Ascension laserBIRD, Installation And Operation Manual

Page: 76 / 98

4: Software Operation: Tools for Successful Tracking
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QUATERNION
ASCII HEX DECIMAL BINARY
Command Byte \ 5C 92 01011100
In the QUATERNION mode, The Bird outputs the four quaternion parameters that describe the
orientation of the sensor with respect to the Scanner. The quaternions, q
0
, q
1
, q
2
, and q
3
where q
0
is the scaler component, have been extracted from the MATRIX output using the algorithm
described in "Quaternion from Rotation Matrix" by Stanley W. Shepperd, Journal of Guidance and
Control, Vol. 1, May-June 1978, pp. 223-4. The output record is in the following format for the
eight transmitted bytes:
MSB LSB
7 6 5 4 3 2 1 0 BYTE #
1 B8 B7 B6 B5 B4 B3 B2 #1 LSbyte q
0
0 B15 B14 B13 B12 B11 B10 B9 #2 MSbyte q
0
0 B8 B7 B6 B5 B4 B3 B2 #3 LSbyte q
1
0 B15 B14 B13 B12 B11 B10 B9 #4 MSbyte q
1
0 B8 B7 B6 B5 B4 B3 B2 #5 LSbyte q
2
0 B15 B14 B13 B12 B11 B10 B9 #6 MSbyte q
2
0 B8 B7 B6 B5 B4 B3 B2 #7 LSbyte q
3
0 B15 B14 B13 B12 B11 B10 B9 #8 MSbyte q
3
Scaling of the quaternions is full scale = +.99996 = 7FFF Hex, 0 = 0 Hex, and
-1.0 = 8000 Hex.