Measuring probe with field generating coil configuration and temperature compensation

A method of operating a measuring probe for a coordinate measuring machine,

• the measuring probe comprising:
• a stylus suspension portion, comprising:
• a stylus coupling portion that is configured to be rigidly coupled to a stylus with a probe tip;
• and
• a stylus motion mechanism that is configured to enable axial motion of the stylus coupling portion along an axial direction, and rotary motion of the stylus coupling portion about a rotation center;
• a stylus position detection portion arranged along a central axis that is parallel to the axial direction and nominally aligned with the rotation center, comprising:
• a field generating coil configuration comprising at least one field generating coil;
• a sensing coil configuration, comprising:
• top position sensing coils, comprising:
• at least one top axial sensing coil;
• at least four top rotary sensing coils;
• at least one top normalization sensing coil;
• bottom position sensing coils, comprising:
• at least one bottom axial sensing coil;
• at least four bottom rotary sensing coils;
• and
• at least one bottom normalization sensing coil;
• a disruptor configuration comprising a conductive disruptor element that provides a disruptor area, wherein the disruptor element is located along the central axis in a disruptor motion volume and the disruptor element is coupled to the stylus suspension portion, wherein the disruptor element moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion, the field generating coil configuration generating a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal;
• signal processing and control circuitry that is operably connected to the coils of the stylus position detection portion to provide the coil drive signal and configured to receive signals comprising respective signal components provided by the respective sensing coils, and provide signals indicative of an axial position and a rotary position of the probe tip;
• and;
• the method comprising:
• providing a coil drive signal to the field generating coil configuration to cause the at least one field generating coil to generate a changing magnetic flux, wherein a temperature dependent component of a temperature dependent compensation portion is coupled to a field generating coil of the field generating coil configuration such that a change in a characteristic of the temperature dependent component due to an increase in temperature of the temperature dependent component causes relatively more current to flow through the field generating coil when driven by the coil drive signal than if the characteristic of the temperature dependent component had not changed;
• and
• receiving signals from sensing coils of the sensing coil configuration.

A system, comprising:

• a measuring probe;
• a drive mechanism configured to move the measuring probe three-dimensionally for moving a probe tip along a surface of a workpiece for measuring the workpiece;
• and
• an attachment portion attaching the measuring probe to the drive mechanism, wherein the measuring probe comprises:
• a stylus suspension portion, comprising:
• a stylus coupling portion that is configured to be rigidly coupled to a stylus with a probe tip;
• and
• a stylus motion mechanism that is configured to enable axial motion of the stylus coupling portion along an axial direction, and rotary motion of the stylus coupling portion about a rotation center;
• a stylus position detection portion arranged along a central axis that is parallel to the axial direction and nominally aligned with the rotation center, comprising:
• a field generating coil configuration comprising at least one field generating coil;
• a sensing coil configuration, comprising:
• top position sensing coils, comprising:
• at least one top axial sensing coil;
• at least four top rotary sensing coils;
• and
• at least one top normalization sensing coil;
• bottom position sensing coils, comprising:
• at least one bottom axial sensing coil;
• at least four bottom rotary sensing coils;
• and
• at least one bottom normalization sensing coil;
• a disruptor configuration comprising a conductive disruptor element that provides a disruptor area, wherein the disruptor element is located along the central axis in a disruptor motion volume and the disruptor element is coupled to the stylus suspension portion, wherein the disruptor element moves in the disruptor motion volume relative to an undeflected position in response to a deflection of the stylus suspension portion, the field generating coil configuration generating a changing magnetic flux generally along the axial direction in the disruptor motion volume in response to a coil drive signal;
• signal processing and control circuitry that is operably connected to the coils of the stylus position detection portion to provide the coil drive signal and configured to receive signals comprising respective signal components provided by the respective sensing coils, and provide signals indicative of an axial position and a rotary position of the probe tip;
• and:
• a temperature dependent compensation portion comprising a temperature dependent component, wherein the temperature dependent component is coupled to a field generating coil of the field generating coil configuration such that a change in a characteristic of the temperature dependent component due to an increase in temperature of the temperature dependent component causes relatively more current to flow through the field generating coil when driven by the coil drive signal than if the characteristic of the temperature dependent component had not changed.