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СообщениеДобавлено: Среда, 21 Август, 2013 10:11 

Зарегистрирован: Воскресенье, 24 Февраль, 2008 15:32
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Система управления американского космического корабля Спейс Шаттл
(аналог нашего Бурана)


http://en.wikipedia.org/wiki/Space_Shut ... ht_systems

Привожу цитату из английского раздела Википедии

Цитата:
Flight systems [edit source]

The Shuttle was one of the earliest craft to use a computerized fly-by-wire digital flight control system. This means no mechanical or hydraulic linkages connected the pilot's control stick to the control surfaces or reaction control system thrusters.

A concern with digital fly-by-wire systems is reliability. Considerable research went into the Shuttle computer system.

The Shuttle used five identical redundant IBM 32-bit general purpose computers (GPCs), model AP-101, constituting a type of embedded system. Four computers ran specialized software called the Primary Avionics Software System (PASS).

A fifth backup computer ran separate software called the Backup Flight System (BFS). Collectively they were called the Data Processing System (DPS).[39][40]

The design goal of the Shuttle's DPS was fail-operational/fail-safe reliability. After a single failure, the Shuttle could still continue the mission. After two failures, it could still land safely.

The four general-purpose computers operated essentially in lockstep, checking each other. If one computer failed, the three functioning computers "voted" it out of the system.

This isolated it from vehicle control. If a second computer of the three remaining failed, the two functioning computers voted it out. In the unlikely case that two out of four computers simultaneously failed (a two-two split), one group was to be picked at random.

The Backup Flight System (BFS) was separately developed software running on the fifth computer, used only if the entire four-computer primary system failed.

The BFS was created because although the four primary computers were hardware redundant, they all ran the same software, so a generic software problem could crash all of them.

Embedded system avionic software was developed under totally different conditions from public commercial software: the number of code lines was tiny compared to a public commercial software, changes were only made infrequently and with extensive testing, and many programming and test personnel worked on the small amount of computer code.

However, in theory it could have still failed, and the BFS existed for that contingency. While the BFS could run in parallel with PASS, the BFS never engaged to take over control from PASS during any Shuttle mission.

The software for the Shuttle computers was written in a high-level language called HAL/S, somewhat similar to PL/I. It is specifically designed for a real time embedded system environment.

The IBM AP-101 computers originally had about 424 kilobytes of magnetic core memory each. The CPU could process about 400,000 instructions per second. They had no hard disk drive, and loaded software from magnetic tape cartridges.

In 1990, the original computers were replaced with an upgraded model AP-101S, which had about 2.5 times the memory capacity (about 1 megabyte) and three times the processor speed (about 1.2 million instructions per second). The memory was changed from magnetic core to semiconductor with battery backup.

Early Shuttle missions, starting in November 1983, took along the GRiD Compass, arguably one of the first laptop computers.

The GRiD was given the name SPOC, for Shuttle Portable Onboard Computer. Use on the Shuttle required both hardware and software modifications which were incorporated into later versions of the commercial product.

It was used to monitor and display the Shuttle's ground position, path of the next two orbits, show where the Shuttle had line of sight communications with ground stations, and determine points for location-specific observations of the Earth.

The Compass sold poorly, as it cost at least US$8000, but it offered unmatched performance for its weight and size.[41] NASA was one of its main customers.[42]


Далее привожу материал из архивов корпорации ИБМ
http://www-03.ibm.com/ibm/history/exhib ... uttle.html


Цитата:
IBM and the Space Shuttle

IBM computers have played a key role in each Space Shuttle mission from liftoff to landing. This role follows more than two decades of IBM support to a variety of NASA space programs, including every manned space flight.

For the Space Shuttle, IBM's support has included programming and data processing equipment for onboard and ground-based Space Shuttle monitoring and control, as well as launch support.

The initial Shuttle orbiter avionics data processing system was provided by IBM' s Federal Systems Division under contract to the Space Division of Rockwell International Corp.

Five IBM computers — four of which were arranged in a redundant configuration, with a fifth computer acting as a backup unit — allowed early Shuttle missions to continue even if multiple failures were experienced. The computers cross-checked each other more than 500 times a second. In flight, the Shuttle orbiter was controlled by electrical signals generated by the digital computers — a concept called fly-by-wire — and sent to hydraulic-driven actuators.

Developed at IBM's Owego, N.Y., facility, the onboard computers were part of an Advanced System/4 Pi, avionics computer series. Input/Output Processors, also built in Owego, acted as an interface between the computers and other orbiter systems.

Computer programming for the onboard units was developed at IBM's Houston, Texas, facility for NASA. In addition to the flight controllers, the programs handled the crew displays, monitoring systems and guidance, navigation and control functions.

Examples of early IBM Shuttle contracts (ca. late-1970s):

The Shuttle Data Processing Complex was the data system at the Lyndon B. Johnson Space Center used for Shuttle Mission Control. It consisted of three IBM System/370 Model 168s as well as system programs. The hardware and standard software for the Shuttle Data Processing Complex was supplied by IBM's Data Processing Division in White Plains, N.Y.

The Space Shuttle General Purpose Computer was one of five computers providing navigation and control processing functions aboard each Shuttle. Each computer consisted of a central processor (IBM's Advanced System/4 Pi) and an input/output processor.

The Space Shuttle Display was an electrically-controlled cathode-ray tube data display and memory facility associated with the onboard data processing system. IBM received a contract from Rockwell International to provide display systems for five orbiters as well as laboratory, simulator and spare systems.

Onboard Shuttle Programming controlled the data processing equipment and application programs. IBM developed some of these programs and provided flight equipment interface devices.

Launch Processing System. The Shuttle launch and launch preparation facilities in Florida were supported by a highly complex test data system designed by IBM.

For details on Space Shuttle history, visit:
http://spaceflight.nasa.gov/shuttle/archives/index.html


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СообщениеДобавлено: Пятница, 23 Август, 2013 00:46 

Зарегистрирован: Воскресенье, 09 Март, 2008 22:38
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У нас на конференции выступал небезызвестный Вадим Котов http://www.ras.ru/win/db/show_per.asp?P=.id-1026.ln-ru

Он уже с начала 1990х живет и работает в США.

В том числе говорил о том, что принимал участие в экспертной оценке программного обеспечения Шаттла - была мысль его полностью переписать унифицировав используемые языки и платформы. На самом деле там помимо основных бортовых компьютеров и HAL/S было множество систем и разных платформ/языков.

В общем, проанализировали они это дело научно и пришли к выводу, что лучше не лезть... Не портить работающее...

В памяти моей примерно так отложилась эта история...

Кстати, он весьма критично отзывался об экономике и социуме в Штатах, говорил, что ясно - это тупиковый путь...


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