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  • 1.
    Alepuz, Javier Pérez
    et al.
    University of Alicante.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Pomares, Jorge
    University of Alicante.
    Direct image-based visual servoing of free-floating space manipulators2016In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 55, p. 1-9Article in journal (Refereed)
    Abstract [en]

    This paper presents an image-based controller to perform the guidance of a free-floating robot manipulator. The manipulator has an eye-in-hand camera system, and is attached to a base satellite. The base is completely free and floating in space with no attitude control, and thus, freely reacting to the movements of the robot manipulator attached to it. The proposed image-based approach uses the system's kinematics and dynamics model, not only to achieve a desired location with respect to an observed object in space, but also to follow a desired trajectory with respect to the object. To do this, the paper presents an optimal control approach to guiding the free-floating satellite-mounted robot, using visual information and considering the optimization of the motor commands with respect to a specified metric along with chaos compensation. The proposed controller is applied to the visual control of a four-degree-of-freedom robot manipulator in different scenarios.

  • 2.
    Felicetti, Leonard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Emami, Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Institute for Aerospace Studies, University of Toronto, Canada.
    Image-based attitude maneuvers for space debris tracking2018In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 76, p. 58-71Article in journal (Refereed)
    Abstract [en]

    This paper proposes an image-based control scheme for tracking space debris using onboard optical sensors. The proposed strategy uses an onboard camera for detecting space debris. The camera is rigidly attached to the satellite; therefore specific attitude maneuvers need to be performed during different phases of the mission. First, the spacecraft orients its attitude to point the camera toward a fixed direction in space, and then when debris traces streak across the field of view of the camera, the spacecraft follows and tracks the motion of the debris. Finally, a disengagement maneuver is executed to stop the spacecraft rotation when the debris disappears from the camera field of view. The model and the developed control scheme take into account the typical characteristics of space-qualified cameras, and a Kalman filter is developed to reduce the effects of the camera noise, detect and predict the path of the debris in the image plane, and estimate the angular velocity of the spacecraft. The entire estimation/control scheme is then validated through numerical simulations, using a model of reaction wheels as the main attitude actuation system. The results demonstrate the viability of such maneuvers in a typical space debris surveillance mission scenario.

  • 3.
    Felicetti, Leonard
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Palmerini, Giovanni B.
    Sapienza Università di Roma, Dipartimento di Ingegneria Astronautica Elettrica Ed Energetica (DIAEE).
    Three spacecraft formation control by means of electrostatic forces2016In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 48, p. 261-271Article in journal (Refereed)
    Abstract [en]

    This paper focuses on electrostatic orbital control in formation flying by using switching strategies for charge distribution. Natural and artificial charging effects are taken into account, and limits in charging technology and in power requirements are also considered. The case of three spacecraft formation, which is intrinsically different and more difficult than the two spacecraft problem often analyzed in literature, has been investigated. A Lyapunov based global control strategy is presented and applied to perform formation acquisition and maintenance maneuvers, producing as output the required overall charge. Then, a selective and optimized charge distribution process among the satellites is discussed for avoiding charge breakdowns to surrounding plasma, for reducing the power requirements and the number of charge switches. The results of numerical simulations show the advantages and drawbacks of the selected control technique

  • 4.
    Felicetti, Leonard
    et al.
    University of Rome la Sapienza.
    Santoni, Fabio
    Università di Roma la Sapienza, Dipartimento di Ingegneria Astronautica Elettrica Ed Energetica (DIAEE).
    Nanosatellite swarm missions in low Earth orbit using laser propulsion2013In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 27, no 1, p. 179-187Article in journal (Refereed)
    Abstract [en]

    Many missions could benefit from the exploitation of very low height orbits, including Earth observation, atmospheric measurement and space weather research missions. However satellite's lifetime decreases very quickly when the mission requires to orbit into the dense layers of the atmosphere. The mission performance could be enhanced using innovative propulsion techniques, counteracting the effect of atmospheric drag. Among these, laser propulsion potentially offers great weight and power savings, obtained by separating the propulsion system energy source from the propelled satellite. The energy source for the propulsion system is a pulsed laser beam generated remotely, while only collecting mirrors and ablative material are necessary on the target spacecraft. A mission architecture for very low altitude nanosatellite swarms using a space-based pulsed laser propulsion is described. A simplified laser-sustained re-orbiting maneuver sequence is proposed, leading to a straightforward evaluation of the maneuver times, showing that the laser propulsion system is suitable for low altitude nanosatellite missions

