Flight Testing of Multiple-Spacecraft Control on SPHERES During Close-Proximity Operations

Abstract

A multiple-spacecraft close-proximity control algorithm was implemented and tested with the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) facility onboard the International Space Station. During flight testing, a chaser satellite successfully approached a virtual target satellite while avoiding collision with a virtual obstacle satellite. This research contributes to the control of multiple spacecraft for emerging missions, which may require simultaneous gathering, rendezvous, and docking. The unique control algorithm was developed at the U.S. Naval Postgraduate School and integrated onto the Massachusetts Institute of Technology's SPHERES facility. The control algorithm implemented combines the efficiency of the linear quadratic regulator (used for attraction toward goal positions) and the robust collision-avoidance capability of the artificial potential field method (used for repulsion from moving obstacles). The amalgamation of these two control methods into a multiple-spacecraft close-proximity control algorithm yielded promising results, as demonstrated by simulations. Comprehensive simulation evaluation enabled implementation and ground testing of the spacecraft control algorithm on the SPHERES facility. Successful ground testing led to the execution of flight experiments onboard the International Space Station, which demonstrated the proposed algorithm in a microgravity environment. NomenclatureA, B, C = state-space matrices a = acceleration due to linear-quadratic-regulator-and artificial-potential-field-determined control effort a APF = acceleration due to artificial-potential-fielddetermined control effort a LQR = acceleration due to linear-quadratic-regulatordetermined control effort a m = maximum acceleration a obs = acceleration of chaser spacecraft toward an obstacle a x;y;z = acceleration due to the control effort

Development and experimentation of LQR/APF guidance and control for autonomous proximity maneuvers of multiple spacecraft

“…1) has been previously developed at NPS for spacecraft relative position, and it is the starting point for this work [14]. It combines the efficiency of the linear quadratic regulator (LQR) with the robust collision avoidance capability of the artificial potential function (APF) method.…”

“…The Massachusetts Institute of Technology (MIT) is currently utilizing the Space Systems Laboratory's synchronized position hold engage and reorient experimental satellites (SPHERES) both on the ground and inside the International Space Station for validation of navigation and control algorithms [13,14].…”

A near-optimal guidance for cooperative docking maneuvers

“…In Table 1 are shown the initial positions and the initial masses of the two FSSs. To evaluate the IDVD-SGRA performances, for both types docking execution D1 and D2, the same maneuvers have been performed using an LQR controller [7][8][9][10][11]. Since such controller does not enforce any constraint on the maximum maneuver time, in order to ensure that this parameter is equal for all the controllers, we have first executed the dockings with the LQR then we have set the resulting maneuver times as t MAX for the IDVD-SGRA (Table 1).…”

“…For comparison purposes, the same set of docking maneuvers has also been executed using an LQR controller [7][8][9][10][11]. The results show that the docking trajectories performed with the IDVD-SGRA guidance are characterized by a lower amount of total maneuver energy and fuel consumption with respect to the LQR.…”

Research on Longitudinal Control Algorithm for Flying Wing UAV Based on LQR Technology

“…In the method of multivariable feedback control system design, the LQR technology is widely used in many practical engineering fields [5][6][7][8][9][10][11], especially in the control of conventional layout fixed-wing UAV and unmanned helicopter [12][13][14][15][16], which has many advantages such as more than 60°phase margin, infinite amplitude margin and strong robustness. In literature [12] [13], it has realized the stability augmentation control of conventional layout fixed-wing UAV by using conventional LQR method.…”