this page.
To program your RCX bot, you can use Robolab. We have bought Robolab for many schools in the Santa Barbara County region to use for building robots for RoboChallenge. The following is an image of a basic Sumo Robot program. With little modification, a program such as this could be used with many possible Sumo robot designs.
You can download a file with this program here:
DOWNLOAD LINK
NXT Sumo Bot
Any basic bot with wheels can be used as a Sumo Robot, including the standard rover-type bot that can be built with the instructions included with the NXT robot kits. Using an ultrasonic sensor, and/or light sensors it relatively easy to get started with Sumo.
This sumo robot is based on the basic rover that can be built with the educational LEGO NXT kits.
The website NXTprograms.com has a nice Sumo Bot
Here is another simple design that uses gears to provide power to 4 wheels. Click on the pictures to get a closer view.
Once you have a basic wheeled NXT robot, you'll need to program it. This is pretty easy using the Mindstorms NXT-G software.
Such a program might look like this:
DOWNLOAD LINK
Example NXT Sumo Bots
Advanced Designs
Here are a few ideas for some more advanced designs for Sumo robots.
Protected Mechanical Components
You can design your sumo so that it shields and protects the working parts of your robot, such as wheels, gears, and sensors. The protective shielding can be some form of wall, wedge, or bumper.
This robot, Torque, uses 2 light sensors and two ultrasonic sensors. It has the ability to "see" a robot in two directions, and it uses the light sensors to avoid driving past the white border.
Compound Gearing
You can decrease the speed of your robot and increase the amount of force it can produce by using gears. There is a video on Compound Gears in the gallery. Link- Video on Compound Gears.
Wedges
A wedge can get under your opponent's robot and cause it to lose traction.
Multiple Motors
If you can find a way to use multiple motors, sometimes you can build a bot with a lot of kinetic energy. The small design below is an example of such a robot, using Mindstorms RCX It uses 4 separate motors to power 4 wheels, but two on each side are wired together, sharing a power source. This bot was built to be under 500 grams for international minisumo rules.
Additional Resources
Teaching Robotics
Where to Buy LEGO Robotics materials
Photos of Sumo Robots
Videos from RoboChallenge Competitions that include TugO'War Tournaments
Videos that Feature International Sumo Events, including mega, mini, and micro sumos
Programming and Building Instructions Resources
The Engineering Design Process
Students can learn and apply the design process for solving technical problems and developing solutions for robotics challenges. This process can be used for solving many kinds of problems, and is used heavily in science and engineering. The process includes the following steps, in a cycle:
Identify the need or problem
Research the need or problem
- Use the internet, books, and other resources. Find out how similar problems have been solved.
Develop possible solutions
- Brainstorm possible solutions
- Use mathematics and science
Select the best solution
- A concept that best meets the need or solves the problem
Construct a prototype
- Draw diagrams and build models of the concept.
Test and evaluate the solution(s)
- Use measurement, observation, and run tests on the models.
- Does it work and does it meet the design constraints?
- Share your ideas with others so that they may provide input.
Redesign
- Overhaul the solution(s) based on test results and new input.
Communicate the solution(s)
- Create a report that explains the problem and solution, so that others may learn from your work.
The Robotics Project Rubric
Instructors can use this rubric for evaluating students and their work on robotics projects.
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