The first phase of OPeRATOR covered the evaluation of the state of the art with respect to mission simulation software, as well as the definition of requirements and model interfaces. The library is written in the high-level programming and modeling language Modelica, which allows physics-based modeling (acausal statement of equations), modularity through object-oriented concept as well as interoperability through various interfaces to other tools and languages (like the industry standard FMI).
Following this, several use cases provided by MISSION, were implemented in the library. These are designed to serve as verification and validation tests for the library and to work as base setups for studies with the partner’s proprietary models. The use cases comprise actuator force-fight in flight, actuator failure cases, rejected take-off scenario, a city-pair mission and landing cases.
Based on this, the final library version was finished, including a fully functional aircraft model based on components from the library and model data for an A320-sized aircraft. The aerodynamics are based on a gridded Vortex Lattice Method (VLM) in combination with manual tuning to meet stall speeds yielding a full aerodynamic model that covers all aircraft flight configurations. Also a weight and balance, landing gear, engine and actuator systems models were implemented. A redundant actuator model allowing actuator failures and force fights in various modes was developed, while a sensor suite modeling common sensor types (inertial, aerodata, GPS, ILS and others) provides realistic feedback variables to the flight control and management systems.
In order to let the aircraft model virtually fly prescribed missions, a fully functional autoflight system and pilot models have been integrated. The control algorithms allow for the simulation of full flights, including taxi, take-off, climb, cruise, descent, approach, landing and flare /cross wind alignment and braking.
All components are replaceable. In this way, MISSION components can be implemented and tested in a "virtual aircraft", which was performed for a proprietary engine model by the MISSION partner Collins Aerospace.
A video-based tutorial was recorded using the library in the SimulationX IDE, to serve as a reference for current and future users of the library. In conclusion of the project, a final demonstration meeting was held online with the stakeholders showing the structure and capabilities of the library.
Aside from the usage of the OPeRATOR library with MISSION partners, exploitation has started within the DLR project HAP (High Altitude Platform), in which a solar powered, autonomous pseudo satellite is being developed. The HAP aircraft needs to be an extremal design with minimum weight and should support operation timespans of days up to weeks, which is why mission simulation and optimization play a key role in evaluating its performance. The industry trend towards More Electric Aircraft with higher integration of different subsystems into a common energy network also requires new methods for the energy management. These research directions are pursued within the DLR in several projects (for example EU project ENERGIZE), and profit from the mission simulation framework developed in OPeRATOR, to conduct realistic performance evaluations of new propulsion and energy system concepts. OPeRATOR also leads to a number of publications, starting with an overview paper at the Modelica Conference 2021 with subsequent journal publication. Future dissemination activities are planned with respect to the delayed CEAS 2021 conference and the European Open Research Platform.
