System Functions

Go Back : Requirements Engineering Next step: Subsystem Integration The System functions step is the first one that helps us generate a design that fufills the design criteria. It consists of two main excercises: Functional Analysis (via FFBD) and Concept Generation.

Functional Analysis
Functional analysis breaks down a complicated operation into simple independent steps. This is done by using a Functional Flow Block Diagram or FFBD. This allows us to easily visualise the operation of our design, and may reveal problems or aspects that we need to consider for our design that was not encapsulated in the requirements engineering process.



The fact that one of the main attractions of Consumer BCI devices is their ease of use, means that they do not lend themselves to detailed, revealing functional block diagrams. No dangerous steps are indicated within the process that need to be considered in design.

Concept Generation
It is difficult to create a very original design when an EEG headset is really the only option, due to cost pressures. But below is a concept classification diagram showing the way this choice is validated by the engineering process. Little concept generation is possible due to the emerging nature of the technology - for many aspects there is only one or two choices. (For example, EEG electrodes are either wet or dry, of which dry is the obvious choice when considering the design requirements ).

Although BCI technology is very complex, the System Functions step focuses on Client interactions with the final product. The complexity of a C-BCI device is entirely hidden, and is extremely simple to use. Therefore the Functional analysis for our device is very simple. The most complicated aspect of operation, the mathematical processing of data, is entirely automated and therefore ignored for this analysis.