摘要 |
An object of the invention is to provide a position measuring apparatus which can execute a stable accuracy assurance at a high accuracy against a deterioration with age and a temperature fluctuation of the apparatus while making a correction of an existing volumetric measuring accuracy effective. In order to achieve the object, in accordance with the present invention, in a position measuring apparatus which measures a target position within a specified coordinate space with respect to a predetermined reference surface (4) on the basis of a coordinate system so as to compensate errors, there is provided a detector (18) for measuring whether or not a change is occurred in a relation with respect to the reference surface (4), in a movement executed by a moving machine (8), and there is further provided with an error corrector (20) for correcting at least any one of a compensation parameter compensating a positional coordinates by an error compensator (16) and a positional coordinate compensated by the error compensator (16), on the basis of an amount of change of a relation measured by the detector (18), in the case that the change is occurred.
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