EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTEREXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Battery Health Quantification for TDRS Spacecraft by Using Signature Discriminability Measurement
Presenter: Kenneth Y. Ma
https://ntrs.nasa.gov/search.jsp?R=20200001625 2020-07-24T11:54:10+00:00Z
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Introduction: Tracking and Data Relay Satellites (TDRS)• NASA’s Goddard Space Flight Center (GSFC) operates a constellation of ten active
geosynchronous Tracking and Data Relay Satellites (TDRS). The primary mission of TDRS constellation is to provide relay communications from low-Earth orbiting spacecraft to the primary ground stations.
• The Space Network project office at GSFC has managed the constellation of spacecraft over the past 30 years.
• This paper presents a new concept of battery analysis called telemetry quality quantification (TQQ) and discusses the progress that has been made in battery performance estimation for the second-generation TDRS spacecraft.
• This activity is important because many of the TDRS fleet of spacecraft have exceeded their on-orbit design lifetime and, therefore, NASA must carefully manage the spacecraft to continue operations while avoiding an end-of-mission scenario that leaves a non-functioning spacecraft in geosynchronous orbit.
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Tracking and Data Relay Satellites (TDRS)
Sensor Extract Telemetry
DataModulation
Transmission
Demodulation
On-Orbit
Ground Station
Raw Telemetry
Data
DataStorage
DataProcessing
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Telemetry Data Quantification Analysis (TDQA)• TDQA is quite different from traditional analysis currently being used, such as expert model and limit
checking.• TDQA makes use of hundreds of different telemetry parameters to characterize spacecraft’s health
situation and function of behavior by using quantification algorithm.• It provides many advantages and benefits that current analysis method cannot. Such as, fast, easy to
implement and real time processing.
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EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Application in TDQA• Application in TDQA
o Subsystem anomalies detectiono Spacecraft behavior classificationo Subsystem anomalies quantificationo Battery quality quantification
• Advantage of TDQAo Fast analyzingo Soft decision rather than hard decisiono Real time processing
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Battery Performance evaluation and discriminability measurement (1)• The second generation of TDRS spacecraft contain a single nickel hydrogen battery consisting of four
battery packs with a total of 29 cells with 110 Amp-hour (Ah) total capacity per spacecraft and provide power to the spacecraft during each eclipse and for contingency support.
• In recent years, several battery cells have exhibited divergence indicating cell capacity loss, which can affect the long-term spacecraft reliability.
• The NASA has a great deal of experience with battery reconditioning on the 1st gen satellites NiCad batteries. That design was 3 for 2 redundant allowing one battery to be reconditioned while the other two were available to support the bus.
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Example of TDRS Battery during eclipse condition• Nickel hydrogen battery provide reliable discharge processes during
each eclipse season to TDRS spacecraft. • Battery during discharge and recharge process provide considerable
information in regrading to battery performance and remaining cell capacity.
• The analysis of battery performance should be executed by using the telemetry data that battery running discharge or recharge rather than trickle charge.
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EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Battery Performance evaluation and discriminability measurement (2)• One critical issue of TDRS batteries is the challenge of battery cell capacity estimation when the
spacecraft is operating on orbit. Since the batteries never fully discharge in each eclipse condition, telemetry can only observed a partial V/Ah curve. Consequently, the current quality of the battery cells is hard to predict until the failure of a cell appears.
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EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Signature Discriminability Measurement (SDM)• SDM is primarily based on measuring the divergence between two input signals. This can be significantly useful
to compute discriminability between health subsystem signal and failed substance signal.• Euclidean Distance (ED):
• Signature Angle Mapper (SAM):
1 11 12 1( , ,..., )Ls s s= Ts 2 21 22 2( , ,..., )Ls s s= Ts
21 2 1 2 1 22 1
ED( , ) ( )Ll ll
s s=
= − = −∑s s s s
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,SAM( , )=cos−
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)ED(𝐬𝐬1, 𝐬𝐬2
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SAM(𝐬𝐬1,𝐬𝐬2)Geometric illustration for SAM and ED
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Signature Discriminability Measurement (SDM)
• Signature Information Divergence (SID) method using relative entropy in information theory to compute discriminability between two signals.
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1 2 1 2 2 1SID( , ) ( ) ( )D D= +s s s s s s
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
SDM Battery Cell Performance Analysis
• In this paper, we focus on the V vs Ah curve analysis to estimate the health of the battery cells during battery discharge process.
• The healthy cell data that we selected as our reference is extracted from TDRS 11 at the launched year. Even though TDRS 11 from a different generation than TDRS 8-10, the batteries that are installed in both spacecraft are similar and can be used as the reference data.
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DCHI( 1) DCHI( )Ah( )2
t tt t− −= ∆
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Non-Linear Regression Approach in Estimation of True Cell Signal• Statistically, linear regression is an approach to modeling the relationship between a scalar response
and one or more variables. • Linear or nonlinear regression function:
1 for 1
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EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
SDM Battery Cell Performance Analysis Results (1)
• SDM applied to quantify current performance of battery cell. The cell with abnormal discriminability when compared to the rest of the cells in same pack indicates the anomalous event. These anomalies could be the failure of a scanner, the leaking of chemical substance or other unknown events.
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SDM results showing that we can observe some signs of failure
since spring 2014
F8 cell 20 failed at fall 2015
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
SDM Battery Cell Performance Analysis (2)• Flight 9 results shows that 2 cells in Pack 1 shows significant divergence from rest of the cells in same pack,
which indicate these 2 cells have loss of capacity. Both SAM and SID shown similar results for cell 1 and cell 3.
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F9 Cell 1 and cell 3 started to diverge
from rest cells since 2016. We can say
these two cells have potential failure.
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
SDM Battery Cell Performance Analysis (3)• Similar examples can also be found in analysis of TDRS 10 data as shown in Figure. Cell 1 and cell 2 in TDRS
10 also diverge from the rest of the cells beginning at 2010. However, these two cells do not seem to become worse as we can see in 2018. Moreover, we can observe that the ED is not as sensitive as SID. This is because ED only considers the distance between two signals and does not take the signal shape into account.
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other cells since 2010.
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Conclusion• Our experiment indicates that the SDM algorithm can be helpful for managing spacecraft batteries
and for quantifying and trending the performance of cells.• A yearly or monthly trending of the data is an important methodology to analyze the performance
of the spacecraft• By using the SDM algorithm to quantify the performance of each individual spacecraft component,
we can easily analyze the spacecraft performance by yearly or monthly trending of the SDM• Continue develop algorithms for analyzing each subsystems to improve the efficiency in
monitoring spacecraft quality.• Future Work:
• Reaction wheel anomaly detection and analysis• Bus voltage limiter (BVL) anomaly detection and analysis.• Thruster anomaly and failure prediction.
EXPLORATION AND SPACE COMMUNICATIONS PROJECTS DIVISION NASA GODDARD SPACE FLIGHT CENTER
Thanks for your attention