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