Periodic Reporting for period 1 - BUBBLES (Defining the BUilding Basic BLocks for a U-Space SEparation Management Service)
Reporting period: 2020-05-01 to 2021-04-30
The development process carried out by the consortium to reach these results was:
Firstly, based on the expertise of the consortium and the baseline information, an initial concept of operations for the U-space separation management was developed by expanding the preliminary concept described in the project proposal, which includes the capability and operational level descriptions, based on the needs of the identified users. Moreover, a preliminary functional architecture was developed supporting the definition of functional requirements and interfaces. The maturity of the proposed concept was self-assessed leading to an Initial Concept of Operations.
Once the Initial ConOps were defined, the project set out the way to update it to achieve the expected level of maturity (V1). To this end, the following components of the concept were developed:
• A catalogue of generic UAS ConOps, with 9 relevant UAS ConOps representing most of the operations in a U-3 environment; based on them, a set of conflict scenarios were developed and the involved individual flights were addressed using SORA, leading to unmitigated and mitigated risk levels linked to them.
• A risk-based, operation-centric collision model for calculating separation minima, defining the service safety level, stated in terms of a TLS, which is expressed in terms of a collision rate.
• A methodology for automatic computation of separation minima for UAS for strategic conflict resolution. The methodology is based on the use of AI decision-making and Machine Learning (ML) techniques to train models and use their predictions to compute separation minima values in new (although operationally similar) use cases using a Sampled Trajectories and Monte-Carlo approach, guaranteeing the TLS given by the BUBBLES risk model in a computationally efficient way.
• An initial OSED based on the identified conflict scenarios encompassing a total of nine sector types and ten types of traffic (attending to the operational risk), and separation minima for them. The required U-space services in each sector type were also defined. The high-level operational description described in the initial ConOps were formulated as detailed operational requirements.
• During the definition of the OSED, the five first steps of MEDUSA were implemented. After the OSED was completed, the definition of the SPR started by de development of an integrated risk model for Mid Air Collision (MAC) was developed leading to the identification of Safety Criteria (SC). The Safety Assessment began with the identification of hazards that will support the Operational Assessment and Performance Assessments.
Within the field of definition of UAS ConOps, BUBBLES consortium developed nine operational scenarios, covering U1 - U4 phases, detailed enough as to support SORA, but they are mission agnostic. As a contribution, these UAS ConOps describe the operation of pairs of UAS so that the hazard of mid-air collisions between UAS can be taken into account. Moreover, BUBBLES extended the SORA model to obtain a quantitative risk level for each pair of UAS ConOps.
On the other hand, BUBBLES also formulated an innovative risk model in order to guarantee a particular TLS expressed in terms of frequency of collisions. It is based on dividing the collision rate in two components:
Freq(collision) = Freq(conflict) × Prob(collision |conflict)
where Freq(conflict) depends on use-case representative trajectories, while Prob(collision |conflict) is estimated with pairwise analysis. More specifically, Freq(conflict) evaluates the impact of strategic mitigations, while Prob(collision |conflict) evaluates the impact of tactical mitigations. These results served to define a preliminary OSED for separation management in the U-space which had not previously been developed. This OSED will support the application of MEDUSA to derive SPR from a quantitative SC (MEDUSA was always applied using qualitative SCs). These results aim at making the work of Competent Authorities and U-space Service Providers easier and at contributing to increase the safety and efficiency of drone operations in the low-level airspace.