# Smart Disaster Response in Vehicular Tunnels: Technologies for Search and Rescue Applications
## 2 Related Works
### Fireighting Robot Technology  
In general, due to the nature of fire disasters, there are many cases where fire fighters cannot enter the burning structure due to high temperatures and thick smoke. If these conditions cannot be overcome, many people may be injured. To this end, robot technologies are being explored to secure fire fighters' safety in such a dangerous environment and to support effective fire fighting activities [17; 18; 19]. Many robotic platforms with various forms, including ground driving and unmanned aerial vehicles (UAVs), have been developed. To help remote operators who are located far away from fire sites, [PERSON] et al. [20] proposed a robot-based remote monitoring system with a wireless image transmitter. In Ref. [21], a mobile rescue robot was employed to explore and monitor the nuclear accident at the Fukushima power plant; this study revealed that reliable communication between the operator and robot system is crucial to gather internal information. This means that interworking and communication with the previously mentioned IoT devices is important [22]. [PERSON] et al. [23] proposed a portable fire evacuation guide robot system; it gathers temperature, O\({}_{2}\) and CO gas information through wireless communication. In addition, it provides voice communication between firefighters and victims at remote sites. Recently, UAVs have been recognized as a promising option because they can replace firefighters' activities in some situations and can be applied for the detection of spreading fires and fire suppression [24]. [PERSON] et al. [25] proposed a distributed control framework designed for a group of UAVs that can monitor a wildfire in a large space from the remote and safedistance. [PERSON] et al. (2016) also presented an integrated system for early forest fire detection by using UAV equipped with gas sensors, a thermal camera and microwave sensors. [PERSON] et al. (2017), proposed another UAV approach for forest fire detection and tracking using median filtering, color space conversion, morphological operation, and blob counter. Since these various types of robots have different advantages and disadvantages and fire scenes are so diverse and unpredictable, it is important to combine appropriate robot solutions. Especially, since it is not possible to use existing global position system (GPS) signals in the tunnel, it is very difficult to track the location of UAVs. Also, in a tunnel of 1 km or more, it is difficult to transfer large-capacity data (e.g., video and thermal image) through the wireless local area network (WLAN)-based communication. Meanwhile, where the various fire detection sensors are pre-distributed, there have been several theoretical studies conducted to optimize the communication routing and the method for constructing the network design to efficiently acquire sensing data in the networks ([PERSON] et al., 2017; [PERSON] et al., 2018; [PERSON] et al., 2019; [PERSON] et al., 2019). However, this assumes that precise flight control and routing are possible beforehand, so it is still difficult in the field of fire that requires extempore and prompt countermeasures for unpredictable risk factors.