Attitude and Orbit Control Subsystem (AOCS)
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The AOCS performs Satellite attitude determination and control and operates the
Reaction Control Subsystem (RCS) during orbit
recovery.
It includes the sensors, actuators and the control laws to ensure a pointing
accuracy of the Satellite's axes within an Absolute Pointing Error (APE) of
1.5 arcmin, during scientific measurements.
The AOCS is modular, consisting of a number of units which communicate with the
Attitude Control Computer (ACC) via a redundant, digital, serial MACS bus.
These units are:
- Redundant ACC and MACS BUS;
- Redundant Magnetometer (MGM);
- Redundant Sun Acquisition Sensors (SAs);
- Four gyroscopes (GYR) in an all-skewed configuration for
three-out-of-four redundancy;
- Four Reaction Wheels (RWS) in an all-skewed configuration for
three-out-of-four redundancy;
- Three redundant magnetic torquers (MTR);
- An internally redundant Power Distribution Unit (PDU);
- Three Star Trackers (STR).
The ACC is the brain of the Subsystem. It houses the basic and operational
Software, interfaces with the communication bus, and manages and controls all
the AOCS units.
The AOCS operations are executed under the control of Attitude Operation Plans
(AOPs).
An AOP is a ground-generated macrocommand that defines the maneuver requested
from the AOCS, e.g. the new target pointing direction and the slew maneuver
required for its acquisition.
This file was last modified on Wednesday, 02-Sep-1998 17:28:57 CEST
by Mauro Orlandini
Next: Reaction Control (RCS)
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