DEPENDABILITY ASSESSMENT FOR MECHATRONIC SYSTEMS:
ELECTRONIC STABILITY PROGRAM (ESP) ANALYSIS
Mihaela Barreau, Alexis Todoskoff, Alin Mihalache,
Fabrice Guerin and Bernard Dumon
University of Angers
LAboratoire de Sûreté de fonctionnement, Qualité et Organisation (LASQUO)
(Quality, Dependability &Management Laboratory)
62, avenue N-D du Lac - 49000 ANGERS – France
Fax. 33.2.41.22.65.21
E-Mail : mihaela.barreau@univ-angers.fr
Keywords: Complex systems, Safety analysis, Reliability evaluation, Active control, Petri Nets, Electronic
applications.
ABSTRACT
Complex mechatronic systems have a potential impact on people’s safety, and on the environment. Furthermore,
technological progress increase these systems performance, but also their importance. The consequences of their
failures are proportional to their performances increase, thus significantly more severe than in the past. The
dependability analysis of such systems becomes then a very important engineering issue, in order to guarantee their
functional behavior. However, this evaluation is extremely difficult, since most of the critical failures are generated
by the interactions between the sub-systems, implemented in different technologies, e.g. mechanics, electronics, and
software. Therefore, the analysis of the system as a whole is not enough and it becomes necessary to study all the
interactions in order to estimate the system’s dependability.
1. INTRODUCTION
Dependability assessment is becoming an integral part
of the design process of complex systems in high capital
cost and high risk applications. The purpose is to
provide insight into the key areas of a system and to
highlight potential areas so they can be dealt with at the
design stage of the project (Liu and Chiou, 1997). This
type of assessment provides a deeper understanding of
the construction and functioning of different sub-systems
and allows comparisons between possible technical
choices, all of which helps to improve system safety.
Nowadays, mechatronic systems have a potential
impact on people’s safety and technological progress
increases not only their performance but also their
importance. Therefore the control of their dependability
(reliability, safety, availability and maintainability) is a
major concern. Since these systems are very complex to
study, the evaluation of their dependability is extremely
difficult.
The complexity of mechatronic systems is inherent to
their structural heterogeneity: their implementation
involves an increasing variety of technologies, e. g.
mechanical, electronic and software components, the
latter frequently controlling the system itself.
Indeed, a mechatronic system combines various
techniques and is computer controlled. The aim of the
control system is to observe the operative part through
physical variables measured by sensors, to detect some
events and choose the suitable command processed by
the actuators (state change of the system) (Tomatis, et
al., 2001 ; cf Figure 1).
Therefore studying each of the sub-systems separately
is insufficient: it is necessary to study both the system as
a whole and all the interactions between the sub-systems,
since these interactions generate most of the failures and
the most critical ones. The most important constraint in
studying the interactions is the variety of the
technologies used, which implies co-operation between
dependability engineers (Barreau, et al., 2003).
Although mechatronic systems are becoming an
important study area, the methods and tools which are
used to evaluate and control their dependability are
specific of the fields of each kind of implemented
technology and do not consider interactions between sub-
.....