Biomedical Engineering Reference
In-Depth Information
messages, and to be able to consult these messages. Therefore, the users
develop new functions. For example, they use the system as an assistant
that will archive the messages in an adequate area, and not as a filter.
Above all, one of the advantages of this software is that it allows each
user to construct his or her own filter, taking into account personal needs
(de Keyser, 1988).
Here, we return to a technological orientation - that of transformable
systems. One of the important roles played by ergonomists in designing
these artifacts is grounded in the fact that they must define the properties
of the artifact and the activity corresponding to those properties. Indeed,
focusing on the artifact itself, it will be necessary to specify the levels in
which the system can be modified (e.g. systems that cannot be modified,
systems that can be modified and adapted within the limits and views
expressed by the designer, and systems that can be modified in new ways,
from a functional point of view) (Randell, 2003). However, this implies
identifying the various kinds of practices that correspond to these lev-
els (for example, choosing between options that have been determined
in advance, or designing new behaviours for the artifact based on exist-
ing elements).
Furthermore, the issue of transformable systems must not be borne
by the ergonomist only at the level of the instrument. Modifying tech-
nical systems requires resources. Those may be, obviously, cognitive
resources (e.g. the existence of an instruction booklet, the possibility of
exchanging information with the designers when required, etc.), but also
time resources. Such an activity of 'sustaining design' in a work situation
requires time. It must therefore be allowed, not just by the artifact, but also
by the simulation.
Engineering resonance between the instrumental
hypotheses of workers and designers during design
In the two directions mentioned above, the activity of the designers and
that of the workers are asynchronous. The third direction is to organize
synchronous work. The specific feature of this third way is that the dia-
logical exchanges between designers and users serve as a driving force for
design, as we will see with an example regarding the design of an alarm
aiming to prevent runaway reactions in SEVESO class chemical plants
(Béguin, 2003).
We are in a production unit in the field of high-precision chemistry.
The product being manufactured is highly explosive, and can exist in
either one of three states. In the cold state, it thickens and hardens, leading
to 'supercooling'. When it heats up, it becomes a liquid, which is its ideal
state. But when it is too hot, it produces a highly explosive gas, leading to
a runaway reaction. Runaway reactions are the primary cause of human
