Portable coordinate measurement machine
First Claim
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1. A portable coordinate measurement machine (CMM) for measuring the position of an object in a selected volume, comprising:
- a manually positionable articulated arm having opposed first and second ends, said arm including a plurality of joints;
a measurement probe attached to a first end of said articulated arm;
an electronic circuit which receives the position signals from transducers in said arm and provides a digital coordinate corresponding to the position of the probe in a selected volume; and
wherein at least one of said joints further comprise;
a periodic pattern of a measurable characteristic;
at least one read head spaced from and in communication with said pattern;
said pattern and said read head being positioned within said joint so as to be rotatable with respect to each other; and
at least one sensor which measures relative movement in said articulated arm with respect to said at least one read head so as to improve the measurement accuracy of said at least one read head.
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Abstract
A portable coordinate measurement machine comprises an articulated arm having jointed arm segments. The arm includes joint assemblies which include at least one read head together with one or more (preferably five) sensors (preferably proximity sensors) in communication with a periodic pattern of a measurable characteristic, the pattern and read heads being positioned within the joint so as to be rotatable with respect to each other.
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Citations
69 Claims
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1. A portable coordinate measurement machine (CMM) for measuring the position of an object in a selected volume, comprising:
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a manually positionable articulated arm having opposed first and second ends, said arm including a plurality of joints;
a measurement probe attached to a first end of said articulated arm;
an electronic circuit which receives the position signals from transducers in said arm and provides a digital coordinate corresponding to the position of the probe in a selected volume; and
wherein at least one of said joints further comprise;
a periodic pattern of a measurable characteristic;
at least one read head spaced from and in communication with said pattern;
said pattern and said read head being positioned within said joint so as to be rotatable with respect to each other; and
at least one sensor which measures relative movement in said articulated arm with respect to said at least one read head so as to improve the measurement accuracy of said at least one read head. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 19, 21, 24, 27, 28, 30, 31, 32, 33, 35, 36, 44, 45, 46, 47, 48, 49, 50)
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- 10. The CMM of claim 10 including a plurality of sensors for measuring relative movement between said shaft and said housing.
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11. The CMM of claim 11 wherein said shaft is rotatable.
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12. The CMM of claim 12 wherein said at least one sensor includes:
at least two sensors for measuring relative movement of said shaft including a first sensor for measuring X axis displacement and a second sensor for measuring Y axis displacement.
- 13. The CMM of claim 13 wherein said plurality of sensors for measuring relative movement of said shaft further include a third sensor for measuring X axis rotation, a fourth sensor for measuring Y axis rotation and a fifth sensor for measuring Z axis displacement.
- 14. The CMM of claim 14 wherein said at least one read head measures Z axis rotation of said shaft.
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20. The CMM of claim 20 wherein said relative movement is caused by deformation of bearings in said joints.
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22. The CMM of claim 22 wherein:
said at least two sensors are positioned at about 90 degrees to each other.
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23. The CMM of claim 23 wherein:
said at least two sensors comprise proximity sensors.
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25. The CMM of claim 25 wherein:
said optical fringe pattern is disposed on an optical encoder disk. - View Dependent Claims (26)
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29. The CMM of claim 29 including three joint pairs, each joint pair comprising a long joint and a short joint.
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34. The CMM of claim 34 wherein:
said pattern is attached directly to said shaft.
- 37. The CMM of claim 37 wherein said at least one of said rotary joints comprises at least two of said rotary joints.
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51. A portable coordinate measurement machine (CMM) for measuring the position of an object in a selected volume, comprising:
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a manually positionable articulated arm having opposed first and second ends, said arm including a plurality of joints;
a measurement probe attached to a first end of said articulated arm;
an electronic circuit which receives the position signals from transducers in said arm and provides a digital coordinate corresponding to the position of the probe in a selected volume; and
wherein at least one of said joints further comprise;
a rotatable shaft surrounded, at least in part, by a housing, said shaft and said housing being adapted to rotate relative to one another;
a periodic pattern of a measurable characteristic;
at least one read head spaced from and in communication with said pattern;
said pattern and said read head being positioned within said joint so as to be rotatable with respect to each other; and
a plurality of displacement sensors which measure relative movement between said shaft and said housing, said relative movement measurement being used to improve the measurement accuracy of said at least one read head.
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- 52. The CMM of claim 52 including at least five sensors which, together with said read head, measure at least six degrees of freedom of said shaft.
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54. The CMM of claim 54 wherein said relative movement is caused by deformation of bearings in said joints.
- 56. The CMM of claim 56 wherein said at least one of said rotary joints comprises at least two of said rotary joints.
Specification