An overview of the BUBBLES first validation campaign.

26 July 2021


BUBBLES is an Exploratory Research project aiming at developing a Concept of Operations (ConOps) to provide separation to aircraft flying in volumes designated as U-space airspace, i.e. where U-space services must be provided by U-space Service Providers (USSP) and used by Unmanned Aircraft Systems (UAS) operators. One of the current tasks of the BUBBLES project is to assess the Initial ConOps for separation management to support the development of an updated version.

To this end, the research team have prepared the Validation Phase I, which addresses three components of the initial ConOps:

  1. The algorithms used to define risk-based, operation-centric separation minima for different types of UAS operations.
  2. The function in charge of detecting tactical conflicts between different types of UAS and issuing alarms to the UAS operator.
  3. The initial Safety Objectives and Safety and Performance requirements for the U-space services and supporting systems involved in the separation provision.

Linked to this, three validation objectives have been defined (each of them addressing one of the components thereof):

  • Validation Objective #1: validate that the algorithms developed in WP4 provide the separation minima needed to attain the conflict ratio which guarantees that a given Target Level of Safety (TLS) is attained.
  • Validation Objective #2: validate that the operational requirements established in the initial ConOps for separation management comply with the Performance Requirements established to attain the Safety Objectives in normal conditions identified by the research team during the Safety Assessment performed by the research team in WP6.
  • Validation Objective #3: validate the set of Safety Objectives and Safety Requirements in abnormal and faulted conditions for the U-space services and supporting systems identified during the Safety Assessment performed by the research team in WP6.

To fulfil these Validation Objectives, BUBBLES Validation Phase I has been structured in three Validation Exercises (Each Validation Objective is addressed by a Validation Exercise), encompassing simulation and experimental validation activities, which will be carried out between July and September 2021.

  • Validation Exercise #1: a variety of simulations using different tools will be run to validate the conflict model developed in Task 4.1, as well as the BB-Planner tool developed also in Task 4.1 and the AI-based algorithms developed in Task 4.2.
  • Validation Exercise #2: execution of test flights involving several UAS and checking the compliance with the Performance Requirements established to attain the Safety Objectives in normal conditions identified by the research team during the Safety Assessment performed in WP6. Numerical thresholds will be proposed for those requirements expressed in a quantitative form. An elementary Human Performance (HP) assessment will be performed using questionnaires. Eight different UAS will execute 12 missions in three U3 scenarios in order to validate the Performance Requirements in relevant environments.
  • Validation Exercise #3: execution of simulated flights involving several UAS in U3 scenarios (the same as the used in Validation Exercise #2) and checking the compliance with the Safety Requirements established to attain the Safety Objectives in abnormal and faulted conditions identified by the research team during the Safety Assessment performed in WP6. Numerical thresholds will be proposed for those requirements expressed in a quantitative form.

In order to obtain representative results, all Validation Exercises will be executed in U3 scenarios selected from the sector types defined in the document D6.5 SPR/INTEROP-OSED. Namely, the following three scenarios will be used:

  • Scenario #1: a 25 km2 area in Uncontrolled Airspace-Low Density scenario in the surroundings of the city of Valencia (Spain).
  • Scenario #2: a 25 km2 area in Controlled Airspace-Medium Density scenario in the urban area of Valencia (Spain); the area includes the city large harbour but not the airport.
  • Scenario #3: a 25 km2 area in Controlled Airspace-High Density scenario in the urban area of Valencia (Spain); the area includes the vicinity of the city airport.

To support the execution of these Validation Exercises, the BUBBLES team developed a mock up consisting of five components:

  • The INDRA-SIM Industrial Based Platform (IBP) version 001, developed by Indra Sistemas S.A. (Indra) team. This platform has two operating modes. Operating mode 1 will be used in the Validation Exercise #1, whereas mode 2 will be used in Validation Exercise #2.
  • The BB-Planer tool prototype version 001, developed by Universitat Politècnica de València (UPV) team. This platform applies the collision model developed in Task 4.1 and a trajectory simulator to compute collision rates. This prototype will be used in the Validation Exercise #1 to two different purposes: (1) to define the trajectories which will be used in all the Validation Exercise #1 simulations and (2) to obtain collision rates using a statistical approach.
  • The BUBBLES-AI tool prototype version 001, developed by Università degli Studi di Roma La Sapienza (UNIROMA1), implements the algorithms developed in Task T4.2. This prototype will be used in the Validation Exercise #1 to compute separation minima and identify separation methods in order to attain a specific conflict rate.
  • The BUBBLES simulation environment 001, developed by Universidade de Coimbra (UC) team. It is composed of the Gazebo/PX4 simulation tool and the Fault Injection tool. This prototype will be used in the Validation Exercise #3 to validate part of the Safety Requirements.
  • The BUBBLES simulation environment 002, composed of the BUBBLES Communications impairment and shaping tool, developed by Universidade de Coimbra (UC) team, and of the BUBBLES tracking & evaluation system, developed by UPV team. The BUBBLES simulation environment 002 will be used in the Validation Exercise #3 to validate part of the Safety Requirements.