A Space Free-Flying Robot (SFFR) includes an actuated base equipped with one or more manipulators to perform on-orbit missions. Distinct from fixed-based manipulators, the spacecraft (base) of a SFFR responds to dynamic reaction forces due to manipulator motions. In order to control such a system, it is essential to consider the dynamic coupling between the manipulators and the base. Explicit d...

In this paper, formation control ideas for multiple spacecraft using the virtual structure approach are presented. If there is no formation feedback from the spacecraft to the virtual structure, the spacecraft will get out of formation when the virtual structure moves too fast for the spacecraft to track due to spacecraft control saturation or the total system must sacrifice convergence speed i...

It is well known that three momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrary reorientation maneuvers of the spacecraft can be accomplished using smooth feedback. If failure of one of the momentum wheel actuators occurs, we demonstrate that two momentum wheel actuators can be used to control the attitude of a rigid spacecraft and that arbitrar...

In this paper, a quaternion-based finite-time sliding mode attitude controller is designed for a spacecraft performing high-thrust orbital maneuvers, with cold gas thrusters as its actuators. The proposed controller results are compared with those of a quaternion feedback controller developed for the linearized spacecraft dynamics, in terms of settling time, steady-state error, number of thrust...

Formation control for multiple vehicles has become an active research area in recent years. Generally there are three approaches to this problem, namely leaderfollowing, behavioral, and virtual structure approaches. In this paper, formation control ideas for multiple spacecraft using virtual structure approach are presented. If there is no formation feedback from spacecraft to the virtual struc...

This paper considers the problem of rotating a constellation of spacecraft using on/oo thrusters such that the relative distance between the spacecraft is maintained to within a speciied tolerance. The basic idea is to resolve all of the constraints into a sphere around the desired tra-jectory of each spacecraft. As the constellation rotates, the sphere sweeps out a tube that constrains the mot...

In this paper the earth’s magnetic field is simulated precisely while the intensity and direction of the field are verified with one of the standard references for selected points on the earth and the results are compared with some low-order models. In another simulation, the complete model is compared with a common approximate model. The magnetic field in orbital frame is described and to empl...

the problem of relative motion control for spacecraft formation flying in eccentric orbits is considered in this paper. due to the presence of nonlinear dynamics and external disturbances, a robust fuzzy sliding mode controller is developed. the slopes of sliding surfaces of the conventional sliding mode controller are tuned according to error states using a fuzzy logic and reach the pre-define...