Architecture of Computing Systems (Lecture Notes in Computer ...

Decentralized Energy-Management to Control Smart-Home Architectures 155
system. An observer/controller loop enables adequate reactions to control the
– sometimes completely unexpected – emerging global behavior resulting from
interactions between local agents.
In other words, a closed control loop is defined to keep the properties of the
self-organizing SuOC within preferred boundaries. The observer monitors certain
(raw) attributes of the system and aggregates them to situation parameters,
which concisely characterize the observed situation from a global point of view,
and passes them to the controller. The controller acts according to an evaluation
of the observation (which might include the prediction of future behavior). If
the current situation does not satisfy the requirements, it will take action(s)
to direct the system back into its desired range, will observe the effect of the
intervention(s), and will take further actions, if necessary. Using this control
loop, an organic system will over time adapt to its changing environment. It
is obvious that the controller could benefit from learning capabilities to tackle
these challenges. The observing and controlling process is continuously executed,
and the SuOC is assumed to run autonomously, even if the observer/controller
architecture is not present (which might result in suboptimal behavior).
The centralized generic observer/controller architecture has been extended in
[7]. Here, we specially focus on a hierarchically structured observer/controller
architecture, where an observer/controller is installed on each system element
as well as one for the whole technical system, as depicted in Fig. 3(b).
In particular, e. g., in larger and more complex systems (where the objective
space drastically increases) it will be necessary to build hierarchically structured
organic computing systems instead of trying to manage the whole system with
one centralized observer/controller. In the case of multiple observer/controller
levels, the SuOC at the lowest level will consist of simple elements like single
software or hardware modules.
Because of the capability of the observer/controller architecture to support
the adaptation of a system to changing environmental requirements it has been
chosen as a design pattern that is well-suited to cope with the management
problems of the smart-home scenario addressed in this paper.
5 Observer/Controller Architecture for Smart-Homes
In our approach of controlling a smart-home, we decided to implement a hierarchically
structured observer/controller architecture, as shown in Fig. 4. Each
household appliance is equipped with a local observer/controller unit (o/c unit)
to observe its current state and to interact with the appliance by turning it on or
off. Based on the measured data the local observer generates a specific demand
set 1 for each appliance. This data is communicated to the central component,
the SHMD.
The observer of the SHMD collects the demand set data from every appliance
and generates a global demand set prediction for the smart-home. Thereby, the
controller of the SHMD decides to re-schedule the demand sets of each appliance
1 Which characterizes an appliance’s power consumption profile.