Target Satellite

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Amanda M Larracuente - One of the best experts on this subject based on the ideXlab platform.

  • the organization and evolution of the responder Satellite in species of the drosophila melanogaster group dynamic evolution of a Target of meiotic drive
    BMC Evolutionary Biology, 2014
    Co-Authors: Amanda M Larracuente
    Abstract:

    Satellite DNA can make up a substantial fraction of eukaryotic genomes and has roles in genome structure and chromosome segregation. The rapid evolution of Satellite DNA can contribute to genomic instability and genetic incompatibilities between species. Despite its ubiquity and its contribution to genome evolution, we currently know little about the dynamics of Satellite DNA evolution. The Responder (Rsp) Satellite DNA family is found in the pericentric heterochromatin of chromosome 2 of Drosophila melanogaster. Rsp is well-known for being the Target of Segregation Distorter (SD) an autosomal meiotic drive system in D. melanogaster. I present an evolutionary genetic analysis of the Rsp family of repeats in D. melanogaster and its closely-related species in the melanogaster group (D. simulans, D. sechellia, D. mauritiana, D. erecta, and D. yakuba) using a combination of available BAC sequences, whole genome shotgun Sanger reads, Illumina short read deep sequencing, and fluorescence in situ hybridization. I show that Rsp repeats have euchromatic locations throughout the D. melanogaster genome, that Rsp arrays show evidence for concerted evolution, and that Rsp repeats exist outside of D. melanogaster, in the melanogaster group. The repeats in these species are considerably diverged at the sequence level compared to D. melanogaster, and have a strikingly different genomic distribution, even between closely-related sister taxa. The genomic organization of the Rsp repeat in the D. melanogaster genome is complex it exists of large blocks of tandem repeats in the heterochromatin and small blocks of tandem repeats in the euchromatin. My discovery of heterochromatic Rsp-like sequences outside of D. melanogaster suggests that SD evolved after its Target Satellite and that the evolution of the Rsp Satellite family is highly dynamic over a short evolutionary time scale (<240,000 years).

Pini Gurfil - One of the best experts on this subject based on the ideXlab platform.

  • stereovision based estimation of relative dynamics between noncooperative Satellites theory and experiments
    IEEE Transactions on Control Systems and Technology, 2014
    Co-Authors: Shai Segal, Avishy Carmi, Pini Gurfil
    Abstract:

    Estimating the relative pose and motion of cooperative Satellites using on-board sensors is a challenging problem. When the Satellites are noncooperative, the problem becomes even more complicated, as there might be poor a priori information about the motion and structure of the Target Satellite. In this paper, the mentioned problem is solved by using only visual sensors, which measurements are processed through robust filtering algorithms. Using two cameras mounted on a chaser Satellite, the relative state with respect to a Target Satellite, including the position, attitude, and rotational and translational velocities, is estimated. The new approach employs a stereoscopic vision system for tracking a set of feature points on the Target spacecraft. The perspective projection of these points on the two cameras constitutes the observation model of an iterated extended Kalman filter (IEKF) estimation scheme. Using new theoretical results, the information contained in the visual data is quantified using the Fisher information matrix. It is shown that, even in the noncooperative case, there is information that can be extracted pertaining to the relative attitude and Target structure. Finally, a method is proposed for rendering the relative motion filtering algorithm robust to uncertainties in the Target's inertia tensor. This is accomplished by endowing the IEKF with a maximum a posteriori identification scheme for determining the most probable inertia tensor from several available hypotheses. The performance of the new filtering algorithm is validated by Monte-Carlo simulations. Also a preliminary experimental evaluation is provided.

