Both interplanetary traveling crafts and stationary systems will be in need of servicing, such as assembly, maintenance, replacement of broken/expendable modules, refueling, inspection and repair. To relieve astronauts from dangerous extra-vehicular activities, enhance performance and extend the feasible tasks range, the international research community has been focusing on the realization of autonomous robotic servicing. While important tasks, such as orbital assembly and debris handling, require passive object handling capabilities, the actual handling of a secured passive object by a number of free-flying robotic servicers, has not been studied adequately, with several issues still open.On-orbit object handling has similarities to cooperative manipulation of passive objects on earth, with the additional complexities that in space no fixed ground to support the manipulators exists, thus letting momentum changes to play a key role in body motion, and that orbital system thrusters are of on-off control nature. In order to protect the thruster valves from the extreme space conditions, proportional or pulse-width-modulation (PWM) thrusters are not used in space, thus reducing system positioning capabilities, when only thrusters are used.The introduction of a number of manipulator-equipped free-flying servicers, where both on-off thruster propulsion and manipulator continuous forces/ torques are used for passive object handling, both for the case of firm grasp and in the more general case of point contact, between the servicer manipulator end-effectors and the passive object, is presented in this thesis.The design of a controller for the free-flying servicer manipulators that enables the stable handling of the passive object by the servicers, in trajectory tracking scenarios, as well as the design of a controller for the free-flying servicer bases that enables them to move within the workspace of their manipulators, under the influence of the reaction generalized forces from their manipulator bases, is also ...


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