The Stability And Control Of Vehicle Following System

The stability of the systems is an important factor in the theory of dynamic systems, it make the controlled object meet the design index exactly. And the property of stability determines whether the disturbed-system can return to the original balance state. In practical control system, due to the limitation of information processing and signal transmission speed etc, the system will perform with time-delay inevitably. And the existence of time-delay may change the stability of the system, so it is necessary to study the stability of the system with time delays. Control of the vehicle following is one of the most interesting subsystem of Automated Highway System (AHS), which studies the vehicles on the longitudinal direction. And it will significantly increase the throughput on the highways.In this paper the vehicle following system of AHS was studied, and its main works include:1. The stability analysis and controller design of the "look both ahead and behind" vehicle following system, whose each subsystem has its own constant time delay was studied, and the controller design of the system was given. The dynamical equation of the system was constructed; via Lyapunov function method the string stability of the following system was analyzed; by sliding mode control method, the longitudinal control laws for vehicle following were designed and the stability of the longitudinal following control system was analyzed by the stability criteria of nonlinear interconnected systems2. The exponential mesh stability of the look-ahead system was defined and analyzed. First it introduced the definition of the mesh stability, then by Cauchy inequality and Lyapunov function method, the global exponential stability and the exponential stability of look-ahead system were analyzed, and the sufficient condition to ensure the global mesh exponential stability was obtained, which showed the relationship and domain of the parameters was convenient to apply to design controller in practice. Finainally the robust stability of the mesh stability of the look-ahead system was studied.3. The stability of the vehicle following system with impulsive effort was studied, and the controller design of the former system was given. First the model of vehicle following system with varying time-delay and impulsive effort was established; then by using vector Lyapunov function method and Mathematical induction, the global exponential stability of the former system was analyzed; finally designed the control law of the system via sliding mode control method, mode control method. Finally the stability of the controlled system was analyzed, and gave out the numerical simulation.