## 1 Introduction  
Recent advances, both in the field of Unmanned Aerial Vehicles (UAVs) and Multi-Robot Systems (MRS), have led to the expansion in the use of this type of system in civilian and military tasks [1, 2]. This expansion has made UAV swarms, commonly known as drone swarms, a technological tool with high applicability in many areas, among which stand out those in which the times of action and response are a key aspect to their success. It is therefore emergency-related work where rapid, efficient and coordinated action can result in a high reduction of personal, social and economic damage. For all this, in recent years, research currents have emerged to improve the autonomous and coordinated action of drone swarms in different environments, whose achievement focuses on providing society with an effective tool capable of supporting, undertaking different tasks, and facilitating the performance of law enforcement when acting in emergency situations [3, 4, 5] such as natural disasters [6, 7, 8, 9], search and rescue of people [10, 11, 12, 13] or forest fires and urban fires [14, 15, 16]. Today, wildfires continue to be established as one of the main causes of the most devastating natural disasters [17, 18]. Throughout 2019, fires such as those declared in the Brazilian Amazon with a burnt area of 6.52 million hectares, fires in Australia in which 1.3 million hectares burned and cost the lives of 6 people, those originating in California burning 31,000 hectares and forcing the eviction of more than 200,000 people and, finally,although to a lesser extent, the fires of Canary Islands that caused the loss of almost 20,000 hectares of natural landscape, show that, to this day, the fight against fires remains a field in which it is necessary to introduce essential technological solutions that facilitate and improve the different tasks carried out in the four classic phases of firefighting such as prevention, detection, extinguishing and damage assessment. Fires are considered to be one of the vital dangers to wildlife, the wild or urban environment, and one of the main factors seriously affecting the economies of countries. In addition, fire fighting requires a large number of people to carry out dangerous activities, which unfortunately cause a large number of victims each year. Forest fires affect 67 million hectares (ha) worldwide per year, approximately 1.7% of the earth's surface [17], and cost more than 2 billion euros per year, considering both fire fighting and economic damage [18]. The social and environmental costs include damage to human health and deaths (estimated at 340,000 premature deaths per year due to fires) [19] and significant damage to wildlife and soil, causing deforestation and release of greenhouse gases, linked to direct economic impact on the landscape (tourism) and damage to infrastructure, which are also considered important. In many cases, these accidents are caused by the lack of real time information on the state of the fire or by the difficulty to reach in time the point of origin of the fire. According to the report on economic losses due to fires in the United States [20], there were about 1,298,000 fires in 2014, which caused 15,775 injuries and an estimated economic cost of $11.6 billion in direct property losses. The possibility of being able to deploy in the same area two or more UAVs capable of working in a coordinated way is presented as a high added value solution in the field of forest fires because, not only can firefighting be carried out, but swarms can consist of UAVs of different characteristics and with different payment charges on board with which to undertake, simultaneously, different tasks such as monitoring a certain region of interest, monitoring of land equipment deployed in the area, capturing and processing essential fire information, generating and expanding communications networks or, accessing remote locations.