Subsystem integration is a very valuable process of C-BCI technology, and will allow us to identify and adress bottlenecks that are observed in some current commercial options. The first part of this process is to identify the subsystems within our device, as well as to state what we are considering to be an external subsystem, and what we are considering outside the scope of our analysis. This is known as a system boundary chart, and is shown below.
|Sensor Subsystem||Computer Software|
|Amplifier subsystem||Mathematical Filters|
|Computer Interface subsystem||User|
|Power Subsystem||Computer and Display|
|Mount and frame subsystem|
Now that we have found the main subsystems required for an EEG-basec C-BCI, we can draw up a Subsystem Interface diagram, or Functional Block diagram.
Functional Block DiagramEdit
The Functional block diagram is relatively complex, as it deals with the interactions between subsystems. We are also required to assign a metric to each interaction. A major advantage of conducting the System Interface analysis is that it becomes much easier to troubleshoot a malfunction in the system, as you can locate it to a specific subsystem by checking each of the subsystem interactions against their expected values.
From the above FBD, we can see that our C-BCI device is not a simple one, it has few subsystems but they interact in complex ways. A particular issue that was raised in this process was the method of implementing the safety subsystem. During the FBD analysis we were required to select a location for our safety subsystem, and this is an important issue. The Way that the safety oversees other subsystems is something that would be tough to design and implement in reality, and this would not have been made so clear without the Subsystem integration process.
The FBD also shows that there is little redundancy in the system. If any of the pieces is removed, the device is ultimately useless. For such a complicated device of course this is unavoidable, but in general this is not a desirable characteristic in a system.