LEE- Makina Mühendisliği Lisansüstü Programı
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Konu "Automobile driving -- Lane changing -- Computer simulation" ile LEE- Makina Mühendisliği Lisansüstü Programı'a göz atma
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ÖgeCollision avoidance and crash mitigation via intelligent steering intervention( 2020) Şahin, Hasan ; Akalın, Özgen ; 636992 ; Makine Mühendisliği Ana Bilim DalıThe first aim of the thesis is to reduce the collision in traffic accidents or to mitigate the collision when it can not be reduced. Collision reduction can be achieved by braking in the first place. However, a suitable distance is required to achieve braking. In this thesis, the steering escape maneuver is processed instead of braking. The distance required for steering escape maneuver is less than the distance required for braking if the relative speed between vehicles is greater than 50 km/h. Therefore, at high speeds, if the braking distance is missed, the steering escape maneuver should be considered. For the steering escape maneuver, lane identification must be made in the transition to the side lane. After the lane definition has been made, the stability limits of the vehicle should also be taken into account in order to change the lane appropriately. Stability limits vary from vehicle to vehicle. In this thesis, the stability limits of different types of vehicles are considered by using various tools in the related simulation programs. The stability to be considered in the escape maneuver is the lateral stability. Verification of lateral stability is very important. We can only do this using a nonlinear simulation model. Nonlinear conditions are also mentioned in the simulations. The next step in the escape maneuver is to properly control the escape lane. It should also be checked whether the strip is suitable for passing. There are various systems for controlling this. In the simulations, the simulations have been completed by considering some of these systems. The whole thesis consists of four separate chapters. In the first part of the thesis, an adaptive trajectory control (ATC) in case of a sudden change in μmax (maximum road friction coefficient) during an emergency lane change manoeuvre is explained. The ATC system was analysed in case of a sudden change in the maximum friction coefficient of road during an emergency lane change manoeuvre in order to maintain the driving safety. Autonomous front wheel steering (FWS) systems have been developed for emergency steering situations. The trajectory design is also a part of these systems. Moreover, in this study ATC has been designed by sensing μmax to complete the emergency steering manoeuvre successfully. Therefore, the originality of this work arises from the necessity of a trajectory change in case of a sudden change in μmax to minimize the distance between the desired and the actual path. Suitable cases were designed by using a two-track model in IPG/CarMaker (MATLAB/Simulink). Results show that ATC could be used during an emergency steering manoeuvre in case of a sudden decrease in μmax as it can be advantageous in certain critical traffic situations. Therefore, ATC could be used as an alternative system instead of Electronic Stability Program. In the second part of the thesis, a driver model supported by a rear wheel steering (RWS) assistance to minimize the distance between the desired path and actual path via steering "out-of-phase" during an emergency lane change maneuver is explained. Rear wheel steering (RWS) systems are commonly used to maintain vehicle lateral stability via steering "in-phase" at high speeds. Conventional RWS systems do not assist the driver to avoid rear-end collisions. However, in this study, a RWS assistance is proposed to avoid rear-end collisions. A driver model is supported by a RWS assistance via steering "out-of-phase" during an emergency lane change maneuver. The proposed RWS assistance uses a yaw rate feedback controller and a disturbance controller. A two-track vehicle model was used where experimental validation studies are widely available. The originality of this paper is using an intelligent RWS assistance to avoid rear-end collisions rather than improving the vehicle lateral stability. The results demonstrate that the intelligent RWS assistance supporting the driver model can both reduce rear-end collisions and also their impacts. The vehicle lateral stability can be maintained depending on the coefficient of road adhesion and distance to obstacle. In the third part of the thesis, the effectiveness of a steering warning system (SWS) for the decrease of tendency of emergency braking maneuvers is explained. The viability of an Emergency Steering Warning System was analysed to improve the safety of vehicles on highways traveling in the same direction. The proposed system evaluates the vehicle's physical limits, driver's reaction and assists in making the most logical decision to avoid a crash using a sound or a similar stimulus. Typical driving simulator events were designed in MATLAB/Simulink and IPG/CarMaker co-simulation environment. In the predetermined scenario, the leading vehicles suddenly move into the host vehicle's lane and the driver is expected to avoid crash by either steering or braking. The SWS system generates a sound stimulus when it is determined that the crash is unavoidable with the use of service brakes and the only way to avoid the obstacle is steering. The simulation events were performed by a group of participants using a driver simulator with and without the SWS system. The proposed SWS encouraged participants to do an earlier and smoother steering maneuver which can be advantageous in some certain critical traffic situations. The statistical results showed that the sound stimulus reduced the drivers' reaction time significantly and a number of accidents can be avoided by the suggested crash warning system. In the final part of the thesis, an articulated vehicle lateral stability management (AVLS) via active rear wheel steering of tractor using fuzzy logic and model predictive control is explained. In-phase rear wheel steering, where rear wheels are steered in the same direction of front wheels, has been widely investigated in the literature for vehicle stability improvements along with stability control systems. Much faster response can be achieved by steering the rear wheels automatically during an obstacle avoidance maneuver without applying the brakes where safe stopping distance is not available. Sudden lane change movements still remain challenging for heavy articulated vehicles, such as tractor and semi-trailer combinations, particularly on roads with low coefficient of adhesion. Different lateral accelerations acting on tractor and semi-trailer may cause loss of stability resulting in jackknifing, trailer-swing, roll-over or slip-off. Several attempts have been made in the literature to use active steering of semi-trailer's rear wheels to prevent jackknifing and rollover. However, loss of stability in an articulated vehicle is usually caused by an over-steered tractor, and the semitrailer's rear wheels have little effect on the tractor's directional control. In this study, viability of active rear wheel steering of tractor to maintain the stability of an articulated vehicle during a high speed obstacle avoidance maneuver is investigated. Two different controllers, fuzzy logic and linear model based predictive controllers are proposed to minimize off-tracking behavior of an articulated vehicle. The controllers were tested in IPG/TruckMaker environment with MATLAB/Simulink interface on roads with various coefficient of adhesions, performing single lane change maneuvers. The simulated results showed that jackknifing occurring right after sudden lane changes can be successfully prevented using tractor's active rear wheel steering based on model predictive control algorithm when the feedback gains are tuned correctly.