Modelling study

Due to the concurrent nature of the situation that needs to be simulated an LSD specification will be constructed. The purpose of this is to identify how the agents in the model interact and provide a better insight into how concurrency is prominent in this study. Furthermore, the LSD specification will help with understanding the fundamental properties of the system that need to be reflected in any model developed. With an LSD specification, it is possible to use the abstract definitive machine (ADM) to animate the situation and in particular the concurrency involved. Though the LSD specification will be of a standard such that the ADM could be used, such an implementation will not be included as part of this paper. Instead this will be seen as a possible extension for anyone wishing to further this work.

The model will be developed in Tkeden and will require a number of things to be developed. These will include a module capable of displaying a car and providing variables with which to interact with it. Another module will be responsible for displaying the roundabout upon which the interaction between the cars in the model occurs. The roundabout should be implemented in a flexible way so that it could be adapted to allow the number of exits and lanes to be changed through the Eden interface. The final aspect of the model that will need developing is the part that will control the animation of the cars around the roundabout and check for collisions. For reasons of simplicity, the initial model used for this paper will contain only two cars on a two lane roundabout with only a few exits. Additionally for simplicity, the cars will either be stopped or moving at one predefined constant speed.

Using Eden users will be able to interact with the model by moving the cars positions, starting or stopping the cars and changing each car’s desired exit. It will then be possible to set how careful the various cars are about avoiding a collision. This will only be done in a very limited sense rather than using a complex algorithm, and so based on all cars moving round the roundabout at the same speed, they will just avoid moving in a lane until it is safe to do so. Additionally, if the model was extended to allow larger roundabouts and more cars, a user would be able to set the parameters associated with this extension to further the potential for experimentation within the Eden environment.

The model will allow other possible extensions to further investigate this issue such as the prospect of cars moving at different speeds and being able to accelerate and brake. This improved control of the cars in the model would make it possible for more complex algorithms to be used for ensuring the cars avoid each other.