Omni Wheels in Robots

  • Robocup Middle Size Robot League (MSL)

In a middle size robot league in Robocup competitions two teams play soccer. Each team has 5 robots as players and the soccer game occurs in an indoor field with 18×12 meter as its dimension. One of the most important equipment which a middle size robot should have is an on-board computer. Moreover, each robot has some sensors in order to analyze the game situations. In order to self-localize and to detect the location of their teammate, opponents and the ball they use omnidirectional cameras. The middle size robots should be fully autonomous and no human invention is allowed during a match. Moreover, the goalkeeper of the middle size team can have a laser scanner or depth cameras. The robots in each team has inner-team communication through wireless LAN, so each has some information about their other teammates. In addition, they receive some referee commands too. The ball used in the Robocup middle size league is an official FIFA approved. The rules of the MSL about handling, tackling and controlling the ball in the match have been tried to be as same as to the law of human football matches. Some rules of the Robocup middle size league are as follows:
  • After a team players gain the ball control and before scoring, the players have to make at least one mandatory pass.
  • Each middle size robot of a team must fill a 52cm×52cm×80cm box and frontal area of the goalkeeper robot can be 62cm.
  • Each middle size robot must have a maximum weight 40kg.
  • The predominant color of each middle size robot must be black.
Robocup middle size league is very challenging, since the teams have some extra freedom to design both Mechatronics and software. Most of middle size teams in Robocup, design a holonomic mobile based which uses three or four Omni directional wheels. The Omni Directional Wheel is a kind of wheel that can freely role in more than one direction which does not need to rotate first for moving from one point to another in a straight path. The main goal of the Robocup middle size league or MSL is to approach to the FIFA compliant robot soccer, however the robots are not human like.
  • Robocup small Size Robot League

In a small size robot league in Robocup competitions two teams play soccer. Each team has 6 robots as players and the soccer game occurs in an indoor field with 6.05×4.05 meter as its dimension and green carpet. There are two camera bar which placed above the soccer field in 4m height. A standard vision system (SSL-vision) is used in order to analyze these two camera data. Each robot gets its referee commands and the information about their teammate positions through some on-field computers. All these communications are wireless. Each small size robot of a team must fill a 180mm diameter circle with 15cmm height Omni directional wheels have some significant advantages so they are popular in small size robots too.
  • Robocup Junior Soccer Robot League

Robocup Junior events are designed for young students as primary and secondary school and undergraduates who cannot involve in senior leagues. The junior soccer league is based on education. It gets the young students a chance to involve in an international competition and helps them to experience cooperation, competition, teamwork and robotic fields as electronics, hardware and software. A RoboCup junior team should have more than one member and each soccer team consists of two robots. In fact, a 2-on-2 soccer play is held in a landmark field in junior soccer leagues. The mobile robots are fully autonomous and play in a highly dynamic environment. The ball is an infrared transmitting one. There are two main league in the Robocup junior: Lightweight league and Open league. Some rules of the Robocup middle size league are as follows:
  • Each soccer robot must fit a cylinder with 220mm diameter and the height less than 220mm.
  • Each soccer robot must have weight as below:
Open league: 2.5kg and Lightweight league: 1.1kg
  • Robots must be fully autonomous and be able to be started manually
  • The communication of the 2 teammates is allowed only via Bluetooth or ZigBee
  • The robots must disable their communication at the referee request.
Soccer robots must be able to move in all directions so using Omni directional wheels is highly recommended.