Meta-Routing: Synergistic Merging of Message Routing and Link Maintenance

The maintenance of network connectivity is essential for effective and efficient mobile team operations. Achieving robust mobile ad hoc networks (MANETs) connectivity requires a capable link maintenance mechanism especially if the network experiences expected intermittent connectivity due to a hostile environment. One applicable example of such network scenarios is multi-robot exploration for urban search and rescue (USAR). With the proliferation of these robotic networks, communication problems such as the link maintenance problem are subject to be raised quickly. Although various routing protocols for wireless ad hoc networks have been proposed, they solve the problems of message routing and link maintenance separately, resulting in additional overhead costs and long latency in network communication. Traditional routing protocols discover existing links, connect these links, find the best path and minimize the path cost. The limitation of previous routing protocols motivates us to develop a new concept of routing mechanism for a robotic network. This routing mechanism is named Meta-Routing. Meta-Routing expands current routing protocols to include not only the normal routing of packets, but also the maintenance of links in mobile agent scenarios. Thus, Meta-Routing minimizes the communication path cost and the overhead cost, the latter of which results from discovering a route, repairing a link or establishing a new communication path between nodes. This dissertation presents a method to achieve Meta-Routing by controlling robot motion based on the radio frequency (RF) environment recognition method and gradient descent method. Mobile robot controlled motion can effectively improve network performance by driving robots to favorable locations with strong links. Moreover, the gradient descent method is used in driving the robots into the direction of favorable positions for maximizing broken or failing links and maintaining network connectivity. The main accomplished goals of this thesis are summarized as follows: firstly, the Meta-Routing protocol, which integrates link maintenance into the normal message routing protocol cost function; secondly, the dissertation examines the unification of the syntax of message routing protocol and the link maintenance process through physical configuration of mobile network nodes by controlling their movement in the field; finally, the dissertation demonstrates that the utilization of the RF environment recognition and classification method improves route repair estimation for achieving link maintenance in the presented Meta-Routing protocol. The numerical experimental results demonstrate promising RF environment recognition and node controlled motion results, as well as confirm their abilities in robot movement control for link maintenance and reduction of the total path cost

A mosaic of eyes

Autonomous navigation is a traditional research topic in intelligent robotics and vehicles, which requires a robot to perceive its environment through onboard sensors such as cameras or laser scanners, to enable it to drive to its goal. Most research to date has focused on the development of a large and smart brain to gain autonomous capability for robots. There are three fundamental questions to be answered by an autonomous mobile robot: 1) Where am I going? 2) Where am I? and 3) How do I get there? To answer these basic questions, a robot requires a massive spatial memory and considerable computational resources to accomplish perception, localization, path planning, and control. It is not yet possible to deliver the centralized intelligence required for our real-life applications, such as autonomous ground vehicles and wheelchairs in care centers. In fact, most autonomous robots try to mimic how humans navigate, interpreting images taken by cameras and then taking decisions accordingly. They may encounter the following difficulties

Wireless Sensor Networks for Building Robotic Paths - A Survey of Problems and Restrictions

The conjugation of small nodes with sensing, communication and processing capabilities allows for the creation of wireless sensor networks (WSNs). These networks can be deployed to measure a very wide range of environmental phenomena and send data from remote locations back to users. They offer new and exciting possibilities for applications and research. This paper presents the background of WSNs by firstly exploring the different fields applications, with examples for each of these fields, then the challenges faced by these networks in areas such as energy-efficiency, node localization, node deployment, limited storage and routing. It aims at explaining each issue and giving solutions that have been proposed in the research literature. Finally, the paper proposes a practical scenario of deploying a WSN by autonomous robot path construction. The requirements for such a scenario and the open issues that can be tackled by it are exposed, namely the issues of associated with measuring RSSI, the degree of autonomy of the robot and connectivity restoration.The authors would like to acknowledge the company Inspiring Sci, Lda for the interest and valuable contribution to the successful development of this work.info:eu-repo/semantics/publishedVersio

A critical analysis of mobility management related issues of wireless sensor networks in cyber physical systems

Mobility management has been a long-standing issue in mobile wireless sensor networks and especially in the context of cyber physical systems; its implications are immense. This paper presents a critical analysis of the current approaches to mobility management by evaluating them against a set of criteria which are essentially inherent characteristics of such systems on which these approaches are expected to provide acceptable performance. We summarize these characteristics by using a quadruple set of metrics. Additionally, using this set we classify the various approaches to mobility management that are discussed in this paper. Finally, the paper concludes by reviewing the main findings and providing suggestions that will be helpful to guide future research efforts in the area

