Computing and Information Systems - Theses
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ItemAgent-based approaches to pedestrian modelling( 2007-02)This thesis investigates the early stages of the software development process for agent-based models of pedestrian behaviour. Planning for pedestrians is becoming more important as planners and engineers become more aware of the sustainability and environmental aspects of transport and infrastructure. It is also necessary for the planning and management of pedestrian areas and events. Pedestrian behaviour is more difficult to model than other transport modes as it is not as constrained and operates at a finer scale. Many approaches have been developed for modelling pedestrian behaviour. The simplest involve a single mathematical equation taking into account area and attractiveness of an area to calculate the maximum capacity. More complicated mathematical models involving differential equations have also been used. Agent-based modelling is a recent development in modelling and simulation. These simulations contain agents who interact with each other and the environment in which they are situated. Their similarity to human societies has led to their use for many social applications. Many modellers are unsure of what agents are and how to develop models using them. In some cases, agents may be useful. In other cases, the model outputs and realism may not offset the learning curve, development time, and increased complexity of an agent-based model. (For complete abstract open document)
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ItemModelling human behaviour with BDI agents( 2009)Although the BDI framework was not designed for human modelling applications, it has been used with considerable success in this area. The work presented here examines some of these applications to identify the strengths and weaknesses of the use of BDI-based frameworks for this purpose, and demonstrates how these weaknesses can be addressed while preserving the strengths. The key strength that is identified is the framework's folk-psychological roots, which facilitate the knowledge acquisition and representation process when building models. Unsurprisingly, because the framework was not designed for this purpose, several shortcomings are also identified. These fall into three different classes. Firstly, although the folk-psychological roots mean that the framework captures a human-like reasoning process, it is at a very abstract level. There are many generic aspects of human behaviour - things that are common to all people across all tasks - which are not captured in the framework. If a modeller wishes to take these things into account in a model, they must explicitly encode them, replicating this effort for every model. To reduce modellers' workload and increase consistency, it is desirable to incorporate such features into the framework. Secondly, although the folk-psychological roots facilitate knowledge acquisition, there is no standardised approach to this process, and without experience it can be very difficult to gather the appropriate knowledge from the subjects to design and build models. And finally, these models must interface with external environments in which they 'exist.' There are often mismatches in the data representation level which hinder this process. This work makes contributions to dealing with each of these problems, drawing largely on the folk-psychological roots that underpin the framework. The major contribution is to present a systematic approach to extending the BDI framework to incorporate further generic aspects of human behaviour and to demonstrate this approach with two different extensions. A further contribution is to present a knowledge acquisition methodology which gives modellers a structured approach to this process. The problems at the agent-environment interface are not straightforward to solve, because sometimes the problem lies in the way that the environment accepts and receives data. Rather than offering the golden solution to this problem, the contribution provided here is to highlight the different types of mismatches that may occur, so that modellers may recognise them early and adapt their approach to accommodate them.