الفهرس 
AbstractOnly 14 pages are availabe for public view
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Abstract
Lack of safety systems leads to a lot of deadly accidents. The safety systems are divided into two categories: passive and active. Passive systems operate only in the event of an accident, while active systems operate continuously to prevent accidents from happening. Approximately one-third of fatal accidents could be avoided if the vehicles had an active safety system installed. By lowering lateral acceleration, body side slip angle, and yaw rate during aggressive maneuvers, these systems enhance a vehicle’s handling characteristics. Thus, there will be a lower chance of the driver losing control.
The study aims to investigate how the Four-Wheel Steering (4WS) and the Vehicle Dynamic Control (VDC) system using an active torque distribution management system affect vehicle stability. Vehicles with independent four-wheel drive can use VDC. In light of this, two primary vehicle models are suggested in order to investigate how using the Four-Wheel Steering system and Vehicle Dynamic Control system might increase vehicle stability and improve maneuverability.
The present thesis studies the lateral stability of vehicles by using a two-degree-of-freedom bicycle model implemented based on MATLAB/Simulink. The proposed model considered the driver model as an expert system to mitigate the vehicle’s lateral deviation. The linear optimal control theory (LQR) is employed to determine the rear wheel steering angle as the control action to minimize the vehicle lateral responses of the vehicle such as body sideslip angle, lateral deviation, lateral acceleration, and yaw rate. To validate the effectiveness of the proposed controller, the Particle Swarm Optimization (PSO) technique is designed to obtain the optimal gain of the LQR. Three scenarios are utilized to evaluate the proposed model. First, at a lateral deviation of 2.5 m; second, at a front steering wheel angle of 4 degrees; and third, activating both previous scenarios together.
Also, the present thesis studies the lateral stability of vehicles by using a seven-degree-of-freedom nonlinear vehicle model is adopted during the study for the Vehicle Dynamic Control incorporating a nonlinear tire model Using the Magic Formula Tire Model implemented based on MATLAB/Simulink. There are two primary components to the control structure. The PID yaw rate controller was the upper controller. The difference between the intended and actual yaw rates is how the PID controller calculates the corrective yaw moment. The Particle Swarm Optimization (PSO) technique is developed to get the optimal gain of the PID. The torque distribution management system, or lower controller, distributes torque among the wheels in accordance with the driving situation and strategy. Three distinct strategies were examined in order to produce the corrective yaw moment. Numerous maneuvers, including the fishhook, dual-lane, FMVSS 126, and J-turn maneuvers, are utilized to assess the controller’s effectiveness.
The Four-Wheel Steering system has a significant improvement in the lateral stability of the vehicle whereas active four-wheel steering is employed, particularly in terms of lateral acceleration, lateral deviation, and yaw rate compared to the typical 2WS vehicle. In terms of Vehicle Dynamic Control, the vehicle’s yaw rate and lateral acceleration have all been successfully tracked by the PID yaw rate controller. The controller does an excellent job of tracking the body side slip angle and maintaining it close to the target value obtained from the bicycle model. When compared to the other strategies during various maneuvers, strategy 3 was determined to be the most effective in tracking yaw rate, lateral acceleration, and body side slip angle.