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Distribution warehouses are considered in this paper with the aim of scheduling the transportation of pallet and roll pallet loads from the storage area to the gates at which the trucks arrive. Transportation activities are carried out by forklift AGVs that can move freely along the warehouse's aisles (guide paths are not considered). In this paper, an optimization procedure is proposed, which is...
Industrial processes use energy to transform raw materials and intermediate goods into final products. Many efforts have been done on the minimization of energy costs in industrial plants. Apart from working on “how” an industrial process is implemented, it is possible to reduce the energy costs by focusing on “when” it is performed. Although, some manufacturing plants (e.g. refining or petrochemical...
The purpose of this paper is twofold: to depict the patient's journey in operating block of the hospital and to provide a flexible model that matches the reality. In operating block of Jeanne de Flandres Hospital, a daily meeting is held in order to establish the operations that will occur the next day. Organizing a schedule in these circumstances leads to a loss of time and can often lead to conflictual...
Reliability is a key requirement in many distributed real-time systems deployed in safety and mission critical applications, and temporal redundancy is a widely employed strategy towards guaranteeing it. The temporal redundancy approach is typically based on task re-executions in form of entire tasks, task alternates or, check-pointing blocks, and each of the re-execution strategies have different...
Real-time Ethernet variants gain importance for communication infrastructure of various time-critical domains, such as in-car networks. Synchronous time-triggered traffic guarantees strict timing but requires a detailed schedule for all participants. Designing these schedules by hand is extensive work and with increasing network size almost impossible. In this paper, we contribute a mapping of the...
Automation systems must primarily be deterministic and reliable, especially in safety-critical environments. With recent trends such as mass customization or Industry 4.0, there is an increasing need for automation systems to be dynamic. Changing parts of the software of today's automation systems, however, typically requires rebooting the controller, which makes software updates a complex and costly...
This paper focuses on the optimization of the TTEthernet communication protocol, which offers three traffic classes: time-triggered (TT), sent according to static schedules, rate-constrained (RC) that has bounded end-to-end latency, and best-effort (BE), the classic Ethernet traffic, with no timing guarantees. In our earlier work we have proposed an optimization approach named DOTTS that performs...
Today's manufacturing industry is under pressure to increase the flexibility of its factory lines. One approach to achieve this goal is the shift from centralized control systems towards distributed, service-oriented architectures (SOA). To fully leverage the benefit of this new paradigm, the SOA should extend down to the device level and even include resource-constrained devices, such as smart sensors...
With multicore controllers becoming available for industrial automation applications, new tools and algorithms to compute efficient partitioning and scheduling solutions for control applications need to be developed. Optimizing the deployment and the schedule of a set of Function Block Diagrams on a parallel architecture are both NP hard. Additionally, control engineers need help to shift from the...
Cluster scheduling is a crucial issue in cluster-tree Wireless Sensor Networks (WSNs). The paper presents a methodology that provides a Time Division Cluster Scheduling (TDCS) mechanism based on the shortest path problem. The objective is to meet all the flows' deadlines defined by the maximum number of crossed periods for each flow to reach its destination assuming one collision domain. Formulating...
Mixed-criticality and high availability distributed systems, like those on large industrial deployments, strongly rely on deterministic communication in order to guarantee the realtime behavior. The time-triggered paradigm-as in TTEthernet-guarantees the deterministic delivery of messages with fixed latency and limited jitter. We look closely at industrial deployments in which production as well as...
Execution of business processes is an important factor that distinguishes residential and office buildings based on their energy usage. Unlike residential buildings, in offices workflows determine how and when energy-consuming devices have to be utilized. Thus, energy efficient building automation systems for office buildings should take into account the dynamic and unpredictable nature of business...
In safety-critical systems a global high-reliability is sought, including in the communication network when a distributed control system is used. The FlexRay protocol was developed within the automotive industry with the necessary characteristics to respond to the demands of safety-critical applications, e.g. X-by-wire. Nevertheless, the FlexRay protocol does not define a mechanism to guarantee message...
On-the-fly adaptability and reconfigurability are recently becoming an interest in real-time communications. To assure a continued real-time behavior, the admission control with a quality-of-service mechanism is required, that screen all adaptation and reconfiguration requests. In the context of switched Ethernet networks, the FTT-SE protocol provides adaptive real-time communication. Recently, we...
Traditional distributed embedded systems are configured using static environment information and thus do not support dynamic behavior of the system. The necessary flexibility in the system may be provided by the Flexible Time-Triggered (FTT) communication paradigm. If, in addition, it is required that the system operates continuously, the suitable fault tolerance mechanisms that provide high reliability...
In this paper, scheduling of robot cells that produce multiple object types in low volumes are considered. The challenge is to maximize the number of objects produced in a given time window as well as to adopt the schedule for changing object types. Proposed algorithm, POPStar, is based on a partial order planner which is guided by best-first search algorithm and landmarks. The best-first search,...
Manufacturing enterprises can only stay profitable if they manage to flexibly respond to changes in markets by adapting their products, product variants, and product volumes. To support such variety in products, we suggest a capability-based approach for production planning and scheduling. Production plans and machines are described in terms of required capabilities and provided capabilities respectively...
Real-time communication networks are often required to operate reliably in harsh environments which expose the system to random errors. Although probabilistic schedulability analysis can employ rich stochastic error models to capture these random behaviors, this is most often at the expense of increased analysis complexity. In this paper, some recent results on probabilistic real-time schedulability...
The complexity of modern industrial automation systems means that designing with change in mind is a necessity. Event-driven and time-driven programming paradigms each have their own benefits for the development of distributed systems control. However, flexibility and reconfiguration will always be required as new technologies are introduced and increased distribution results in greater chances for...
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