Autonomous path planning and experiment study of free-floating space robot for spinning satellite capturing

Abstract

Robotic systems are expected to play an increasingly important role in future space activities with the development of space technology. The robotic on-orbital service, whose key is the capturing technology, becomes research hot in recent years. This paper focuses on the guidance of a robot manipulator to capture a spinning satellite with unknown dynamics parameters. In capturing a spinning satellite, a reference trajectory for control of the manipulator is generated with time delay due to the processing time of the target motion estimator and the manipulator controller. Consequently, the control system shows a poor performance and the end-effector sometimes fails to capture the target satellite. To solve this problem, the motion characteristics and motion prediction of the spinning satellite is analyzed Firstly, and using Unscented Kalman Filter (UKF) to predict its movement. Then, a method of autonomous path planning of a free-floating space robot for target capturing is proposed, which is based on motion prediction and speed compensation. Finally, a ground experiment system is set up based on the concept of dynamic emulation and kinematic equivalence. With the experiment system, the autonomous target capturing experiments are conducted. The experiment results validate the proposed algorithm.

Application Status and Prospect of Digital Twin for On-Orbit Spacecraft

“…Autonomous cognition refers to the intelligent agent with cognitive awareness established on spacecraft, which can perceive its own state and external environment in real-time, and complete the missions without relying on human instruction. Spacecraft should be flexible and intelligent in its mission completion, with a spatial adaptability and behavioral autonomy, to solve problems such as orbital transfer [31], interplanetary flight path planning [32], celestial collision avoidance [33], on-orbit service [34], etc.. Autonomous flight is considered to be a typical autonomous cognition problem.…”

Design of variable stiffness joint of manipulator

“…The space capture task is an important link for the space manipulator to implement the on-orbit service and maintenance tasks of the spacecraft [1]- [4] In order to reduce the requirements of the manipulator on satellite attitude control during the capture process, it is necessary for the capture device to have a wide range of system stiffness and motion control adjustment capabilities, and can actively adjust its own stiffness [5]- [7] . The capture device can improve the system motion control accuracy during the approach process and the system connection stiffness after capture through high stiffness, and also can increase the system flexibility through low stiffness to reduce the contact impact force during the contact capture process.The above requirements require the variable stiffness capability of manipulator joint.…”

“…The variable stiffness flexible joint AwAS designed by VIACTORS of IIT has a stiffness variation range of 30Nm/rad-1300Nm/rad [14] . In view of the technical development requirements of high precision and high stability faced by the moving target capture on orbit by manipulator, based on the variable stiffness principle of leaf spring and lever, this paper designs a new modular variable stiffness joint that can adjust the stiffness in a large range, describes the mechanical structure of the joint, and verifies the large stiffness change range of the joint through experiments [1], [13], [14] .…”

Coupling minimization with obstacles avoidance of free-floating space robots based on hybrid map in configuration space

“…1 With the development of robotics, the manipulation of space robots continues to show great advantages and benefits in on-orbital servicing missions, including docking, berthing, refueling, repairing, upgrading, transporting, rescuing, and orbital debris removal. [2][3][4] Because of the microgravity environment in space, the space robot is usually in a free-floating state to avoid the saturation of momentum wheels and the harm due to the thruster plume. 5,6 The dynamic coupling between the manipulator and the base makes it more difficult to control motion.…”