A METHOD AND AN APPARATUS FOR COMPENSATING FOR GEOMETRICAL ERRORS BETWEEN WORK OBJECTS AND A HOLDING DEVICE

The present invention relates to a method and an apparatus for compensating for errors in a certain number of degrees of freedoms in the geometric relation between a work object (1) and a device (2) holding the object. A measurement system including at least one sensor (3) is providing surface measurements on the object. The method comprises measuring a first reference surface (10) of a reference object, calculating the position and orientation of the first reference surface based on the measurements, moving the reference object in a first degree of freedom, measuring on the first reference surface, calculating the position and orientation of the first reference surface after the moving based on the measurements, repeating those steps for at least the same number of degrees of freedom as the number of degrees of freedom in which the object may have errors in relation to the device, performing the same procedure for at least two more reference surfaces (11, 12, 13), calculating the position and orientation changes of all the reference surfaces, and calculating a relationship between the calculated position and orientation changes and corresponding changes of the position and orientation of the object. Using the relationship for compensating for the errors in object position and orientation.