Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943676
Dan Shen, B. Jia, Genshe Chen, K. Pham, Erik Blasch
This paper presents a pursuit-evasion (PE) orbital game approach for space situational awareness (SSA), where imperfect measurements and/or informational uncertainties are addressed. Whether deliberate or unintentional, some of space objects may cause confusion to observers (satellites) by performing orbital maneuvers. Generally, the space-object tracking problem can be modeled as a one-sided optimization (optimal control) setup or a two-sided optimization (game) problem. In the optimal control setup, the states (positions and velocities) of space objects are computed (filtered) based on the sensor measurements. However, the optimal control approach does not consider the intelligence of the space objects that may change their orbits intentionally to make it difficult for the observer to track it. The proposed PE approach provides a method to solve the SSA problem, where the evader will exploit the sensing and tracking model to confuse the pursuer by corrupting their tracking estimates, while the pursuer wants to decrease the tracking uncertainties. The uncertainties are modeled based on the tracking entropy. For the applied consensus-based filters, the entropy is simplified as the product of eigenvalues of error covariance matrices. The fictitious play framework has been exploited to solve the non-linear PE games. Examples are presented for different maneuvering scenarios with optical tracking used space-based optical (SBO) sensors.
{"title":"Game optimal sensor management strategies for tracking elusive space objects","authors":"Dan Shen, B. Jia, Genshe Chen, K. Pham, Erik Blasch","doi":"10.1109/AERO.2017.7943676","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943676","url":null,"abstract":"This paper presents a pursuit-evasion (PE) orbital game approach for space situational awareness (SSA), where imperfect measurements and/or informational uncertainties are addressed. Whether deliberate or unintentional, some of space objects may cause confusion to observers (satellites) by performing orbital maneuvers. Generally, the space-object tracking problem can be modeled as a one-sided optimization (optimal control) setup or a two-sided optimization (game) problem. In the optimal control setup, the states (positions and velocities) of space objects are computed (filtered) based on the sensor measurements. However, the optimal control approach does not consider the intelligence of the space objects that may change their orbits intentionally to make it difficult for the observer to track it. The proposed PE approach provides a method to solve the SSA problem, where the evader will exploit the sensing and tracking model to confuse the pursuer by corrupting their tracking estimates, while the pursuer wants to decrease the tracking uncertainties. The uncertainties are modeled based on the tracking entropy. For the applied consensus-based filters, the entropy is simplified as the product of eigenvalues of error covariance matrices. The fictitious play framework has been exploited to solve the non-linear PE games. Examples are presented for different maneuvering scenarios with optical tracking used space-based optical (SBO) sensors.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"15 2 Pt 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123724021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943875
Nicole Chen, Ying Lin, D. Jackson, Shirley Y. Chung
In a previous study, the cleaning efficiency of a CO2 composite cleaning system for particulate removal was tested. The study covered particles from spores to fluorescent particles of different sizes as well as a variety of substrate surfaces, including aluminum, titanium, stainless steel, and nitinol. Particles were deposited using aerosol (dry) and droplet (wet) deposition. Results from the previous study show that the CO2 composite spray system is capable of cleaning to sterility for aerosol deposited spores and is capable of cleaning a minimum of a 4-log reduction for droplet deposited spores. This minimum 4-log reduction matches current Planetary Protection dry heat microbial reduction requirements. In this paper we will present new data to further correlate the cleaning efficiency with how contamination was introduced to the surface, the surface roughness, and particle size. Possible causes for such correlations will be discussed.
