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首页> 外文会议>Space Technology amp; Applications International Forum (STAIF-99) ptol January 31-February 4, 1999, Albuquerque Hyatt Hotel, NM >Non-linear sequencing and cognizant failure
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Non-linear sequencing and cognizant failure

机译：非线性测序和认知失败

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摘要

Spacecraft are traditionally commanded using linear sequences of time-based commands. Linear sequences work fairly well, but they are difficult and expensive to generate, and are usually not capable of resonding to contingencies. Any anomalous behavior while executing a linear sequence gnerally results in the spacecraft entering a safe mode. Critical sequences like oribit insertions which must be able to respond to faults without going into safe mode are particularly difficult to design and verify. The effort needed to generate command sequences can be reduced by extending the vocabulary of sequences to indlucde more sophisticated control constructs. The simplext extensions are conditionals and loo9ps. Adding these constructs would make a sequencing language look more or less like a traditional programming language or scipting language, and would come with all the difficulties associated wth such a language. In particular, verifying the correctness of a sequence would be tantamount to verifying the correctness of a prgram, which is undecidable in general. We describe an extended vocabulary for non-linear sequencing based on the architectural notion of cognizant failure A cognizant failure architecture is divided into components whose contract is to either achieve (or maintain) a certain condition, or report that they have failed to do so. Cognizant failure is an easier condition to verify than correcntess, but it can provide high confidence in the afety of the spacecraft. Because cognizant failure inherently implies some kind of representation of the intent of an action, the system can respond to coontingencies in more robust and general ways. We will describe an implmented non-linear sequencing system that is being flown on the NASA New Millennium Deep Space 1 Mission as part of the Remote agent Experiment.
机译：传统上，航天器是使用基于时间的命令的线性序列来命令的。线性序列工作得很好，但是生成它们很困难且昂贵，并且通常无法引起意外事件。在执行线性序列时，任何异常行为都会导致航天器进入安全模式。诸如oribit插入之类的关键序列必须能够对故障做出响应而不进入安全模式，这尤其难以设计和验证。可以通过扩展序列的词汇表来表达更复杂的控制结构，从而减少生成命令序列所需的工作量。 simplext扩展是条件和loo9ps。添加这些构造将使排序语言看起来或多或少像传统的编程语言或编码语言，并且将伴随着与这种语言相关的所有困难。特别地，验证序列的正确性将等同于验证prgram的正确性，这通常是无法确定的。我们基于认知失败的体系结构概念描述了用于非线性排序的扩展词汇表。认知失败的体系结构分为多个组成部分，这些组成部分的合同要达到（或保持）某种条件，或者报告它们未能达到一定条件。认知失误比正确性更容易验证，但它可以为航天器的安全性提供高度的信心。由于认知失败本质上意味着某种行为意图的某种表示，因此系统可以更健壮和更通用的方式来响应语言。我们将描述一种实施的非线性排序系统，该系统将作为远程特工实验的一部分在NASA新千年深空1号任务中飞行。

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