Wyniki wyszukiwania - Biblioteka Nauki

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Active 6 DoF force/torque control based on Dynamic Jacobian for free-floating space manipulator

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Dyba F. , Rybus T. , Wojtunik M. , Basmadji F. L.

Artificial Satellites : Journal of Planetary Geodesy

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2023

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tom Vol. 58, Special Issue 1

214--229

EN

In-orbit capture of a non-cooperative satellite will be a major challenge in the proposed servicing and active debris removal missions. The contact forces between the manipulator end-effector and the elements of the target object will occur in the grasping phase. In this paper, an active 6 Degrees of Freedom (DoF) force/torque control method for manipulator mounted on a free-floating servicing satellite is proposed. The main aim of the presented method is to balance the relation between end-effector position and force along each direction in the Cartesian space. The control law is based on the Dynamic Jacobian, which takes into account the influence of the manipulator motion on the state of the servicing satellite. The proposed approach is validated in numerical simulations with a simplified model of contact. Comparison with the classical Cartesian control shows that the active 6 DoF force/torque control method allows to obtain better positioning accuracy of the end-effector and lower control torques in manipulator joints in the presence of external forces.

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Identyfikacja parametrów elastycznego przegubu manipulatora kosmicznego

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Wojtunik M. , Basmadji F. L. , Granosik G. , Seweryn K.

Prace Naukowe Politechniki Warszawskiej. Elektronika

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2022

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tom z. 197, t. 1

157-168

PL

Wykorzystanie manipulatora umieszczonego na satelicie jest jedną z metod rozpatrywanych w kontekście przeprowadzenia misji usuwania kosmicznych śmieci. Układy sterowania manipulatorami kosmicznymi muszą wykorzystywać model dynamiki ze względu na wpływ ruchu manipulatora na pozycję i orientację satelity serwisowego. Istotne jest więc projektowanie precyzyjnych modeli matematycznych pozwalających na odzwierciedlenie rzeczywistego układu. W tym celu konieczna jest identyfikacja parametrów modelu. W pracy przedstawiona została identyfikacja parametrów elastycznego przegubu manipulatora kosmicznego w oparciu o model dynamiki. Testy wykonano w emulowanych warunkach mikrograwitacji. Wykorzystanie modelu uwzględniającego elastyczność w przegubie pozwoliło na poprawę zgodności pomiędzy symulacją a przebiegami testowymi. Zidentyfikowane parametry osiągają wartości zgodne z rzeczywistymi.

EN

It is considered to use a manipulator mounted on a satellite in order to perform active debris removal missions. Space manipulator control systems need to take dynamic model into account because of the influence of the manipulator motion on the position and attitude of the satellite. Therefore, precise modelling of the system’s dynamics as well as parameter identification are needed in order to reflect the real systems behaviour better. In this paper we presented the identification of the flexible-joint space manipulator model based on dynamic equations of motion. Experiments were performed in emulated microgravity environment using planar air bearings. Including joint flexibility in the dynamic model allowed to reflect the experimental measurements better than the reference model. Identified parameters of the flexible joint have values corresponding to real system parameters.

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Application of the obstacle vector field method for trajectory planning of a planar manipulator in simulated microgravity

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Rybus T. , Aleksiejuk K. , Basmadji F. L. , Sikorski A.

Artificial Satellites : Journal of Planetary Geodesy

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2023

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tom Vol. 58, Special Issue 1

171--187

EN

Capture and removal of large space debris is needed to prevent the growth of the debris population in low Earth orbit. Capture of a non-cooperative object by a manipulator mounted on a chaser satellite requires collision-free trajectory of the manipulator. The obstacle vector field (OVF) method allows to solve the trajectory planning problem in difficult scenarios. The OVF method is based on a vector field that surrounds the obstacles and generates virtual forces that drive the manipulator around the obstacles. The original formulation of the OVF method allows to obtain the desired position of the gripper, but not the desired orientation. To perform the grasping manoeuvre, the gripper has to be positioned in a specific point and aligned with the grasping interface. In this paper, we propose a modification to the OVF method that allows to obtain the desired position and orientation of the gripper. Moreover, we investigate the practical applicability of the OVF method. The OVF method is demonstrated in experiments performed on a planar air-bearing microgravity simulator. The presented results prove that the OVF method can be applied for a real system operating in simulated microgravity conditions.

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Parameter identification of space manipulator’s flexible joint

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Wojtunik M. , Basmadji F. L. , Granosik G. , Seweryn K.

Journal of Automation Mobile Robotics and Intelligent Systems

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2023

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tom Vol. 17, No. 3

78--87

EN

A manipulator mounted on a satellite is often used to perform active debris removal missions. The space manipulator control system needs to take the dynamic model of the satellite‐manipulator system into account because of the influence of the manipulator motion on the position and attitude of the satellite. Therefore, precise modeling of the space manipulator dynamics as well as parameter identification are needed to improve the credibility of the simulation tools. In this paper, we presented the identification of the flexible‐joint space manipulator model based on dynamic equations of motion. Experiments were performed in an emulated microgravity environment using planar air bearings. The arbitrarily selected joint‐space trajectory was performed by the manipulator’s control system. The experiments were repeated multiple times in order to analyze the identification method sensitivity. The identification is based on the Simulink SimMechanics model. Thus, the procedure can be used for any space manipulator without the need to obtain analytical relations for dynamic equations each time. Including joint flexibility and spring viscous damping in the dynamic model allowed it to reflect the experimental measurements better than the reference model could. Identified parameters of the flexible joint have values of the same magnitude as corresponding real system parameters.