Design and Modeling of Digital Input-Output unit for Automatic Train Protection System in order to Apply Brakes and Compare with Real Model

One of the most important parts of the safety of each rail network is the fleet cruise control system. All break application processes are carried out in today's modern systems with the help of a system called ATP. This system consists of several units. One of the most important parts of this system is vital digital input and output unit for brake control, which is called VDX. We analyze the automatic train protection system of the made by the Bombardier Company, which is used in the Tehran Metros. Since the VDX unit in this system is responsible for controlling the emergency brakes and the right and left train doors, after examining the unit in this system, a design is presented that, while simplicity all safety and reliability    considerations are observed. as well as the proposed design consists of two processors, four brakes, two controllers for the right and left doors, six relays, six drivers, three flow sensors, a pressure pipe for the brake system and a switch for each door. In addition, the proposed design consists of two processors; four break control circuits, two door controllers, six relays, six drivers, three current sensors, a pressure Cylinder pipe for the brake system, and one switch for each door. Initially, the status of the switches on the right and left doors is checked if the doors are closed, the brakes are released, and if the doors are open, the brakes are engaged. The door status is checked once several milliseconds and opening the doors are considered as an error. The designed system has two units, which act as processor and controller, a fault detection unit, brake interface circuits, and right and left door interface circuits. Fault detection and troubleshooting are performed alternatively within milliseconds. This unit monitors the processors based on high/low signals received from controllers of them. This system monitors the drivers, brake interface & relays via some dedicated sensors as well. Current of the switches help monitoring left and right sides door.