04/12/07 - Functional Specification

Today we submitted our functional specification, which can be obtained here. Last week, we met with our supervisor, Alan Smeaton, to discuss the direction of our project, as described in the functional specification.

Graham also received some more of the hardware components and has started constructing the headset. In the meantime, I am working on the central router application.

The image shows how my router program will interact with the rest of the system. Put simply, each component will, at some point, pass it's data to the router program. The application can then specify how it wants to route the data through the system (should the users position be passed to the audio system? Will the ultrasonic data generate sound? etc). Eventually, I intend on writing a graphical tool where you simply drag and drop components and connect them together with lines to route the information between the components as this is, in my opinion, the most user friendly way to configure the system.

As well as the routing capabilities, I have created a simple state machine. A configuration file, containing a list of state transitions, can be loaded by the application and events triggered (or even routing of components) would depend on the current state. Changing state when the user is within a certain radius of specified locations is something else planned for this aspect of the program, as we foresee that (location based state changes) to be an integral part of a large number of potential applications. For example, the waypoint demonstration application could be almost entirely implemented using only a number of state transitions.

The state transition configuration file is described in more detail in the functional specification. The basic layout is a list of entries (one per line), in the following syntax:

current_state x y z radius next_state

This means that a transition occurs from state current_state to next_state if the person is within radius of the position (x, y, z). To create the waypoint application, a state transition file would simply be set up to contain a sequential list of state transitions.

The application also gets notified when a state transition occurs, so that it can perform some extra action when it happens.