ASTROgyro – ASTROgyro Qualification

Objectives

The purpose of ASTROgyro is to establish a reliable and performant attitude determination system combining the star tracker’s fundament of absolute and drift-free attitude information based on star pattern recognition with the broad dynamic range and low noise rate spectrum of Coriolis Vibratory Gyroscopes (CVG) in an IRU compound.

Benefits

Present state-of-the-art attitude and orbit control systems (AOCS) in telecom satellites make use of autonomous star trackers (STR) and gyroscopes as separate sensors, with individual data processing located in the spacecraft central AOCS computer. In such a configuration, the star tracker has no direct access to gyroscopic data. On the other hand,

the gyroscope provides its pre-processed angle rate or rate-integrated information with low data rate solely to the central processing unit. There exists complementarity between the two types of sensors, but it is obvious that any hybridizing of sensor data is confined to execution in the spacecraft on-board computer.

 

In order to reduce costs and complexity of their platforms, satellite and spacecraft manufacturers worldwide seek for new technologies and unitized subsystems making their AOCS busses robust and reliable.

Features

ASTROgyro perfectly fulfils customer needs as it minimizes computational loads for the satellites’ AOCS computers by pre-processing, monitoring and harmonizing four attitude determination sensors of two independent technologies.

Furthermore, ASTROgyro makes full use of both star tracker and gyroscope capabilities in order to provide even

  • higher dynamic ranges,
  • lower attitude and rate noise, and
  • faster attitude re-acquisition

than any other attitude sensor system in its price segment.

System Architecture

Contrasting to the traditional concept, the ASTROgyro system raises the synergies between star trackers and gyroscopes in a simplified manner. Its basic concept is an integrated but flexible system that allows for sensor data fusion without additional processing load for the AOCS computer. The star tracker is able to take full advantage of the high data rate information of the gyroscope e.g. for outage bridging, thus also improving the subsequent entering of the attitude re-acquisition phase. The gyroscope, in return, profits from periodic, star tracker-based recalibration.

ASTROgyro system with 2 autonomous star trackers and a gyro box © Jena-Optronik

The ASTROgyro project is currently in the qualification phase.

The milestones after the Kick-Off are CDR, TRR and Final Review of the qualification results. 

Plan

The ASTROgyro project is currently in the qualification phase.

The milestones after the Kick-Off are CDR, TRR and Final Review of the qualification results. 

Current status

An engineering model of the ASTROgyro IRU has successfully been set up and has been calibrated and performance tested. After successful verification of the ASTROgyro Inertial Reference Unit design principles, the qualification model of ASTROgyro IRU is currently being manufactured and put into operation.

Contacts

ESA Contacts

Status date

Wednesday, August 9, 2017 - 13:34