CMM with improved sensors
A method of operating an articulated arm CMM is provided. One or more coordinates on an object can be measured with the articulated arm CMM. At least one of the encoders can then be at least partially powered-off. The encoder can then be powered on and one or more coordinates on the same object can be measured without recalibrating the encoder.
1. An articulated arm for a coordinate measurement machine comprising:
a plurality of transfer members;
a plurality of articulation members connecting at least two transfer members to each other;
a base at a proximal end of the articulated arm;
a coordinate acquisition member at a distal end of the articulated arm; and
an encoder positioned at each of the plurality of articulation members for measuring a position of each transfer member;
wherein each encoder comprises a single serialized disk that is read by one or more read heads.
2. The articulated arm for a coordinate measurement machine of claim 1 , wherein the one or more read heads are CCD imagers.
3. The articulated arm for a coordinate measurement machine of claim 1 , wherein each encoder comprises a single serialized disk that is read by at least two read heads that are CCD imagers.
4. The articulated arm for a coordinate measurement machine of claim 1 , wherein each encoder comprises a single serialized disk that is read by at least two read heads that are configured to improve the accuracy of the measurement by measuring the eccentricity of the axis and subtracting out the eccentricity of the axis from the angle measurement.
5. The articulated arm for a coordinate measurement machine of claim 1 , wherein each encoder comprises a single serialized disk that is read by at least two read heads that are CCD imagers, and an angle measurement from each encoder is an average of angle measurements from the at least two CCD imagers of each encoder.
6. The articulated arm for a coordinate measurement machine of claim 1 , wherein the encoder is an absolute encoder.
7. The articulated arm for a coordinate measurement machine of claim 1 , wherein the encoder is an absolute encoder that is powered off during a sleep mode of the articulated arm.
8. The articulated arm for a coordinate measurement machine of claim 1 , wherein the encoder comprises a non-repeating pattern.
9. The articulated arm for a coordinate measurement machine of claim 1 , wherein the pattern comprises varying reflective properties.
10. The articulated arm for a coordinate measurement machine of claim 1 , wherein the pattern comprises varying translucent properties.
11. The articulated arm for a coordinate measurement machine of claim 1 , wherein the pattern comprises varying magnetic properties.
12. The articulated arm for a coordinate measurement machine of claim 1 , wherein the arm comprises a plurality of measured axes of rotation and at least one absolute encoder for each measured axis of rotation.
13. The articulated arm for a coordinate measurement machine of claim 1 , wherein each articulation member comprises a hinge joint and a swiveling joint, wherein the articulation arm comprises an encoder comprising a single serialized disk that is read by one or more read heads at each hinge joint and each swiveling joint.
14. The articulated arm for a coordinate measurement machine of claim 1 , wherein each articulation member comprises a hinge joint and a swiveling joint, wherein the articulation arm comprises an encoder comprising a single serialized disk that is read by one or more read heads at each hinge joint and each swiveling joint.
15. The articulated arm for a coordinate measurement machine of claim 1 , further comprising electronics configured to perform additional signal processing such as digitizing an analog signal from the encoders.
16. The articulated arm for a coordinate measurement machine of claim 1 , further comprising a tilt sensor coupled with the base, the tilt sensor configured to detect a tilting angle of the base.
17. The articulated arm coordinate measurement machine CMM of claim 16 , wherein the arm or an external device is configured to compensate the data for tilting sensed by the tilt sensor.
18. A method of operating an articulated arm coordinate measurement machine comprising:
measuring one or more coordinates on an object with an articulated arm coordinate measurement machine;
at least partially powering off at least one encoder in the articulated arm coordinate measurement machine;
powering on said at least one encoder; and
measuring one or more coordinates on said object after powering on the encoder without re-indexing the encoder;
wherein the encoder comprises a single serialized disk that is read by one or more read heads.