چكيده به لاتين
Railway Level Crossing (RLC) is one of the most Critical Section of the Railway systems. The model of system may be derived using discrete event systems. In this thesis, a petri net structure for RLCs is provided in such a way that different subsystems such as control system, yellow and red lights, road barriers, train equipped with ETCS and possible failures are modeled. In order to control the speed of the train, a supervisor has been designed. The supervisor determines safe speed of the train based on line condition and distance between train and RLC. By determining the safe speed of the train, speed and distance to RLC is updated by using the ETCS protocols and equipment used in the petri net model of the train. In addition, in train modeling, priority is considered for incoming messages and higher priority messages are chosen as the decision maker for speed supervisor. LTE network has been used to transfer information between train and the RLC. To achieve this goal, petri net model of LTE is augmented to the current model and supervisory control is developed to prevent unauthorized events and improve system performance. In order to ensure delivery of urgent messages between train and RLC, a discrete event model is provided. Proposed model keeps sending emergency messages until the delivery message arrives. By integrating all the subsystems the hierarchical structure of the system consists of RLC control system, red and yellow lights, barriers and conditions that lead to emergency stop of the train, wireless telecommunication network and the train movement has been provided. Then the state space model of the telecommunication is represented manually and state space analysis including dead and live locks, home marking, liveness, fairness, boundedness, stability and safety has studied. Finally, the state space of system is extracted by using CPN tools software, several scenarios including normal situation, failure of track-side equipment and the presence of obstacles in the rail has been simulated. The simulation results indicate high performance of system efficiency based on safety indexes by the presented supervisory control strategies.
