Simulation & Models : How Simulations Work

Simulations are models of reality. A simulation should copy the behaviour of the real life system that it simulates. The designer of the simulation will incorporate as much of his knowledge about how the real system works as possible into the simulation software. Any simulation will have two important components :

• Variables : Variables are things in a simulation that can change.

• Rules : Rules determine how the variables in the model are changed and how they affect each other.

In a car driving simulation the variables might include :

• The direction that the car is travelling in.
• The car's speed.
• The position of the steering wheel.
• The condition of the road surface.
• The position of the accelerator pedal.

A simulation will incorporate many hundreds of variables. Some variables such as the position of the accelerator pedal can be changed directly by the user. Other variables such as the car's speed are changed by the rules of the simulation. Two simple rules that you might want to incorporate into a car simulator are :

• If the car steering wheel is rotated anti-clockwise and the car is moving forward then the car should move to the left.
• If the accelerator pedal is pressed down further then increase the speed the car is travelling at.

These two rules would have to be refined considerably before they could be used in a real simulation.

The rules and variables that make a simulation work are often implemented as mathematical calculations. The mathematical calculations that make a simulation work are known as a model.

GCSE ICT Companion 04 - (C) P Meakin 2004