Experimental Characterization of Inverse Dynamics Guidance in Docking with a Rotating Target

The performance of an inverse dynamics guidance and control strategy is experimentally evaluated for the planar maneuver of a “chaser” spacecraft docking with a rotating “target.” The experiments were conducted on an air-bearing proximity maneuver testbed. The chaser spacecraft simulator consists of a three-degree-of-freedom autonomous vehicle floating via air pads on a granite table and actuated by thrusters. The target consists of a docking interface mounted on a rotational stage with the rotation axis perpendicular to the plane of motion. Given a preassigned trajectory, the guidance and control strategy computes the required maneuver control forces and torque via an inverse dynamics operation. The recorded data of 150 experimental test runs were analyzed using two-way analysis of variance and post hoc Tukey tests. The metrics were maneuver success, vehicle mass change, maneuver duration, thruster duty cycle, and maneuver work. The results showed that the guidance and control algorithm provided robust performance over a range of target rotation rates from 1 to 4 deg/s. The effects of the rate estimation errors are measurable but not dominant.