Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Aeronautical vehicle
Reexamination Certificate
1999-04-24
2001-10-02
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Aeronautical vehicle
C244S158700
Reexamination Certificate
active
06298289
ABSTRACT:
TECHNICAL FIELD
This invention relates to spacecraft telemetry, command and control architecture and more specifically, to a system that has spacecraft attitude determination, control, telemetry and command functions and data processing functions integrated into a single control electronics unit.
BACKGROUND OF THE INVENTION
Traditionally, spacecraft customers order one or two spacecraft at a time from a spacecraft manufacturer for its business venture because of the cost associated with the purchase and launch of the spacecraft. A spacecraft manufacturer may have two to four spacecraft designs in its portfolio, from which the customer typically picks. The manufacturer will customize the payload and antennas to fit the customer's needs, thus leveraging the economies possible with a standardized manufacturing process while maintaining flexibility in design. Spacecraft manufacturers typically need from 15 months to 2 years to build a standard spacecraft.
Every spacecraft has a payload section and a bus section. The payload section houses the transponder/repeaters and the antennas of the spacecraft. The bus section of the spacecraft is the structure that supports many of the functions needed to operate and control the spacecraft. Manufacturing of a spacecraft is organized into areas of specialization, such as structures, propulsion, power, telemetry and command, attitude control, thermal control, and solar array assembly hardware and electronics, and payload integration and test, antenna fabrication, spacecraft integration and test. As a spacecraft is constructed, it passes through each of these areas of specialization. The spacecraft undergoes final integration and test before shipment to the launch site. Specialized test equipment, alignment tools, and large rollover fixtures, which allow technicians to reposition the spacecraft for easy access, are featured in the area of final integration.
With as many as seven specialization areas to be completed sequentially during the manufacture of the bus section of the spacecraft, the manufacturing process itself is time consuming and complex. It would be nice if the manufacturing process could be shortened. However, each of the functions carried by the bus section is necessary for spacecraft operation.
Much effort by the spacecraft manufacturer goes into research and development of new materials to make the bus section lighter weight, while maintaining its strength requirements. However, due to the small size of typical spacecraft orders, it had not been economically feasible for the spacecraft manufacturer to redesign the spacecraft bus to improve manufacturability. Much work has been done to continuously improve the existing manufacturing processes each year to stay competitive.
As in the manufacture of any product, the more of that product that you sell, the more feasible and desirable it becomes to streamline the manufacturing process and reduce production costs and risk. The same is true in the spacecraft manufacturing business. Satellite communications have become such an intricate part of society that more and more satellites are being purchased each year. The spacecraft manufacturers are realizing backlogs in the manufacture of spacecraft as much as 5 to maybe 10 years.
A more recent trend is the large volume orders of identical spacecraft for satellite constellations to support mobile telephone services, paging, faxing, videoconferencing, broadband multimedia and remote monitoring and tracking around the world. Motorola has recently launched approximately 66 satellites for its Iridium program and is working on another large volume satellite constellation with Teledesic having over 200 satellites. The assignee to this application is manufacturing 12 satellites for ICO Global Communications for estimated launches starting in 1999 and has another constellation of 8 satellites in development for its SPACEWAY™ Program. Therefore there is a need to streamline the design and manufacture of these satellites to reduce manufacturing time and cost and to maintain reliability to meet the competitive and ambitious schedules of the customer.
Thus, it would be advantageous to have a low cost, lightweight spacecraft telemetry, command and control architecture which integrates into a single electronic system many functions that previously have been implemented as physically separate systems on the spacecraft.
SUMMARY OF THE INVENTION
The present invention provides a system that integrates multiple functions, such as spacecraft attitude determination, control, telemetry and command and data processing functions in a highly efficient single internally redundant electronic system or unit, namely the spacecraft control electronics (SCE). The multi-functional SCE system has a plurality of electronic subsystems or subunits that all plug into a single housing or card cage and electrically interconnect to a serial data bus included in the backplane of the housing. The plurality of electronic subunits provide spacecraft attitude determination, control, telemetry and command and data processing functions to the spacecraft in the single housing. In the preferred embodiment, the subunits are modular printed wiring board subassemblies and the serial data bus is an industry standard interface. Moreover, in the preferred embodiment, the integrated SCE has selectively applied internal redundancy and the backplane serial data bus is redundant. Selective application of redundancy within the SCE, together with the redundant back plane serial data bus, allows full cross-strapping between all SCE subunits to optimized reliability while minimizing interface complexity and cost.
One of the plurality of subunits is a Telemetry and Command subunit for communicating with spacecraft transponders and antennas. A second of the plurality of subunits is a Wheel Drive subunit for communicating with spacecraft reaction wheels. Moreover, there is an Actuator subunit that communicates with spacecraft motors, thrusters and deployment mechanisms. Lastly, there is a Central Processing subunit for processing data between all the subunits and the spacecraft. In a preferred embodiment, the Central Processing subunit includes a high-throughput, commercial processor, comprising three microprocessors voted together on a single multi-chip module. Multiple functions can be consolidated into the high-throughput processor. This allows use of simple, low cost sensors and actuators, which contain few or no electronic elements themselves.
In a preferred embodiment of the SCE, each of the subunits has an automatic built-in self-test (BIST) feature for automatically testing all internal circuitry and external interfaces. Additionally, the SCE BIST provides an end-to-end spacecraft harness verification automatically. The BIST features, along with a modular packaging approach, greatly reduce production cycle time and cost from the circuit card level through spacecraft level integration. BIST allows each modular subunit for the integrated SCE system to be delivered directly to spacecraft-level integration, thereby bypassing the typical unit-level test program. In the event of a failure, the modular subunits can be quickly removed, replaced and re-verified at the spacecraft level in a fully automated fashion using the BIST features of the present invention.
The present invention further provides a spacecraft having a minimum number of spacecraft harness connections. The spacecraft of the present invention includes a bus section and a payload section, as in conventional spacecraft. However, the spacecraft of the present invention further comprises a multi-functional spacecraft control electronics unit on the bus section that communications with the payload section and the spacecraft hardware. The spacecraft control electronics unit includes a plurality of control electronics subunits that plug into a single housing that has a serial data bus in a housing backplane and external interfaces from the housing to the spacecraft. The subunits provide spacecraft attitude determination, control, telemetr
Botzong Bret M.
Lloyd David W.
Gibson Eric M.
Gudmestad Terje
The Boeing Company
Zanelli Michael J.
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