  • 5.
    Hakima, Houman
    et al.
    Institute for Aerospace Studies, University of Toronto, Toronto, Ontario, Canada.
    Emami, M. Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Concurrent attitude and orbit control for deorbiter CubeSat2020In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 97, article id 105616Article in journal (Refereed)
    Abstract [en]

    This paper details a concurrent attitude and orbit control method for a debris-removing nanosatellite, called deobriter CubeSat, during the rendezvous and synchronization maneuver with an uncontrollable tumbling debris object. The CubeSat is designed based on the utilization of an eight-unit form factor and commercially-available components with substantial space heritage, and is intended for the removal of sizable debris objects in low-Earth orbit. In particular, a low-thrust propulsion system is used for orbit control, as well as three reaction wheels allowing for a three-axis attitude control. Since the thruster can only produce force in one direction in the body frame, the spacecraft is considered to be underactuated. The controller employs the reaction wheels and the thruster to simultaneously rendezvous and synchronize the attitude of the CubeSat with the tumbling debris object, allowing for a concurrent attitude and position tracking. Detailed derivation of the concurrent controller is discussed, the effects of high-order derivatives are analyzed, and the stability of the system is proved. Simulation scenarios are created for two different thruster operation modes, namely, unsaturated thrust force and continuously-saturated thrust force, in order to verify the performance of the controller, as well as its robustness against gravity gradient disturbance torque and gravitational perturbation force.

  • 6.
    Pisculli, Andrea
    et al.
    University of Rome la Sapienza, Dipartimento di Ingegneria Meccanica e Aeronautica (DIMA), University of Rome la Sapienza.
    Felicetti, Leonard
    Dipartimento di Ingegneria Astronautica Elettrica Ed Energetica (DIAEE).
    Gasbarri, Paolo
    University of Rome la Sapienza, Dipartimento di Ingegneria Meccanica e Aeronautica (DIMA), University of Rome la Sapienza.
    Palmerini, Giovanni B.
    Sapienza Università di Roma, Dipartimento di Ingegneria Astronautica Elettrica Ed Energetica (DIAEE).
    Sabatini, Marco
    University of Rome la Sapienza, Dipartimento di Ingegneria Astronautica Elettrica Ed Energetica (DIAEE).
    A reaction-null/Jacobian transpose control strategy with gravity gradient compensation for on-orbit space manipulators2014In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 36, p. 30-40Article in journal (Refereed)
    Abstract [en]

    The dynamics and the control of space manipulators floating in 3D space is analyzed in this paper. A minimum state variable approach for describing the dynamics of a free-floating space manipulator under gravity and gravity gradient forces is presented. A new control strategy involving a combination of Reaction Null and Jacobian Transpose controllers, including also the gravity gradient compensation, is suggested and compared with the Jacobian Transpose control and the conventional Proportional Derivative control. Several numerical examples will be presented and discussed, considering platforms with single and double manipulators, showing the advantages and drawbacks related to these control strategies.

  • 7.
    Zong, Lijun
    et al.
    National Key Laboratory of Aerospace Flight Dynamics, Northwestern Polytechnical University, 710072 Xi'an, People's Republic of China. Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ontario M3H 5T6, Canada.
    Emami, M. Reza
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Institute for Aerospace Studies, University of Toronto, 4925 Dufferin Street, Toronto, Ontario M3H 5T6, Canada.
    Concurrent base-arm control of space manipulators with optimal rendezvous trajectory2020In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 100, article id 105822Article in journal (Refereed)
    Abstract [en]

    This paper proposes a control method for space manipulators, involving concurrent operation of an optimal and a coordinated controller. The optimal controller moves center of mass of the base spacecraft to a desired position along an optimal rendezvous trajectory for minimizing the energy. The optimal control problem is solved through Calculus of Variations, using saturation functions to represent the physical limitations in thrust forces. The coordinated controller drives the arm end-effector to a desired pose (for rendezvousing with the target), as well as making the base attitude follow a desired profile. It also generates augmented reactive moments on the base spacecraft to ensure controlling its attitude when the base actuators reach their limits. Simulations of a realistic space manipulator model demonstrate the performance of the proposed concurrent control method.

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