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Tethered Variable Inertial Attitude Control Mechanisms through a Modular Jumping Limbed Robot

Yusuke Tanaka, Alvin Zhu, Dennis Hong

TL;DR

The paper tackles attitude control for small jumping robots operating in low-gravity environments where aerodynamic or flywheel-based methods are impractical due to mass constraints. It introduces SPLITTER, a tethered dual-quadruped system whose attitude is controlled in flight by inertial morphing through limb reconfiguration and tether length adjustments, governed by a model predictive control framework. A five-dumbbell inertia model is developed to represent variable inertia, and the MPC optimizes changes in principal-axis inertia to stabilize 3D orientation during successive jumps, supported by a custom dynamics simulator and actuator analysis. The results indicate that the approach can stabilize during flight without traditional attitude hardware, enabling rapid, robust exploration for sub-10 kg planetary robots, with clear avenues for experimental validation and optimization for real-world missions.

Abstract

This paper presents the concept of a tethered variable inertial attitude control mechanism for a modular jumping-limbed robot designed for planetary exploration in low-gravity environments. The system, named SPLITTER, comprises two sub-10 kg quadrupedal robots connected by a tether, capable of executing successive jumping gaits and stabilizing in-flight using inertial morphing technology. Through model predictive control (MPC), attitude control was demonstrated by adjusting the limbs and tether length to modulate the system's principal moments of inertia. Our results indicate that this control strategy allows the robot to stabilize during flight phases without needing traditional flywheel-based systems or relying on aerodynamics, making the approach mass-efficient and ideal for small-scale planetary robots' successive jumps. The paper outlines the dynamics, MPC formulation for inertial morphing, actuator requirements, and simulation results, illustrating the potential of agile exploration for small-scale rovers in low-gravity environments like the Moon or asteroids.

Tethered Variable Inertial Attitude Control Mechanisms through a Modular Jumping Limbed Robot

TL;DR

The paper tackles attitude control for small jumping robots operating in low-gravity environments where aerodynamic or flywheel-based methods are impractical due to mass constraints. It introduces SPLITTER, a tethered dual-quadruped system whose attitude is controlled in flight by inertial morphing through limb reconfiguration and tether length adjustments, governed by a model predictive control framework. A five-dumbbell inertia model is developed to represent variable inertia, and the MPC optimizes changes in principal-axis inertia to stabilize 3D orientation during successive jumps, supported by a custom dynamics simulator and actuator analysis. The results indicate that the approach can stabilize during flight without traditional attitude hardware, enabling rapid, robust exploration for sub-10 kg planetary robots, with clear avenues for experimental validation and optimization for real-world missions.

Abstract

This paper presents the concept of a tethered variable inertial attitude control mechanism for a modular jumping-limbed robot designed for planetary exploration in low-gravity environments. The system, named SPLITTER, comprises two sub-10 kg quadrupedal robots connected by a tether, capable of executing successive jumping gaits and stabilizing in-flight using inertial morphing technology. Through model predictive control (MPC), attitude control was demonstrated by adjusting the limbs and tether length to modulate the system's principal moments of inertia. Our results indicate that this control strategy allows the robot to stabilize during flight phases without needing traditional flywheel-based systems or relying on aerodynamics, making the approach mass-efficient and ideal for small-scale planetary robots' successive jumps. The paper outlines the dynamics, MPC formulation for inertial morphing, actuator requirements, and simulation results, illustrating the potential of agile exploration for small-scale rovers in low-gravity environments like the Moon or asteroids.
Paper Structure (37 sections, 20 equations, 14 figures, 2 tables)

This paper contains 37 sections, 20 equations, 14 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Related Works
  3. Robotics in Space Planetary Exploration
  4. Limbed Robotics in Space
  5. Modular and Tethered Robotics in Space
  6. Attitude Control
  7. SPLITTER System Dynamics
  8. Jumping Flight Gait Mechanisms
  9. Variable Inertial System
  10. Tension
  11. Actuator Selection Considerations
  12. Torque and Angular Velocity Requirements
  13. Dynamics Simulation
  14. Euler's Equations of Motion:
  15. Contact Dynamics
  16. ...and 22 more sections

Figures (14)

  • Figure 1: A render of SPLITTER when arms spread out and tether elongated for inertial morphing attitude control.
  • Figure 2: SPLITTER One quadruped in biped mode with two manipulators inside of a creator and the other quadruped as an anchor.
  • Figure 3: SPLITTER Arms spread out and tether shortened.
  • Figure 4: SPLITTER Arms shortened and tether elongated.
  • Figure 5: SPLITTER Arms shortened and tether shortened.
  • ...and 9 more figures