{"title":"Analysis of CO2 composite spray cleaning system results","authors":"Nicole Chen, Ying Lin, D. Jackson, Shirley Y. Chung","doi":"10.1109/AERO.2017.7943875","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943875","url":null,"abstract":"In a previous study, the cleaning efficiency of a CO2 composite cleaning system for particulate removal was tested. The study covered particles from spores to fluorescent particles of different sizes as well as a variety of substrate surfaces, including aluminum, titanium, stainless steel, and nitinol. Particles were deposited using aerosol (dry) and droplet (wet) deposition. Results from the previous study show that the CO2 composite spray system is capable of cleaning to sterility for aerosol deposited spores and is capable of cleaning a minimum of a 4-log reduction for droplet deposited spores. This minimum 4-log reduction matches current Planetary Protection dry heat microbial reduction requirements. In this paper we will present new data to further correlate the cleaning efficiency with how contamination was introduced to the surface, the surface roughness, and particle size. Possible causes for such correlations will be discussed.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"92 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129503139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943802
Jane Jean Kiam, A. Schulte
This work focuses on the development of a highly automated mission management system (MMS) for solar-powered long-endurance unmanned aerial vehicles (UAVs). The objective of the MMS is to produce a “best” plan for long endurance missions subject to the specific application's requirements and multilateral constraints, i.e. mission, energy and safety constraints. The MMS adopts the hybrid architecture of a symbolic planner based on the hierarchical task-network (HTN), working cooperatively with a Markov decision process (MDP) based policy generator to reduce the search space for a numeric path planner. The hybrid structure allows hard and soft constraints to be considered independently: the hard constraints are accounted for at each abstraction level in the task-network, while soft-constraints are considered by the policy generator. The policy generator is extended by introducing k-best policies. If the plan found by the optimal policy violates the hard constraints, a suboptimal plan will instead be selected using the suboptimal policies as ranked in the k-best policies. If multiple policies of the k-best policies find a valid plan, the operator can select the best plan by applying a Pareto rule to take into other soft constraints not considered in the determination of the k-best policies. With multilateral constraints accounted for at different hierarchical levels of the MMS, we offer more transparency to the human operator, enabling customization of the objective functions or the relaxation on hard constraints by the operator during mission execution. The MMS described in this article is especially needed for increasing autonomy of a specific fixed-wing UAV platform, namely the high altitude pseudo-satellite (HAPS). Being lightweight and fully solar-powered, the platform is practical for long-endurance surveillance and mapping missions. Due to the continuous operation over long periods, higher autonomy can yield economic and safety benefits. The MMS was tested with a lab-simulator of the HAPS.
{"title":"Multilateral quality mission planning for solar-powered long-endurance UAV","authors":"Jane Jean Kiam, A. Schulte","doi":"10.1109/AERO.2017.7943802","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943802","url":null,"abstract":"This work focuses on the development of a highly automated mission management system (MMS) for solar-powered long-endurance unmanned aerial vehicles (UAVs). The objective of the MMS is to produce a “best” plan for long endurance missions subject to the specific application's requirements and multilateral constraints, i.e. mission, energy and safety constraints. The MMS adopts the hybrid architecture of a symbolic planner based on the hierarchical task-network (HTN), working cooperatively with a Markov decision process (MDP) based policy generator to reduce the search space for a numeric path planner. The hybrid structure allows hard and soft constraints to be considered independently: the hard constraints are accounted for at each abstraction level in the task-network, while soft-constraints are considered by the policy generator. The policy generator is extended by introducing k-best policies. If the plan found by the optimal policy violates the hard constraints, a suboptimal plan will instead be selected using the suboptimal policies as ranked in the k-best policies. If multiple policies of the k-best policies find a valid plan, the operator can select the best plan by applying a Pareto rule to take into other soft constraints not considered in the determination of the k-best policies. With multilateral constraints accounted for at different hierarchical levels of the MMS, we offer more transparency to the human operator, enabling customization of the objective functions or the relaxation on hard constraints by the operator during mission execution. The MMS described in this article is especially needed for increasing autonomy of a specific fixed-wing UAV platform, namely the high altitude pseudo-satellite (HAPS). Being lightweight and fully solar-powered, the platform is practical for long-endurance surveillance and mapping missions. Due to the continuous operation over long periods, higher autonomy can yield economic and safety benefits. The MMS was tested with a lab-simulator of the HAPS.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"13 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130127093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943775
F. Vanegas, D. Campbell, N. Roy, K. Gaston, Felipe Gonzalez
Unmanned Aerial Vehicles (UAVs) are increasingly being used in numerous applications, such as remote sensing, environmental monitoring, ecology and search and rescue missions. Effective use of UAVs depends on the ability of the system to navigate in the mission scenario, especially if the UAV is required to navigate autonomously. There are particular scenarios in which UAV navigation faces challenges and risks. This creates the need for robust motion planning capable of overcoming different sources of uncertainty. One example is a UAV flying to search, track and follow a mobile ground target in GPS-denied space, such as below canopy or in between buildings, while avoiding obstacles. A UAV navigating under these conditions can be affected by uncertainties in its localization and motion due to occlusion of GPS signals and the use of low cost sensors. Additionally, the presence of strong winds in the airspace can disturb the motion of the UAV. In this paper, we describe and flight test a novel formulation of a UAV mission for searching, tracking and following a mobile ground target. This mission is formulated as a Partially Observable Markov Decision Process (POMDP) and implemented in real flight using a modular framework. We modelled the UAV dynamic system, the uncertainties in motion and localization of both the UAV and the target, and the wind disturbances. The framework computes a motion plan online for executing motion commands instead of flying to way-points to accomplish the mission. The system enables the UAV to plan its motion allowing it to execute information gathering actions to reduce uncertainty by detecting landmarks in the scenario, while making predictions of the mobile target trajectory and the wind speed based on observations. Results indicate that the system overcomes uncertainties in localization of both the aircraft and the target, and avoids collisions into obstacles despite the presence of wind. This research has the potential of use particularly for remote monitoring in the fields of biodiversity and ecology.
