Shakouri, Payman (2012) Designing of the adaptive cruise control system-switching controller. (PhD thesis), Kingston University, .
Abstract
Over the recent years, a considerable growth in the number of vehicles on the roads has been observed. This increases importance of vehicle safety and of minimization of fuel consumption, subsequently prompting manufacturers of cars to equip their products, with more advanced features such as Adaptive Cruise Control (ACC) and Collision Avoidance and Collision Warning System (CWS). In this thesis we concentrate on new methods for ACC. This work will include: Design of the simulation models suitable for this application, Investigation and design of suitable hybrid control algorithm by using classical and advanced control algorithm's consisting of the gain scheduling PI and Linear Quadratic (LQ) controllers, Design of the Nonlinear Model Predictive Control (NMPC) and the nonlinear Balance-Based Adaptive Control (B-BAC), Real-time implementation and tests of the algorithms by using NI Lab View Starter Kit Robot from National Instruments, Implementation and tests of the models and the controllers in MA TLAB/Simulink(R). The applications of the different control methods in the ACC are tested and compared against different traffic scenarios considering both velocity tracking (CC) and distance tracking (ACC) modes. Judging about the performance of ACC by utilizing the two advanced control methods; B-BAC and NMPC includes trade-offs between tracking-distance and velocity and the vehicle acceleration. However, both the B-BAC and the NMPC has demonstrated significantly smoother responses in controlling the throttle and the brake compared to PI control and linear MPC which in tum could improve the vehicle acceleration and fuel efficiency. The methods in order of producing better performance in terms of the values of control errors and their influences on fuel saving; NMPC, B-BAC, linear MPC and PI control. Improvement of fuel efficiency is investigated in this thesis through two approaches; first, by calculating the optimal control actions corresponding to the throttle and the brake signals through utilising the advanced control methods, second, by reducing the engine speed to idle speed during coast phase of the vehicle which causes the engine friction to be reduced. The engine speed can be reduced through transition between locked and unlocked states of the torque convertor. Possibility of achieving fuel efficiency through coasting in the vehicle has been investigated in the simulation and it has been demonstrated that longer coasting duration could be achieved i.e. more distance can be covered, and the fuel efficiency could be improved.
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