Designing for Distributed Heterogeneous Modularity: On Software Architecture and Deployment of MoonBots

TL;DR

The paper tackles the challenge of scalable, modular robotics for space-oriented missions by proposing distributed heterogeneous modularity that decouples hardware form from software deployment. It presents a data-centric, component-based architecture built on ROS2 and Zenoh, orchestrated deployment, and a modular API stack to enable reconfigurable multi-robot assemblies across heterogeneous hardware and networks. Field tests and development-time analyses demonstrate modularity, rapid prototyping, and improved resilience, while addressing ROS2 limitations and network scalability. Although space-hardening is not yet achieved, the architecture offers generalizable design patterns and open-source tooling (Motion Stack) intended to guide scalable distributed robotics across terrestrial and extraterrestrial environments.

Abstract

This paper presents the software architecture and deployment strategy behind the MoonBot platform: a modular space robotic system composed of heterogeneous components distributed across multiple computers, networks and ultimately celestial bodies. We introduce a principled approach to distributed, heterogeneous modularity, extending modular robotics beyond physical reconfiguration to software, communication and orchestration. We detail the architecture of our system that integrates component-based design, a data-oriented communication model using ROS2 and Zenoh, and a deployment orchestrator capable of managing complex multi-module assemblies. These abstractions enable dynamic reconfiguration, decentralized control, and seamless collaboration between numerous operators and modules. At the heart of this system lies our open-source Motion Stack software, validated by months of field deployment with self-assembling robots, inter-robot cooperation, and remote operation. Our architecture tackles the significant hurdles of modular robotics by significantly reducing integration and maintenance overhead, while remaining scalable and robust. Although tested with space in mind, we propose generalizable patterns for designing robotic systems that must scale across time, hardware, teams and operational environments.

Figures (4)

• Figure 1: A variety of MoonBot assemblies. (a): Dragon assembly -- 4 modules, made of 2 MoonBot G-line limbs and 2 MoonBot H-line V1 wheels. Specialized in nimble navigation. (b): Dragon x4 assembly -- 8 modules, made of a mix of MoonBot H-line V1 and V2, wheels and limbs. Specialized in redundancy. (c): Tricycle assembly -- 6 MoonBot H-line V1 modules. Spacialized in cargo. (d): MoonBot H-line V1 limb and V2 wheel assembling themselves.
• Figure 2: Zenoh network overview of distributed Moon bases and robot assemblies. It combines multiple topologies to maximize reliability and performance under various communication interfaces.
• Figure 3: Structure of a software component, pushing for separation of concern down to the subcomponent level.
• Figure 4: Two assemblies of independent robot modules, connecting to form one large assembly. (a) Left: Moonbot Dragon assembly, made of 2 H-line wheels V2 and 2 H-line limbs V2. Right: Variant with V1 modules. (b) The large heterogeneous assembly moving.