Adoption of Vehicular Ad Hoc Networking Protocols by Networked Robots

Wim Vandenberghe, Ingrid Moerman, Piet Demeester
2012 Wireless personal communications  
This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed
more » ... cally with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan. 2 Wim Vandenberghe et al. In the last decade, a tremendous amount of technical developments have lead to significant progression in the domain of robotics. Robots have been applied successfully in a large number of diverge use cases such as rescue operations, fire fighting, underground mining, exploration, robot sports, etc. Key driver behind these scientific advancements is the integration of several fields such as mechanics, sensor systems, artificial intelligence, ubiquitous computing, wireless networking, and so on. In this paper we focus on the application of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. A team of robots can handle a wider range of tasks and accomplish some tasks more efficiently than a single robot. An example is path finding in a random maze composed of walls and paths, where cooperation results in significant better performance [1] . Teams of robots can also be beneficial in terms of reliability and scalability [2] . Reliability means that a failure in some robots does not seriously affect the system performance itself. Scalability means that the system is applicable to a wide variety of scenario's and environments for an envisaged application. Using teams of robots also greatly enhances the supported distance between a tele-operated robot and the human operator in dangerous situations [3] . Finally, in several cases the cost of building many simple robots is also significantly lower than the cost of a large and complex monolithic robot [4] . Typically, this integration of wireless communication is tackled in a quite pragmatic manner. In a large amount of published studies, the robots are equipped with IEEE 802.11 technology, in combination with an existing Mobile Ad Hoc Network (MANET) protocol. Such a protocol enables the robots to form an ad hoc network. There are no fixed routers in such a network, all nodes are capable of movement and can be connected dynamically in an arbitrary manner. Nodes of these networks function as routers which discover and maintain routes to other nodes in the network [5] . In some cases, these existing MANET protocols are enhanced to comply better with specific requirements of the studied robotic application. Such protocols are also called known as Robotic Ad Hoc Networks (RANET). However, only a few authors presented novel RANET protocols that were designed from scratch with the robotic use case in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). Such networks support vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication to increase the "time horizon", the quality and reliability of information available to drivers. In research, this technology is applied in a large number of applications. When approaching dangerous situations such as a the tail of a traffic jam, an obstacle on the road or a ghost driver, drivers can be warned in time to avoid collision. Detected hazardous road conditions such as black ice or an oil trail can be automatically communicated. Drivers can be notified well in advance about approaching emergency vehicles, and can be directed to yield way in a uniform manner. This is just a small selection from the large number of applications that are made possible, but it is obvious that these systems can make a significant positive contribution to traffic safety. Attracted by this important potential, numerous research efforts Adoption of Vehicular Ad Hoc Networking Protocols by Networked Robots 3 developed novel VANET protocols, focusing on aspects such as high mobility, scalability and latency. This observation that the field of VANET protocols is quite mature in comparison with the field of RANET protocols is the starting point of this paper. If the results of all previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the state of the art in the domain of networked robots in section 2. This survey aims to illustrate the level of matureness of the domain, and to define the requirements of a RANET. In section 3 the same approach is followed for networked vehicles. In section 4, the two domains are compared and recommendations are specified to transfer results from the VANET to the RANET domain. Final conclusions are drawn at the end of the paper. Networked robots This section elaborates on different aspects of networked robots. A good starting point for this discussion is to provide a definition of such robots. In this paper, we rely on the definition provided by the IEEE Society of Robotics and Automation's Technical Committee on Networked Robots, since it is both clear and thorough [6]: "A 'networked robot' is a robotic device connected to a communications network such as the Internet or LAN. The network could be wired or wireless, and based on any of a variety of protocols such as TCP, UDP or 802.11. Many new applications are now being developed ranging from automation to exploration. There are two subclasses of Networked Robots: (1) Tele-operated, where human supervisors send commands and receive feedback via the network. Such systems support research, education and public awareness by making valuable resources accessible to broad audiences; (2) Autonomous, where robots and sensors exchange data via the network. In such systems, the sensor network extends the effective sensing range of the robots, allowing them to communicate with each other over long distances to coordinate their activity. The robots in turn can deploy, repair and maintain the sensor network to increase its longevity, and utility. A broad challenge is to enable such new capabilities." This definition indicates that networked robots can be deployed for a large number of various applications, leading to quite diverse RANET communication patterns in terms of network topology and data types. The next subsection presents a survey of these applications and the existing RANET solutions that support them. The idea is that the insights provided by such an investigation of the related work will result in a solid foundation for the definition of the communication requirements for networked robots. In section 4 they will be applied to assess the similarities between the requirements of RANET and VANET protocols. Adoption of Vehicular Ad Hoc Networking Protocols by Networked Robots 25 Use cases Approximately 40 applications concerning networked cars are common in literature 1 . Reviewing all these applications in detail is clearly unfeasible within the constraints of this paper. For more information we therefore refer the reader to the two technical standards regarding these applications. These are provided by the Car 2 Car Communication Consortium (C2C-CC) [72] and the European Telecommunications Standards Institute (ETSI) [73] . However, for the definition of the VANET requirements in section 3.3, the classification of the C2C-CC of all these applications can be very useful. The consortium was able to define six generic applications that together can support all known use cases. This classification is illustrated in Fig. 5 . "Vehicle 2 Vehicle Cooperative Awareness" supports the requirement for applications to share information with each other without any persistent communication link between the vehicles. Example use cases are lane change assist, wrong way driver warning, emergency vehicle warning, crossroads collision warning, cooperative glare reduction and cooperative adaptive cruise control. "Vehicle 2 Vehicle Unicast Exchange" enables a communication link between vehicles for the exchange of information. Examples of this application are pre-crash sensing, lane merging assistance, highway platooning and instant messaging. "Vehicle 2 Vehicle Decentralized Environmental Notification" provides information about events and roadway characteristics that are probably interesting to drivers for a certain time in a certain area. Some examples are approaching traffic jam alert, slow vehicle indication, warning of incidents, road adhesion alert and notification of a broken down vehicle. "Infrastructure 2 Vehicle (One-Way)" supports the communication from roadside units (RSU) to vehicles without a persistent communication link between vehicles and RSUs. A few possibilities are contextual speed limit alerts, traffic light optimal speed advisory and wind status information at elevated road segments. "Local RSU connection" supports use cases where data between a vehicle and a RSU needs to be sent from the vehicle to the RSU or bidirectionally. This can be applicable in the case of automatic access control, free flow tolling, payment at drive-through, signal violation warning, etc. The last application, "Internet Protocol Roadside Unit Connection", supports services that are offered to the driver by servers located in the Internet. Some example use cases for this generic application are eCall, remote diagnostic, enhanced route guidance, map download, fleet management and parking management. A technical analysis of all six generic applications, containing among others the required communication techniques, is described in the C2C-CC Manifesto [72] .
doi:10.1007/s11277-012-0598-2 fatcat:6olcfuic3jg7rgjau4cefw5joa