Omnidirectional robot models have no fewer than three identical omnidirectional wheels or Mecanum wheels (hereinafter collectively referred to as Mecanum wheels), and they are distributed in at least three quadrants of the robot base coordinate system. Since the wheel roller angle (the angle between the wheel axis and the roller axis, ranging from 0~90°) is a chassis parameter, the Mecanum wheels are required to be installed in an O-shape, that is, the projection distance from the origin of the robot base coordinate system to the roller axis (hereinafter referred to as roller axis) of each wheel in contact with the ground is longer, to eliminate the ambiguity of the roller axis directions in different quadrants, as shown in the figure below:
The layout of the wheels also needs to meet the following requirements:

1. Must not be placed on the coordinate axis of the robot base coordinate system, otherwise the roller axis direction will be ambiguous;
2. Cannot make all Mecanum wheel roller axes parallel to each other;
3. Cannot make all Mecanum wheel roller axes intersect at one point.