On Credibility Assessment in Aircraft System Simulation

Abstract

HE aeronautical industry is becoming increasingly reliant on Modeling and Simulation (M&S) for use throughout all system development phases, for system verification, and end-user training. To justify and to utilize the full potential of today's model-based approach and to enable the industrially requested transition towards virtual testing and virtual certification, the development of efficient and industrially applicable methods for M&S credibility assessment is a key challenge. Credibility assessment of an M&S effort using one individual simulation model is undoubtedly a challenging task involving several vital aspects like verification, validation, uncertainty quantification, and model use history. Building confidence in simulator applications in which several individual models are connected and simulated together is even more problematic.This work addresses methods facilitating credibility assessment of simulation models and simulator applications used in aircraft system development. For models of individual aircraft subsystems, like liquid cooling or environmental control systems, an uncertainty aggregation method is proposed that facilitates early model validation through approximate uncertainty quantification. The central idea is to integrate information obtained during component level validation directly into the component equations, and to utilize this information in model level uncertainty quantification. The method is applicable in early development phases when the availability of system level measurement data for traditional model validation purposes is typically very limited. To clarify, the model may describe a system not yet realized, neither in a test rig nor in a test aircraft.In addition to methods intended for models of individual subsystems, this work also proposes a method and an associated tool for credibility assessment of large-scale simulator applications. As a complement to traditional document-centric approaches, static and dynamic credibility information is here presented to end-users directly during simulation. This implies a support for detecting test plan deficiencies, or that a simulator configuration is not a suitable platform for the execution of a particular test. The credibility assessment tool has been implemented and evaluated in two large-scale system simulators for the Saab Gripen fighter aircraft. The work presented herein also includes an industrially applicable workflow for development, validation, and export of simulation models.Thanks to the close connection to industry, some of the research results have already been successfully implemented in operations and are currently in industrial use. T vii Populärvetenskaplig SammanfattningLYGINDUSTRIN förlitar sig i allt högre utsträckning på modellering och simulering inom såväl systemutveckling som verifiering, samt för träning av piloter och flygtekniker. För att kunna styrka och dra maximal nytta av dagens modellbaserade arbetssätt krävs utveckling av effektiv och industriellt relevant metodik för bedömning av tro...

On Standardized Model Integration : Automated Validation in Aircraft System Simulation

“…The schematic description of Industry-as-laboratory presented by Muller et al is clarified with respect to the context of the research presented here, see Figure 1.1. The presented methodology has previously been used in several similar research project constellations [6,19].…”

“…The simulation models that are the primary focus here are of the mathematical sort. Here, simulation models are executable representations, able to describe the dynamic properties of the SoI via constituent Algebraic Equations (AEs) and Differential Equations (DEs) [6,1]. A different class of models considered in this thesis, which are not easily placed in any of the provided categories, are models describing System architecture.…”

“…Various types of simulation models and simulators are used during the development of aircraft sub-systems. Eek [5,6] and Steinkellner [4] provide overviews of various sub-system modeling techniques that are applicable during aircraft vehicle system development. Even though closely related, the focus here is instead on aircraft vehicle systems simulator development.…”

“…Saab has been conducting research continuously to improve upon the used methods for model and simulator credibility assessment. Three recent projects are Modeling and Simulation for the 2010s Energy Management Systems [4], Validation of Complex Simulation Models [5], and Model Validation -from Concept to Product [6]. A key result of the project Validation of Complex Simulation Models was the formulation of the Saab Aeronautics Handbook for Development of Simulation Models [7].…”

“…Furthermore, this thesis covers the work conducted within the frame of the ITEA3 project Open Cyber-Physical System Model-Driven Certified Development (OpenCPS) [13] in evaluating and influencing the SotA in standardized co-simulation, simulator exchange, and automated model validation in later development phases. The chronologically earlier work of the thesis was conducted within the frame of the Nationellt Flygtekniskt Forskningsprogram (NFFP) project Model Validation -from Concept to Product [6].…”