Battery-Swapping Multi-Agent System for Sustained Operation of Large Planetary Fleets

TL;DR

This work proposes a battery-swapping, hub-mediated power architecture to sustain fleets of small planetary rovers, reducing rover SWAP-C by outsourcing generation to a central hub and swapping in fully charged modules for near-continuous operation. It presents a low-cost, open-source test platform and a docking/swapping protocol validated through autonomous docking, swapping, and field testing, achieving an average service time of $98$ seconds and expanding the robust docking configuration space by $258\%$ through design optimization. The approach leverages a generalized hub-rover architecture with a formal capacity equation $n_r=\left\lfloor\frac{P_{gen}-P_h}{\max(Q_bV_b/C, P_m)}\right\rfloor$, enabling scalable fleets and potential extensions for communications and computation at the hub. While demonstrated on Earth as a proof of concept, the work discusses environmental, thermal, and radiation considerations and outlines future steps toward space readiness and more extensive trade studies on power transfer modalities and cost-benefit analyses.

Abstract

We propose a novel, heterogeneous multi-agent architecture that miniaturizes rovers by outsourcing power generation to a central hub. By delegating power generation and distribution functions to this hub, the size, weight, power, and cost (SWAP-C) per rover are reduced, enabling efficient fleet scaling. As these rovers conduct mission tasks around the terrain, the hub charges an array of replacement battery modules. When a rover requires charging, it returns to the hub to initiate an autonomous docking sequence and exits with a fully charged battery. This confers an advantage over direct charging methods, such as wireless or wired charging, by replenishing a rover in minutes as opposed to hours, increasing net rover uptime. This work shares an open-source platform developed to demonstrate battery swapping on unknown field terrain. We detail our design methodologies utilized for increasing system reliability, with a focus on optimization, robust mechanical design, and verification. Optimization of the system is discussed, including the design of passive guide rails through simulation-based optimization methods which increase the valid docking configuration space by 258%. The full system was evaluated during integrated testing, where an average servicing time of 98 seconds was achieved on surfaces with a gradient up to 10°. We conclude by briefly proposing flight considerations for advancing the system toward a space-ready design. In sum, this prototype represents a proof of concept for autonomous docking and battery transfer on field terrain, advancing its Technology Readiness Level (TRL) from 1 to 3.

Figures (12)

• Figure 1: Field Testing of the prototype battery-swapping multi-agent rover architecture. The large rover, left, generates and distributes power to an internal cache of battery modules. The small rover, right, docks with the base to hot-swap its spent battery for one with full charge.
• Figure 2: Battery swapping method represented schematically.
• Figure 3: Final prototype with labeled components.
• Figure 4: Step-by-step process diagram of docking and battery swap procedure. After step D, the procedure is reversed to complete a swap.
• Figure 5: Block diagram representing critical electrical components for power transfer across a hub, battery module, and rover.