Study Of The Influence Of Contact Model Parameters On A Berthing Operation

The MUSAPOEM project aims to develop models and architectures for multi-satellite rendezvous, docking and berthing missions in Earth and lunar orbit. The current mission architecture consists of a target satellite, a chaser satellite, a monitoring satellite and a communication satellite. The chaser maneuvers to approach the target to a separation of a few centimeters, then the target is cached by a robotic manipulator which performs a berthing and docking operation. The ultimate goal of the project is to develop a digital twin of the system, useful for the control during specific phases of the maneuver. Within different tasks of the project, this paper focuses on the contact mechanics behaviour between the robotic manipulator and the target. A detailed description of contact mechanic can be obtained by FEM and multibody models, which provides a high fidelity representation of the system but are not suitable for real time simulation. For this purpose lumped parameters model are necessary, suitable for real time simulation but representative of a specific phase of the berthing or docking operation. The project methodology involves developing a high-fidelity model and interpreting its results to define lumped parameters models representative of specific mission phases. This paper discusses the development of a multibody model of the free floating chaser and target satellites, built in Matlab/Simscape environment. In the model a robotic manipulator suitable for the berthing operation is introduced. The geometry of the end effector and the grasped element on the target are defined. A contact model, defined by parameters dependent by materials and the geometry of contacts elements, is introduced to describe contact during the berthing operations. The interaction between the end effector and the target influences the attitude of both satellites, with incorrect material and geometry choices risking the failure of the berthing operation. An analysis of model parameters' influence on the target and chaser satellite attitudes is conducted. Results allow to define a range of parameters which leads to a successful berthing. Results allow also to propose geometries and materials for the end effector and the target. Next steps regard the extrapolation of lumped parameters contact model from the high fidelity analysis.