The Experts below are selected from a list of 4692 Experts worldwide ranked by ideXlab platform
Hao Zhang - One of the best experts on this subject based on the ideXlab platform.
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density based pattern control for spacecraft swarms around Circular Orbits
Chinese Control Conference, 2019Co-Authors: Chihang Yang, Hao ZhangAbstract:Multi-agent system is promising in space applications, because of its high flexibility and robustness. This work considers controlling a large-scale spacecraft swarm to generate a specified spatial pattern. Due to the fact that a swarm has hundreds of spacecraft, traditional control techniques are incapable of achieving an effective performance. The density-based feedback control via velocity fields has been used to tackle the control difficulties with a large number of spacecraft. This method has two parts, namely, local density estimation and velocity field design. To achieve collision avoidance during spacecraft maneuvering, the classical density estimation is augmented by a repulsive term. The Q-guidance scheme is used to track the desired velocity and to compute the control acceleration for each spacecraft. In addition, the desired density is also addressed in this paper to obtain a wide convergence region. The new desired density construction method guarantees that each agent can reach the target area and it also supports injections of distant new agents. To apply the density-based feedback control to Circular Earth Orbit, the periodic solution of Clohessy-Wiltshire (CW) equation is transformed into a new coordinate system that permits a nullified steady state velocity. Numerical simulations demonstrate the validity of the methodology.
Chihang Yang - One of the best experts on this subject based on the ideXlab platform.
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density based pattern control for spacecraft swarms around Circular Orbits
Chinese Control Conference, 2019Co-Authors: Chihang Yang, Hao ZhangAbstract:Multi-agent system is promising in space applications, because of its high flexibility and robustness. This work considers controlling a large-scale spacecraft swarm to generate a specified spatial pattern. Due to the fact that a swarm has hundreds of spacecraft, traditional control techniques are incapable of achieving an effective performance. The density-based feedback control via velocity fields has been used to tackle the control difficulties with a large number of spacecraft. This method has two parts, namely, local density estimation and velocity field design. To achieve collision avoidance during spacecraft maneuvering, the classical density estimation is augmented by a repulsive term. The Q-guidance scheme is used to track the desired velocity and to compute the control acceleration for each spacecraft. In addition, the desired density is also addressed in this paper to obtain a wide convergence region. The new desired density construction method guarantees that each agent can reach the target area and it also supports injections of distant new agents. To apply the density-based feedback control to Circular Earth Orbit, the periodic solution of Clohessy-Wiltshire (CW) equation is transformed into a new coordinate system that permits a nullified steady state velocity. Numerical simulations demonstrate the validity of the methodology.
R Jedicke - One of the best experts on this subject based on the ideXlab platform.
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development of a realistic set of synthetic Earth impactor Orbits
IEEE Aerospace Conference, 2019Co-Authors: Steven R Chesley, G B Valsecchi, Siegfried Eggl, Mikael Granvik, D Farnocchia, R JedickeAbstract:We present a refined method for creating Orbits of fictitious Earth impactors that are representative of the actual impactor population. Such Orbits are crucial inputs to a variety of investigations, such as those that seek to discern how well and how early a particular asteroid survey can detect impactors, or to understand the progression of impact probability as an object is tracked after discovery. We will describe our method, which relies on Opik's b-plane formalism, and place it in context with previous approaches. While the Oplk framework assumes the restricted three body problem with a Circular Earth Orbit, our final synthetic impactors are differentially corrected to ensure an impact in the N-body dynamics of the solar system. We also test the validity of the approach through brute force numerical tests, demonstrating that the properties of our synthetic impactor population are consistent with the underlying Near-Earth Object (NEO) population from which it is derived. The impactor population is, however, distinct from the NEO population, not only by virtue of the proximity of the asteroid Orbit to that of the Earth, but also because low encounter velocities are strongly favored. Thus the impacting population has an increased prominence of low inclination and low eccentricity Orbits, and Earth-like Orbits in particular, as compared to the NEO population as a whole.
Steven R Chesley - One of the best experts on this subject based on the ideXlab platform.
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development of a realistic set of synthetic Earth impactor Orbits
IEEE Aerospace Conference, 2019Co-Authors: Steven R Chesley, G B Valsecchi, Siegfried Eggl, Mikael Granvik, D Farnocchia, R JedickeAbstract:We present a refined method for creating Orbits of fictitious Earth impactors that are representative of the actual impactor population. Such Orbits are crucial inputs to a variety of investigations, such as those that seek to discern how well and how early a particular asteroid survey can detect impactors, or to understand the progression of impact probability as an object is tracked after discovery. We will describe our method, which relies on Opik's b-plane formalism, and place it in context with previous approaches. While the Oplk framework assumes the restricted three body problem with a Circular Earth Orbit, our final synthetic impactors are differentially corrected to ensure an impact in the N-body dynamics of the solar system. We also test the validity of the approach through brute force numerical tests, demonstrating that the properties of our synthetic impactor population are consistent with the underlying Near-Earth Object (NEO) population from which it is derived. The impactor population is, however, distinct from the NEO population, not only by virtue of the proximity of the asteroid Orbit to that of the Earth, but also because low encounter velocities are strongly favored. Thus the impacting population has an increased prominence of low inclination and low eccentricity Orbits, and Earth-like Orbits in particular, as compared to the NEO population as a whole.
G B Valsecchi - One of the best experts on this subject based on the ideXlab platform.
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development of a realistic set of synthetic Earth impactor Orbits
IEEE Aerospace Conference, 2019Co-Authors: Steven R Chesley, G B Valsecchi, Siegfried Eggl, Mikael Granvik, D Farnocchia, R JedickeAbstract:We present a refined method for creating Orbits of fictitious Earth impactors that are representative of the actual impactor population. Such Orbits are crucial inputs to a variety of investigations, such as those that seek to discern how well and how early a particular asteroid survey can detect impactors, or to understand the progression of impact probability as an object is tracked after discovery. We will describe our method, which relies on Opik's b-plane formalism, and place it in context with previous approaches. While the Oplk framework assumes the restricted three body problem with a Circular Earth Orbit, our final synthetic impactors are differentially corrected to ensure an impact in the N-body dynamics of the solar system. We also test the validity of the approach through brute force numerical tests, demonstrating that the properties of our synthetic impactor population are consistent with the underlying Near-Earth Object (NEO) population from which it is derived. The impactor population is, however, distinct from the NEO population, not only by virtue of the proximity of the asteroid Orbit to that of the Earth, but also because low encounter velocities are strongly favored. Thus the impacting population has an increased prominence of low inclination and low eccentricity Orbits, and Earth-like Orbits in particular, as compared to the NEO population as a whole.