Organizations: Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA · Department of Mechanical Engineering, University of Nevada, Reno, NV, USA
Autonomous small-body proximity operations require continuous-thrust guidance under uncertain gravity, solar-radiation pressure (SRP), and stochastic disturbances. We combine iterative covariance steering (iCS) with L1 distributionally robust adaptive control (L1-DRAC) to provide risk-aware collision avoidance despite mismatch between the nominal planning model and the true dynamics. Iterative covariance steering plans a nominal feedback policy satisfying distributionally robust conditional value-at-risk keep-out constraints, while L1-DRAC compensates for dynamics uncertainty and bounds the residual distributional mismatch through a Wasserstein radius used by the planner. In 1000 paired Monte Carlo trials with gravity, SRP, and diffusion mismatch, L1-DRAC adaptive control reduces the keep-out violation rate from 32.7% to 0.2% and the physical collision rate from 16.4% to zero, without actuator saturation.
Figures & tables
Fig. 1 : Signed keep-out clearance over the maneuver. Solid curves show the ensemble medians, shaded regions span the empirical 0th – 1st percentile clearance tails, and dotted curves show the corresponding lower-tail CVaR, CVaR0.01(Dt) . The dash-dotted horizontal line marks the keep-out boundary; negative clearance denotes a keep-out violation.
Fig. 2 : Effect of L1 -DRAC on the uncertain closed-loop spacecraft motion. Panels (a)–(b) show representative true-system trajectories and their empirical means under the same nominal iCS policy with adaptation disabled and enabled, respectively. Panels (c)–(d) compare the nominal and empirical means and their 95% kernel-density-estimated highest-density regions (KDE-HDRs). The gray body represents the asteroid, and the dotted circle in (c)–(d) denotes the keep-out boundary. The green circle and magenta triangle in (a)–(b) mark the initial and terminal positions. All distributional statistics are computed using the complete 1000 -trial ensemble.
Spacecraft rendezvous and proximity operations cover the navigation, guidance, and control needed to approach, inspect, dock with, or capture spacecraft safely.
*Postdoctoral Associate, Department of Aerospace Engineering Sciences, University of Colorado Boulder, AAS Member. · †Associate Professor, University of Colorado Boulder, Department of Aerospace Engineering Sciences, and AAS Fellow.