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wise, the use of these systems leads to high develop-
ment costs and maintenance, besides requiring a deep
knowledge of them. On the other hand, the imple-
mentation of control laws in these evaluation systems
must obey certain pre-established criteria for the sys-
tem. This can result in a problem, since the control
algorithm would have to be adjusted or reconfigured,
producing a change in its structure and in the system
behavior when finally applied.
To our knowledge, there is not yet a generic plat-
form, in process control, being able to implement dif-
ferent types of operating systems and/or processes.
The use of an open-source hypervisor and RTOS
(PaRTiKLe), could improve the development process
in many ways, such as a low price in the development
and maintenance and good robustness when other ap-
plications are running. Specifically, the model of de-
velopment conceived in the open source community
could be successfully adapted to the design and im-
plementation of real-time critical application, improv-
ing the reliability and the extensibility of the software
components.
In this paper we introduce a new partitioned plat-
form composed by XtratuM and PaRTiKLe systems,
allowing a robust design of embedded control sys-
tems. A Linux partition provides the advantage of the
interaction between the user and the process, while
PaRTiKLe partition ensures the real-time execution
of the control tasks even when the system is run-
ning other tasks. XtratuM allows for strong safety of
the application, always required in ECS. The major
applications of the platform are to analyze, evaluate
and improve the performance of future embedded sys-
tems. Additionally, the proposed platform can be used
in critical embedded systems, i.e. where the dynamics
of the system is very fast and the processing time must
be executed under strict constraints. A more detailed
description of the proposed platform is presented in
section 2.
The validation of the platform and its application
to the design of embedded control systems for fast
dynamic plants (UAV) are introduced in section 3. A
comparison of the proposed platform with respect to
a platform under only Linux RT environment is also
provided. Finally, some comments and conclusions
are included in the last section.
2 SYSTEM DESCRIPTION
Embedded control systems are increasingly being
used in safety critical applications and infrastructures
such as, aircraft flight control and electric grids (Cre-
spo and Alonso, 2006) (Parkinson and Kinnan, 2003)
(J. Loyall and Fernandez., ). It is well known that,
the integrity of these critical systems will depend on
the good performance of the installed software com-
ponents. And, a bad performance or losing data in
the framework, may cause massive material and even
human life losses.
In many critical systems, and the proposed plat-
form is not an exception, it is required that numerous
software functions with varying levels of exigency
(for example, hard, soft and non real time tasks) are
running at the same time. This kind of integration
creates a special challenge because it is required to
guarantee the execution of every task and the non in-
terference with each other. In (Masmano et al., 2009),
the authors present a software architecture based on
a virtualization layer offering virtual machines to ex-
ecute partitions. This approach offers the capability
to define several partitions guaranteing their temporal
and spatial isolation and achieving the deterministic
behavior required by safety-critical systems.
To ensure the previous requirements, the designed
platform uses an open source based hypervisor (Xtra-
tuM) which executes real-time constrained partitions
based on PaRTiKLe RTOS. Moreover, this fact will
facilitate the reuse of the code and will enable the de-
velopment of more complex software without sacri-
ficing real-time performance. In the following, the
main characteristics of XtratuM and ParTiKle sys-
tems are described.
2.1 XtratuM
XtratuM is an hypervisor for embedded devices,
it provides a framework to run multiple concur-
rent operating systems in a robust partitioned en-
vironment (Masmano et al., 2005). XtratuM can
be also defined as an open source nanokernel
(www.opensource.org/docs/definition.php, ), just im-
plementing two simple device drivers: interrupt and
timer. Likewise, XtratuM can be considered as a
small subset of the lowest operating system layers that
can meet the hard real-time system requirements: fast,
compact, portable, simple and predictable.
The main characteristics of the XtratuM system
are (see Figure 1):
• Bare metal hypervisor designed for real-time em-
bedded systems.
• Several partitions can be simultaneously executed
• Every partition contains the most appropriated OS
according to the application needs.
• Every partition is executed in separated memory
areas or regions. It prevents for errors or attacks
DevelopingEmbeddedControlSystemswithXtratuM-ApplicationtoControltheAttitudeofaMini-helicopter
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