  • vision based relative state estimation of non cooperative spacecraft under modeling uncertainty
    IEEE Aerospace Conference, 2011
    Co-Authors: Shai Segal, Avishy Carmi, Pini Gurfil
    Abstract:

    Estimating the relative pose and motion of cooperative Satellites using on-board sensors is a challenging problem. When the Satellites are non-cooperative, the problem becomes far more complicated, as there might be poor or no a priori information about the motion or structure of the Target Satellite. In this work we develop robust algorithms for solving the said problem by assuming that only visual sensory information is available. Using two cameras mounted on a chaser Satellite, the relative state of a Target Satellite, including the position, attitude, and rotational and translational velocities is estimated. Our approach employs a stereoscopic vision system for tracking a set of feature points on the Target spacecraft. The perspective projection of these points on the two cameras constitutes the observation model of an EKF-based filtering scheme. In the final part of this work, the relative motion filtering algorithm is made robust to uncertainties in the inertia tensor. This is accomplished by endowing the plain EKF with a maximum a posteriori identification scheme for determining the most probable inertia tensor from several available hypotheses.

Shai Segal - One of the best experts on this subject based on the ideXlab platform.

  • stereovision based estimation of relative dynamics between noncooperative Satellites theory and experiments
    IEEE Transactions on Control Systems and Technology, 2014
    Co-Authors: Shai Segal, Avishy Carmi, Pini Gurfil
    Abstract:

    Estimating the relative pose and motion of cooperative Satellites using on-board sensors is a challenging problem. When the Satellites are noncooperative, the problem becomes even more complicated, as there might be poor a priori information about the motion and structure of the Target Satellite. In this paper, the mentioned problem is solved by using only visual sensors, which measurements are processed through robust filtering algorithms. Using two cameras mounted on a chaser Satellite, the relative state with respect to a Target Satellite, including the position, attitude, and rotational and translational velocities, is estimated. The new approach employs a stereoscopic vision system for tracking a set of feature points on the Target spacecraft. The perspective projection of these points on the two cameras constitutes the observation model of an iterated extended Kalman filter (IEKF) estimation scheme. Using new theoretical results, the information contained in the visual data is quantified using the Fisher information matrix. It is shown that, even in the noncooperative case, there is information that can be extracted pertaining to the relative attitude and Target structure. Finally, a method is proposed for rendering the relative motion filtering algorithm robust to uncertainties in the Target's inertia tensor. This is accomplished by endowing the IEKF with a maximum a posteriori identification scheme for determining the most probable inertia tensor from several available hypotheses. The performance of the new filtering algorithm is validated by Monte-Carlo simulations. Also a preliminary experimental evaluation is provided.

  • vision based relative state estimation of non cooperative spacecraft under modeling uncertainty
    IEEE Aerospace Conference, 2011
    Co-Authors: Shai Segal, Avishy Carmi, Pini Gurfil
    Abstract:

    Estimating the relative pose and motion of cooperative Satellites using on-board sensors is a challenging problem. When the Satellites are non-cooperative, the problem becomes far more complicated, as there might be poor or no a priori information about the motion or structure of the Target Satellite. In this work we develop robust algorithms for solving the said problem by assuming that only visual sensory information is available. Using two cameras mounted on a chaser Satellite, the relative state of a Target Satellite, including the position, attitude, and rotational and translational velocities is estimated. Our approach employs a stereoscopic vision system for tracking a set of feature points on the Target spacecraft. The perspective projection of these points on the two cameras constitutes the observation model of an EKF-based filtering scheme. In the final part of this work, the relative motion filtering algorithm is made robust to uncertainties in the inertia tensor. This is accomplished by endowing the plain EKF with a maximum a posteriori identification scheme for determining the most probable inertia tensor from several available hypotheses.

Sabatini Marco - One of the best experts on this subject based on the ideXlab platform.

