Engineering Design Process 4

The system attributes step is the final step in establishing our raw design

Go Back: Subsystem Integration Next Step: Verification and Evaluation

The system attributes process is a technical and linear one, by which we are able to determine very specific design criteria through the iteration of the question "How?" towards each of our design requirements. This set of system attributes becomes both a metric for the evaluation of current C-BCI systems, and the beginning of the properties of our eventual Ideal C-BCI device. The system attributes process also gives us an idea of the relative importance of each subsystem, and can give a recommendation as to which subsystems should be invested in the most.

Attributes CascadeEdit

The aforementioned 'how?' iteration is displayed effectively in a diagram called an Attributes cascade, this allows the information to be viewed quickly, as well as showing the follow through effect of a change to each subsystem. When we are constructing the attributes cascade we need to refer to the Design requirements. Note that for the purposes of this analysis, the software library for our device is not considered, as we cannot obtain meaningful data for it from this process. An important thing to note when conducting system attributes analysis is that the practicality of each attribute is not considered. Clearly if we were to fufill all of our tertiary attributes in the table below we would completely price ourselves out of the consumer market.

Attribute Cascade

Attributes Cascade for C-BCI device.


This Attributes cascade provides a multitude of good information, as we expected. Interestingly, the cascade revealed the importance of what originally seemed like the least important subsystem, the 'mount and frame subsystem'. It is second only to the sensor subsystem in the way that it impacts the overall quality of the device. This is due to the way that it impacts the amount and location of sensors. Another concerning aspect raised by the cascade is the appeared potential cost of implementing all the safety features that are desired. Perhaps we need to seek an alternate method to ensure safety, as the current one has been shown to increase complexity and cost greatly when analysed with regards to subsystem integration (in the FBD) and system attributes (in the attributes cascade).

From this information we determine the specifications of our Ideal Consumer BCI device .