الفهرس 
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Abstract
Road crashes not only affect people’s lives but also, they have bad effect on the victims and the economy. Due to the high number of Road crashes, active safety systems are developed to assist the driver to reduce the severity of unavoidable crashes and to prevent injuries as well. There are many types of Active safety systems such as Anti-lock Braking System (ABS), traction control system (TCS).
Traction control is designed to help vehicles make effective use of all the traction available on the road when accelerating on low-friction road surfaces. TCS become increasingly important to maintain the driver’s controllability of the vehicle to enhance the driving experience under different road conditions. The amount of traction changes depending on variety of factors such as the surface of the road, the conditions of the tire and the weight of the vehicle as well as the driver’s behavior. There are different types of controllers that can be used to control vehicle traction such as PID controller, Fuzzy PID controller, Fuzzy controller, sliding mode controller (SMC), super twisting sliding mode controller (STA).
This research compares between the usage of three different types of controllers with a nonlinear observer to obtain a traction control of electric vehicle. The three types of the controllers used here are: PID, sliding mode controller and super twisting algorithm-based controller. The advantage of the PID controller is its simplicity, so it is widely used. One of the limitations of the PID controllers is that they are linear and symmetric So that, the performance of the PID system in nonlinear systems is variable. Because of the robustness property of SMC, it has been used excessively for the control of uncertain nonlinear systems. Second order sliding mode controller is a better solution for the chattering phenomena found in the conventional sliding mode controller. As it uses the time derivative of the sliding variable instead of the first derivative and this result in the reduction of the chattering phenomena appears in the conventional SMC. Super twisting controller is considered as a better solution for the chattering phenomena found in sliding mode controller and its implementation is easier than the second order SMC as it doesn’t require the time derivative of the sliding variables.
The performance of the three controllers is validated using a vehicle model in MATLAB Simulink. Each controller is combined with a nonlinear observer. The output of the controller is the driving torque that is required to operate the vehicle at the desired slip ratio. A novel unified structure is used to estimate tire forces by using nonlinear observer. The independence of the estimates from the vehicle tire model is the reason of the novelty in this structure. This strategy is also validated using a four DOF vehicle model and the controllers in MATLAB Simulink.
The results of the simulation illustrate the success of the controllers to operate the vehicle at the desired wheel slip ratio. When a sudden change occurs, super twisting controller yields the best control performance compared to the other systems. Also, it shows that the super twisting controller yields better controller performance and overcomes the chattering phenomena.