## 2 Application of Networked Mobile Sensors
### Search and Rescue Operations  
One of the main application areas for mobile robot teams is search and rescue operations in disaster environments. Different kinds of catastrophe occur in nature such as earthquakes, landslides and fires. Usage of networked robot systems is of great importance under these disaster situations [54]. Robots consistently help humans in dangerous and complex tasks, providing information about areas that cannot be directly reached by the humans, especially in disaster areas, which are typically highly unstructured and uncertain. Search and rescue teams of living humans have the main disadvantage of tiredness from continuous and tedious long hours of works, so robotic aids are increasingly being considered in search and rescue tasks [40]. Networked mobile robots show promise to be a highly versatile system for disaster reconnaissance, building the inventory of the disaster while searching for survivors. The most important search and rescue task for networked robot teams in a disaster environment is the localization of victims within the disaster rubble, so as to provide information about the condition of detected possible survivors in the disaster areas not easily reachable by humans. Heterogeneous networked robot teams were constructed by [PERSON] _et al._[55] to cooperatively control each other to find survivors. The heterogeneous rescue teams are composed of three kinds of robots, each of them equipped with different abilities: MA-I is a track type inspired from tanks and is remotely controlled by an operator over a radio signal, IGA is a track type with flippers, which gives the ability of navigation in rough terrain, and KOHGA is a snake-like robot. Differently structured robots are used to improve mobility with the help of the robots' flippers, snake-like motion and the capability of physical support. For example, when a robot is trapped into the rough terrain by obstacles and cannot recover its mobility, other robot team members can give physical support to the trapped robot to escape from its failed position. This improved robustness in mobility has promising capabilities for safe navigation in challenging unstructured environments. Task execution, like for exploration, mapping and navigation, can be very difficult due to the structural characteristics of the disaster environments. Networked robot systems can handle these difficulties, not only by using information sharing but also by reshaping their morphology and passing some components to each other; this is called force cooperation in the literature. These networked robots are called reconfigurable robots and can execute complex tasks that the information-only coordinated robot team with fixed structure cannot execute [56,57]. Reconfiguration capability provides flexibility to the robot team when accomplishing difficult tasks in urban search and rescue missions such as transportation of victims in the catastrophe area and helping other failed robots in the team to recover, or coverage of the failed robots in accomplishing the rest of the given mission [56]. [PERSON] _et al._[57] investigated force cooperation between networked robots to enhance the mobility of the team. The proposed networked robot system can dock and adjust each team member's position and orientation according to other robots' states to easily execute a given task using force cooperation. Hard environmental conditions such as hills and being trapped in a trench are handled by using this docking skill. Another problem for search and rescue teams is the mechanical development of robot platforms, since some of the robots need to be small and have high mobility while others need be powerful and robust. Simple small devices are used for debris exploration making use of their high maneuvering capabilities and powerful robotic devices are used for treating heavy debris, opening passages and carrying victims out of collapsed buildings. There are various types of rescue robots, being either autonomous or human operated [58, 59, 60].