Patent ID: 8468869

Claim:
A method of calibrating a group of parameters in an articulated coordinate measuring apparatus, the group of parameters including primary calibration parameters and secondary calibration parameters, wherein an articulated measuring arm of the apparatus is operated and a probe mounted to one end of said measuring arm is brought into contact with a measurement point on an object to be measured in order to measure a space coordinate of said measurement point, the method comprising: placing a primary standard unit having a plurality of primary calibration reference portions in an operation space of said measuring arm; operating said measuring arm to bring said probe into contact with each of said plurality of primary calibration reference portions in order to measure a space coordinate of each primary calibration reference portion at a plurality of arm positions, said plurality of arm positions corresponding to said primary calibration parameters, said primary calibration parameters being parameters in which parameter errors increase more than a predetermined reference when a predetermined time period passes; performing a parameter calibration process of said primary calibration parameters based on measurement results of said plurality of primary calibration reference portions; placing a secondary standard unit having a secondary calibration reference portion smaller in number than said plurality of primary calibration reference portions in the operation space of said measuring arm; operating said measuring arm to bring said probe into contact with said secondary calibration reference portion in order to measure a space coordinate of said secondary calibration reference portion at a smaller number of arm positions than said plurality of arm positions, said smaller number of arm positions corresponding to said secondary calibration parameters, said secondary calibration parameters being parameters in which parameter errors increase more than a predetermined reference when a shorter time period than said predetermined time period passes; and performing a parameter calibration process of said secondary calibration parameters based on measurement results of said secondary calibration reference portion.