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

Rybus Tomasz, Aleksiejuk Konrad, Basmadji Fatina Liliana, Sikorski Adam

Artificial Satellites : Journal of Planetary Geodesy

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2023

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

Dyba Filip, Rybus Tomasz, Wojtunik Mateusz, Basmadji Fatina Liliana

Artificial Satellites : Journal of Planetary Geodesy

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2023

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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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Application of predictive control for manipulator mounted on a satellite

Rybus T., Seweryn K., Sąsiadek J. Z.

Archives of Control Sciences

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2018

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Vol. 28, No. 1

105--118

EN

Specific conditions of on-orbit environment are taken into account in the design of all devices intended to be used in space. Despite this fact malfunctions of satellites occur and sometimes lead to shortening of the satellite operational lifetime. It is considered to use unmanned servicing satellite, that could perform repairs of other satellites. Such satellites equipped with a manipulator, could be used to capture and remove from orbit large space debris. The critical part of planned missions is the capture manoeuvre. In this paper a concept of the control system for the manipulator mounted on the satellite is presented. This control system is composed of the trajectory planning module and model predictive controller (the latter is responsible for ensuring precise realization of the planned trajectory). Numerical simulations performed for the simplified planar case with a 2 DoF manipulator show that the results obtained with the predictive control are better than the results obtained with adaptive control method.