FREE-FLYING 3D SPACE ROBOT PROTOTYPE DESIGN AND ZERO-G EXPERIMENTS ON ESA PARABOLIC FLIGHTS

摘要

Space robotics has an important role in modem space missions. In particular free-flying robots are going to be extensively employed for Extra Vehicular Activities and in Space Servicing missions. The reproduction of the space microgravity environment for the effective on-ground testing of a 3D free-flying robot is a real challenge. A lot of works can be found in literature about testing 2D free-flying robots by means of air cushions to make them floating, robotic suspension systems and underwater tests. This project is aimed at designing a 3D free-flying robot prototype with weight and overall dimensions constraints in order to test it in the microgravity environment created by means of ESA parabolic flights. A robust control has been implemented, which has been designed in order to reduce up to one order of magnitude the reaction motion of the base during a 3D end-effector movement. This implies fuel savings for thrusters, or any other stabilizing device of the base attitude, and therefore a longer operational life. The robot prototype has been specially designed with a high dynamic coupling between the arm and the base to amplify the effect of the arm movement on the base motion. An innovative mechanical solution with axial-symmetric links is introduced to limit the modelling error introduced using a robust control.