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decay continuously and are reproduced sequentially by the elements of the system itself. An autopoietic
system appears now as entirety contrary to the system-theoretical basic postulate of the necessary can-
didness of complex systems. These entireties are closed in their core region, their internal control
structure.
In the theory of social systems, humans are regarded as a system as well. On the one hand, this personal
system can be part of a superordinate system or part of a system environment. On the other hand, the
system “human” consists of subsystems like the genetic, organic, neuro-physiological, or mental systems.
The idea of man is characterized by a high degree of abstraction. An entire, human-orientated point of
view is not undertaken.
5.3 Work System Approach as an Analytical Framework
5.3.1 Overview of Work System Approach
5.3.1.1 Purpose and Characteristics of Work System Approach
The realizations of systems theory particularly were introduced into ergonomics via the work system
approach. A work system is understood as an open, socio-technical system, which consists of elements.
Candidness is expressed by the fact that the system receives an input from its environment, which is
transformed by purposeful cooperating of the system elements into an output, in order to fulfill the
system purpose. Synonymously to the term of work system, the terms “man-machine system” and
“socio-technical system” are also used (Heeg, 1988).
The work system approach acts particularly as an analysis framework. It is conducive to systemic
thinking, because it does not regard individual elements in isolation, but considers the various interde-
pendences between the elements. Besides, the application of this analysis framework forces the ergono-
mist to draw up a system limitation and, thus, make a clear problem definition.
Ergonomic literature refers to different concepts of work systems (e.g., Rohmert and Rutenfranz, 1975;
Karwowski, 1991; REFA, 1993; Hettinger and Wobbe, 1993; Luczak, 1998; Carayon and Smith, 2000;
Hendrick, 2001). These differ from each other regarding individual system components. Most of the
system concepts have the following in common, humans in work systems change work pieces coming
from the system environment in a purposeful way and dispense them into the system environment
again. This happens with the help of working equipment and operating resources. Hereby, the work
environment affects the working person.
In addition to this general work system approach, job order, and work task should be differentiated in
accordance with Figure 5.5. In order to be able to execute an order, the work system receives different
system inputs from its environment. Among these are work object, energy, and information. The infor-
mation concerning the job order contains rules for the work process. This process determines the spatial
arrangement and temporal sequence of cooperation between inputs, human, and techniques and is
designated as working method. The information about the job order is interpreted by the working
person. The person takes over the job order as a task in a redefined form. In accordance with the
task, the work object is converted to a nominal condition by activities of the working person with the
help of the working equipment and operating resources. Energies are converted and information is
produced so that the essential output of a work system consists of a changed work piece, as well as infor-
mation and energy. During the process of transformation of inputs to outputs the physical environ-
mental influences affect humans. These are known as the work environment.
The term “work system” is widely interpreted in the literature, that is, parts of an individual workplace
can be constituted as a work system like a whole enterprise (Luczak, 1998). Z¨lch (1992) differentiates
between work systems on a macro- and micro-level. Micro-work systems refer on the one hand to indi-
vidual jobs and on the other hand to working methods. The macro-level of a work system corresponds
with the level of working groups. On this level the work organization and the technical process are
regarded.
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