Comment: Controlling the skies with digital engineering

The next generation of air superiority platforms will heavily rely on software-defined capabilities like scalable autonomy, collaborative combat, reconfigurable communications, and situational awareness. However, this software on its own is not sufficient and the physical systems of the aircraft must perform in tandem with software to accomplish diverse missions against evolving adversaries. The sheer complexity of interconnected cyber-physical systems has the potential to make costs and time to market spiral out of control.

To meet these vast engineering and technological challenges, model-based software engineering coupled with physics-based simulation and analysis is now a vital part of the process. Current simulation workflows are often isolated and lack traceability across different engineering domains like requirements, software, electrical, mechanical design, testing etc. This means that a fundamental shift to a model-based digital ecosystem connecting all aspects of design through a traceable digital thread, called digital engineering, is required.

Digital Engineering

Digital engineering is an integrated digital approach that uses authoritative sources of data and models as a continuum across disciplines for the entire lifecycle, from concept to disposal. Within this definition there are three key aspects:

·     That the entire design is encapsulated as models

·     That a set of authoritative sources is established to manage the models and data in a trusted manner

·     And that the continuum of data shared between models must span the entire lifecycle – this is called the digital thread.

The digital thread connects many engineering disciplines like requirements, systems engineering, software design, electronic/mechanical design, and analysis and through its implementation information siloes and unsynchronised efforts can be dispelled.

The benefits of this approach are particularly attractive for aerospace and defence entities because many of these programmes span over significant periods of time, often decades. Throughout this process, costs are divided between development, operations, maintenance and sustainment – however, the vast majority of the total cost is fully committed to the decisions made in the development process. Digital engineering facilitates discovering critical issues early in this life cycle, which significantly reduces risks to development cost, schedule, and performance.

Digital engineering is a vast discipline that includes many different aspects, however, two that are particularly relevant as it relates to the development of next-gen air platforms are digital mission engineering and the integration of software and physical systems.

Digital Mission Engineering

Digital mission engineering (DME) is the use of digital modelling, physics-based simulation, and analysis to incorporate the operational environment to evaluate mission outcomes and effectiveness at every phase of the life cycle. During early-stage conceptual design, digital mission engineering allows designers to verify and iterate on evolving design requirements as part of a system of systems approach. Throughout the design process, the fidelity of models increases, solidifying the digital evidence required for later certification.  Central to DME is a time dynamic geometry engine that calculates the position and orientation of assets via propagation algorithms or external inputs. With these dynamic positions and orientations, engineers can model the properties of sensors, communications, and other payloads. The quality of these links, which include a broad range of constraining conditions and environmental effects, ultimately evaluates the mission outcome.

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A concept of operations (CONOPS) is a record of the top-level performance requirements of a proposed system from the perspective of the individual operator of that system. This can be translated to produce a Design Reference Mission (DRM), which outlines the environment and situation of the proposed mission. Next-generation air superiority platforms will be an interconnected family of systems. In the future, we can envisage a central crewed fighter aircraft supported by a mix of uncrewed collaborative systems and uncrewed co-operative weapons. This increased complexity of the operation requires modelling and simulation to manage it. By digitising the DRM, DME centralises the mission — directly linking design trades and decisions to CONOPS. Incorporated with digital engineering, it provides a direct link to engineering and physics data and models, which enables the validation of system behaviour against requirements as well as enabling teams to rapidly iterate on requirements and design, continuously.

Integrated Software and Physical Systems

Thanks to advancements in semiconductor technologies, almost all modern systems use embedded electronics, which requires a tremendous amount of software. Model-based software development environments facilitate highly advanced approaches to creating safety-critical embedded software. These environments provide linkage to requirements management, model-based design, verification, qualifiable code generation capabilities, widespread automation and interoperability with other development tools and disciplines. They support the open standards that are required by Defence such as Modular Open Systems Approach (MOSA), the UK MOD's PYRAMID, or Future Airborne Capability Environment (FACE). These technologies enforce interoperability between engineering software vendors and system suppliers so there are no proprietary interfaces. Key to the development of the cyber-physical systems related to autonomy, collaborative teaming, and situational awareness is fully grasping the output of sensors and the effectiveness of communications within a mission context. It is the interoperability with other disciplines that will assist the efficient development of deeply integrated cyber-physical systems.

For example, designing an autonomous system will involve multiple disciplines that must be designed and tested coherently and holistically. Consider the example of a drone which is required to follow an aircraft, necessitating the coordination of multiple disciplines in unison. Firstly, the sensors team will need to design and position the sensors on the vehicle. Secondly, software teams need to develop software to translate the feed from the sensors and provide controls to steer the drone, as well as potentially using AI. And finally, the mission or Operational Analyst must make sure that the requirements of the system are met.

To efficiently design and test the system, a model-based co-simulation approach can be applied. First, the scenarios can be tested in a simulated world or environment. This requires accurate underlying physics — for instance, flight models used to propagate the drone and high-fidelity physics-based sensor models to generate accurate image feeds from the simulated world. The simulated world’s output feed can then be used to validate (or train) the software with its specific control task, which can then be fed back into the simulated world. Then, digital mission engineering can assess if the DRM’s defined measures of performance are met. With the use of digital engineering as the framework to coordinate intra-discipline communication and collaboration, teams can successfully derisk and manage the complexity of the system early in the design cycle.

Importantly, by allowing engineers to simulate and optimize designs before physical prototypes are built, it helps reduce development costs, schedule and risk – not only the cost of development but particularly the future cost of operations and sustainment.

Due to the complexity of next-generation air superiority platforms set to grow exponentially in the future, the need for this approach will only rise in importance.  Digital engineering will transform the design process to dramatically accelerate the delivery of new capabilities and this is why we believe that nations will not reach their next-generation air superiority objectives without the widespread use of digital engineering.

Steve Bleymaier, CTO, A&D at Ansys, Brig Gen (Ret) USAF