Open-loop distance adjustment for a coordinate measuring machine

A method for automatically controlling a distance between a non-contact measurement probe head of a coordinate measuring machine (CMM) and a work piece during a measurement process, the method comprising the steps of:

• providing nominal steering commands regarding a lateral movement of the probe head relative to the work piece, the nominal steering commands being configured to provide steering of the work piece and/or the probe head through a measuring path comprising a plurality of measuring positions,
• performing at a first measuring position a first measuring step comprising:
• providing first distance adjustment steering commands configured to provide setting of the distance between the probe head and the work piece,
• projecting a primary measuring beam pattern onto the work piece, wherein the primary measuring beam pattern providing a plurality of measurement points,
• acquiring a secondary measuring beam pattern, wherein the secondary measuring beam pattern originating from an interaction of the primary measuring beam with the work piece,
• deriving surface information based on the acquired secondary measuring beam pattern,
• wherein probe distance target data regarding a target distance between the probe head and the work piece being provided,
• the first measuring step further comprising:
• deriving first probe distance information regarding the distance between the probe head and the work piece based on the acquired secondary measuring beam pattern,
• deriving a first probe distance deviation based on the probe distance target data and the first probe distance information,
• providing the first probe distance deviation to be processed in a step of providing second distance adjustment steering commands for performing a second measuring step at a second measuring position.