چكيده به لاتين
In this Thesis, a new approach is presented to prevent SUV rollover. The car is modeled in CarSim and is controlled with Matlab/Simulink Co-simulation. To control the car a combination of brake system and active camber has been used. Studying the results of camber angle on vehicle behavior leads to design controllers in order to create stability in vehicle conditions. Initially, the devised controller, based on a linear relation between camber angle and lateral acceleration, would be triggered at higher value of lateral acceleration. The proposed controller was not as effective as needed. In order to alleviate the problems of the designed controller, a PID controller was replaced. PID needs a reference value to track and thus, the reference value for yaw rate was estimated in two methods: firstly, by using the understeer gain of the vehicle for the reference value which was much higher than real values and secondly, by devising a fuzzy model based on Carsim steady state which had both linear and nonlinear regimes. In spite of PID robust characteristics, because it has the tendency to elevate lateral acceleration which is unfavorable, a Fuzzy controller was proposed. In the end, an ESC was added to the designed controller to enhance and improve the results. In sum, stability of the vehicle is gained with lowering the tire lateral force and minimizing the use of brakes. Moreover, effects of important parameters on the vehicle stability have been studied. For the evaluation of the model, results of Toyota 4runner 2001 at Fishhook test which was studied by NHTSA, are derived and used in CarSim model. The vehicle modeled in CarSim was tested in various scenarios and the results were used to design fuzzy controller. The final controller contains active camber and brake system which work together. Last but not least, this thesis delineates a unified control of active camber and brake system can be employed to prevent rollover and increase the safety speed range of the vehicle at the limits of handling.
