Equivalent Capture Strategy for a Space Netting Interface

During space capture process, because of the joints flexibility and the distortion of long tubular booms, high precision tracking and positioning performance of large space manipulator can hardly be achieved. As a result, it is difficult to realize successful capture. To solve this problem, a typical kind of netting interface fit for space capture application is introduced to improve the capture ability of the end effecter. Moreover, an equivalent capture strategy is put forward to avoid the complicate modeling problem of the unknown correcting force that acts on the grapple of the target during capture process. The proposed strategy makes the complicate capture problem to be a simple position tracking problem, thus capture can be achieved even a relative velocity exit between the end effecter and the target. Experiments show that the proposed strategy can improve the autonomous capture ability of the large end effecter.

The Design and Comparison Study on the Large-Scale End-Effector of Large Space Manipulator

The space manipulator which is mounted on a space structure or spacecraft to manipulate space payloads is important for the on-orbit-servicing. Its manipulation tasks depend on its end-effector. The flexibility of the large space manipulator will result in residual vibration on its tip, and let the manipulator have poor capability of end positioning. To overcome the drawbacks mentioned-above, the end-effector needs strong capability of misalignment tolerance and soft capturing. On the base of these requirements and analysis, two kinds of end-effector schemes are presented and designed in detail. The essential performances are in comparison based on the results of dynamic simulations and experiments. Consequently, the conclusion is drawn that the steel cable-snared end-effector which captures the interface by winding the grapple fixture probe, is the best scheme that can combine the ability of soft capturing and great misalignment tolerance perfectly.

Space Robotics Researches at Electrotechnical Laboratory: Dexterous EV Robot Technology

Studies on basic technologies on space robots have been conducted at the Electrotechnical Laboratory (ETL) since 1983. The research emphasizes on developing key technologies of dexterous extravehicular robots. It is categorized into four areas: space adaptive mechatronics; telerobotics; on-board skill technology; and motion control of free flying robots in 0-gravity. We have been developing several pilot models such as a dexterous space manipulator system working in a vacuum, a graphic simulator augmented teleoperation system for long-distance robots, a smart end-effector for a large space manipulator arm, and an astronaut reference flying robot. This paper overviews the space robotics research efforts at ETL and presents a current topic of the precise space telerobotics experiment on ETS-VII.