closed-loop control system. Among the cases cited,
the reference (Rui et al. 2020) maintenance decisions
oriented with a novel non-probabilistic reliability
assessment approach is an example close to the
proposal in this paper but in a different system.
Figure 1 describes the block diagram of the
engineering solution proposed, called in this paper as
Integrate Maintenance-e (IMe), e- referring to
electronic or digital.
Figure 1: Risk based Maintenance Management Efficiency
Control System.
In the presented model, the control risk
management effectivity depends on the maintenance
scheduling optimization. By nature, in the literature,
this process is an open problem because engineering
systems increase their complexity and variety every
single day and new researches are needed to fill the
gabs of the challenges.
Maintenance scheduling as a general problem,
can be decomposed essentially by hierarchical levels,
holistic objective (referring to global or integrated
strategies) or multi-objectives (referring to
decentralized strategies), and optimization criteria
cost, reliability, or hybrid approach. Examples are
cost-holistic (Akaria et al., 2019), cost-multi-
objectives sequential (Briskorn et al., 2019) and
holistic-reliability approach (Luo et al., 2019). For
any of the cases, the problem is to find the best
scheduled maintenance sequence of actions for each
component considered in the system.
Generally, the objectives and restrictions are not
well defined because depends on the individual
system requirements. However, as a consensus, the
optimization problem is defined as a multi-criteria
combinatorial problem of non-linear objective
functions with constrains (adding by us stochastics),
and the problem objective is to determine the timing
and sequence of the maintenance tasks periods of
each component analysed. Therefore, the variables x
in a maintenance scheduling problem is represented
by the start time of the maintenance tasks for all the
component considered.
Especially, the paper is focuses on defining the
exploitation efficiency system based on risk
management for overhead cranes under operation into
the steel plant, and in a specific scenario description
as an application example. The idea is to contribute
with an example of overhead cranes adaptation to the
digital industry and with a clear union of control risk
management with maintenance scheduling.
The motivation of the investigation starts with the
identification of organization issues in the dedicated
maintenance department of the steel plant, which is
focusing on cranes operation into the continuous
transportation process in the hot rolling mills system.
In this system, overhead cranes are critical devices,
because in case of failure or maintenance the
production line can stop.
The department have a risky situation also when a
scheduled maintenance of selected cranes (existing as
hot redundancy) is performed and at the same time an
unexpected fail of cranes in use in the system are
reported.
In practice, we consider a set of cranes in the
operation process of the plant. We learn about the
results of technical degradation of cranes under the
operation processes, implementation results of
dedicated to cranes maintenance focused procedures,
as well as the existing environmental conditions and
applied plant operation strategies.
The presented exploitation efficiency system
based on risk management for proper engineering
decision making and controls, considers the plant
operation strategies. The system platform helps also
to adapt crane maintenance processes to the existing
operation problems and events and available
resources, as well as unexpected critical events into
the hot mill system.
The IMe platform supports decision-making
processes aimed at minimizing the risk of the
operational safety of cranes and the risk of losing their
operational reliability, as a result of the degradation
of the structure and utility functions of devices and
the possibility of a combination and association of
events and failures resulting in a safety hazard under
operation processes.
In our case, maintenance-task distribution or
maintenance scheduling solution implemented is a
holistic-reliability approach.
The approach was selected holistic for an easy
interpretation of the maintenance impact on the
system by the entity manager (unique indicator), and
reliability, because overhead cranes in a steel plant
are critical devices working in a continuous process,
by construction, the system must be reliable.
In this paper, the approach selection is driven by
individual system requirements and the contribution
is strongly guided by the CLE framework (Barari et
al., 2009).
Conceptually, the proposed model considers two
layers (live and digital) guided by independent