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Holonomic Systems

This type of system uses wheels with rollers on them and by placing the rollers at an angle to each other and powering each wheel with a motor, the force vectors between wheels can be changed. This allows the robot to move in 2 different planes and rotate. The two types of roller wheels used for this purpose are the omni directional wheels (sample P/N: 276-2185) and the mecanum wheels (P/N: 276-1447). The omni wheels are usually placed on the corners of the robot frame with the wheels placed at 45o to the corner. The mecanum wheels achieve the same action by the rollers set at 45o so the wheels can be in line with the robot frame. Special care must be used in placing the mecanum wheels so the rollers are in opposition to one another (see diagram below). (A.K.A. X holonomic)

Pros

  • can move in 2 different planes (front to back and sided to side), plus pivot
  • very hard to trap in a corner
  • very effective for lining up with game pieces
  • there is a holonomic joystick block for ease of programming in EasyC V4

Cons

  • requires a motor for each drive wheel
  • because the force vectors are always in different directions, the resultant force vector of the motors is never equal to the summation of the forces.
  • easily pushed from any direction that is not being powered
  • longer time may be required for driver training and driving the orientation of robot can sometimes be challenging
  • multiple motors draw more current and use up motor ports on controller
  • does not climb field obstacles well

Special note: another popular variation to the holonomic system is to orientate the omni wheels at 90o to one another. (A.K.A. H holonomic)

                                             
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