MTS SWIFT 20 Ultra Sensor - Manual (Page 22)

SWIFT 20 Sensors 22
Construction
Hardware Overview
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 sensor is machined from a solid, specially forged billet of high
strength aluminum or 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 minimize temperature induced
variations in accuracy. Since minimal electronics reside on the SWIFT sensor, it
can easily tolerate high temperatures. 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
On-board amplification of the transducer bridges minimizes noise contribution
prior to data transmission via low noise slip ring.
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 nonrotating coordinate system).
Any small amount of cross talk present is compensated by the TI.
Velocity information
Angular position output is available from the TI when it is used in the spinning
mode with the encoder. For the Low-Profile TI, this angular output can be used to
calculate wheel velocity. In non-spinning applications, accelerometers can be
integrated into the transducer connector housing.
The Mini TI has a user selectable angle or angular velocity output.
Note MTS does not supply any conditioning electronics for accelerometers.
Ask your MTS consultant for more information about this option.