Abstract The National Aeronautics and Space Administration (NASA) is currently developing the next generation of spacesuits for use in future exploration missions. This effort, referred to as the Exploration Extravehicular Mobility Unit (xEMU), has been underway since 2015 with the goal of demonstrating the new technologies during a mission to the International Space Station (ISS). Due to the complexity of the xEMU system, and particularly its portable life support system (PLSS), computer simulations are heavily relied on in the development process, from dynamic loads analysis to software verification. The models of the physical systems that are currently being used for system-level simulations are mostly empirical, where the underlying formulas are mathematical fits to test or simulation data. An advantage of this approach is the fact that these models are very performant and can be used in real-time applications such as user interface testing and operator training. The research presented in this paper describes a different approach to modeling and simulation. A simulation tool focused on life support systems for human spaceflight in general and PLSSs in particular has been under development at the Technical University of Munich (TUM) since 2006. The spacesuit specific variant of this tool is called The Virtual Spacesuit (V-SUIT) and is now being utilized in the current spacesuit development process at the NASA Johnson Space Center (JSC). In contrast to the previously mentioned empirical models, V-SUIT uses a first-principles-based, bottom up modeling approach, where basic physical, chemical or biological effects are modeled at the lowest level and the component and system models are created using these fundamental building blocks. This enables the simulation to account for effects, and especially off-nominal situations, that may not be within the range of validity of the empirical models. This paper presents the structure of and the rationale behind V-SUIT itself as well as a status report on the ongoing effort to integrate it with the existing simulation systems in use at JSC, which is based on Trick/GUNNS. As a proof of concept, a single component model from V-SUIT, that of the spacesuit water membrane evaporator (SWME), has been integrated with NASA's simulation tool. Results include comparisons of the performance of the two simulation systems and a description of challenges that were encountered during implementation. The paper closes with an outlook towards the future developments that are planned for V-SUIT within the xEMU development program.

中文翻译：

---

一种混合保真系统模拟舱外活动的方法

摘要 美国国家航空航天局 (NASA) 目前正在开发用于未来探索任务的下一代宇航服。这项工作被称为探索舱外机动装置 (xEMU)，自 2015 年以来一直在进行，目的是在执行国际空间站 (ISS) 任务期间展示新技术。由于 xEMU 系统的复杂性，特别是其便携式生命支持系统 (PLSS)，从动态载荷分析到软件验证，在开发过程中严重依赖计算机模拟。目前用于系统级模拟的物理系统模型大多是经验性的，其中基础公式是对测试或模拟数据的数学拟合。这种方法的一个优点是这些模型的性能非常好，可用于实时应用程序，例如用户界面测试和操作员培训。本文中提出的研究描述了一种不同的建模和仿真方法。自 2006 年以来，慕尼黑工业大学 (TUM) 一直在开发一种专注于人类航天生命支持系统的模拟工具，尤其是 PLSS。该工具的太空服特定变体称为虚拟太空服 (V-SUIT)现在正在美国宇航局约翰逊航天中心 (JSC) 的当前宇航服开发过程中使用。与前面提到的经验模型相比，V-SUIT 使用基于第一性原理的、自下而上的建模方法，其中基本物理、化学或生物效应在最低级别建模，组件和系统模型是使用这些基本构建块创建的。这使模拟能够考虑可能不在经验模型有效性范围内的影响，尤其是非标称情况。本文介绍了 V-SUIT 本身的结构和原理，以及关于将其与 JSC 使用的现有模拟系统（基于 Trick/GUNNS）集成的持续努力的状态报告。作为概念验证，来自 V-SUIT 的单个组件模型，即宇航服水膜蒸发器 (SWME) 的模型，已与 NASA 的仿真工具集成。结果包括比较两个模拟系统的性能以及在实施过程中遇到的挑战的描述。本文最后展望了 xEMU 开发计划中为 V-SUIT 计划的未来发展。