MTS SWIFT 40 Sensor - Manual (Page 92)

SWIFT 40 Sensors 92
Test Track Vehicle
Installing the Transducer
D. Press the Shunt button on the front of the TI box, or use option 5 in the
TISHUNT program.
The shunt indicator will light continuously for 30–45 seconds. If the
indicator continues to flash after shunt calibration is complete, the
shunt calibration has failed.
Connect the shunt calibration cables
6. Verify that the outputs from the TI box matches those on the calibration
report.
Use either the TISHUNT or TIXFER program to look at the shunt values of
the individual bridges.
The shunt calibration will fail if the measured shunt values are >2% of the
reference values that were set at the factory. Typically, the shunt values will
vary a maximum of 0.20-0.30 V from the reference values.
Refer to the chapter, “Troubleshooting”, for more information on dealing
with shunt calibration failures.
Effect of Zero
Reference on SWIFT
Output
When the SWIFT sensor is used in spinning applications, it is important that a
correct absolute zero of each strain gage bridge is used to ensure the proper
computation and transformation of the transducer outputs to a non-rotating
vehicle coordinate system. An error in the absolute zero of each bridge will
produce a one-time-per-revolution modulation error in the output signals. To
achieve absolute zero of each bridge, the zeroing process must account for the
tare weight acting on the transducer.
When the vehicle is lifted and the tire and wheel assembly are suspended, the
mass of the tire, rim, outer diameter fasteners, and outer ring of the transducer are
all reacted through the beams of the transducer. With gravity acting on this outer
tire/rim assembly, the SWIFT sensor measures a vertical force pulling down on
the transducer.
The SWIFT output cannot be zero, because it is not possible to set the vehicle on
the ground precisely enough that the ground supports only the outer tire/rim
weight.
Connect to
Data Acquisition
System
Shunt B
Board B
Shunt A
Board A
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