Design, Modeling and Direction Control of a Wire-Driven Robotic Fish Based on a 2-DoF Crank-Slider Mechanism

2026-03-03

AI Summary

This study addresses the longstanding trade-off between high-speed swimming and high maneuverability in tendon-driven biomimetic robotic fish. To overcome this limitation, the authors propose a novel design based on a two-degree-of-freedom crank-slider mechanism that decouples propulsion and steering functions, thereby breaking the performance bottleneck imposed by their mutual interference. The system integrates an elastic skeletal structure, waterproof encapsulation, and a hybrid feedforward–feedback control strategy, supported by a corresponding dynamic model. Experimental results demonstrate that the prototype achieves high-speed straight-line swimming, smooth turning, and precise heading control, effectively validating the feasibility and superiority of the proposed mechanical architecture and control methodology.

Technology Category

• Intelligent Robots: Manipulation
• Search and Optimization: Sampling/Simulation-based Search
• Computer Vision: Low Level & Physics-based Vision

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

Robotic fish have attracted growing attention in recent years owing to their biomimetic design and potential applications in environmental monitoring and biological surveys. Among robotic fish employing the Body-Caudal Fin (BCF) locomotion pattern, motor-driven actuation is widely adopted. Some approaches utilize multiple servo motors to achieve precise body curvature control, while others employ a brushless motor to drive the tail via wire or rod, enabling higher oscillation and swimming speeds. However, the former approaches typically result in limited swimming speed, whereas the latter suffer from poor maneuverability, with few capable of smooth turning. To address this trade-off, we develop a wire-driven robotic fish equipped with a 2-degree-of-freedom (DoF) crank-slider mechanism that decouples propulsion from steering, enabling both high swimming speed and agile maneuvering. In this paper, we first present the design of the robotic fish, including the elastic skeleton, waterproof structure, and the actuation mechanism that realizes the decoupling. We then establish the actuation modeling and body dynamics to analyze the locomotion behavior. Furthermore, we propose a combined feedforward-feedback control strategy to achieve independent regulation of propulsion and steering. Finally, we validate the feasibility of the design, modeling, and control through a series of prototype experiments, demonstrating swimming, turning, and directional control.

Problem

• robotic fish
• maneuverability
• swimming speed
• BCF locomotion
• actuation trade-off

Innovation

• wire-driven actuation
• 2-DoF crank-slider mechanism
• decoupled propulsion and steering
• robotic fish
• feedforward-feedback control