{"title":"UAV tracking and following a ground target under motion and localisation uncertainty","authors":"F. Vanegas, D. Campbell, N. Roy, K. Gaston, Felipe Gonzalez","doi":"10.1109/AERO.2017.7943775","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943775","url":null,"abstract":"Unmanned Aerial Vehicles (UAVs) are increasingly being used in numerous applications, such as remote sensing, environmental monitoring, ecology and search and rescue missions. Effective use of UAVs depends on the ability of the system to navigate in the mission scenario, especially if the UAV is required to navigate autonomously. There are particular scenarios in which UAV navigation faces challenges and risks. This creates the need for robust motion planning capable of overcoming different sources of uncertainty. One example is a UAV flying to search, track and follow a mobile ground target in GPS-denied space, such as below canopy or in between buildings, while avoiding obstacles. A UAV navigating under these conditions can be affected by uncertainties in its localization and motion due to occlusion of GPS signals and the use of low cost sensors. Additionally, the presence of strong winds in the airspace can disturb the motion of the UAV. In this paper, we describe and flight test a novel formulation of a UAV mission for searching, tracking and following a mobile ground target. This mission is formulated as a Partially Observable Markov Decision Process (POMDP) and implemented in real flight using a modular framework. We modelled the UAV dynamic system, the uncertainties in motion and localization of both the UAV and the target, and the wind disturbances. The framework computes a motion plan online for executing motion commands instead of flying to way-points to accomplish the mission. The system enables the UAV to plan its motion allowing it to execute information gathering actions to reduce uncertainty by detecting landmarks in the scenario, while making predictions of the mobile target trajectory and the wind speed based on observations. Results indicate that the system overcomes uncertainties in localization of both the aircraft and the target, and avoids collisions into obstacles despite the presence of wind. This research has the potential of use particularly for remote monitoring in the fields of biodiversity and ecology.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121238927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943576
G. Kazarians, J. Benardini, Moogega Stricker, W. Schubert, Fei Chen, P. Vaishampayan, L. Newlin, Melissa A. Jones, J. Barengoltz, R. Koukol
NASA has developed requirements dedicated to the prevention of forward and backward contamination during space exploration. Historically, international agreements provided guidelines to prevent contamination of the Moon and other celestial bodies, as well as the Earth (e.g., sample return missions). The UN Outer Space Treaty was established in 1967 and the Committee on Space Research (COSPAR) maintains a planetary protection policy complying with Article IX of this treaty. By avoiding forward contamination, the integrity of scientific exploration is preserved. Planetary Protection mission requirements are levied on missions to control contamination. These requirements are dependent on the science of the mission and on the celestial bodies encountered or targeted along the way. Consequently, categories are assigned to missions, and specific implementation plans are developed to meet the planetary protection requirements. NASA missions have evolved over time with increasingly more demanding scientific objectives and more complex flight systems to achieve those objectives and, thus, planetary protection methods and processes used for implementation have become much more intricate, complicated, and challenging. Here, we will portray the evolution of planetary protection implementation at JPL in several important areas throughout the course of NASA sponsored robotic Mars lander or rover missions, starting from Mars Pathfinder through the beginning of Mars 2020. Highlighted in the discussion will be process changes in planetary protection requirements development and flow down. Development and implementation of new and improved methods used in the reduction of spacecraft bioburden will be discussed as well as approaches and challenges that come along with setting up remote laboratories to perform bioassays. The consequences and forward planning of delays on missions will be highlighted as well as lessons learned on the impact of communication and training in achieving planetary protection requirements. The evolution of methods used for the detection of microbial bioburden on spacecraft hardware will be considered. These methods use standard microbiology as well as the adaptation of advances in biotechnology, molecular biology, and bioinformatics. Technical approaches developed for the prevention of contamination and recontamination of hardware during Assembly, Test, and Launch Operations will be discussed.
