Method to determine a control parameter in a measurement control system

Abstract

N pieces of gains Gare sequentially and temporarily set in a control circuit (), and a stylus () is brought in contact with a workpiece (W) for conducting a temporary measurement. At this time, a sensor detection signal output from a sensor detection circuit () is filtered by a filter () to take out only a frequency component corresponding to a frequency of hunting generated in a closed loop (L) including the control circuit (). Gains Gthat do not generate hunting in the closed loop (L) are extracted, and the largest gain Gis set in the control circuit () in view of enhancement in responsivity etc. of the measurement. Alternatively, by pressing the stylus () into the workpiece (W), a displacement signal indicating a pressing amount and a sensor signal output from a sensor () are measured in accordance with a measurement load applied to the stylus () to calculate a gain G' of the sensor () based on the two signals. By compensating the gain of the control circuit in accordance with the gain G′, frequency characteristics of the measurement control system can be kept to the largest even when the stylus () or the workpiece (W) is replaced with another one having different properties.