Probe head for scanning the surface of a workpiece
AssigneeRenishaw PLC
InventorsGeoffrey McFarland, Kenneth Cheng Hoe Nai, Nicholas John Weston, Ian William McLean
Life of this patent
Estimating the term…
Abstract
A measurement system has a surface sensing device mounted on an articulating probe head, which in turn is mounted on a coordinate positioning apparatus. The surface sensing device is moved relative to a surface by driving at least one of the coordinate positioning apparatus and probe head in at least one axis to scan the surface. The surface sensing device measures its distance from the surface and the probe head is driven to rotate the surface sensing device about at least one axis in order to control the relative position of the surface sensing device from the surface to within a predetermined range in real time.
Claims12
An articulating probe head comprising;
- a first member;
- a second member that is mounted for rotation with respect to the first member about a first axis:
- a third member that is mounted for rotation with respect to the second member about a second axis, and on which a surface sensing device is mountable, the second and third members providing rotational movement of the surface sensing device about the first and second axes;
- and
- a first rotary measurement device acting between the first and second members to measure an angular position of the surface sensing device about the at least one first axis,
- wherein a first error map is provided that relates to, separately from other errors in the articulating probe head, measurements of the angular position made by the first rotary measurement device about the first axis,and
- wherein the first error map is derived from errors in measurement of the angular position of the third member about the first axis while the third member is mounted on the second member.
A measuring system comprising:
- a motorized probe head, onto which a surface sensing device is mountable, the motorized probe head including:
- a first member:
- a second member that is mounted for rotation with respect to the first member about a first axis;
- a third member that is mounted for rotation with respect to the second member about a second axis, and on which the surface sensing device is mountable;
- a first motor acting between the first and second members to produce rotational movement of the surface sensing device about the first axis;
- and
- a first rotary measurement device that measures the rotational movement about the first axis;
- and
- the measuring system further comprising a processor that is configured to receive a positional input from the first rotary measurement device and to send an output to control the first motor of the motorized probe head,
- wherein the first rotary measurement device has a calibration that is separate from other errors in the motorized probe head,
- wherein the calibration of the first rotary measurement device is derived from errors in measurement of the angular position of the third member about the first axis while the third member is mounted on the second member, and
- wherein the processor is configured to compensate in real time for errors derived during the calibration of the first rotary measurement device when the processor creates the output to control the first motor from the positional input.
Dependencies are inferred from the claim text.