McKenney Owen, Zhu Joseph, Han Tianjun, Bart-Smith Hilary
Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, United States of America.
Bioinspir Biomim. 2025 Aug 19;20(5). doi: 10.1088/1748-3190/adf67a.
Maneuvering in fish is complex and offers inspiration in the development of the next generation bio-inspired underwater vehicles (BUVs). Balancing desired functionality with minimal mechanical complexity is a challenge in developing a BUV. This study presents a single-actuator turning strategy for the Tunabot, a bio-inspired robotic fish, using asymmetric tail-beat timing to generate turning forces. Biological fish, such as tuna, adjust tail kinematics for maneuverability. Following this principle, the proposed control method modifies stroke duration through a single motor, synchronized by a digital encoder. Experiments were conducted in a tank, using the dorsal-view high-speed video and DeepLabCut motion tracking technology to analyze and quantify turning radius and swimming velocity. A 66% asymmetric difference in tail-beat timing resulted in a turning radius of 1.42 body lengths at a certain base frequency. Scaling laws were developed to reveal the fluid dynamics and predict the turning radius and swimming speed of the Tunabot given known tailbeat frequencies. Power consumption data was gathered for asymmetric maneuvers and compared to their symmetric equivalents. These findings demonstrate that asymmetric tail-beat control enables effective turning without dedicated steering mechanisms, offering novel insights for designing highly maneuverable underwater bio-robots with low power consumption.
鱼类的机动动作复杂，为下一代仿生水下航行器（BUV）的开发提供了灵感。在开发BUV时，如何在期望的功能与最小的机械复杂性之间取得平衡是一项挑战。本研究提出了一种针对仿生机器人鱼Tunabot的单驱动转向策略，利用不对称的尾鳍摆动时机来产生转向力。像金枪鱼这样的生物鱼会调整尾鳍运动学以实现机动性。遵循这一原理，所提出的控制方法通过单个电机修改冲程持续时间，并由数字编码器进行同步。实验在水箱中进行，使用背视高速视频和DeepLabCut运动跟踪技术来分析和量化转弯半径和游泳速度。在特定基频下，尾鳍摆动时机66%的不对称差异导致转弯半径为1.42个体长。制定了比例定律以揭示流体动力学，并在已知尾鳍摆动频率的情况下预测Tunabot的转弯半径和游泳速度。收集了非对称机动动作的功耗数据，并与对称等效动作进行了比较。这些发现表明，不对称尾鳍摆动控制能够在没有专用转向机构的情况下实现有效转弯，为设计低功耗、高机动性的水下生物机器人提供了新的见解。
