Gait generation and sliding mode control design for anguilliform biomimetic robotic fish

In this paper, different locomotion patterns design and measures to resist parameter uncertainties are presented for a biomimetic robotic fish. The Anguilliform robotic fish consists of N links and N - 1 joints, and its dynamic model is given in previous work [1]. Using this model, three major gaits of Anguilliform fish-forward moving, backward moving and turning-are investigated. We find that by giving different reference angles of joints, such as adding reversed phase difference, or adding deflections to the original reference angles, the fish exhibits different locomotion patterns. Furthermore, we adopt sliding mode control (SMC) to attenuate the impact from parameter uncertainties. Results of numerical examples validate the effectiveness of SMC. Comparison of those results shows that SMC works better than traditional computed torque control when performing the tracking task in joint space.