RS-ModCubes: Self-Reconfigurable, Scalable, Modular Cubic Robots for Underwater Operations

Jiaxi Zheng1, Guangmin Dai2, Botao He3, Zhaoyang Mu2, Zhaochen Meng2, Tianyi Zhang1, Weiming Zhi1, Dixia Fan2
1Carnegie Mellon University, 2Westlake University, 3University of Maryland, College Park
 Open Source  Validated  Underwater  Modular
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A comprehensive simulation, control, and mission planning framework for self-reconfigurable underwater robots.

Abstract

This paper introduces a reconfigurable underwater robot system, RS-ModCubes, which allows scalable multi-robot configurations. An RS-ModCubes system comprises multiple ModCube modules, that can travel underwater with 6 DoFs and assemble with each other into a larger structure with onboard electromagnets. This system is designed to explore the feasibility of modularity and reconfigurability in underwater robotics, eliminating the need to customize mechanical designs for a specific task. We develop a modeling framework for reconfigurable robot systems, incorporating hydrodynamic effects via Monte Carlo approximation. A model-based feedforward Proportional Derivative (PD) controller serves as the baseline for control. Inspired by dexterous manipulation, we evaluated the robot's maximum task wrench space and power efficiency, compared against four commercial underwater robots. RS-ModCubes is validated via both real-world experiments and simulations, including individual and multi-module trajectory tracking and hovering docking.

Key Features

Modular Self-Reconfiguration

Dynamic morphology adaptation during missions with electromagnetic coupling

Underwater Physics Simulation

Comprehensive hydrodynamic modeling with Gazebo and Monte Carlo approximation

Mission Planning

Autonomous navigation and task execution with teleoperation support

Multi-Robot Coordination

Scalable swarm behavior implementation tested up to 8 robots

ROS-Based Framework

Extensible modular architecture compatible with ROS Melodic and Noetic

Validated Performance

Real-time factor 0.8-1.0, <5% error in hydrodynamic forces

System Architecture

The RS-ModCubes framework is built on a modular ROS-based architecture designed for scalability and flexibility. The system consists of four main layers: Mission Planning, Control, Simulation, and Hardware Interface layers.

Core Framework

  • modcube_common: Core utilities and shared libraries
  • modcube_config: Configuration files and robot descriptions
  • modcube_mission: Mission execution and teleoperation
  • modcube_msgs: Custom ROS message definitions

Simulation & Hardware

  • modcube_sim: Gazebo simulation interface
  • modcube_sim_gazebo_plugins: Custom Gazebo plugins
  • modcube_sim_worlds: Simulation environments
  • modcube_vehicle: Vehicle-specific hardware drivers

Interactive Model

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BibTeX

@article{zheng2025rs,
      title={RS-ModCubes: self-Reconfigurable, Scalable, Modular Cubic Robots for Underwater Operations},
      author={Zheng, Jiaxi and Dai, Guangmin and He, Botao and Mu, Zhaoyang and Meng, Zhaochen and Zhang, Tianyi and Zhi, Weiming and Fan, Dixia},
      journal={IEEE Robotics and Automation Letters},
      year={2025},
      publisher={IEEE}
    }