Adaptive SMC of a Space Vehicle with a Robotic Manipulator for Proximity Operations

The importance of space flight and satellite activities in the modern economy is significantly increasing, they are not used exclusively by government as it was in the past, but by privates too. The space economy is growing larger and as a consequence the space activities are becoming more affordable. The growing complexity and ambition of the space projects is driving the space industry to detach from the traditional method of launching a fully integrated system on a single launch vehicle. In the future, the majority of the systems could be built and repaired in space. On-orbit Servicing, Assembly and Manifacturing (OSAM) offers a solution that can remarkably increase the performance, resilience and lifetime of space systems compared to the traditional method. By encouraging the application of OSAM into the missions, the basic space operations concept could be changed, establishing a new path to a sustainable functioning. The key aspect of this concept is the need to perform space activities like satellite refuelling, on-orbit inspection, orbit transfer, end-of-life servicing and debris removal on a recurrent basis using safe, resilient and adaptive space vehicles. The use of Robotic Manipulators in space flight is crucial to obtain this goal and robust and advanced control and navigation technology needs to be developed thinking about this type of scenarios. The goal of this work is to model and study a Robotic Manipulator mounted on an orbiting Spacecraft, accounting for all the coupling effects that derives from the two bodies moving independently but being attached one to another. The Relative Dynamics is implemented with the prospective of applying the formulation to a maneuver withing two satellites thinking about proximity operations. The spacecraft is to be actuated by Thrusters and a set of four Variable Speed Control Moment Gyros (VSCMG). The four VSCMGs are going to account for an optimal usage of the two different actuation possibilities (as Classical Control Moment Gyros or Reaction Wheels) and for the avoidance of singularities (Gymbal Lock). The Attitude Control and the Manipulator Control are to be actuated by a Super Twisting Adaptive Sliding Mode Control. The Position Control is to be actuated by a first order Sliding Mode control embedded with an Artificial Potential Field Algorithm.