In context
Underwater robots are increasingly vital for ocean exploration, monitoring, search and rescue, and maintenance. Traditional AUVs and ROVs face challenges in motion efficiency for long-duration autonomous operations. Underwater snake robots, with their multi-joint flexible bodies, offer advantages in efficiency and adaptability, but their biomimetic motion is often slow and limited in confined spaces. This study addresses these limitations by integrating a rear thruster and optimizing motion modes.
What was reported
Researchers from Tianjin University and Ritsumeikan University developed a dynamic model of an underwater snake robot with a rear thruster using the iterative Newton-Euler method. They employed the transportation economic metric to evaluate motion efficiency, defined as the ratio of energy consumption to speed. To optimize efficiency, they used the NSGA-II multi-objective genetic algorithm, varying four parameters: joint amplitude, frequency, phase shift, and thruster force.
Simulation results across three motion modes revealed that at low speeds, pure lateral undulation is most efficient; at medium speeds, a hybrid mode combining undulation and thruster achieves higher speeds than undulation alone while maintaining better efficiency than thruster-only; at high speeds, thruster-only propulsion offers the highest efficiency and maximum forward speed. The optimized parameters for undulation included phase shifts between 0.5–0.7 rad and amplitudes between 0.4–0.5 rad.
Pool experiments validated the proposed motion mode, confirming that it maximizes the robot's movement capability, improves efficiency, and extends battery life.
Why it mattered
This research provides a systematic method for optimizing the motion of underwater snake robots with thrusters, offering a practical framework for enhancing speed and energy efficiency. The findings guide the design of control strategies for industrial underwater inspection and maintenance robots, potentially enabling longer missions and better performance in complex environments.
“The proposed motion mode can maximize the movement ability of the underwater snake robots with thrusters, improve the movement efficiency of the robot, and elongate the battery life.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2023-07-08 · “尾部带有推进器的水下蛇形机器人的高效运动模式”