Design a state machine to operate the two trains avoiding collisions but minimizing their idle time. Trains must not crash by moving the wrong direction into an open switch. Develop a simulation to verify your state machine is operating correctly before running the video train system. The trains are assumed to be in the initial positions as shown in Figure 8.14. Train A is to move counterclockwise around the outside track until it comes to Sensor 1, then move to the inside track stopping at Sensor 5 and waiting for B to pass Sensor 3 twice. Trains can move at different speeds, so no assumption should be made about the train speeds. A train hitting a sensor can be stopped before entering the switch area.
Once B has passed Sensor 3 twice, Train A moves to the outside track and continues around counterclockwise until it picks up where it left off at the starting position as shown in Figure 8.15. Train B is to move as designated only stopping at a sensor to avoid collisions with A. Train B will then continue as soon as there is no potential collision and continue as designated. Trains A and B should run continuously, stopping only to avoid a potential collision.
