Table of Content

• Introduction
• Solution Approach
  • Modelling
  • Simulating
  • Testing - ESG & Test Suites
  • Experiments

• Conclusion

Introduction

Traffic light controllers are very important systems which ensure that traffic moves as smoothly and safely as possible and that pedestrians are protected when they cross the roads.

The goal of our project is to prove that such important systems are indeed reliable and working precisely. So we decided to test these systems. In order to execute our tests, we modelled and simulated an existing crossroad.

Ulusal Egemenlik Street in Marmaris, Muğla

• Four traffic lights 

• Only one green light at a time 

• All lights turn red when reseted

Solution Approach

We used several useful techniques to be able to model, simulate and test a traffic light controller.

• Modelling - Moore and Mealy Automatas
• Simulating - Petri net
• Testing - ESG & Test Suites
• Experiments - Homing & Diagnosing

Modelling

Mealy Automata

JFLAP

Moore Automata

JFLAP

Simulation

Petri Net

TAPAAL

Animation

Testing

Event Sequence Diagram

TEST SUITE DESIGNER

Test Suites

Test Suite Designer

Experiments

After applying 010, 000 input sequences to our machine

the machine generates same output and moves to state q0 for the given input sequence. It is not possible to identify the initial states for the input sequence, but it is obvious that the final state is q0 for the input sequence. Therefore, the 010 000 is valid for homing sequence and not valid for distinguishing sequence.

After applying 000 input sequence to our machine

The machine generates again same output for all states and moves to q0. Initial states can not be identified from the table by observing the outputs but final state is q0 for all cases. Therefore, this input is valid for homing sequence and not valid for distinguishing sequence.

Conclusion

• Petri net for simulation of the system and easing the modelling part

• Mealy and Moore finite state automata for modelling

• Event sequence diagram for testing transitions between states using test suites

• Carried out experiments to predict the system's states

  •           Homing

  •           Diagnosing - Non-deterministic

With these steps, we tried to show how a traffic light controller system should work and how it can be tested.

Steps that we accomplished;