111 research outputs found
Six-DOF Spacecraft Dynamics Simulator For Testing Translation and Attitude Control
This paper presents a method to control a manipulator system grasping a
rigid-body payload so that the motion of the combined system in consequence of
externally applied forces to be the same as another free-floating rigid-body
(with different inertial properties). This allows zero-g emulation of a scaled
spacecraft prototype under the test in a 1-g laboratory environment. The
controller consisting of motion feedback and force/moment feedback adjusts the
motion of the test spacecraft so as to match that of the flight spacecraft,
even if the latter has flexible appendages (such as solar panels) and the
former is rigid. The stability of the overall system is analytically
investigated, and the results show that the system remains stable provided that
the inertial properties of two spacecraft are different and that an upperbound
on the norm of the inertia ratio of the payload to manipulator is respected.
Important practical issues such as calibration and sensitivity analysis to
sensor noise and quantization are also presented
DETC2009-86529 IMPEDANCE CONTROL OF MANIPULATORS WITH HEAVY PAYLOAD FOR SPACECRAFT RENDEZVOUS & DOCKING SIMULATORS
ABSTRACT This paper presents a method to control a manipulator system grasping a rigid-body payload so that the motion of the combined system in consequence of external applied forces to be the same as another free-floating rigid-body (with different inertial properties). This allows zero-g emulation of a scale
Hybrid Simulator for Space Docking and Robotic Proximity Operations
In this work, we present a hybrid simulator for space docking and robotic
proximity operations methodology. This methodology also allows for the
emulation of a target robot operating in a complex environment by using an
actual robot. The emulation scheme aims to replicate the dynamic behavior of
the target robot interacting with the environment, without dealing with a
complex calculation of the contact dynamics. This method forms a basis for the
task verification of a flexible space robot. The actual emulating robot is
structurally rigid, while the target robot can represent any class of robots,
e.g., flexible, redundant, or space robots. Although the emulating robot is not
dynamically equivalent to the target robot, the dynamical similarity can be
achieved by using a control law developed herein. The effect of disturbances
and actuator dynamics on the fidelity and the contact stability of the robot
emulation is thoroughly analyzed
Analysis of Load-Carrying Capacity for Redundant Free-Floating Space Manipulators in Trajectory Tracking Task
The aim of this paper is to analyze load-carrying capacity of redundant free-floating space manipulators (FFSM) in trajectory tracking task. Combined with the analysis of influential factors in load-carrying process, evaluation of maximum load-carrying capacity (MLCC) is described as multiconstrained nonlinear programming problem. An efficient algorithm based on repeated line search within discontinuous feasible region is presented to determine MLCC for a given trajectory of the end-effector and corresponding joint path. Then, considering the influence of MLCC caused by different initial configurations for the starting point of given trajectory, a kind of maximum payload initial configuration planning method is proposed by using PSO algorithm. Simulations are performed for a particular trajectory tracking task of the 7-DOF space manipulator, of which MLCC is evaluated quantitatively. By in-depth research of the simulation results, significant gap between the values of MLCC when using different initial configurations is analyzed, and the discontinuity of allowable load-carrying capacity is illustrated. The proposed analytical method can be taken as theoretical foundation of feasibility analysis, trajectory optimization, and optimal control of trajectory tracking task in on-orbit load-carrying operations
Automated Rendezvous & Docking Using 3D Vision
The robustness and accuracy of a vision system for motion estimation of a
tumbling target satellite are enhanced by an adaptive Kalman filter. This
allows a vision-guided robot to complete the grasping of the target even if
occlusion occurs during the operation. A complete dynamics model, including
aspects of orbital mechanics, is incorporated for accurate estimation. Based on
the model, an adaptive Kalman filter is developed that estimates not only the
system states but also all the model parameters such as the inertia ratio,
center-of-mass, and the rotation of the principal axes of the target satellite.
An experiment is conducted by using a robotic arm to move a satellite mockup
according to orbital mechanics while the satellite pose is measured by a laser
camera system. The measurements are sent to the Kalman filter, which, in turn,
drives another robotic arm to grasp the target. The results demonstrate
successful grasping even if the vision system is blocked for several seconds
Emulating On-Orbit Interactions Using Forward Dynamics Based Cartesian Motion
The paper presents a novel Hardware-In-the-Loop (HIL) emulation framework of
on-orbit interactions using on-ground robotic manipulators. It combines Virtual
Forward Dynamic Model (VFDM) for Cartesian motion control of robotic
manipulators with an Orbital Dynamics Simulator (ODS) based on the Clohessy
Wiltshire (CW) Model. VFDM-based Inverse Kinematics (IK) solver is known to
have better motion tracking, path accuracy, and solver convergency than
traditional IK solvers. Therefore it provides a stable Cartesian motion for
manipulator-based HIL on-orbit emulations. The framework is tested on a
ROS-based robotics testbed to emulate two scenarios: free-floating satellite
motion and free-floating interaction (collision). Mock-ups of two satellites
are mounted at the robots' end-effectors. Forces acting on the mock-ups are
measured through an in-built F/T sensor on each robotic arm. During the tests,
the relative motion of the mock-ups is expressed with respect to a moving
observer rotating at a fixed angular velocity in a circular orbit rather than
their motion in the inertial frame. The ODS incorporates the force and torque
values on the fly and delivers the corresponding satellite motions to the
virtual forward dynamics model as online trajectories. Results are comparable
to other free-floating HIL emulators. Fidelity between the simulated motion and
robot-mounted mock-up motion is confirmed.Comment: Submitted to ICRA2023, for associated video, see:
https://www.youtube.com/watch?v=N2KYCKJ4KM
Robotic Manipulation and Capture in Space: A Survey
Space exploration and exploitation depend on the development of on-orbit robotic capabilities for tasks such as servicing of satellites, removing of orbital debris, or construction and maintenance of orbital assets. Manipulation and capture of objects on-orbit are key enablers for these capabilities. This survey addresses fundamental aspects of manipulation and capture, such as the dynamics of space manipulator systems (SMS), i.e., satellites equipped with manipulators, the contact dynamics between manipulator grippers/payloads and targets, and the methods for identifying
properties of SMSs and their targets. Also, it presents recent work of sensing pose and system states, of motion planning for capturing a target, and of feedback control methods for SMS during motion or interaction tasks. Finally, the paper reviews major ground testing testbeds for capture operations, and several notable missions and technologies developed for capture of targets on-orbit
Space station systems: A bibliography with indexes (supplement 6)
This bibliography lists 1,133 reports, articles, and other documents introduced into the NASA scientific and technical information system between July 1, 1987 and December 31, 1987. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future Space Station
Technology for large space systems: A bibliography with indexes (supplement 19)
This bibliography lists 526 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1988 and June 30, 1988. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems
Space station systems: A bibliography with indexes (supplement 9)
This bibliography lists 1,313 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1989 and June 30, 1989. Its purpose is to provide helpful information to researchers, designers and managers engaged in Space Station technology development and mission design. Coverage includes documents that define major systems and subsystems related to structures and dynamic control, electronics and power supplies, propulsion, and payload integration. In addition, orbital construction methods, servicing and support requirements, procedures and operations, and missions for the current and future Space Station are included
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