Distributed Space Systems Laboratory

Engineering, Israel

Distributed Space Systems Laboratory

Engineering, Israel
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Zhang H.,Technion - Israel Institute of Technology | Zhang H.,Distributed Space Systems Laboratory | Gurfil P.,Technion - Israel Institute of Technology | Gurfil P.,Distributed Space Systems Laboratory
Journal of Guidance, Control, and Dynamics | Year: 2014

One of the emerging topics in the realm of distributed space systems is cluster flight of nanosatellites. As opposed to formation flight, cluster flight does not dictate strict limits on the geometry of the cluster, and is hence more suitable for implementation in nanosatellites, which usually do not carry highly accurate sensors and actuators. The actuators are usually simple fixed-magnitude thrusters, which are prone to many sources of errors, such as attitude determination and control errors. In this context, the purpose of this paper is to develop a cluster-keeping control law that is capable of long-term operation under thrust uncertainties, assuming fixed-magnitude thrust provided by a simple cold-gas thruster. To that end, mean orbital elements are used for designing an inverse-dynamics controller. It is shown that, in the differential mean elements space, this controller is time-optimal. An adaptive enhancement is developed to mitigate the thrust pointing errors and restore the original optimal performance, thus saving much fuel. Several simulations and comparative studies are performed to validate the analytical results. Copyright © 2014 by the authors.


Mazal L.,Technion - Israel Institute of Technology | Mazal L.,Distributed Space Systems Laboratory | Mingotti G.,Technion - Israel Institute of Technology | Mingotti G.,Distributed Space Systems Laboratory | And 2 more authors.
Journal of Guidance, Control, and Dynamics | Year: 2014

When a group of satellites is equipped with a particularly simple propulsion system (e.g., cold-gas thrusters), constraints on the thrust level and total propellant mass renders cluster keeping extremely challenging. This is even more pronounced in disaggregated space architectures, in which a satellite is formed by clustering a number of heterogonous free-flying modules. The research described in this paper develops guidance laws aimed at keeping the relative distances between the cluster modules bounded for long mission lifetimes, typically more than a year, while using constant-magnitude low thrust, with a characteristic on-off profile. A cooperative guidance law capable of cluster establishment and maintenance under realistic environmental perturbationsis developed. The guidance law is optimized for fuel consumption, subject to relative distance constraints. Some of the solutions found to the optimal guidance problem require only a single maneuver arc to keep the cluster within relatively close distances for an entire year. Copyright © 2013 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc.


Ben-Yaacov O.,Technion - Israel Institute of Technology | Ben-Yaacov O.,Distributed Space Systems Laboratory | Gurfil P.,Technion - Israel Institute of Technology | Gurfil P.,Distributed Space Systems Laboratory
54th Israel Annual Conference on Aerospace Sciences 2014 | Year: 2014

Differential drag (DD) as a means for passive satellite cluster keeping is an old idea, but so far using DD-based cluster keeping while relying on mean orbital elements feedback has not been proposed. This paper develops a DD-based maximum distance keeping method that uses Brouwer-Lyddane differential mean elements feedback for long-term control of the secular drift among satellites. The stability of the maximum distance keeping controller is proven using finite-time stability theory, and high-precision simulation results confirm that the new controller is able to arrest satellite relative drift for mission lifetimes exceeding a year. The maximum distance controller is automatically activated, and does not require a pre-determined activation time.


Mazal L.,Technion - Israel Institute of Technology | Gurfil P.,Distributed Space Systems Laboratory
53rd Israel Annual Conference on Aerospace Sciences 2013 | Year: 2013

Space Autonomous Mission for Swarming and Geolocation with Nano-satellites (SAMSON) is a new satellite mission, led by the Distributed Space Systems Lab at the Technion - Israel Institute of Technology. SAMSON will include three nanosatellites, built based on the CubeSat standard. The mission is planned for at least one year, and has two main goals: (i) Demonstrate long-term autonomous cluster flight of multiple satellites, and (ii) Determine the position of a radiating electromagnetic terrestrial source based on time difference of arrival and/or frequency difference of arrival. In this paper, the cluster flight control strategy for SAMSON is discussed. This strategy performs cooperative maneuvers upon necessity, when any inter-satellite distance reaches either the upper or lower bound. The maneuvers are conceived to avoid that the secular component of the inter-satellite distances exceed the prescribed distance bounds. To compute the maneuvers, a logic scheme is first applied, which establishes constraints on the differential mean semimajor axes to provide desired post-maneuver behavior. Then, a Lyapunov based control law steers the mean semimajor axis, eccentricity and inclination, to hold the aforementioned constraints. The considered actuators are constant-thrust-magnitude thrusters. Simulations for 1 year are shown, validating the potential implementability of the proposed algorithm on-board the SAMSON satellites.


Ben-Yaacov O.,Technion - Israel Institute of Technology | Ben-Yaacov O.,Distributed Space Systems Laboratory | Gurfil P.,Technion - Israel Institute of Technology | Gurfil P.,Distributed Space Systems Laboratory
53rd Israel Annual Conference on Aerospace Sciences 2013 | Year: 2013

The idea to use differential drag (DD) for satellite formationkeeping emerged in the mid-Eighties, when the feasibility of DD-based control was proven assuming linearized relative dynamics for two satellites. Although almost three decades have passed, the most prevalent approach for investigating DD-based formationkeeping still utilizes linear models written for only a pair of satellites. However, such models are not adequate for long-term cluster flight of multiple satellites or multiple modules forming, e.g., a disaggregated satellite, with typical mission lifetimes exceeding a year. In the current work, an alternative, nonlinear method for DD-based cluster-keeping is developed. The method relies on orbital elements instead of Cartesian coordinates. The results are verified using simulations based on the forthcoming Space Autonomous Mission for Swarming and Geolocation with Nanosatellites.


