Information related to the vehicle's dynamics behavior have
a huge importance on several subjects, safety is certainly one of
them. For the purpose of improving the knowledge about the lateral
rollover limit of a vehicle, under a steady state condition, an
experiment was made aiming to evaluate the lateral acceleration
gain in function of the steering angle established for several
turning radiuses and speeds and with that, verify if this
acceleration gain causes the rollover situation, identifying the
critical level of steering angle.
To accomplish that, the experimental analysis were performed on
a Baja SAE vehicle, designed and built by students from Centro
Universitário da FEI. For the field tests, the vehicle was prepared
with a fifth lateral wheel system, which avoids the complete
rollover of the vehicle, ensuring the driver's safety. To
measure the wheel's steering angle, vehicle's speed and the
moment when the first wheel leaves the ground, a data logger system
was properly installed on the vehicle.
This study also seeks to obtain the validation of the
mathematical model introduced by Gillespie who describes this
movement. Due to this, the understeer gradients had to be
calculated, inasmuch as they change according to radius, speed,
wheel camber, roll of the suspended mass, and other situations. For
the cinematic analysis of the vehicle's suspension geometry,
the ADAMS CAR software was used.
A comparative analysis presents similar values between the
results obtained with the mathematical model, developed with the
MATLAB software, and the results from the field tests, validating
thus the purposed equations.