3.3.2 TMAG5170 On-Axis
The on-axis alignment is the ideal case for measuring the angle of a magnetic field but requires additional area
about the motor. Either the motor must be dual shaft or the end of the shaft is not available to drive the load. This
results in the least compact solution size when implemented with any given motor. The impact of mechanical
error is minimized in this orientation; however, which results in best uncalibrated results.
The mounting plate was configured to match the simulation results shown in
.
Note
are all present to some degree in each test case
and the captured data reflects the result of these conditions after amplitude and offset corrections
were applied.
The manual assembly and manufacturing tolerances of the entire setup resulted with mechanical
errors which must be addressed. These alignment flaws demonstrated in the test results are crucial
for the purpose of demonstrating the significance of alignment errors and how the calibration process
can correct even large scale angle error. Strictly controlled manufacturing practices results with a
reduced error from what is depicted for each case.
Figure 3-10. On-Axis Configuration
On-Axis Mechanical Angle Error
shows the resulting pre-calibrated error captured for this alignment.
Angle (deg)
A
ngle E
rror (d
eg)
0
45
90
135
180
225
270
315
360
-3
-2.7
-2.4
-2.1
-1.8
-1.5
-1.2
-0.9
-0.6
-0.3
0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2.7
3
CORDIC Output Error
Calculated Arctangent Error
Figure 3-11. On-Axis Mechanical Angle Error
Hardware, Software, Testing Requirements, and Test Results
24
Absolute Angle Encoder Reference Design With Hall-Effect Sensors for
Precise Motor Position Control
Copyright © 2022 Texas Instruments Incorporated
