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

Overview

This paper introduces SPLITTER, a tethered dual-robot system designed for planetary exploration in low-gravity environments, emphasizing its unique approach to attitude control through inertial morphing. SPLITTER consists of two sub-10 kg quadrupedal robots connected by a tether, enabling successive jumping locomotion and mid-flight stabilization by adjusting limb configurations and tether length. Utilizing a model predictive control (MPC) framework, the system modulates its principal moments of inertia to achieve stable flight and precise landings without relying on traditional reaction wheels or aerodynamics. Simulation results demonstrate that SPLITTER's innovative design supports efficient and agile exploration on planetary bodies like the Moon or asteroids, offering a scalable and cost-effective alternative to conventional rovers.

The Jumping Flight Trajectory Planner is responsible for generating the desired trajectories for SPLITTER's jumping and mid-air flight phases, ensuring stability and precise landings in low-gravity environments. It calculates the required angular velocities and limb configurations to achieve targeted trajectories while considering the system's dynamic constraints, such as tether tension and inertial adjustments. By leveraging a model predictive approach, the planner accounts for the coupled dynamics of the tethered dual-robot system, enabling synchronized control of jumps and mid-flight attitude. The planner ensures efficient use of energy, precise trajectory tracking, and smooth transitions between the jumping and landing phases, forming the foundation for SPLITTER's agile and adaptive locomotion.

SPLITTER's dual-robot system can theoretically perform a coordinated exploration maneuver in a low-gravity environment. One robot acts as an anchor on stable terrain, securing the tether, while the other descends into a steep crater to explore and deploy its manipulators for data collection or interaction with the environment. This configuration allows safe and effective exploration of hazardous areas, with the tether providing stability, controlled movement, and the ability to retrieve the exploring robot if needed.