Fish-inspired aquatic robots are gaining increasing attention in marine robot communities due to their high swimming speeds and efficient propulsion enabled by flexible bodies that generate undulatory motions. To support the design optimization and control of such systems, accurate, interpretable, and computationally tractable modeling of the underlying swimming dynamics is indispensable. In this letter, we present a full-body dynamics model for motor-actuated robotic fish, rigorously derived from Hamilton's principle. The model captures the continuously distributed elasticity of a deformable fish body undergoing large deformations and incorporates fluid-structure coupling effects, enabling self-propelled motion without prescribing kinematics. Preliminary open-loop simulations examine how actuation frequency and body stiffness influence the swimming speed and energy efficiency of the robotic fish. Closed-loop simulations further assess how stiffness distribution impacts the controller's velocity-tracking performance and energy efficiency. The results demonstrate the model's potential for performance evaluation and control optimization of soft robotic swimmers when stiffness is treated as a design variable.

翻译：受鱼类启发的仿生水下机器人因其高游动速度和高效推进能力而日益受到海洋机器人学界的关注，其柔性身体产生的波动运动是实现这些优势的关键。为支持此类系统的设计优化与控制，建立精确、可解释且计算可行的底层游动动力学模型至关重要。本文基于哈密顿原理，严格推导了电机驱动的仿生机器鱼全身动力学模型。该模型捕捉了可变形鱼体在大变形下的连续分布弹性特性，并融合了流固耦合效应，实现了无需预设运动学的自主推进运动。初步开环仿真研究了驱动频率与身体刚度对机器鱼游动速度和能量效率的影响。闭环仿真进一步评估了刚度分布对控制器速度跟踪性能及能量效率的作用。结果表明，当将刚度作为设计变量时，该模型在软体游泳机器人性能评估与控制优化方面具有显著潜力。