# The Use of Drones in Spain: Towards a Platform for Controlling UAVs in Urban Environments
## 1 Introduction  
Unmanned Aerial Vehicles (UAVs) are not new; they have been in existence for dozens of years, however only recently have they become popular. With the development of technologies, modern UAVs have also become more advanced and our possibilities for using them have become greater, which poses new legal and regulatory questions. Initially, they were designed for military purposes: to transport balloon bombs and as a form of training for anti-aircraft weapons during World War II. Today, their use is becoming more frequent and they can carry out a wider range of tasks in both the military and professional sectors. This second case is the focus of this article. The popularity of using UAVs for professional tasks was largely achieved thanks to the appearance of multirotor systems about eight years ago, a new type of UAV that offers great benefits and advantages over the UAV and manned systems used up to that time.  
Some of the advantages of these systems over other types of UAVs are their mechanical simplicity, greater stability and tuning. In comparison to UAV aircraft, rotorcraft do not need a runway to take off since they can lift vertically off the ground. Traditional UAV helicopters are not as stable as multirotorsare and they require complex mechanical components to achieve stability. On the other hand, stability can be achieved much more simply and effectively in multirotors, which use speed variations in their motors for this purpose.  
UAV systems have many advantages over other manned aerial systems, especially when used in the professional or commercial fields. Their cost is lower; they are portable (smaller in size); and they can fly in small, enclosed or crowded areas. For example, they can fly in urban areas at low altitude or even inside buildings. Moreover, the fact that UAVs are steered remotely is also a big advantage; no persons on board means that, in the case of it crashing, no people would be harmed.  
The chance of a UAV falling is minimal, but possible and can be caused by several factors, such as collision with an object or some error of the pilot. However, there is also the possibility that pilots purposefully use a UAV to cause damage or infringe the privacy of citizens.  
The problem with flying devices is that they can easily access private and restricted environments. There are no legal, nor physical barriers that would prohibit their access, which means that UAVs can be used to intrude peoples' privacy and there is uncertainty about whether this practice is legal.  
Different proposals have been made that attempted to regulate the use of UAVs and their access to certain areas by proposing measures such as licensing or banning urban hubs, however these measures often limit the possibilities that technology offers. Moreover, legislation varies from region to region and between countries.  
This article takes a proactive approach towards state of the law in Europe, especially in Spain. In this paper, we present a platform that has been developed under this legal framework. UAVs can connect to this platform, which monitors them to comply with all the laws. For example, competent authorities can monitor and control UAVs through the platform in real time. In this way, suspicious behavior can be detected, access to restricted areas can be controlled, security protocols can be added to prevent the pilot from losing control or signal, autonomous flights can be created or collisions between the UAVs connected to the platform can be avoided.  
The rest of the article is structured as follows: Section 2 provides a brief review of the state of the art on UAVs. Section 3 analyzes current European law, focusing on the legislations in Spain in more detail. Section 4 describes the proposed system. Section 5 shows the results obtained when the proposed system was tested with UAVs. The last section presents the conclusions drawn from the conducted research work and possible lines of work for the future.