Rule 1 of Sumo club is we don t talk about sumo club!

Transcription

1 SumoBot Notes 1

2 The SumoBot Game General Overview: Two robots placed in the ring, facing away from each other. At the start of the match each robot must travel to the edge of the ring before it can engage the other. The first one to push the other out of the ring wins. Game Rules Rule 1 of Sumo club is we don t talk about sumo club! Robots are placed in the centre of the ring, back to back. Any opponent locating sensor such as an ultrasonic sensor must be facing to the outside of the ring at the commencement of a bout. Opponents must travel directly to the outside of the ring and physically turn around before engaging the opponent. If any part of a robot touches the ground outside the ring they immediately lose the match. In the event of a section of the robot becoming detached, if it is still tethered to the robot and touches the ground outside the ring the robot loses that bout. If the detached section is completely detached it is no longer counted as part of the robot and therefore will not be considered in determining whether a robot wins or loses. In the event of both robots leaving the ring at once, the losing bot is the one that touches the ground first as decided by the judge In the event of a simultaneous ground touch, the bout will be rerun. Each bout is best of 3 (3rd bout will not be run if a team wins two in a row). Robot must weigh less that 1000 grams. All bot must use wheels of any size. Caterpillar tracks style bots are not permitted. Before activation, a robot must pass through a 220*280mm square in plan and must not be higher than 180mm in elevation. A robot cannot be designed to inflict damage to the opposing robot. Destabilising devices are allowed but spinning objects are not permitted. If two robots are locked together for more than 30 seconds, the bout may be reset at the judge s discretion. If the bout continues for 1 minute or more without opponents engaging, a null bout will be declared with neither opponent scoring a point. If at the end of the 3 bouts each robot has won one each then the judge will declare the winner based on future potential performance. 2

3 The Ring (Dohyo) A raised circle 1.2 m in diameter. The surface is painted white, around the edge is a black circle 5 cm wide. SumoBot Building We find that it's best to construct your SumoBot bot in a series of steps. 3

4 1. Decide how your motors are going to be connected together to make a solid chassis. This may or may not include the NXT/EV3 brick. Make sure they are connected in at least two places to ensure that they don't twist, and make sure they are aligned squarely to each other. Use lots of black studs. 2. Add the NXT/EV3 if it's not part of the original drive chassis. Once again, make sure you have at least two points of connection. Four is even better. 3. Add the third wheel, skid or slider that will keep your robot on an even keel. A wide base gives the best support, and if you use a wheel, it's best to remove the tire to enable the robot to turn smoothly. 4. Add a line sensor. It's important that it is about 5mm off the ground pointing straight down. These should be in front of the forward-most ground-contact point of the robot to ensure that they sense the black line BEFORE the robot reaches the edge. 5. Add the ultrasonic sensor once everything else is on the robot. This must be at the front, pointing forward, level to the ground, or tilted slightly down. Ideally it should be 50-75mm off the ground. 6. Finally add the cables to the motors and sensors. Ensure that NO parts of the robot are anywhere near the front of the eyes as the SumoBot will start chasing it's tail (so to speak). General SumoBot Building Tips 1. When two well-built robots compete, the tires become the deciding factor. The better the tires grip the ring surface, the more the robot can shove and the less the robot can be shoved. Unless severely underpowered, motors rarely stall; almost always the tires spin. Narrow, worn tires spell disaster. Wide, clean, abundant tires spell victory. Don t stifle creativity, tracks and even legs should be considered. 4

5 2. A scoop or arm is vital. Anything that shifts the opponent s weight of off its wheels is desirable. A scoop can both reduce the grip of the opponent s wheels (by tilting weight off) and also increase the grip on the scooper s wheels (by tilting the opponent s weight on top). Also, a scoop may topple or tip an opponent onto its side or over the ring edge. Grabbers and pushers should also be considered for similar reasons. 3. Dark robots are more difficult for the opponent s infrared or light sensors to see. Fuzzy-surfaced robots are more difficult for sonic sensors to detect. 4. Slick, encased robots are more difficult for the opponent to grip or accidentally damage. 5. Although not required, infrared or other opponenttargeting sensors improve a robot s chances of contacting the opponent in a motion with the greatest forward momentum. Additionally, a robot with opponent sensors is less likely to get struck from an undesirable angle, such as on the side or from behind. To get started the following provides a basic starting point for a SumoBot but to be competitive you will need to put a lot of thought into the physical design of your SumoBot. NXT EV3 DomoBot The core kit comes with a booklet for a basic robot. This can also be found in the start menu of the EV3 Mindstorms software. Riley Rover: from classroom-robot-design.html Tommabot: from 5

6 Game Playing Basic Strategy There are two major tasks that your SumoBot will need to be able to do in order to be competitive. Firstly it needs to be able to find the edge of the ring and then turn around. At a basic level if your Bot can continually drive forward to the edge of the ring and turn around you can enter the SumoBot competition Secondly it needs to search for the opponent and charge when the opponent is located, while still staying in the ring. Finding the edge of the ring This can be done in two ways. Using senor wait blocks: o Start the motors running. o Wait until the colour sensor sees black. 6

7 Using a loop and a switch: o Inside a loop use a switch that is conditional on the colour sensor. If black, stop, reverse. If not black (white), move forward turning. o You can use the colour sensor in either colour model or reflected light intensity mode. In a switch, the top section is executed if the conditional statement is true. The bottom section is executed if the statement is false. Finding the Opponent The objective here is to find the opponent using a sensor such as the ultrasonic sensor then charge at the opponent while ensuring that your Sumobot still stays within the ring. This requires nested switches inside a loop: Inside a loop you need a switch that is checking whether you are on the playing surface. o If no, then turn around. o If yes then enter the second switch based on the ultrasonic sensor: o In the second switch, if the opponent cannot be seen, turn in a circle at low speed looking for the opponent. If the opponent can be seen then charge full power. 7

8 Take care when you turn the motors on, if you ask for a set number of revolutions or time, the execution will stop whilst the motors are turning. Setting the motors to On, allows the execution to carry on, leaving the motors running. 8

9 Tips and common problems 1. Remember a motor block can be switched on, switched on for a period of time, switched on for number of rotations or switched off. If the motor block switched on for a period of time or a number of revolutions the execution of the program will stop until that task is done. That means it will be stuck at that block, not going round the loop looking for the line or opponents. For our use, it is always best to have a motor block simply switched on. 2. Check that your motor ports on each block match the motor blocks on the Sumobot. 3. Check the sensor ports match the sensor ports on the SumoBot. 4. Check that your Mindstorms Brick is charged. 9