Modeling and control on hysteresis nonlinearity in biomimetic undulating fins

In this paper, biomimetic undulating fins are considered with the focus on their hysteresis nonlinearity. Hysteresis is confirmed with experimental data on the biorobotic fin prototype, and qualitative modeling on this nonlinear action is then achieved by using Preisach equations. The developed iterative learning control is applied to eliminate hysteresis nonlinearity in biorobotic undulating fins. Both the simulation and experimental results show that the proposed control method is effective and feasible to improve the tracking performance of biorobotic fins by considering the hysteresis effect. Furthermore, the control methods should facilitate biomimetic investigation on propulsive modes and waveforms of fish swimming.