Hybrid path-lifting algorithm and Equivalence of Stability results for MRP-based control strategies

TL;DR

This paper introduces a hybrid path-lifting algorithm for MRPs that ensures robust, globally stable attitude control by unambiguously extracting attitude information and avoiding unwinding phenomena.

Contribution

It proposes a novel hybrid path-lifting mechanism for MRPs that preserves stability and robustness, and demonstrates equivalence of stability results between attitude spaces.

Findings

The hybrid algorithm unambiguously extracts MRPs from attitude space.

The proposed control achieves robust global exponential stability.

The method prevents unwinding phenomena in attitude control.

Abstract

The modified Rodrigues parameters (MRP) consist of two numerically different triplets that, by switching between them, yield a minimal globally non-singular attitude description with advantageous properties. The MRP space results from the Alexandroff compactification of the three-dimensional Euclidean space and is a double cover of $\mathrm{SO(3)}$. By capitalizing on instrumental properties of the covering map, this paper proposes a novel hybrid dynamic path-lifting mechanism to unambiguously and robustly extract the MRP from the attitude space. This hybrid solution allows applying an MRP-based feedback controller to the attitude dynamics in the base space while preserving its asymptotic and exponential stability properties. Furthermore, by profiting from the distinct characteristics of the MRP, the resulting interconnection is impervious to the unwinding phenomenon. The design and validation of an MRP-based controller exemplify the application of the proposed algorithm alongside the novel results for equivalence of stability between spaces. The solution renders the attitude space tracking dynamics robustly globally exponentially stable, demonstrating the potential of this novel methodology.