{"title":"The Evolution of planetary protection implementation on Mars landed missions","authors":"G. Kazarians, J. Benardini, Moogega Stricker, W. Schubert, Fei Chen, P. Vaishampayan, L. Newlin, Melissa A. Jones, J. Barengoltz, R. Koukol","doi":"10.1109/AERO.2017.7943576","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943576","url":null,"abstract":"NASA has developed requirements dedicated to the prevention of forward and backward contamination during space exploration. Historically, international agreements provided guidelines to prevent contamination of the Moon and other celestial bodies, as well as the Earth (e.g., sample return missions). The UN Outer Space Treaty was established in 1967 and the Committee on Space Research (COSPAR) maintains a planetary protection policy complying with Article IX of this treaty. By avoiding forward contamination, the integrity of scientific exploration is preserved. Planetary Protection mission requirements are levied on missions to control contamination. These requirements are dependent on the science of the mission and on the celestial bodies encountered or targeted along the way. Consequently, categories are assigned to missions, and specific implementation plans are developed to meet the planetary protection requirements. NASA missions have evolved over time with increasingly more demanding scientific objectives and more complex flight systems to achieve those objectives and, thus, planetary protection methods and processes used for implementation have become much more intricate, complicated, and challenging. Here, we will portray the evolution of planetary protection implementation at JPL in several important areas throughout the course of NASA sponsored robotic Mars lander or rover missions, starting from Mars Pathfinder through the beginning of Mars 2020. Highlighted in the discussion will be process changes in planetary protection requirements development and flow down. Development and implementation of new and improved methods used in the reduction of spacecraft bioburden will be discussed as well as approaches and challenges that come along with setting up remote laboratories to perform bioassays. The consequences and forward planning of delays on missions will be highlighted as well as lessons learned on the impact of communication and training in achieving planetary protection requirements. The evolution of methods used for the detection of microbial bioburden on spacecraft hardware will be considered. These methods use standard microbiology as well as the adaptation of advances in biotechnology, molecular biology, and bioinformatics. Technical approaches developed for the prevention of contamination and recontamination of hardware during Assembly, Test, and Launch Operations will be discussed.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"301 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131077856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943865
D. Kaslow, B. Ayres, P. T. Cahill, L. Hart, Rose Yntema
This paper describes an eight-step approach for defining the behaviors of CubeSats that begins with mission requirements and ends with a functional architecture modeled as an activity hierarchy using the Object Management Group's (OMG) Systems Modeling Language (SysML). This approach could be applied to other satellite development efforts but the emphasis here is on CubeSats because of their historically high mission failure rate and the rapid growth in the number of these missions over the last few years. In addition, this approach complements the International Council on Systems Engineering's (INCOSE) Space Systems Working Group's (SSWG) efforts to develop a CubeSat Reference Model. This approach provides a repeatable, generalized method for CubeSat development teams to follow that incorporates standard systems engineering practices such as: a top-down approach, requirements analysis, use case development, and functional analysis. This effort uses a Model-Based Systems Engineering (MBSE) approach. Some of the benefits of using an MBSE approach over a traditional document-based approach are: enhanced communications, reduced development risk, improved quality, and enhanced knowledge transfer [1]. Systems engineering artifacts produced using this approach, such as definitions of the mission domain elements, requirements, use cases, and activities, are captured in a system model which serves as a single-source-of-truth for members of the CubeSat development team. Examples are provided throughout the paper which illustrates the application of this approach to a CubeSat development effort. Since most space missions are concerned with the generation or flow of information, the examples focus on requirements to collect and distribute mission data ending with a definition of the required system functionality to satisfy those requirements.
