MTS SWIFT 45 GLP Sensor - Manual (Page 21)

Construction
SWIFT ® 45 GLP Sensors Hardware Overview 21
Design Features
Flexure isolation
The SWIFT sensor has a very stiff outer ring and flexured beam isolation which
render it relatively insensitive to stiffness variations in matings with rims and
road simulator fixtures.
Flexure isolation minimizes thermal expansion stresses. With flexure isolation, if
the inner hub experiences thermal expansion the beams are allowed to expand
out, resulting in lower compressive stress on the beams.
Thermal stability
The entire outward sensor is machined from a solid, specially forged billet of
high strength titanium. The absence of bolted joints permits an efficient transfer
of heat across the sensor structure, minimizing temperature differentials in the
gaged area.
As mentioned earlier, flexure isolation allows thermal expansion with minimal
stresses.
The transducer is designed to accommodate the high temperature environments
that occur during severe driving and braking events. Individual temperature
compensation of each strain gage bridge minimizes temperature-induced
variations in accuracy. The temperature rating for the SWIFT sensor is 125° C
(257° F) at the spindle hub.
Temperature compensation is done on each bridge for better performance in
transient or non-uniform temperature occurrences.
Low hysteresis
The SWIFT sensor has very low hysteresis, since the sensing structure is
constructed with no bolted joints. Micro slippage in bolted joints contributes
most of the hysteresis in highly stressed structures. Hysteresis errors due to
micro-slip at joints can contribute to unresolvable compounding errors in
coordinate transformation of the rotating sensor.
Low noise
The SWIFT sensor uses a slip ring rather than telemetry for the transducer output
signals. On-board amplification of the transducer bridges minimizes any slip ring
noise contribution.
Low cross talk
The advanced design of the SWIFT sensor means that it has very low cross talk.
The alignment of the sensing element is precision machined. This alignment is
critical to achieving minimum cross talk error between axes and minimum errors
in coordinate transformation (from a rotating to a non rotating coordinate
system). Linear cross talk is compensated by the TI.
Velocity information
Angular output is available from the TI when it is used in the spinning mode with
the encoder. This angular output can be used to calculate wheel velocity. In non-
spinning applications, accelerometers can be integrated into the transducer
connector housing.
MTS does not supply any conditioning electronics for accelerometers. Ask your
MTS consultant for more information about this option.