MTS SWIFT 50 GLP Sensor Heavy Trucks - Manual (Page 82)

SWIFT 50 GLP Sensors 82 Troubleshooting
Spinning Application:
Vehicle Coordinate System
Outputs have unusual or
incorrect waveform shapes
to them. (Continued) A four-time-per-revolution
of tire signal is showing up
when the vehicle is driving
straight on a flat surface. Wheel force transducers often have a
modulation error with a cyclic frequency equal
to the number of beams on the transducer. The
SWIFT transducer has four beams, and will
inherently have some level of four times per
revolution modulation. This level will vary from
±0.5% to as high as ±5% of the equivalent radial
load.
For example, a 4000 N mean level vertical Fz
load (and negligible Fx loading) will result in a
±20 N to ±200 N error on the vertical Fz and Fx
channels.
The magnitude of this modulation error is based
on the geometries and stiffnesses of the
components in the assembly.
A transducer on a steel rim will have lower
modulation than the same transducer on a very
lightweight stainless steel rim. The trade-offs
between lower added mass, load capacity
requirements, and desired modulation should all
be considered in choosing components for the
wheel force transducer assembly.
Angle/Angular Velocity
Output There is no angle or angular
velocity output while the
transducer and slip ring are
spinning. Check that all power and signal cables are
connected, and that the antirotate device is
securely attached. The angle output should be
0 to 5 V sawtooth output per revolution of the
tire. The angular velocity signal should be
proportional to the rotational speed.
If the output is set to Angular Velocity, check
the VelocityFullscale value in the calibration
file.
Check that the encoder output is present. The
angle output signal from the TI should be a 0 to
5 volt sawtooth output while the transducer is
spinning at a constant velocity.
If this signal is not present, check that the slip
ring/encoder assembly has not been damaged. If
you suspect encoder damage, swap the slip ring
assembly with a known functioning unit to
verify it. If the slip ring/encoder assembly is
damaged, call MTS or replace it with a spare
slip ring assembly.
System coordinate offset is
not working properly The output Fullscale**
values have been modified
in the calibration file. Make sure the fullscale values in the calibration
file are correct and represent units of kN and
kN·m.
Troubleshooting Guide (part 11 of 11)
Symptom Possible Causes Solution