Uav-assisted data collection in wireless sensor networks: A comprehensive survey

Wireless sensor networks (WSNs) are usually deployed to different areas of interest to sense phenomena, process sensed data, and take actions accordingly. The networks are integrated with many advanced technologies to be able to fulfill their tasks that is becoming more and more complicated. These networks tend to connect to multimedia networks and to process huge data over long distances. Due to the limited resources of static sensor nodes, WSNs need to cooperate with mobile robots such as unmanned ground vehicles (UGVs), or unmanned aerial vehicles (UAVs) in their developments. The mobile devices show their maneuverability, computational and energystorage abilities to support WSNs in multimedia networks. This paper addresses a comprehensive survey of almost scenarios utilizing UAVs and UGVs with strogly emphasising on UAVs for data collection in WSNs. Either UGVs or UAVs can collect data from static sensor nodes in the monitoring fields. UAVs can either work alone to collect data or can cooperate with other UAVs to increase their coverage in their working fields. Different techniques to support the UAVs are addressed in this survey. Communication links, control algorithms, network structures and different mechanisms are provided and compared. Energy consumption or transportation cost for such scenarios are considered. Opening issues and challenges are provided and suggested for the future developments

Mobile ad hoc networks for intelligent systems

Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. Mobile ad hoc networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. They do not rely on specialized routers for path discovery and traffic routing. Research on ad hoc networks has been extensively investigated in the past few years and related work has focused on many of the layers of the communications architecture. This research intends to investigate applications of MANET for intelligent systems, including intelligent transportation system (ITS), sensor network and mobile intelligent robot network, and propose some approaches to topology management, link layer multiple access and routing algorithms. Their performance is evaluated by theoretical analysis and off-the-shelf simulation tools. Most current research on ad hoc networks assumes the availability of IEEE 802.11. However, the RTS/CTS protocol of 802.11 still leads to packet collision which in turn decreases the network throughput and lifetime. For sensor networks, sensors are mostly battery operated. Hence, resolving packet collision may improve network lifetime by saving valuable power. Using space and network diversity combination, this work proposes a new packet separation approach to packet collision caused by masked nodes. Inter-vehicle communication is a key component of ITS and it is also called vehicular ad hoc network. VANET has many features different from regular MANETs in terms of mobility, network size and connectivity. Given rapid topology changes and network partitioning, this work studies how to organize the numerous vehicular nodes and establish message paths between any pair of vehicular nodes if they are not apart too far away. In urban areas, the inter-vehicle communication has different requirements and constraints than highway environments. The proposed position-based routing strategy for VANETs utilizes the traffic pattern in city environments. Packets are forwarded based on traffic lights timing sequence and the moving direction of relaying vehicles. A multicast protocol is also introduced to visualize the real time road traffic with customized scale. Only vehicles related to a source node\u27s planned trajectory will reply the query packet. The visualized real time traffic information therefore helps the driver make better decision in route planning when traffic congestion happens. Nowadays robots become more and more powerful and intelligent. They can take part in operations in a cooperative manner which makes distributed control necessary. Ad hoc robot communication network is still fresh field for researchers working on networking technology. This work investigates some key issues in robot ad hoc network and evaluate the challenges while establishing robot ad hoc networks

Energy Efficient Multi-Flow Routing in Mobile Sensor Networks.

International audienceControlled mobility is one of the most complex challenges in Wireless Sensor Networks (WSN). Only a few routing protocols consider controlled mobility in order to extend the network lifetime. They are all designed to optimize the physical route topology from a source to a destination. However, there is often more than one sensor which reports an event to the sink in WSN. In existing solutions, this leads to oscillation of nodes which belong to different routes and their premature death. Experiments show that the need of a routing path merge solution is high. As a response we propose the first routing protocol which locates and uses paths crossing to adapt the topology to the network traffic in a fully localized way while still optimizing energy efficiency. Furthermore the protocol makes the intersection to move away from the destination, getting closer to the sources, allowing higher data aggregation and energy saving. Our approach outperforms existing solutions and extends network lifetime up to 37%

A Novel Communications Protocol Using Geographic Routing for Swarming UAVs Performing a Search Mission

This research develops the UAV Search Mission Protocol (USMP) for swarming UAVs and determines the protocol\u27s effect on search mission performance. It is hypothesized that geographically routing USMP messages improves search performance by providing geography-dependent data to locations where it impacts search decisions. It is also proposed that the swarm can use data collected by the geographic routing protocol to accurately determine UAV locations and avoid sending explicit location updates. The hypothesis is tested by developing several USMP designs that are combined with the Greedy Perimeter Stateless Routing (GPSR) protocol and a search mission swarm logic into a single network simulation. The test designs use various transmission power levels, sensor types and swarm sizes. The simulation collects performance metrics for each scenario, including measures of distance traveled, UAV direction changes, number of searches and search concentration. USMP significantly improves mission performance over scenarios without inter-UAV communication. However, protocol designs that simply broadcast messages improve search performance by 83% in total searches and 20% in distance traveled compared to geographic routing candidates. Additionally, sending explicit location updates generates 3%-6% better performance per metric versus harvesting GPSR\u27s location information