{"title":"A Model-Based Systems Engineering (MBSE) approach for defining the behaviors of CubeSats","authors":"D. Kaslow, B. Ayres, P. T. Cahill, L. Hart, Rose Yntema","doi":"10.1109/AERO.2017.7943865","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943865","url":null,"abstract":"This paper describes an eight-step approach for defining the behaviors of CubeSats that begins with mission requirements and ends with a functional architecture modeled as an activity hierarchy using the Object Management Group's (OMG) Systems Modeling Language (SysML). This approach could be applied to other satellite development efforts but the emphasis here is on CubeSats because of their historically high mission failure rate and the rapid growth in the number of these missions over the last few years. In addition, this approach complements the International Council on Systems Engineering's (INCOSE) Space Systems Working Group's (SSWG) efforts to develop a CubeSat Reference Model. This approach provides a repeatable, generalized method for CubeSat development teams to follow that incorporates standard systems engineering practices such as: a top-down approach, requirements analysis, use case development, and functional analysis. This effort uses a Model-Based Systems Engineering (MBSE) approach. Some of the benefits of using an MBSE approach over a traditional document-based approach are: enhanced communications, reduced development risk, improved quality, and enhanced knowledge transfer [1]. Systems engineering artifacts produced using this approach, such as definitions of the mission domain elements, requirements, use cases, and activities, are captured in a system model which serves as a single-source-of-truth for members of the CubeSat development team. Examples are provided throughout the paper which illustrates the application of this approach to a CubeSat development effort. Since most space missions are concerned with the generation or flow of information, the examples focus on requirements to collect and distribute mission data ending with a definition of the required system functionality to satisfy those requirements.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129044995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943754
A. Raza, Volodymyr Ulanskyi, K. Augustynek, K. Warwas
In this study, the generalized cost functions are proposed for choosing the optimal option of breakdown maintenance strategy of avionics systems. A mathematical model of avionics line replaceable unit (LRU) is developed. The model considers the main characteristics of the preflight checks and continuous testing of the LRU using built-in test equipment (BITE) in-flight. The equation for the mean time between unscheduled removals (MTBUR) is derived for an arbitrary and exponential distribution of time to failure. The cost functions are determined as the total operating costs separately for the warranty and post warranty period of operation. Different options of single-level, two-level and three-level maintenance are mathematically modeled and numerically analyzed for the warranty and post-warranty period of operation. The proposed analytical expressions take into account the trustworthiness of BITE, periodicity of preflight testing, cost of different maintenance operations, permanent and intermittent failure rate of LRUs and some other parameters. Numerical examples are included to illustrate the main features of the proposed mathematical models.
{"title":"Generalized cost functions of avionics breakdown maintenance strategy","authors":"A. Raza, Volodymyr Ulanskyi, K. Augustynek, K. Warwas","doi":"10.1109/AERO.2017.7943754","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943754","url":null,"abstract":"In this study, the generalized cost functions are proposed for choosing the optimal option of breakdown maintenance strategy of avionics systems. A mathematical model of avionics line replaceable unit (LRU) is developed. The model considers the main characteristics of the preflight checks and continuous testing of the LRU using built-in test equipment (BITE) in-flight. The equation for the mean time between unscheduled removals (MTBUR) is derived for an arbitrary and exponential distribution of time to failure. The cost functions are determined as the total operating costs separately for the warranty and post warranty period of operation. Different options of single-level, two-level and three-level maintenance are mathematically modeled and numerically analyzed for the warranty and post-warranty period of operation. The proposed analytical expressions take into account the trustworthiness of BITE, periodicity of preflight testing, cost of different maintenance operations, permanent and intermittent failure rate of LRUs and some other parameters. Numerical examples are included to illustrate the main features of the proposed mathematical models.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134314447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943580
Jan-Gerd Mess, R. Schmidt, G. Fey
Extended monitoring of housekeeping data is required to increase the observability of a spacecrafts health status, its environment and resulting mechanical stress as well as physical parameters like the spacecrafts position and orientation. This implies the application of an increasing number of onboard sensors for various physical quantities like temperature, vibration, acceleration, voltage, current and others. These sensors need to offer high resolution in the time domain and high accuracy. The amount of data produced by an extended housekeeping system proves increasingly significant. However, to customers, housekeeping data is not of direct value and has therefore been subordinated to scientific payload data in terms of the allocation of bandwidth towards ground. In order to optimize the information throughput for a given bandwidth budget, data compression such as entropy coding as well as lossy data compaction need to be applied. At the same time, the accuracy and the allowed magnitude of error of housekeeping data is crucial to its value for ground engineers. As a result, especially lossy data compaction has to be applied carefully taking into account the nature of the data to be processed. In this paper, we evaluate transform-based compression techniques and analyze their effect on housekeeping data and suitability for subsequent entropy coding on board spacecrafts. To do so, we apply a variety of transforms to real sensor data collected by launchers (ARIANE5) as well as satellites (AISat) and analyze their performance in terms of data quality, compression ratio, computing effciency and effectiveness of subsequent entropy coding. Our results show that a data reduction of 96.5% for quickly oscilatting vibration sensors and of 99.5% for slower temperature sensors can be achieved without introducing a significant error during critical time frames within data sequences.
