Marco Ciarcià

Fast and Near-Optimal Guidance for Docking to Uncontrolled Spacecraft

This paper proposes a guidance scheme for autonomous docking between a controlled spacecraft and an uncontrolled tumbling target in circular orbit. The onboard trajectory planning consists of a direct optimization method based on the inversion of the system dynamics. The trajectory components of the controlled spacecraft are imposed by using polynomial functions. Some of the polynomial coefficients are constrained to satisfy path constraints, whereas the remaining coefficients are varied parameters to be optimized. The optimal control problem is converted into a nonlinear programming problem by inverting the system dynamics. The proposed guidance scheme, based on the closed-loop implementation of this optimization problem, is applied to several scenarios. The resulting trajectories closely match the solutions of the correspondent optimal control problems. The guidance scheme is shown to perform precise maneuvers in most maneuvering situations, even in the presence of orbital perturbations. The sensitivity...

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 p...

Simulations of Multiple Spacecraft Maneuvering with MATLAB/Simulink and Satellite Tool Kit

A software interface between the MATLAB/Simulink environment and the Satellite Tool Kit Environment is introduced. This research is based on the need for validating model performance and visualizing simultaneous multiple-spacecraft proximity maneuvers for emerging missions. It is common for spacecraft systems to be modeled with MATLAB and Simulink. Furthermore, the software package Satellite Tool Kit is often used for animating and evaluating spacecraft maneuvers. In this research, a MATLAB/Satellite Tool Kit interface was developed to propagate six-degree-of-freedom spacecraft models, compared against Satellite-Tool-Kit-generated ephemeris, and animated for analysis. MATLAB script with necessary formatting is used for Satellite Tool Kit initialization and animation. The MATLAB/Satellite Tool Kit simulation interface allows variations in number, shape, and dimensions of spacecraft. Additionally, numerous model and simulation parameters can be selected and synchronized between MATLAB and Satellite Tool Kit...

Emulating Scaled Clohessy–Wiltshire Dynamics on an Air-Bearing Spacecraft Simulation Testbed

This work addresses the problem of experimentally reproducing the orbital relative motion on a planar floating spacecraft simulator testbed. Floating spacecraft simulators are characterized by doub...

Best Initial Conditions for the Rendezvous Maneuver

Abstract The majority of the papers dedicated to the rendezvous problem have employed the assumption of given initial position and given initial velocity of the chaser spacecraft vis-a-vis the target spacecraft. In this research, the initial separation velocity components are assumed free and the initial separation coordinates are subject to only the requirement that the chaser-to-target distance is given. Within this frame, two problems are studied: time-to-rendezvous free and time-to-rendezvous given. It is assumed that the target spacecraft moves along a circular orbit, that the chaser spacecraft has variable mass, and that its trajectory is governed by three controls, one determining the thrust magnitude and two determining the thrust direction. Analyses performed with the multiple-subarc sequential gradient-restoration algorithm for optimal control problems show that the fuel-optimal trajectory is zero-bang; namely, it includes a long coasting zero-thrust subarc followed by a short powered max-thrust braking subarc. While the thrust direction of the powered subarc is continuously variable for the optimal trajectory, its replacement with a constant (yet optimized) thrust direction produces a very efficient guidance trajectory.