Appeal No. 2004-0278 Page 11
Application No. 09/626,362
bracket directly to the feature sensor 240. Referring to Figure 6, the portable reference
target 400 comprises a framework of individual struts 402 with light-emitting diodes 404
at the vertices. The light-emitting diodes are preferably separately controllable to allow
them to be selectively and individually illuminated by the calibration system.
Greer teaches (column 7, lines 28-57) that:
Referring to FIGS. 7a-7c, the calibration technique will now be described.
Referring to FIG. 7a, the sensor array 300 is first calibrated with respect to the
fixed reference frame RE. This is done by sequentially illuminating light-emitting
diodes 280a-280c while the sensor array collects data on the position of each.
These data are then used to calibrate the sensor array with respect to the
external reference frame RE. This is illustrated diagrammatically by the dashed
line C1.
Referring next to FIG. 7b, the portable reference target is placed within the
calibration field of the sensor array and the light-emitting diodes at the vertices of
the reference target 400 are sequentially illuminated while data are collected by
the sensor array. These data are then used to calibrate the position of the
portable reference target with respect to the fixed reference frame RE. This is
illustrated diagrammatically by dashed line C2.
Finally, the feature sensor 240 projects structured light onto the portable
reference target 400 and the feature sensor collects reflected light data from the
portable reference target. Specifically, the position of the straight edges of the
target are ascertained and these are used to describe the spatial position of the
reference target in the reference frame of the feature sensor. Once these data
are collected the feature sensor is then calibrated to the fixed reference frame
RE, as diagrammatically illustrated by dashed line C3.
In the foregoing example, the sensor array was calibrated first, the
position of the portable reference target was calibrated second and the feature
sensor was calibrated third. Of course, these operations could be performed in a
different sequence to achieve the same end result.
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Last modified: November 3, 2007