Manipulator mounted on an unmanned satellite could be used for performing orbital capture maneuver in order to repair satellites or remove space debris from orbit. Use of manipulators for such purposes presents unique challenges, as high level of autonomy is required and the motion of the manipulator influences the position and orientation of the manipulator-equipped satellite. This paper presents a new control system that consists of two modules: trajectory planning module (based on trajectory optimization algorithm) and Model Predictive Controller. Both modules take into account the free-floating nature of the satellite-manipulator system. Proposed control system was tested in numerical simulations performed for a simplified planar case. In the first set of simulations Nonlinear Model Predictive Control (NMPC) was used to ensure realization of a square reference end-effector trajectory, while in the second set control system was used for optimizing and then ensuring realization of the trajectory that leads to grasping of the rotating target satellite. Simulations were performed with disturbances and with the assumed non-perfect knowledge of parameters of the satellite-manipulator system. Results obtained with NMPC are better than results obtained with the controller based on the Dynamic Jacobian inverse and with the Modified Simple Adaptive Control (MSAC).

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Keywords Free-floating manipulator, Nonlinear model predictive control (NMPC), Space robotics, Trajectory optimization
Persistent URL
Journal Journal of Intelligent and Robotic Systems: Theory and Applications
Rybus, T. (Tomasz), Seweryn, K. (Karol), & Sasiadek, J. (2017). Control System for Free-Floating Space Manipulator Based on Nonlinear Model Predictive Control (NMPC). Journal of Intelligent and Robotic Systems: Theory and Applications, 85(3-4), 491–509. doi:10.1007/s10846-016-0396-2