Aiming at the problem of spanwise deformation during the operation of oscillating hydrofoils, this study adopts the computational fluid dynamics (CFD) method. Based on the k-ω turbulence model under the simulation condition of Reynolds number N_Re=150 000, a user-defined function (UDF) is utilized to control the spanwise deformation, so as to investigate the influence of different spanwise deformation degrees on the hydrodynamic performance of the oscillating hydrofoil with a twin-support configuration. By actively controlling the spanwise deformation of the hydrofoil and combining different deformation coefficients, the flow field simulation of the oscillating hydrofoil and the calculation of hydrodynamic coefficients are carried out, and the evolution laws of the pressure distribution on the hydrofoil surface and the vortex shedding characteristics are analyzed simultaneously. The computational results indicate that: spanwise deformation affects the shedding of spanwise vortices on the pressure side and the formation of vortices on the suction side of the oscillating hydrofoil, thereby altering the pressure distribution along the spanwise direction of the hydrofoil; compared with the rigid hydrofoil (α=0), the energy extraction efficiency of the oscillating hydrofoil with spanwise deformation decreases by 2% to 5.8%, and the efficiency reduction amplitude increases with the increase of the deformation coefficient α. When α=1.5, the system power coefficient decreases by 5.4% compared with that of the rigid hydrofoil, indicating that the spanwise deformation degree exhibits a significant negative correlation with the energy capture performance. In engineering applications, methods such as material selection should be adopted to suppress the spanwise deformation of the hydrofoil, thereby achieving the optimal overall performance of the device.

The advantages of fish such as high propulsion efficiency, strong maneuverability and low environmental disturbance have sparked extensive research on bionic robotic fish by both domestic and international scholars. The basic-level gait control method and closed-loop motion control method are currently two hot topics in research on robotic fish control. According to the propulsion mode classification method, this paper summarizes the prototype development and performance of various robotic fish, introduces the research progress of the propulsion mechanisms and hydrodynamics of robotic fish, focuses on two basic gait control ideas, namely the trajectory approximation method and central pattern generator（CPG）, and summarizes the typical closed-loop motion control method. The CPG method has stronger flexibility, stability and operability, and it is easy to introduce feedback items and achieve closed-loop control, for which it plays a leading role in the basic gait control of robotic fish; while the improved learning-based control method and hybrid control method combining multiple methods based on the significant characteristics of robotic fish have broader development prospects, which is in line with the development direction of intelligent biomimetic robotic fish. Establishing a reasonable gait control system and an accurate and efficient closed-loop motion control system based on working conditions and motion requirements is the key to improving the overall performance of robotic fish.