A system health monitoring software application called AMISS, based on the Intelligent Systems Division’s Inductive Monitoring System (IMS), has been deployed on the Attitude Determination and Control (ADCO) and the Thermal Operations and Resources (THOR) ISS mission control consoles to provide real-time ISS health monitoring. During the past week, AMISS monitoring alerted ADCO controllers to unusual behavior in one of the Control Moment Gyroscopes (CMG) used to control ISS attitude. These alerts prompted ADCO to request a CMG analysis from the engineering support team. Additional IMS analysis was performed on the past month of data to support this effort. Analysis results indicate off-nominal distribution of CMG bearing lubricant as the probable cause. Since there are no immediate operational issues from the anomaly, the controllers plan to continue to monitor the situation closely to detect any further degradation.
Additionally, specially focused AMISS models were built by TI personnel to monitor the ISS External Thermal Control System (ETCS) after the failure of an ETCS nitrogen tank assembly (NTA) valve during the STS-131 Shuttle mission. The NTA is used to maintain pressure in the ETCS liquid ammonia cooling loops. THOR controllers are concerned that loss of NTA-provided pressure could cause ammonia bubbles to form in the cooling loops, resulting in reduced ISS cooling capacity. ETCS system reconfiguration has significantly reduced the possibility of ammonia bubbles, but THOR controllers are still watching the system carefully with support from the custom-built AMISS models.
BACKGROUND: The Inductive Monitoring System (IMS) is an Ames-developed health monitoring software application that uses data mining techniques to establish a baseline of normal behavior for the monitored system derived from archived telemetry. IMS then uses that baseline to identify off-normal behavior in real-time telemetry, potentially prior to any caution and warning annunciation for the system. In FY-07, ARC/TI delivered IMS-based tools to JSC that allow ADCO mission controllers to monitor CMG systems in real time. In subsequent years, the IMS CMG tool has been generalized for use by any flight control discipline and is now used for real-time flight control room monitoring of 19 ISS subsystems, with additional deployments under consideration.
ARC TEAM MEMBERS: David Iverson, William Taylor, Vijay Baskaran, and Pat Castle
NASA PROGRAM FUNDING: JSC ITA supported by SSP and JSC MER
Contact: David Iverson (ARC), Andrew Hillin (JSC)