The Experts below are selected from a list of 4722 Experts worldwide ranked by ideXlab platform

John V. Breakwell - One of the best experts on this subject based on the ideXlab platform.

Oded M. Golan - One of the best experts on this subject based on the ideXlab platform.

Yongxuan Huang - One of the best experts on this subject based on the ideXlab platform.

  • tracking and positioning maneuvering target with low Thrust Acceleration
    Fuzzy Systems and Knowledge Discovery, 2009
    Co-Authors: Yongxuan Huang
    Abstract:

    The uncertainty of Thrust Acceleration will cause enormous error to model and track the accelerated motion of maneuvered target during orbit transfer process. An on-line minimum-variance estimator was developed for Thrust Acceleration applied to orbit transfer using discrete-time radar measurements. The mass-flow-rate of propellant was selected as a state variant, which was estimated by employing an integral state model and Extended Kalman filter. The variation equations for the measurement vector to mass-flow rate have been established to linearize the discrete-time measurement equations. The algorithm has applied successfully to maneuver process in commanding satellite into Geo-stationary orbit and lunar insertion orbit. The results show the algorithm developed here can monitor and determine whether engine works well or failure precisely and quickly during orbit transfer process.

  • minimum variance estimation of Thrust Acceleration during orbit transfer process
    20th AIAA International Communication Satellite Systems Conference and Exhibit, 2002
    Co-Authors: Yongxuan Huang
    Abstract:

    A minimum-variance estimation is developed for Thrust Acceleration applied to orbit transfer using discrete-time Radar measurements. An integral state model is used for the unknown Mass-Flow-Rate during transfer process. An extended Kalman Filter(EKF) is developed for the forward estimate in real time. And variation equations about the motion states to Mass-Flow-Rate are developed in the Earth Centered Inertial (ECI) coordinate frame. The method was used on many Geosatationary satellite transfer process successfully. The results show the method developed here can detect and determinate whether engines applied for orbit transfer work well or failure precisely and quickly.

Livia Ionescu - One of the best experts on this subject based on the ideXlab platform.

  • analytical solution for low Thrust transfer orbits using bang bang control without gravity losses
    2019
    Co-Authors: Livia Ionescu
    Abstract:

    This thesis research has focused on developing an analytical solution for low-Thrust transfer orbits. Low-Thrust propulsion is an attractive option for space manoeuvres and transfers, since it provides a large specific impulse and hence efficient use of propellant. Thus, the propellant mass can be decreased, which brings advantages such as higher payload mass and extended mission life. Two constraints have been posed on the Thrust Acceleration, which often appear as a result of optimal solutions. Firstly, only bang-bang control is allowed, thus the rocket engine can only be turned on or off. Secondly, no radial Thrust is allowed, such that no gravity losses occur. The modified equinoctial elements have been chosen to describe the trajectory. If it is assumed that the eccentricity is equal to zero, analytical solutions have been derived. While this seems as a substantial restriction on the developed method, it is shown that the analytical solution provides very reasonable results for eccentricities smaller than 0.2. Furthermore, separate analytical expressions have been developed when no in-plane Thrust acts on the spacecraft. For the implementation of the bang-bang control, each individual revolution around the central body is allowed to have two Thrust arcs and two coasts arcs, where the analytical solutions have been used to describe the motion of the spacecraft during the Thrust arcs. By cleverly choosing the switching points where the rocket engine is turned on and off, the transfer orbit is achieved in an efficient way. The performance of the developed algorithm has been assessed for different input parameters. More specifically, different magnitudes of Thrust Accelerations have been analyzed. Furthermore, the lengths of the Thrust and coast arcs, together with the direction of the Thrust force, have been varied to evaluate the applicability of the algorithm. Lastly, the algorithm has been tested with the introduction of a stop criterion, which determines the required propellant and time of flight to arrive at a set target element. The algorithm has proved to give results with relatively good accuracy for orbits with an eccentricity smaller than 0.2. However, if the time of flight or the Thrust Acceleration become too high, less feasible solutions are perceived.

Ionescu Livia - One of the best experts on this subject based on the ideXlab platform.

  • Analytical Solution for Low-Thrust Transfer Orbits using Bang-Bang Control without Gravity Losses
    2019
    Co-Authors: Ionescu Livia
    Abstract:

    This thesis research has focused on developing an analytical solution for low-Thrust transfer orbits. Low-Thrust propulsion is an attractive option for space manoeuvres and transfers, since it provides a large specific impulse and hence efficient use of propellant. Thus, the propellant mass can be decreased, which brings advantages such as higher payload mass and extended mission life.Two constraints have been posed on the Thrust Acceleration, which often appear as a result of optimal solutions. Firstly, only bang-bang control is allowed, thus the rocket engine can only be turned on or off. Secondly, no radial Thrust is allowed, such that no gravity losses occur. The modified equinoctial elements have been chosen to describe the trajectory. If it is assumed that the eccentricity is equal to zero, analytical solutions have been derived. While this seems as a substantial restriction on the developed method, it is shown that the analytical solution provides very reasonable results for eccentricities smaller than 0.2. Furthermore, separate analytical expressions have been developed when no in-plane Thrust acts on the spacecraft. For the implementation of the bang-bang control, each individual revolution around the central body is allowed to have two Thrust arcs and two coasts arcs, where the analytical solutions have been used to describe the motion of the spacecraft during the Thrust arcs. By cleverly choosing the switching points where the rocket engine is turned on and off, the transfer orbit is achieved in an efficient way. The performance of the developed algorithm has been assessed for different input parameters. More specifically, different magnitudes of Thrust Accelerations have been analyzed. Furthermore, the lengths of the Thrust and coast arcs, together with the direction of the Thrust force, have been varied to evaluate the applicability of the algorithm. Lastly, the algorithm has been tested with the introduction of a stop criterion, which determines the required propellant and time of flight to arrive at a set target element. The algorithm has proved to give results with relatively good accuracy for orbits with an eccentricity smaller than 0.2. However, if the time of flight or the Thrust Acceleration become too high, less feasible solutions are perceived.Aerospace Engineerin