Unmanned Ground Vehicle navigation and coverage hole patching in Wireless Sensor Networks

This dissertation presents a study of an Unmanned Ground Vehicle (UGV) navigation and coverage hole patching in coordinate-free and localization-free Wireless Sensor Networks (WSNs). Navigation and coverage maintenance are related problems since coverage hole patching requires effective navigation in the sensor network environment. A coordinate-free and localization-free WSN that is deployed in an ad-hoc fashion and does not assume the availability of GPS information is considered. The system considered is decentralized and can be self-organized in an event-driven manner where no central controller or global map is required. A single-UGV, single-destination navigation problem is addressed first. The UGV is equipped with a set of wireless listeners that determine the slope of a navigation potential field generated by the wireless sensor and actuator network. The navigation algorithm consists of sensor node level-number assignment that is determined based on a hop-distance from the network destination node and UGV navigation through the potential field created by triplets of actuators in the network. A multi-UGV, multi-destination navigation problem requires a path-planning and task allocation process. UGVs inform the network about their proposed destinations, and the network provides feedback if conflicts are found. Sensor nodes store, share, and communicate to UGVs in order to allocate the navigation tasks. A special case of a single-UGV, multi-destination navigation problem that is equivalent to the well-known Traveling Salesman Problem is discussed. The coverage hole patching process starts after a UGV reaches the hole boundary. For each hole boundary edge, a new node is added along its perpendicular bisector, and the entire hole is patched by adding nodes around the hole boundary edges. The communication complexity and present simulation examples and experimental results are analyzed. Then, a Java-based simulation testbed that is capable of simulating both the centralized and distributed sensor and actuator network algorithms is developed. The laboratory experiment demonstrates the navigation algorithm (single-UGV, single-destination) using Cricket wireless sensors and an actuator network and Pioneer 3-DX robot

An architecture for the integration of Wireless Actuation Capabilities with IP Multimedia Subsystem

The IP Multimedia Subsystem (IMS) is an architecture that aims at seamlessly delivering multimedia services. It enables IP multimedia services for end-user using standard Internet based protocols such as Session Initiation Protocol (SIP). Examples of multimedia services include presence, instant messaging, enhanced voice and video, pervasive gaming and emergency services. Wireless actuators are small scale devices that can receive/accept instructions and act on their surrounding environment. They are broadly used in automation industry and intelligent control systems. With the rapid development of Internet and mobile telecommunication technologies, more and more actuators are being deployed in applications such as environment monitoring, home automation and health care to improve human beings’ living conditions. Combining actuators’ actuation capabilities with IMS will certainly enable novel value added services. However, the actuator networks are application specific and provide proprietary interfaces to the external world. Integrating wireless Actuator Networks (AN) with IMS to enable actuation service to IMS end users through standard protocols and interfaces is the objective of this thesis. There are several challenges related to this integration: First, there is no ready-to-use architecture for the integration. New functional entities and suitable protocols for actuation triggering are needed. Second, there are no actuators in the market with open interfaces to the external world, we need to find alternative solutions for the realization of the integrated architecture. Third, there is no information model for abstracting actuation command semantics and this has to be defined. In this thesis we derive a set of requirements for the integration of AN actuation capabilities with IMS, we review and evaluate related work, and then propose a novel architecture. This architecture includes two new functional entities for IMS: The Actuation Control Function (ACF) and the Wireless Actuator Gateway (WAG). The ACF handles high level actuation requests from other applications. It acts as an intermediate component and hides the low level actuation commands from the applications. The WAG transforms high level actuation commands to low level, proprietary and actual actuation commands that can be understood and executed by actuators. A detailed survey and evaluation of existing protocols for actuation command carrying is also provided. We define an actuation command information model to abstract the actuation triggering instructions. We implement the key components of the proposed architecture. A proof of concept prototype has been implemented using simulated robots equipped with actuators. The average end-to-end actuation delay of our architecture is evaluated through experiments with the prototype