Model Reference Adaptive Control for Net-Based Debris Towing

Because of its ability to capture large, uncooperative objects from a safe distance, the tether-net system is considered one of the most favorable solutions for active debris removal. However, additional developments and analyses of control algorithms are needed for the post-capture phase of a net-based debris removal mission (i.e., debris towing for detumbling and deorbiting). In fact, previous research has either employed open-loop thrust control or designed feedback controllers for a simplified model, where the debris is rigidly attached to one or more tethers. In this work, tether elongation control laws based on the Model Reference Adaptive Control algorithm are designed to stabilize the full coupled chaser-tether-net-debris system, with the flexible net completely modeled in simulation. The system model and the control derivation processes are discussed for two algorithms (each with its own advantages and disadvantages), along with the results of towing simulations involving varying angular velocities and orientations of debris. Compared with a Proportional-Integral-Derivative control baseline, the simulation results show that the proposed algorithms are robust under varying conditions, enabling the debris removal system to achieve desired steady, safe behavior.