Qualification of a New CVG-Based Inertial Reference Unit in a Combined Stellar-Inertial Attitude Determination System for Space Applications

Today's state of the art telecom satellites feature centralized attitude fusion based on the individual input of all-separate AOCS (attitude and orbit control system) sensors. In such a configuration, autonomous star sensors (STR) have no direct access to high bandwidth gyroscopic data as the gyroscopes provide their pre-processed angle rates or rate-integrated information at a low data rate solely to the central processing unit. It is obvious that any hybridization of sensor data which is confined to execution in the s/c board computer does not fully unfold the well-known synergies between the two types of sensors.By introducing the ASTROgyro (AGY), Jena-Optronik offers a modular stellar-inertial sensor system, comprising two star sensors and two gyroscopic Inertial Reference Units (IRU, each 3 axis) in a combined product. ASTROgyro improves the operational availability, robustness, and performance of rate and attitude measurements for the navigation tasks performed by the satellite AOCS system.In a dedicated qualification campaign, the newly introduced ASTROgyro IRU (AGI) was subjected to extensive unit testing and has successfully proven its suitability for demanding LEO, MEO and GEO space applications. This paper describes the ASTROgyro key features and budgets as well as the system design. Special emphasis is put on the ASTROgyro IRU qualification test results regarding single gyroscope and overall unit performance under the influence of shock, vibration, thermal vacuum cycling, and electromagnetic compatibility testing in the context of general space mission requirements for IRUs.