{"title":"Adaptive compression schemes for housekeeping data","authors":"Jan-Gerd Mess, R. Schmidt, G. Fey","doi":"10.1109/AERO.2017.7943580","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943580","url":null,"abstract":"Extended monitoring of housekeeping data is required to increase the observability of a spacecrafts health status, its environment and resulting mechanical stress as well as physical parameters like the spacecrafts position and orientation. This implies the application of an increasing number of onboard sensors for various physical quantities like temperature, vibration, acceleration, voltage, current and others. These sensors need to offer high resolution in the time domain and high accuracy. The amount of data produced by an extended housekeeping system proves increasingly significant. However, to customers, housekeeping data is not of direct value and has therefore been subordinated to scientific payload data in terms of the allocation of bandwidth towards ground. In order to optimize the information throughput for a given bandwidth budget, data compression such as entropy coding as well as lossy data compaction need to be applied. At the same time, the accuracy and the allowed magnitude of error of housekeeping data is crucial to its value for ground engineers. As a result, especially lossy data compaction has to be applied carefully taking into account the nature of the data to be processed. In this paper, we evaluate transform-based compression techniques and analyze their effect on housekeeping data and suitability for subsequent entropy coding on board spacecrafts. To do so, we apply a variety of transforms to real sensor data collected by launchers (ARIANE5) as well as satellites (AISat) and analyze their performance in terms of data quality, compression ratio, computing effciency and effectiveness of subsequent entropy coding. Our results show that a data reduction of 96.5% for quickly oscilatting vibration sensors and of 99.5% for slower temperature sensors can be achieved without introducing a significant error during critical time frames within data sequences.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132548875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943894
A. Niklas, M. Sambora
The WorldView-3 and Landsat-8 satellites are the most recently deployed systems in their constellations and the unique data from these sensors can positively impact environmental and military target detection applications. The research team uses spectral library data in the VNIR and SWIR spectral bands of WorldView-3 and Landsat-8 to determine the best combination of spectral bands and spectral distance measure to yield the largest spectral distance value for each target material. Spectral distance measures include Euclidean Distance, Spectral Angle Mapper, Spectral Correlation Measure, and Spectral Information Divergence. The optimal configuration results are stored in a look-up-table for implementation in an automated target detection system. The Freedman-Diaconis and Shimazaki-Shinomoto methods for optimal histogram bin width determination are applied to spectral distance measures that are cross computed for each material in the spectral library and for each sensor. The bin width determination is used to characterize material clusters based on intercluster and intracluster spectral distances. The material cluster characterization results are stored in a look-up-table for fast histogram based initialization of clustering algorithms. The research team uses the in-band spectral library data for determining end member abundance estimates based on combinations of spectral bands, end member combinations, spectral distance measure, and additive white Gaussian noise for both sensors. The endmember abundance estimates are optimized using Differential Evolution, Least Squares, and Linear Simplex. The numerical accuracy of the end member abundance determination is compared across the three optimization algorithms. The completion of this foundational work increases the data exploitation potential of WorldView-3 and Landsat-8 by providing a fundamental characterization of material separability with respect to these sensors.