Zimmerman F.G.,Technion - Israel Institute of Technology | Gurfil P.,Technion - Israel Institute of Technology | Gurfil P.,Distributed Space Systems Laboratory
Journal of Guidance, Control, and Dynamics | Year: 2015

One of the methods for maintaining a cluster of satellites in long-term bounded relative distances is keeping the satellites on near-circular orbits having the same mean semimajor axes and mean inclinations. This approach allows some freedom in determining the reference mean semimajor axis and reference mean inclination for the cluster. In this paper, this freedom is used to find the optimal target values of the mean semimajor axis and mean inclination, with the optimization criteria being either the total propellant consumption of the cluster or the fuel consumption differences among satellites. The optimization problems are solved analytically, assuming that a fixed-magnitude thruster is used for closed-loop orbit control, and new results are presented, providing simple closed-form expressions for the optimal target states. Simulations are used for validating the results, showing that much propellant can be saved by properly setting the cluster reference orbit. Copyright © 2014 by the authors.


Ben-Yaacov O.,Technion - Israel Institute of Technology | Ben-Yaacov O.,Distributed Space Systems Laboratory | Edlerman E.,Technion - Israel Institute of Technology | Edlerman E.,Distributed Space Systems Laboratory | And 2 more authors.
Advances in Space Research | Year: 2015

Calculating the projected cross-sectional area (PCSA) of a satellite along a given direction is essential for implementing attitude control modes such as Sun pointing or minimum-drag. The PCSA may also be required for estimating the forces and torques induced by atmospheric drag and solar radiation pressure. This paper develops a new analytical method for calculating the PCSA, the concomitant torques and the satellite exposed surface area, based on the theory of convex polygons. A scheme for approximating the outer surface of any satellite by polygons is developed. Then, a methodology for calculating the projections of the polygons along a given vector is employed. The methodology also accounts for overlaps among projections, and is capable of providing the true PCSA in a computationally-efficient manner. Using the Space Autonomous Mission for Swarming and Geo-locating Nanosatellites mechanical model, it is shown that the new analytical method yields accurate results, which are similar to results obtained from alternative numerical tools. © 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.


Martinusi V.,Distributed Space Systems Laboratory | Gurfil P.,Distributed Space Systems Laboratory
Celestial Mechanics and Dynamical Astronomy | Year: 2013

While solutions for bounded orbits about oblate spheroidal planets have been presented before, similar solutions for unbounded motion are scarce. This paper develops solutions for unbounded motion in the equatorial plane of an oblate spheroidal planet, while taking into account only the J2 harmonic in the gravitational potential. Two cases are distinguished: A pseudo-parabolic motion, obtained for zero total specific energy, and a pseudo-hyperbolic motion, characterized by positive total specific energy. The solutions to the equations of motion are expressed using elliptic integrals. The pseudo-parabolic motion unveils a new orbit, termed herein the fish orbit, which has not been observed thus far in the perturbed two-body problem. The pseudo-hyperbolic solutions show that significant differences exist between the Keplerian flyby and the flyby performed under the the J2 zonal harmonic. Numerical simulations are used to quantify these differences. © 2012 Springer Science+Business Media Dordrecht.


Martinusi V.,Distributed Space Systems Laboratory | Gurfil P.,Distributed Space Systems Laboratory
Advances in the Astronautical Sciences | Year: 2012

The paper develops the closed-form solution for the motion around an oblate planet in the situation when the orbit is unbounded. It is proven that when the effect of the J2 zonal harmonic is taken into account, the orbit is different from its Keplerian counterpart, having a marked influence on the deflection angle, thereby changing the Keplerian flyby geometry. Numerical simulations quantify this difference, which is closely related to the minimum flyby altitude of the spacecraft. The analytic developments can be applied to the preliminary design of gravity-assisted maneuvers.


Mazal L.,Technion - Israel Institute of Technology | Mazal L.,Distributed Space Systems Laboratory | Mingotti G.,Technion - Israel Institute of Technology | Mingotti G.,Distributed Space Systems Laboratory | And 2 more authors.
AIAA/AAS Astrodynamics Specialist Conference 2012 | Year: 2012

The basic idea behind disaggregated satellites is to distribute the functionality of a single monolithic satellite among multiple physically-separated inter-communicating modules. The research described in this paper develops optimal guidance laws aimed at keeping the relative distances between the modules bounded for extended mission lifetimes while using constant-magnitude chemical low-thrust. A cooperative guidance law capable of cluster establishment and maintenance under environmental perturbations is proposed. The optimal guidance law is constructed using a bang-off-bang thrust profile. The cost functional is the total fuel consumption, and the constraints are maximum and minimum distances, balanced fuel utilization - so as to minimize differential drag - and stationkeeping about a nominal reference orbit. © 2012 by The Authors.

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