Texas Instruments TIDA-060040, Manual

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Off-Axis Mechanical Angle Error shows the resulting error for both a direct arctangent calculation and for the
CORDIC output after applying the harmonic data.
Angle (deg)
Mec
hanical
Angle
Error (deg
)
0 45 90 135 180 225 270 315 360
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
CORDIC Output
Calculated Arctangent
Figure 3-17. Off-Axis Mechanical Angle Error
Table 3-4. Off-Axis Harmonic Correction Factors
HARMONIC α
i
β
i
1 –6.97 –0.55
2 –0.05 1.12
3 –0.15 0.07
4 –0.13 –0.13
5 0.02 0.03
Off-Axis Calibrated Angle Error shows the resulting error after applying the harmonic data.
Angle (deg)
A
ngle E
rror (d
eg)
0 45 90 135 180 225 270 315 360
-1
-0.9
-0.8
-0.7
-0.6
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Calibrated Arctangent Error
Calibrated CORDIC Error
Figure 3-18. Off-Axis Calibrated Angle Error
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28 Absolute Angle Encoder Reference Design With Hall-Effect Sensors for
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