A parametric analysis of a controlled deployable space manipulator for capturing a non-cooperative flexible satellite

• Published in: Acta astronautica 2018-07, Vol.148, p.317-326
• Main Authors: Stolfi, A., Gasbarri, P., Sabatini, M.
• Format: Article
• Language: English
• Subjects: Architecture; Computer simulation; Control algorithms; Control theory; Grasping (robotics); Impedance control; Maintenance; Manipulation; Manipulators; Mass-spring-damper systems; On-orbit servicing; Parametric analysis; Parametric statistics; Reaction wheels; Robot arms; Robotics; Satellites; Space applications; Space debris; Space debris active removal; Space Manipulator Systems; Space robots; Spacecraft; Spacecraft recovery; Structural dynamics; Thrusters
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2018.04.028

In the near future robotic systems will be playing an increasingly important role in space applications such as repairing, refueling, re-orbiting spacecraft and cleaning up the increasing amount of space debris. Space Manipulator Systems (SMSs) are robotic systems made of a bus (which has its own actuators such as thrusters and reaction wheels) equipped with one or more deployable arms. The present paper focuses on the issue of maintaining a stable first contact between the arms terminal parts (i.e. the end-effectors) and a non-cooperative target satellite, before the actual grasp is performed. The selected approach is a modified version of the Impedance Control algorithm in which the end-effector is controlled in order to make it behave like a mass-spring-damper system regardless of the reaction motion of the base, so to absorb the impact energy. The effects of non-modeled dynamics in control determination such as the structural flexibility of the manipulator and the target satellite are considered as well, and their impact on control effectiveness is analyzed. The performance of the proposed control architecture and a parametric analysis are studied by means of a co-simulation involving the MSC Adams multibody code (for describing the dynamics of the space robot and target) together with Simulink (for the determination of the control actions). The results show that the first contact phase of the grasping operation of a large satellite requires careful tuning of the control gains and a proper selection of the end-effector dimensions; otherwise, the large geometric and inertia characteristics of the target could lead to a failure with serious consequences. Both successful and underperforming cases are presented and commented in the paper. •Debris removal is a serious problem that must be faced in near future.•Robotic arms are one of the most promising options for orbital servicing.•A standard impedance control is modified to include the base control.•Robustness of the controller is verified by means of a parametric analysis.•Flexibility effects on the performances of the proposed control have been analyzed.