MTS SWIFT 20 Ultra Sensor - Manual (Page 137)

SWIFT 20 Sensors Troubleshooting 137
Spinning Application:
Vehicle Coordinate System
Outputs have unusual or
incorrect waveform shapes
to them. (Angular output
may need to also be
recorded to troubleshoot
based on per-revolution
outputs) A one-time-per-revolution
of tire signal appears while
the vehicle is driving
straight on a flat surface.
The mean level on FX and
FZ is equal to zero, and the
amplitude is fairly
consistent during straight
driving on a flat surface.
The amplitudes on FX and
FZ are about the same and
equal to the vehicle tare
weight. Angle Mode: Check that the AngleMode value
is set to zero in the TI calibration file as
accessed by the TIXFER utility. AngleMode=0
sets the TI to use the encoder to give angular
transformation to the spinning signal, to provide
non-spinning vehicle coordinate system output.
Angle Input: Verify that the encoder output is
present. The Angle output from the TI box
should be a 0 to 5 V sawtooth output. If this
signal is not present, check that the encoder and
slip ring assembly has not been damaged. To
verify if encoder damage is suspected, swap the
slip ring assembly with a known functioning
unit to verify. If the slip ring/encoder assembly
is damaged call MTS or replace it with spare
slip ring assembly if available.
A one-time-per-two-
revolutions of tire signal
appears while the vehicle is
driving straight on a flat
surface. The mean level on
FX and FZ is equal to zero,
and the amplitude is fairly
consistent during straight
driving on a flat surface.
The amplitudes on FX and
FZ are about the same and
equal to the vehicle tare
weight. Check that the EncoderSize parameter is set
properly for the slip ring (EncoderSize=1) being
used.
Spinning Application:
Vehicle Coordinate System
Outputs have unusual or
incorrect waveform shapes
to them. A one-time-per-revolution
of tire signal appears while
the vehicle is driving
straight on a flat surface.
Mean level of the FZ output
is roughly equal to the
weight of the vehicle on that
corner. Temperature Effects: The SWIFT transducer
is temperature compensated to reduce
temperature induced errors, but any significant
changes in temperature will induce zero shifts.
In the spinning application, these bridge zero
shifts will result in a one-time-per rev
modulation error. For best results, zeroing
should occur at the conditions closest to those of
the test conditions.
Incorrect Bridge Zero: An incorrect bridge
zero, in the spinning application, will result in a
one-time-per-rev modulation error. See “Zero
Offset” earlier in this Troubleshooting Guide.
Troubleshooting Guide (part 11 of 14)
Symptom Possible Causes Solution