MTS SWIFT 45 GLP Sensor - Manual (Page 68)

SWIFT ® 45 GLP Sensors 68
Acceleration and Braking Events Example
Analyzing SWIFT Data
Acceleration and Braking Events Example
Shown below is actual road data taken with the MTS SWIFT Sensor, located at
the front passenger side of a mid-size passenger vehicle. Data shown is post-
processed to translate the forces and moments from the center of the transducer to
the center of the tire.
The outputs from this acceleration and braking event are shown above. It should
be noted that output fluctuations are primarily due to actual road surface
irregularities.
Time 0 to 3.8 seconds: The car is at rest, with the brakes applied; no motion. The
vertical force of the vehicle on this wheel is noted as slightly over 1000 lb.
Time 3.8 to 4.3 seconds: The brake pedal is released with the transmission
engaged. Note the forces generated from the slight drive torque of the idle in this
automatic transmission vehicle.
Time 4.3 to 6 seconds: Acceleration begins and transient forces and moments
are shown.
Fx: Slightly less than 1000 lb of tractive force is reacting at the tire patch.
Fy: Minimal Fy force is noted as the steering angle is maintained roughly
straight. Slight variations are noted with steering angle and vehicle suspension
toe-in geometry effects.
Fz: The normal force is the result of weight transfer from the front wheel to the
rear of the vehicle, and the anti-squat forces present in this front wheel drive
vehicle.
Mx: The Mx output noted is corrected to give the overturning moment at the
center of the tire. Minimal Mx moments are generated during these acceleration
and braking events.
My: The acceleration torque of roughly 12000 in · lb acting on the vehicle is
directly measured.
Acceleration and Braking Events
-2000
-1500
-1000
-500
0
500
1000
1500
2000
0 2 4 6 8 10 12 14
time in seconds
Out
put
-
Lbs
-15000
-10000
-5000
0
5000
10000
15000
Ou
tp
u
t- In
-L
b
s Fx (tractive force) - Lbs
Fy ( lateral force) - Lbs
Fz (normal force) - Lbs
Mx (overturning moment) - In
My (wheel torque) - In-Lbs
Mz (aligning torque) -In-Lbs