A Six Degree-of-Freedom Spacecraft Dynamics Simulator for Formation Control Research

摘要

This paper presents a new six-degree-of-freedom robotic spacecraft simulator, the Multi-Spacecraft Testbed for Autonomy Research (M-STAR), for testing formation
\nguidance, relative navigation, and control algorithms. The simulator dynamics are governed by five degrees of frictionless translational and rotational air-bearing
\nmotion and one degree of kinematic motion in the gravity direction with flight-like actuators, in a 1-g environment. M-STAR is designed to be modular and accommodates
\n3-DOF, 4-DOF, 5-DOF, and 6-DOF operation with minimal mechanical modifications. The simulator is modelled as a 3-D pendulum on a floating platform with sixteen thrusters and four reaction wheels as on-board actuators. Based
\non this plant model, a nonlinear hierarchical control law is proposed for position and attitude trajectory tracking. A weighted generalized pseudo-inverse strategy
\nfor control allocation to map control inputs to actuator inputs is discussed. The thruster actuation model for mapping smooth allocated input to non-smooth actuator
\ninput that achieves equivalent performance is derived. The control law, allocation scheme, and thruster model are tested on the simulator for real-time position tracking control using a Robot Operating System (ROS) based software
\nframework.