US Patent 7689379 Method of determining measurement probe orientation

A dimensional measurement probe (10) is mounted in a machine tool (48), which reorientates the probe about at least one axis A. Strain gauges (34) sense when a stylus (20) of the probe contacts a workpiece (50), to produce a trigger signal. False trigger signals may be produced when the probe is reorientated. To overcome this, the reorientation is detected by monitoring changes in the fluctuations of the strain gauge outputs, caused by vibrations of the stylus.