Digital and Robotic Twinning for Validation of Proximity Operations and Formation Flying

2025-07-26

AI Summary

Ground-based verification of Guidance, Navigation, and Control (GNC) systems for spacecraft on-orbit rendezvous, proximity operations (RPO), and formation flying (FF) is hindered by the irreproducibility of space environments and insufficient fidelity of terrestrial testing. Method: This paper proposes an integrated digital–robotic twin verification framework that unifies Software-in-the-Loop (SIL) and Hardware-in-the-Loop (HIL) testing. It jointly integrates radio-frequency (RF) and optical navigation modalities, and couples three testbeds: the GNSS/RF Autonomous Navigation Demonstrator (GRAND), the Rendezvous and Optical Navigation (TRON) testbed, and the Optical Stimulator (OS). Contribution/Results: Employing a high-fidelity simulation–physical experiment closed-loop, the framework enables end-to-end GNC validation across all phases of LEO-based RPO missions. Experimental results demonstrate strong consistency between the digital and robotic twins, significantly enhancing the realism and credibility of ground-based verification relative to actual space conditions.

Technology Category

• Intelligent Robots: Localization, Mapping, and Navigation
• Natural Language Processing: Language Grounding & Multi-modal NLP
• Planning, Routing, and Scheduling: Activity and Plan Recognition

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web applications in cross-disciplinary domains and verticals such as mixed reality, smart cities, and digital health
• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Security and Privacy: Data transparency and provenance

Abstract

In spacecraft Rendezvous, Proximity Operations (RPO), and Formation Flying (FF), the Guidance Navigation and Control (GNC) system is safety-critical and must meet strict performance requirements. However, validating such systems is challenging due to the complexity of the space environment, necessitating a verification and validation (V&V) process that bridges simulation and real-world behavior. The key contribution of this paper is a unified, end-to-end digital and robotic twinning framework that enables software- and hardware-in-the-loop testing for multi-modal GNC systems. The robotic twin includes three testbeds at Stanford's Space Rendezvous Laboratory (SLAB): the GNSS and Radiofrequency Autonomous Navigation Testbed for Distributed Space Systems (GRAND) to validate RF-based navigation techniques, and the Testbed for Rendezvous and Optical Navigation (TRON) and Optical Stimulator (OS) to validate vision-based methods. The test article for this work is an integrated multi-modal GNC software stack for RPO and FF developed at SLAB. This paper introduces the hybrid framework and summarizes calibration and error characterization for the robotic twin. Then, the GNC stack's performance and robustness is characterized using the integrated digital and robotic twinning pipeline for a full-range RPO mission scenario in Low-Earth Orbit (LEO). The results shown in the paper demonstrate consistency between digital and robotic twins, validating the hybrid twinning pipeline as a reliable framework for realistic assessment and verification of GNC systems.

Problem

• Validating GNC systems for spacecraft RPO and FF missions
• Bridging simulation-real-world gaps in space environment testing
• Developing unified digital-robotic twinning for multi-modal GNC verification

Innovation

• Unified digital and robotic twinning framework
• Multi-modal GNC software-in-the-loop testing
• Hybrid pipeline for realistic GNC verification