Method and machine for determining a space coordinate of a measurement point on a measurement object

A coordinate measuring machine for determining during a measurement run at least one space coordinate of a measurement point on a measurement object, comprising

• a displacement mechanism having a first and a second movable support,
• a probe head arranged on the displacement mechanism for approaching the measuring point,
• a first and a second measuring instrument for determining a first displacement position of the first movable support and a second displacement position of the second movable support, respectively,
• an actual difference formation unit for determining an actual difference value between the first and second displacement positions,
• a memory for permanently storing and providing a static difference value representing a static difference between the first and second displacement positions, said static difference value being determined by means of a previously conducted calibration run and then stored in the memory, and
• a calculation unit for determining the space coordinate of the measurement point, the calculation unit comprising a subtractor for subtracting the static difference value from the actual difference value in order to obtain a dynamic difference value, and further configured to correct the first displacement position using the dynamic difference value in order to obtain a pre-corrected displacement position, and subsequently correct the pre-corrected displacement position by using the static difference value, thereby determining the space coordinate of the measurement point.

A computer program product comprising program code configured for carrying out a method, when executed on a processor of a coordinate measuring machine, comprising the following steps:

• approaching the measuring point with a probe head arranged on a displacement mechanism which comprises a first and a second movable support,
• determining a first displacement position of the first support and determining a second displacement position of the second support,
• determining an actual difference value between the first and the second displacement positions,
• receiving a static difference value which represents a static difference between the first and the second displacement positions, said static difference value being determined by means of a previously conducted calibration run and then stored in a memory,
• subtracting the static difference value from the actual difference value in order to obtain a dynamic difference value,
• correcting the first displacement position using the dynamic difference value in order to obtain a pre-corrected displacement position, and
• subsequently correcting the pre-corrected displacement position by using the static difference value,
• thereby determining the space coordinate of the measurement point.

A method for determining at least one space coordinate of a measurement point on a measurement object, comprising the steps of:

• approaching the measuring point with a probe head arranged on a displacement mechanism which comprises a first and a second movable support,
• determining a first displacement position of the first support and determining a second displacement position of the second support,
• determining an actual difference value between the first and the second displacement positions,
• providing a static difference value which represents a static difference between the first and the second displacement positions,
• subtracting the static difference value from the actual difference value in order to obtain a dynamic difference value, and
• determining the space coordinate of the measurement point as a function of the dynamic difference value and the static difference value,
• wherein the measurement point is approached by means of at least two drives, a first drive moving the first support, and a second drive mechanically independent of said first drive for moving the second support, and further wherein the first and second drives are actuated by a common electronic regulator which receives the dynamic difference value as an input quantity.