Manipulider: A Multi-Engine Buoyancy-Controlled Robot for Thrusterless Underwater Gliding and Manipulation

2026-06-19

AI Summary

This study addresses the limitations of conventional underwater robots that rely on propellers, which are prone to entanglement and incapable of achieving passive gliding or precise attitude control. The authors propose a novel thruster-free underwater robot based on multi-engine buoyancy regulation, employing four syringe-type buoyancy engines to cooperatively modulate net buoyancy and center of buoyancy. This design enables large-angle static stable tilting (up to 64.6°) and passive gliding motion without propulsion. The system innovatively integrates a center-of-gravity–center-of-buoyancy coordination mechanism with magnetic modular interfaces for rapid payload exchange. Experimental validation demonstrates successful execution of ascent/descent maneuvers, attitude adjustment, and object grasping and transport, achieving a total buoyancy regulation capacity of 160 grams.

Abstract

The Manipulider is a buoyancy-actuated underwater robot that enables thrusterless, glide-like locomotion and attitude-based manipulation, while providing a magnetic modular interface for rapid payload swapping (e.g., a gripper or sensors). Four syringe-based buoyancy engines distributed around the body jointly regulate net buoyancy and the center of buoyancy, allowing the vehicle to maintain large tilt angles through static force balance without continuous thrust and to avoid propeller entanglement risks. We present the mechanical and electrical design, calibration procedure, and control architecture. Experiments with a gripper attached (no external payload) show a controllable buoyancy-displacement range of 40 mL per engine ({\approx}160 g total buoyancy authority), maximum statically stable tilts of 64.6° (single-engine) and 61.8° (dual-engine), and representative vertical and tilt-transition dynamics. We further demonstrate tilt regulation, controlled ascent/descent primitives, and a proof-of-concept gripper-based payload-transport sequence without thrusters.

Problem

• thrusterless underwater locomotion
• buoyancy control
• underwater manipulation
• modular payload
• gliding robot

Innovation

• buoyancy-controlled
• thrusterless locomotion
• underwater manipulation
• modular payload
• static attitude balance