# A Platform of Unmanned Surface Vehicle Swarms for Real Time Monitoring in Aquaculture Environments
## 2 Related Work  
Many monitoring platforms have been developed for aquatic environments. They can be classified as static or mobile, with single or multiple sensing units, or even with a single or multiple communication technologies. The authors of Reference [7] present a platform to measure pH and temperature levels in a fish farm, with a master slave architecture in a centralized approach. The sensing unit collects and transmits the information to a central unit through a wireless protocol. The central unit manages the network and stores all the received data. The wireless transmission follows the standard IEEE 802.15.4 and implements the routing protocol based on the ZigBee standard. The work in Reference [8] presents an aquatic drone equipped with a Raspberry Pi connected to an array of air and water quality sensors for quality monitoring. For air quality measurements, temperature, humidity and gas sensors were considered, while for water quality monitoring water, temperature and conductivity sensing channels were implemented. The collected data is stored on the drone's computational platform and synchronized with a remote server database. In a similar way, the works in References [9; 10] present the prototype and proof of concept of a distributed monitoring system for aquaculture. The solution is capable of monitoring the water quality based on static wireless sensor networks, without any type of movement, and therefore, mission control. All these works are characterized by the lack of movement with respect to the sensing devices and considering a single communication technology. With respect to USV platforms for aquatic monitoring, several works have also been proposed. In Reference [11] the authors present a solution to monitor and quantify the pollution in the water produced by the feeding activities in marine fish farms. This platform uses an Underwater wireless system network in order to distribute the data to the nearest sync with a single communication technology. In order to improve the efficiency of the data sent, this platform can perform data fusion. In Reference [12], FLEXUS is presented, an affordable USVs' swarm for water monitoring, imaging and air monitoring. This platform uses multiple Wi-Fi technologies (2.4 GHz and 5 GHz). Similarly, AquaBotix proposed the SwarmDiver [13] platform, where a team works as a single coordinated entity, while communicating with each other. However, it only includes pressure and temperature sensors and uses only one communication technology. The work in Reference [14] proposes a heterogeneous Unmanned Aerial Vehicles multi-system, where a mechanism based on dividing the area between vehicles is implemented to increase the coverage area. By using a network and its protocols, the team can build up navigation information. In Reference [15] a communication-aided navigation mechanism platform is presented, where periodically, through a mobile _ad-hoc_ network (MANET), all robots share their navigation tables. The work in Reference [16] proposes a heterogeneous cooperative platform composed of USVs and aerial drones to monitor the degradation indices and water parameters of a dam. The platform performs a mission with a pre-defined mission waypoint, delivering in real time the messages by radio in Line-of-Sight to the Command and Control Station or with the help of an aerial drone acting as a relay performing a mesh network. The platform cooperative builds a 3D map of the area. Again, these works only consider one technology and strict planned missions. Regarding the motion planning algorithm used in USVs aquatic monitoring platforms, the work in Reference [17] proposes a motion planning algorithm in a fleet of commercialized USVs for aquatic monitoring which implements an offline mechanism to generate trajectories taking into account the connectivity to the ground station.