Development of a Multi-Segment Mission Planning Tool for SCEPTOR X-57

AIAA Scitech 2019 Forum

2019

Self Cite

Multidisciplinary design, analysis and optimization involves modeling the interactions of complex systems across a variety of disciplines. The optimization of such systems can be a computationally expensive exercise with multiple levels of nested nonlinear solvers running under an optimizer. The application of optimal control in project development often involves performing trajectory optimization for fixed vehicle designs or parametric sweeps across some key vehicle properties. This information is then relayed to the subsystem design teams who update their designs and relay some bulk characteristics back to the trajectory optimization procedure. This iteration is then repeated until the design closes. However, with increasing interest in more tightly coupled systems, such as electric and hybrid-electric aircraft propulsion and boundary layer ingestion, this process is prone to ignore subtle coupling between vehicle subsystem designs and vehicle operation on a given mission. Integrating trajectory optimization into a tightly coupled multidisciplinary design procedure can be computationally prohibitive, depending on the complexity of the subsystem analyses and the optimal control technique applied. To address these issues, a new optimal control software tool, Dymos, has been developed. Dymos is built upon NASA's OpenMDAO software and can leverage its capabilities to efficiently compute gradients for the optimization and optimize complex models in parallel on distributed memory systems. This report explains the numerical methods employed in Dymos and provides several use cases that demonstrate its performance on traditional optimal control problems and improvements in situations that often arise in multidisciplinary optimization.

Section: Discussionmentioning

confidence: 99%

Optimal Control within the Context of Multidisciplinary Design, Analysis, and Optimization

Falck

AIAA Scitech 2019 Forum

2019

Self Cite

“…To date, Dymos has been used to solve a range of optimal control problems (Falck et al 2019), including canonical problems such as Bryson's minimum time to climb problem (Bryson 1999), as well as the classic brachistochrone problem posed by Bernoulli (1696). It has also been used to solve more complex optimal trajectory problems for electric aircraft (Falck et al 2017;Schnulo et al 2018).…”

Section: Computational Savings From Combined Linear Solutionsmentioning

confidence: 99%

“…Other work that used OpenMDAO V2 includes a framework for the solution of ordinary differential equations (Hwang and Munster 2018), a conceptual design model for aircraft electric propulsion (Brelje and Martins 2018), and a mission planning tool for the X-57 aircraft (Schnulo et al 2018).…”

Section: Applicationsmentioning

confidence: 99%

OpenMDAO: an open-source framework for multidisciplinary design, analysis, and optimization

Hwang

Martins

et al. 2019

Struct Multidisc Optim

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419

150

Multidisciplinary design optimization (MDO) is concerned with solving design problems involving coupled numerical models of complex engineering systems. While various MDO software frameworks exist, none of them take full advantage of state-of-the-art algorithms to solve coupled models efficiently. Furthermore, there is a need to facilitate the computation of the derivatives of these coupled models for use with gradient-based optimization algorithms to enable design with respect to large numbers of variables. In this paper, we present the theory and architecture of OpenMDAO, an open-source MDO framework that uses Newton-type algorithms to solve coupled systems and exploits problem structure through new hierarchical strategies to achieve high computational efficiency. OpenMDAO also provides a framework for computing coupled derivatives efficiently and in a way that exploits problem sparsity. We demonstrate the framework's efficiency by benchmarking scalable test problems. We also summarize a number of OpenMDAO applications previously reported in the literature, which include trajectory optimization, wing design, and structural topology optimization, demonstrating that the framework is effective in both coupling existing models and developing new multidisciplinary models from the ground up. Given the potential of the OpenMDAO framework, we expect the number of users and developers to continue growing, enabling even more diverse applications in engineering analysis and design.

“…The inclusion of thermal management models presents an additional challenge as it has been shown that transient thermal models integrated into the trajectory analysis are required to capture performance constraints. [16,17] One final practical consideration is that the introduction of new tightly coupled disciplinary analyses into the design process significantly increases the complexity and computational cost of the model, while at the same time decreasing its numerical stability. The decrease in numerical stability comes from the increased likelihood that at least one code will fail and the difficulties that arise in computing gradient information across coupled models.…”

Section: Traditional Design and Analysis Environmentmentioning

confidence: 99%

Multidisciplinary Optimization of a Turboelectric Tiltwing Urban Air Mobility Aircraft

Hendricks

Falck

AIAA Aviation 2019 Forum

et al. 2019

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Urban air taxis, also known as urban air mobility (UAM) vehicles, are anticipated to be an area of significant market growth in the near future. These vehicles are typically vertical takeoff and landing (VTOL) designs which are capable of carrying 1 to 30 passengers in an intra-urban environment with flights of less than 50 nautical miles. Development of UAM vehicles and their integration into the airspace will be enabled by advancements in a number of areas including electrified propulsion systems, structures, acoustics, automation, and controls. However, the strong multidisciplinary interactions for these unique vehicles presents a significant new design challenge. This work describes the development of a multidisciplinary analysis and optimization environment which can be used to support the conceptual design of these UAM vehicles, using efficient gradient based optimization with analytic derivatives. The tools included in this multidisciplinary analysis model the aircraft trajectory, vehicle aerodynamics, structures, and electrified propulsion system. The multidisciplinary environment created in this research is unique in that all the physics tools are tightly integrated together, with the trajectory model directly calling the aerodynamics, structures, and propulsion models. This multidisciplinary analysis environment is then demonstrated in the design optimization of a turboelectric tiltwing UAM vehicle concept.