Dalimir Orfanus

Self-Organization as a Supporting Paradigm for Military UAV Relay Networks

The modern battlefield scenario presents a number of challenges that highlights the importance of data gathering and information flow as crucial to the success of a military operation. In this context, network-centric warfare systems play an important role to bridge the gap between data and information sources and consumers. These systems are generally composed of different types of networks both deployed on the field and on back-end facilities. A paramount problem faced when conceiving the interconnection between the networked devices is how to provide robust and dependable connections to the devices on the field. This work tackles this issue proposing the use of the self-organizing paradigm to design efficient UAV relay networks to support military operations. As a proof of concept, realistic simulation experiments are performed providing clear indications of the claimed benefits of the self-organizing paradigm applied to these military systems.

EtherCAT-based platform for distributed control in high-performance industrial applications

Industrial Ethernet is gradually becoming pervasive in the automation field. EtherCAT is one such technology, combining high real-time performance with a rich functionality set. Besides that, EtherCAT offers short cycle times, accurate time synchronization, redundancy and high data throughput. Most EtherCAT applications are in the 500-1000μs domain. There are only few EtherCAT master implementations in the sub-100 or sub-50μs range for high-performance applications. This paper presents EtherCAT based distributed controller which is capable of less than 30μs cycle times and was implemented on P2020 processor. Total HW and SW overhead per cycle is 9.6μs including jitter of 5μs. Achieved preciseness of the distributed time is below 20ns. The stack was designed to be modular and also reused on different platforms.

A Survey of Ant Colony Optimization-Based Approaches to Routing in Computer Networks

Nature has provided an elegant solution for the routing problem millions of years ago, when ant colonies started to use swarm intelligence to discover food and route it reliably to their formicaries. The approach utilized by ants has several advantages that are also useful in computer networks: complete distribution, load balancing, finding shortest paths with a high probability. Several routing protocols designed for the area of computer networks have made use of this approach, called ant colony optimization. This paper provides first a broad overview of ant colony optimization-based routing protocols, while focusing on four selected approaches in later sections, describing their operation and discussing their properties in detail.

Self-organizing relay network supporting remotely deployed sensor nodes in military operations

Data acquisition is an important task to provide context awareness of a military operation scenario in order to support informed decisions. Wireless sensor networks (WSN) play a remarkable service in this context by collecting data on remote areas to support decision support systems in control centers. However, due to the nature of the locations where they are deployed, it is out of the question provision a conventional communication infrastructure to access them. Thus, alternative communications approaches have to be used, such as relay links via unmanned aerial vehicles (UAVs) flying over the sensor network deployed on the ground. However, solutions based on this approach often propose intermittent connectivity to the WSN and/or exclusive use of the UAVs to support this connectivity. In this paper the problem is tackled by a self-organizing approach to control a UAV-relay network that provides persistent communication between WSN and back-end systems while the UAVs are not exclusively used for communication, but also have other missions to accomplish. Experimental results show the effectiveness of the proposed approach, which increased the connectivity among UAVs nearly by a factor of three compared to the deployment without any relay algorithm.

Evaluating Aspect- and Object-Oriented Concepts to Model Distributed Embedded Real-Time Systems Using RT-UML

The growing design complexity of todays embedded real-time systems requires new techniques aiming the raising of the abstraction level since earlier stages of design in order to deal with such com ...

Recovery of distributed clock in EtherCAT with redundancy for time-drift sensitive applications

EtherCAT is one of the most prominent representative of Industrial Ethernet communication technology. It provides high real-time performance together with rich functionality set. Some of its important features are very accurate distributed clock (DC) and cable redundancy. These features work perfectly when standalone. However there are some inherent problems when combined. There exist couple of solutions dealing with different aspects of this issue. Here we analyze and propose a solution how to quickly recover DC after a cable failure in order to minimize drift in the system clock without being disruptive to cyclic time-critical application traffic. Presented solution aims at high-performance industrial applications with cycle time below 100 microseconds.

High-level construction of emergent self-organizing behavior in massively distributed embedded systems

Nowadays, a range of applications and systems are emerging that consist of hundreds or thousands of computing devices, which are available at low cost but severely limited in their resources. A proper orchestration of these elements can yield a powerful system, which performs complex tasks, while staying simple and making efficient use of its resources. Designing such systems is a challenging task. The classical approach is to develop them in an ad hoc manner, which does not fully leverage the potential of these systems and is far from what can be achieved. There are methodologies which try to overcome this challenge but they do not address essential issues. Moreover, most of them do not provide a design environment to support the design process. In this paper, we propose a new methodology and design environment for systematic construction of emergent behavior in large-scale distributed embedded systems which address issues at both micro- and macroscopic layer. Our approach and simulator were successfully used to design emergent clustering and data collection in large scale wireless sensor networks.