  • Performance analysis and gains tuning procedure for a controlled space manipulator used for non-cooperative Target capture operations
    'AIDAA Associazione Italiana di Aeronautica e Astronautica', 2018
    Co-Authors: Stolfi Angelo, Gasbarri Paolo, Sabatini Marco
    Abstract:

    In the near future robotic systems will be playing an increasingly important role in space applications such as repairing, refuelling, re-orbiting spacecraft and cleaning up the increasing amount of space debris. Space Manipulator Systems (SMSs) are robotic systems made of a bus (which has its own actuators such as thrusters and reaction wheels) equipped with one or more deployable arms. The present paper focuses on the issue of maintaining a stable first contact between the arms terminal parts (i.e. the end-effectors) and a non-cooperative Target Satellite, before the actual grasp is performed. The selected approach is a modified version of the Impedance Control algorithm, in which the end-effector is controlled in order to make it behave like a mass-spring-damper system regardless of the reaction motion of the base, so to absorb the impact energy. A very important aspect in the analysis of the control performance is the evaluation of the field of applicability of the controller itself. In the present work the influence of this issue on the effectiveness of the proposed control architecture will be analysed, together with the control gains tuning which allows for a robust achievement of the mission requirements. Several numerical results will be presented and discussed

  • Parametric analysis of a controlled deployable space manipulator used for capturing a non-cooperative Satellite
    International Astronautical Federation IAF, 2017
    Co-Authors: Stolfi Angelo, Gasbarri Paolo, Sabatini Marco
    Abstract:

    In the near future robotic systems will be playing an increasingly important role in space applications such as repairing, refueling, re-orbiting spacecraft and cleaning up the increasing amount of space debris. Space Manipulator Systems (SMSs) are robotic systems made of a bus (which has its own actuators such as thrusters and reaction wheels) equipped with one or more deployable arms. The present paper focuses on the issue of maintaining a stable first contact between the arms terminal parts (i.e. the end-effectors) and a non-cooperative Target Satellite, before the actual grasp is performed. The selected approach is a modified version of the Impedance Control algorithm, in which the end-effector is controlled in order to make it behave like a mass-spring-damper system regardless of the reaction motion of the base, so to absorb the impact energy. The effects of non-modeled dynamics in control determination such as the structural flexibility of the manipulator and the Target Satellite are considered as well, and their impact on control effectiveness is analyzed. The performance of the proposed control architecture and a parametric analysis is studied by means of a co-simulation involving the MSC Adams multibody code (for describing the dynamics of the space robot and Target) together with Simulink (for the determination of the control actions). The results show that the first contact phase of the grasping operation of a large Satellite requires careful tuning of the control gains and a proper selection of the end-effector dimensions; otherwise, the large inertia characteristics of the Target could lead to a failure with serious consequences. Both successful and underperforming cases are presented and commented in the paper

Bin Liang - One of the best experts on this subject based on the ideXlab platform.

  • adaptive coordinated motion control with variable forgetting factor for a dual arm space robot in post capture of a noncooperative Target
    International Journal of Advanced Robotic Systems, 2019
    Co-Authors: Chunting Jiao, Jun Yang, Xueqian Wang, Bin Liang
    Abstract:

    To overcome the problem of dynamics coupling between a space robot and a Target Satellite, this study introduces a new coordinated motion control approach with an adaptive filtering algorithm for a...

  • vibration suppression of a large flexible spacecraft for on orbit operation
    Science in China Series F: Information Sciences, 2017
    Co-Authors: Bin Liang, Deshan Meng, Houde Liu
    Abstract:

    Flexible appendages, such as solar panels, communication antennas and other large structures, are mounted on the base of a space robot and Target Satellite. The vibration of the flexible structure is excited by operations of a space manipulator. It is very challenging to control the vibration of large flexible appendages for on-orbit operation and, especially when the manipulator operates a non-cooperative Target with unknown structural parameters and vibration information. In this study, a hybrid control method is proposed based on wave-based control and PD control methods to control the motion of a manipulator while suppressing the vibration of appendages. First, the rigid-flexible coupled dynamic model of a compounded system is established. This is followed by designing a hybrid control strategy combining wave-based control and PD control for rest-to-rest maneuvers based on the characteristics of the compounded system. Finally, the simulation of a 3D compounded system is provided to verify the effectiveness of the presented approach. The simulation results indicate that the space robot can successfully berth the Target while suppressing the vibrations of the structure.