摘要 |
The position of a working point relative to a working space, such as a working point of a carriage on a gantry beam of an XY positioning table, is determined by measuring at least two sets of displacements. A first set of displacements, of the working point relative to an intermediate component, such as the gantry beam, includes a relatively large displacement (X) in a first linear degree of freedom and relatively small displacements (Y1', Y2'), in at least two of the five degrees of freedom other than the first. The second set of displacements, of the intermediate component relative to the working space, includes a relatively large displacement (Y1, Y2), in a second linear degree of freedom, and relatively small displacements (X1', X2'), in at least two of the five degrees of freedom other than the second.
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