Sensitivity-Based Tube NMPC for Cooperative Aerial Structures Under Parametric Uncertainty

2026-04-28

AI Summary

This work addresses the robust control of cooperative flight chains under parametric uncertainties in link mass, length, and inertia by proposing a sensitivity-based tube nonlinear model predictive control (NMPC) framework. For the first time, first-order parameter-state sensitivities are embedded within a tube NMPC scheme to dynamically tighten state and input constraints through online propagation of sensitivity information. A smooth cosine embedding technique is further integrated to handle geometric separation constraints. Leveraging an input-rate-driven dynamic model, the proposed approach demonstrates significantly improved constraint satisfaction margins while maintaining trajectory tracking accuracy comparable to that of nominal NMPC, as validated through close-proximity maneuvering and Monte Carlo simulations.

Abstract

This paper presents a sensitivity-based tube Nonlinear Model Predictive Control (NMPC) framework for cooperative aerial chains under bounded parametric uncertainty. We consider a planar two-vehicle chain connected by rigid links, modeled with input-rate actuation to enforce slew-rate and magnitude limits on thrust and torque. Robustness to uncertainty in link mass, length, and inertia is achieved by propagating first-order parametric state sensitivities along the horizon and using them to compute online constraint-tightening margins. We robustify an inter-link separation constraint, implemented via a smooth cosine embedding, and thrust-magnitude bounds. The method is implemented in MATLAB and evaluated with boundary-hugging maneuvers and Monte-Carlo uncertainty sampling. Results show improved constraint margins under uncertainty with tracking performance comparable to nominal NMPC.

Problem

• parametric uncertainty
• cooperative aerial structures
• robust control
• constraint satisfaction
• Nonlinear Model Predictive Control

Innovation

• sensitivity-based tube NMPC
• parametric uncertainty
• constraint tightening
• cooperative aerial structures
• input-rate actuation