Virtual security bubbles prevent drones from crashing into each other

In the near future, more and more drones will come into the air, even in our residential areas. As the number of aircraft – including flying taxis – is also expected to increase in the coming years, safety standards need to be improved. A new drone flight control platform aims to control the flight of drones in such a way as to avoid mutual accidents. This is done by creating so-called virtual bubbles that protect the flying drones.

With funding from Horizon Europe 2020, a consortium led by the Polytechnic University of Valencia, consisting of the University of Coimbra, the University of Sapienza in Rome, EUROCONTROL and the Spanish company Indra, has developed a security system called bubbles designed.

In 2023, the EU U-space regulation will enter into force. It states that drones must perform tasks in the airspace safely and efficiently. The aircraft and the person responsible for it must be pre-registered in the airspace. Flight plans must also be drawn up to avoid conflicts with other flights. The system developed for this purpose can monitor the various drone flights just like with current flight control.

“The name says it all: our idea is to define security bubbles around drones. This is not a new idea. Manned aircraft are already using this concept. With them it will be the minimum separation called, ”said Juan Vicente Balbastre Tejedor, researcher at ITACA and coordinator of BUBBLES.


Juan Vicente Balbastre Tejedor

Researcher at ITACA and coordinator of BUBBLES

Teacher and researcher for UPV. Coordinated the BUBBLES project.

Virtual bubbles prevent collisions

Three aspects of minimum distance for aircraft have been established: in front of and behind the aircraft, next to the aircraft and below and above the aircraft. Breaking this bubble is an important warning signal for the pilot. He can adjust his route to avoid a collision.

“Things change with drones. They can perform different maneuvers, they differ in technical characteristics and speed, they can fly vertically and hang in the air. It is harder to determine their minimum range values,” explains Balbastre.

By collecting GPS data from drones, the UPV platform detects when two bubbles threaten to overlap. The system sends the drone operator a message, which they receive on their drone control dashboard. A list of conflicts is displayed – arranged by urgency. By clicking on each conflict, the operator is shown speed and route data so he can avoid a collision.

BUBBLES dashboard – © BUBBLES

Safety before anything

BUBBLES sought a balance between safety and the ability to fly multiple drones at the same time. The larger the bubble, the less space there is for flying aircraft. Conversely, the safety level decreases at shorter distances. Finding the right balance depends on what level of security is required.

“The European Commission has conducted several studies to gain insight into citizens’ attitudes towards flying drones. People find it acceptable as long as the risk is as great as for airplanes. Based on this, we were able to calculate what minimum distances are required. Then we focused on the communication and positioning systems and developed the platform we have today, ”explains Balbastre.


To test the technology, large drone flights were conducted in Europe. In an airspace of fifteen km², fourteen drones underwent a series of simulations to test the reliability of the platform. Different situations were played out. For example, the loss of the GPS signal. Dangerous situations such as a potential collision were also deliberately induced to measure the pilots’ reaction time and determine how long it would take them to solve the problem.

“The reaction time is significantly shorter when the drone operator knows that the two bubbles have come into contact with each other. Another thing we achieved was that we could adjust the minimum distance in real time depending on the scenario, if that changed, ”says Balbastre.

Alarms, advice and orders

As part of U-Space’s services, drones and control platforms must be able to communicate with each other. The drone pilot must be informed about where to fly, which drones are nearby and – if necessary – be able to change the drone’s route. In addition, there is an escalation scale that European air traffic control can intervene against.

“It will consist of five levels: traffic information, warnings, advice, instructions, mandatory instructions and then notifications to the operator that a maneuver will be performed, without the possibility of rejecting it,” explains Balbastre.

As with aircraft, the rejection of an order may lead to further investigation by the authorities. Planes, ships and cars all have rules to keep traffic flowing. With an increasing number of professional drones in the air, the need to establish traffic rules and guidelines for these devices is also increasing.

“In manned aviation, the rules determine how you should behave in specific situations. It is different with drones because the pilot is not present. That is why another European project – CORUS XUAM, led by Eurocontrol – is working on drafting these rules, ”added Balbastre.

Social acceptance

The Valencia research group has also tested so-called vertical gates; takeoff and landing sites for drones. They are hubs for the aviation of the future and can be built in urban areas. Air One recently opened the first European vertiport in Coventry, UK. The airport for drones will soon be tested in other countries as well.

“What we’ve done is look at how we can control drones that take off and land from there,” Balbastre points out. “In order to be accepted by the public, we need to optimize all the operations that take place there, from landing to charging the battery. For example, we need to prevent drones from flying around for minutes without landing. They are noisy and cause nuisance to the people. Social acceptance is crucial to integrating this kind of technology into society. “

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