Browse Publications Technical Papers 2011-36-0186

Validation of a Mathematical Model that Studies the Critical Steering Angle for a Lateral Rollover on a Baja SAE Vehicle 2011-36-0186

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.


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