Fig. 2.

Schematic of the geometric relations and the coordinate system of the stage (scaled drawing). {W}, {B}, ${\mathbf{u}}_1^W$ and ${\mathbf{u}}_2^W$ is the world frame (fixed frame), the body frame (moving frame), and the input velocity vector of linear actuators in x^W and y^W direction, respectively. The parameters denoted by * represent the known values due to the structure or measurements.