A Hybrid Procedural/Deductive Executive for Autonomous Spacecraft

The New Millennium Remote Agent (NMRA) will be the first AI system to control an actual spacecraft. The spacecraft domain places a strong premium on autonomy and requires dynamic recoveries and robust concurrent execution, all in the presence of tight real-time deadlines, changing goals, scarce resource constraints, and a wide variety of possible failures. To achieve this level of execution robustness, we have integrated a procedural executive based on generic procedures with a deductive model-based executive. A procedural executive provides sophisticated control constructs such as loops, parallel activity, locks, and synchronization which are used for robust schedule execution, hierarchical task decomposition, and routine configuration management. A deductive executive provides algorithms for sophisticated state inference and optimal failure recovery planning. The integrated executive enables designers to code knowledge via a combination of procedures and declarative models, yielding a rich modeling capability suitable to the challenges of real spacecraft control. The interface between the two executives ensures both that recovery sequences are smoothly merged into high-level schedule execution and that a high degree of reactivity is retained to effectively handle additional failures during recovery.     

Formal analysis of a space-craft controller using SPIN

The paper documents an application of the finite state model checker SPIN to formally analyze a multithreaded plan execution module. The plan execution module is one component of NASA's New Millennium Remote Agent, an artificial intelligence-based spacecraft control system architecture which launched in October of 1998 as part of the DEEP SPACE 1 mission. The bottom layer of the plan execution module architecture is a domain specific language, named ESL (Executive Support Language), implemented as an extension to multithreaded COMMON LISP. ESL supports the construction of reactive control mechanisms for autonomous robots and spacecraft. For the case study, we translated the ESL services for managing interacting parallel goal-and-event driven processes into the PROMELA input language of SPIN. A total of five previously undiscovered concurrency errors were identified within the implementation of ESL. According to the Remote Agent programming team, the effort has had a major impact, locating errors that would not have been located otherwise and, in one case, identifying a major design flaw. In fact, in a different part of the system, a concurrency bug identical to one discovered by this study escaped testing and caused a deadlock during an in-flight experiment, 96 million kilometers from Earth. The work additionally motivated the introduction of procedural abstraction in terms of inline procedures into SPIN     

航天器威胁规避智能自主控制技术研究综述

当前,轨道空间日益拥挤、太空竞争不断加剧,对航天器执行既定任务时的轨道威胁自主应对能力提出了新的挑战,使得航天器智能自主控制技术迎来新的发展机遇.在调研分析了轨道威胁感知、自主决策规划、规避机动动作执行、自主控制系统架构相关研究进展的基础上,总结提出了威胁规避智能自主控制面临的主要瓶颈问题,并分析指出发展“感知-决策-执行”一体化控制是破解瓶颈难题的有效手段,最后从一体化控制系统建模、设计、分析与验证多方面,系统讨论了威胁规避智能自主控制需要重点关注的若干基础问题,为未来航天器智能自主控制的理论研究和技术发展提供启发和参考.     

自主航天器的规划系统建模研究

根据自主航天器的特点,分析了其规划问题中活动的并行特性以及约束的复杂性,提出了自主航天器规划系统的系统结构,并对规划模型的模型要素进行分析,然后采用规划域定义语言对规划域进行建模,以时间区间理论为基础对规划问题的持续时间约束进行表示,采用时间线模型表现航天器的并行活动,最终解决了自主航天器规划系统的建模与约束表达问题。最后通过一个算例验证了所提方法的正确性。     

面向自主运行的深空探测航天器体系结构设计 及自主任务规划方法

传统的航天器运行管控方式严重依赖地面指控、人力成本耗费大且对任务响应时间长,难以满足深空探测远距离通信时延突出的任务特点,航天器的智能化水平亟待进一步提高.本文通过对航天器自主运行问题进行系统地分析,提出一种基于多智能体的航天器自主运行的体系结构,面向自主系统结构、运行流程等进行了设计.重点针对小行星探测任务,提出了一种包含平台和载荷任务管理的两阶段航天器自主任务规划算法设计方案,能够实现平载一体的航天器自主任务管理,根据高级任务目标输出完整的指令序列.并通过自主任务规划仿真,对相关算法和模型的正确性和可行性进行了可视化验证和分析,为航天器自主运行技术研究提供了一种有益的思路和方法.     

追踪器本体坐标系下航天器姿轨一体化控制律设计

在追踪航天器本体坐标系下, 联合相对轨道动力学模型和四元素姿态动力学模型, 引入推进器配置矩阵, 建立六自由度姿态和轨道一体化模型. 该模型避免了控制输入向追踪器本体坐标系下的转换. 在此基础上, 采用输入-状态(ISS) 稳定性原理, 在干扰输入信息完全未知的情况下, 设计了非线性鲁棒一体化控制律. 该控制律实现了对椭圆轨道上目标航天器的扰动抑制和跟踪, 具有较好的鲁棒性和跟踪性. 最后, 针对运行在椭圆轨道上的目标给出仿真结果, 表明了所提出的一体化控制律的可行性和有效性.

     

An application of artificial intelligence to object-orientedperformance design for real-time systems

The paper describes an application of artificial intelligence technology to the implementation of a rapid prototyping method in object-oriented performance design (OOPD) for real-time systems. OOPD consists of two prototyping phases for real-time systems. Each of these phases consists of three steps: prototype construction, prototype execution, and prototype evaluation. We present artificial intelligence based methods and tools to be applied to the individual steps. In the prototype construction step, a rapid construction mechanism using reusable software components is implemented based on planning. In the prototype execution step, a hybrid inference mechanism is used to execute the constructed prototype described in declarative knowledge representation. MENDEL, which is a Prolog based concurrent object-oriented language, can be used as a prototype construction tool and a prototype execution tool. In the prototype evaluation step, an expert system which is based on qualitative reasoning is implemented to detect and diagnose bottlenecks and generate an improvement plan for them     

深空探测器自主健康管理需求及其软件架构

由于深空探测器距离远,要求具有很强的自主健康管理能力.目前大多数深空探测器自主健康管理功能为型号特定、缺乏统一的健康管理方法及软件架构,难以实现星载自主健康管理软件的通用化.针对此问题,本文对深空探测器自主健康管理需求进行了分析,提出了一种基于包应用标准和航天器接口业务标准的自主健康管理方法,设计了分层的通用软件架构.本文对架构中与健康管理相关的在轨监视业务构件、事件报告业务构件、事件动作业务构件等3个核心构件进行了详细设计,并进一步说明了架构在原理样机中的应用验证情况.     

Specification and analysis of system architecture using Rapide

Rapide is an event-based, concurrent, object-oriented language specifically designed for prototyping system architectures. Two principle design goals are: (1) to provide constructs for defining executable prototypes of architectures and (2) to adopt an execution model in which the concurrency, synchronization, dataflow, and timing properties of a prototype are explicitly represented. This paper describes the partially ordered event set (poset) execution model and outlines with examples some of the event-based features for defining communication architectures and relationships between architectures. Various features of Rapide are illustrated by excerpts from a prototype of the X/Open distributed transaction processing reference architecture     

深空探测航天器控制系统自主管理软件架构研究

深空探测航天器距离远、环境复杂,测控站遥测和遥控操作不能满足控制的实时性和安全性要求,自主管理技术是提高航天器对未知环境的应对能力、提升飞控实效性的主要手段。回顾了深空探测航天器自主管理技术发展的现状,分析了实现自主管理的关键技术,并结合深空探测工程实施和技术发展需求,提出了未来航天器自主管理系统体系结构和软件架构,并进行了仿真实验。