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Defining the BUilding Basic BLocks for a U-Space SEparation Management Service

Periodic Reporting for period 2 - BUBBLES (Defining the BUilding Basic BLocks for a U-Space SEparation Management Service)

Período documentado: 2021-05-01 hasta 2022-10-31

Unmanned Air Systems (UAS), commonly known as drone, arouse people’s interest due to their potentially disruptive effect on many economic sectors and their impact on citizens’ quality of live. For this reason, the number of uncrewed air operations is projected to uptake in the short-term and to skyrocket in the mid and long-term, especially in the very low level over densely populated areas. This will enable new business models and contribute to create thousands of highly-skilled jobs. However, the massive use of unmanned aircraft over cities poses safety concerns that must be properly tackled since safety is as paramount in unmanned aviation as it has been in manned aviation for decades. Indeed, safety stands out among the drivers of the social acceptance of urban air mobility applications identified in a survey recently published by the EU authorities.
To address these issues, BUBBLES has developed a concept of operations (CONOPS) describing how the risk of collisions between UAS and other aircraft (either manned or unmanned) can be mitigated using U-space services so that an acceptable level of safety can be attained without impairing the airspace capacity. The key for a trade-off between safety and capacity is the effectiveness of the mitigation barriers that the U-space may rise between an aircraft and the hazards that can cause a collision.
The BUBBLES CONOPS has been defined as a new SESAR solution, the ‘U-space Separation management service’. The concept has been validated using a prototype of U-space platform featuring the Separation management service in a flight test campaign. The validation has demonstrated that the BUBBLES solution will bring significant benefits to U-space airspace users, especially in terms of safety. In addition, the concept benefits the U-space airspace capacity, as it proposes a methodology to balance the capacity with the Target Level of Safety and the requirements of the U-space services.
During the project, the research team developed an operation-centric, risk-based CONOPS to provide separation management to UAS in U-3 environments. The CONOPS describes how tactical conflicts are detected and solved, the conflict horizon where tactical conflicts must be searched for, the separator agent and the level of human intervention, the separation minima and methods and the required safety and performance requirements (SPR) needed to achieve an agreed level of safety (TLS).
To support the operation-centric, risk-based approach pursued by BUBBLES, the research team developed a catalogue of generic UAS CONOPS and a set of conflict scenarios. A SORA assessment was applied to each individual flight. The results of this risk assessments led to the definition of 10 traffic classes (depending on the operational risk) and 9 generic sector types (depending on the air and ground risk) representative of real scenarios where U-3 U-space services could be deployed.
To identify the SPR, as well as the pairwise applicable separation minima, needed to achieve a TLS of 2.5e-7 fatalities per flight-hour in each generic sector type, BUBBLES expressed this TLS in terms of scenario dependent maximum allowable collision rates. Then, the research team developed a collision model for calculating the required effectiveness of all the mitigation barriers that can be applied to prevent mid-air collisions.
The applicable separation minima are affected by the performance of the communication and surveillance systems (C&S). Hence, BUBBLES proposed a performance-based C&S framework inspired by the one used in manned aviation and developed C&S performance monitoring tools. Based on the results of the performance monitoring, BUBBLES developed a procedure to adapt the separation minima to the actual performance of the C&S systems in quasi-real time. This procedure is based on the use of AI techniques to train models and compute separation minima values in new (although operationally similar) use cases.
The BUBBLES CONOPS to provide separation management by means of the U-space were validated through a combination of simulation and experimental tests. To this end, BUBBLES developed seven simulation tools and integrated some of them into the Indra’s industrial U-space platform. Two test flight campaigns were run to validate the BUBBLES’ concept: a preliminary one involving pairs of UAS to assess and update the initial concept formulation and a second one involving 14 UAS flying simultaneously in a simulated U-3 environment.
At the end of the project, the maturity assessment showed that the BUBBLES concept for separation management is beyond the targeted TRL2/V1 maturity but there is still some work to be performed to attain the TRL4/V2 level. According to the project exploitation plan, the BUBBLES concept has been used as part of the baseline of a fast-track project proposal aimed at setting up separation management processes in the U-space at TRL7.
Also related to the exploitation of the project results, the BUBBLES CONOPS has been defined as a SEASAR solution in EATMA, and it will be included as a new service (Tactical separation management service) in the future U-space CONOPS Ed. 4.
The results of the project were presented in 3 workshops/seminars organized by the BUBBLES’ team and in 13 workshops/seminars organized by third parties. Among the dissemination actions organized by BUBBLES stands out the summer school on Artificial Intelligence for Urban Air Mobility (AI4UAM), hosted by the University of Rome La Sapienza in September 2022. Among the third-party dissemination events where BUBBLES was presented stand out the ATM-UTM Interface webinar and the Drone Enabler 2022 symposium, both organized by the ICAO.
Moreover, the results of the project have been published in 2 refereed journal papers and have been presented in 7 international conferences.
BUBBLES has contributed to extend the state-of-the-art definition of the U-space in several ways:

1. By defining a new SESAR solution in EATMA, paving the way to define new advanced U-space services, such as the Tactical separation management service, in the new edition of the U-space CONOPS.
2. By proposing a performance-based communication and surveillance framework for the U-space pursuing to enable levels of safety comparable to those of the manned aviation by guaranteeing that the system’s performance is compatible with the safety requirements.
3. By developing new AI-based algorithms that allow to adapt in quasi-real time the separation minima to the measured performance of the communication and surveillance systems.


The main potential impacts of the project’s results are:

1. BUBBLES validation activities have demonstrated that advanced stat-or-the-art U-space services may enable the safe and efficient use of the airspace with UAS densities representative of what could be found in the initial deployments of the U-space.
2. BUBBLES has contributed to the definition of requirements applying a state-of-the-art performance-based approach already used in manned aviation, thus laying the foundations to achieve similar levels of safety.
3. Being an Exploratory Research project, BUBBLES has contributed to show the public (especially citizens and non-aviation authorities) how UAS operations supported by the U-space can be acceptably safe, thus fostering their social acceptance
BUBBLES Concept