{"title":"Spectral library material separability using WorldView-3 and Landsat-8 spectral bands","authors":"A. Niklas, M. Sambora","doi":"10.1109/AERO.2017.7943894","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943894","url":null,"abstract":"The WorldView-3 and Landsat-8 satellites are the most recently deployed systems in their constellations and the unique data from these sensors can positively impact environmental and military target detection applications. The research team uses spectral library data in the VNIR and SWIR spectral bands of WorldView-3 and Landsat-8 to determine the best combination of spectral bands and spectral distance measure to yield the largest spectral distance value for each target material. Spectral distance measures include Euclidean Distance, Spectral Angle Mapper, Spectral Correlation Measure, and Spectral Information Divergence. The optimal configuration results are stored in a look-up-table for implementation in an automated target detection system. The Freedman-Diaconis and Shimazaki-Shinomoto methods for optimal histogram bin width determination are applied to spectral distance measures that are cross computed for each material in the spectral library and for each sensor. The bin width determination is used to characterize material clusters based on intercluster and intracluster spectral distances. The material cluster characterization results are stored in a look-up-table for fast histogram based initialization of clustering algorithms. The research team uses the in-band spectral library data for determining end member abundance estimates based on combinations of spectral bands, end member combinations, spectral distance measure, and additive white Gaussian noise for both sensors. The endmember abundance estimates are optimized using Differential Evolution, Least Squares, and Linear Simplex. The numerical accuracy of the end member abundance determination is compared across the three optimization algorithms. The completion of this foundational work increases the data exploitation potential of WorldView-3 and Landsat-8 by providing a fundamental characterization of material separability with respect to these sensors.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124880477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-03-04DOI: 10.1109/AERO.2017.7943577
R. Conversano, D. Goebel, R. Hofer, Nitin Arora
The increase in performance resulting from optimization of the magnetic field in a low-power magnetically shielded Hall thruster is investigated. The magnetic circuit of the MaSMi-60 Hall thruster was modified to improve the magnetic field topology while increasing the strength of the field across the discharge channel gap. Direct thrust measurements were then taken to assess the changes to thruster efficiency, thrust, and specific impulse. The MaSMi-60's total efficiency increased by nearly 30% as a result of the improved magnetic field, resulting in a peak value of 32.1% (38.6% anode efficiency). Peak thrust and total specific impulse values of 35.8 mN and 1,440 s (1,550 s anode specific impulse) were observed. To demonstrate the thruster's enabling capabilities when paired with a smallsat-class spacecraft, three example mission trajectories to 118401 LINEAR, an icy asteroid-belt comet, were calculated. For each trajectory, the MaSMi-60's experimentally demonstrated performance was used for the throttling table inputs. The trajectory solutions show a delivered mass fraction of between 35–49% for an initial spacecraft mass of up to 350 kg, a solar array power of up to 2.0 kW, and a total transfer time of ∼6.5 years.
{"title":"Performance enhancement of a long-life, low-power hall thruster for deep-space smallsats","authors":"R. Conversano, D. Goebel, R. Hofer, Nitin Arora","doi":"10.1109/AERO.2017.7943577","DOIUrl":"https://doi.org/10.1109/AERO.2017.7943577","url":null,"abstract":"The increase in performance resulting from optimization of the magnetic field in a low-power magnetically shielded Hall thruster is investigated. The magnetic circuit of the MaSMi-60 Hall thruster was modified to improve the magnetic field topology while increasing the strength of the field across the discharge channel gap. Direct thrust measurements were then taken to assess the changes to thruster efficiency, thrust, and specific impulse. The MaSMi-60's total efficiency increased by nearly 30% as a result of the improved magnetic field, resulting in a peak value of 32.1% (38.6% anode efficiency). Peak thrust and total specific impulse values of 35.8 mN and 1,440 s (1,550 s anode specific impulse) were observed. To demonstrate the thruster's enabling capabilities when paired with a smallsat-class spacecraft, three example mission trajectories to 118401 LINEAR, an icy asteroid-belt comet, were calculated. For each trajectory, the MaSMi-60's experimentally demonstrated performance was used for the throttling table inputs. The trajectory solutions show a delivered mass fraction of between 35–49% for an initial spacecraft mass of up to 350 kg, a solar array power of up to 2.0 kW, and a total transfer time of ∼6.5 years.","PeriodicalId":224475,"journal":{"name":"2017 IEEE Aerospace Conference","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126224092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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