Research On Motion Control Of Bionic Robotic Fish Based On Sliding Mode Control Mechanism

The demand for resources is keeping increasing with the rapid development of social economy,which lead to the gradual depletion of land resources.Thus,many researchers began to explore and develop the ocean,lakes and rivers for their abundant mineral resources reserves.As a new type of autonomous underwater vehicle,bionic robotic fish realizes motion by simulating the propulsion of fish,which not only has excellent maneuverability and flexibility like fish,but also has the characteristics of simple structure,low noise and low impact on the environment.The difficulty of the research on the bionic robotic fish lies in complexity of dynamic model,high nonlinearity of the system and the numerous external disturbance.In order to improve the dynamic model,the control accuracy and response speed of the robotic fish system,the deep researches on dynamic model optimization and second-order sliding mode implementation for robotic fish system have been carried out in this thesis.Firstly,the basic dynamic model of steering motion is analyzed and established.Then,the novel dynamic model of head-yawing on steering motion is proposed and established,and the data-assisted method is applied to optimize the steering dynamic model of robotic fish.Secondly,the discrete-time super-twisting-like control strategy(DTSTC)is adopted to overcome the nonlinear influence and the interference caused by the complex external factors in the robotic fish system.In addition,an improved DTSTC is further proposed to effectively improve the control accuracy.Finally,aiming at verifying the accuracy and effectiveness of the proposed control strategy,three set of comparison experiments have been conducted based on the completed robotic fish control system experimental platform with comparison of existing controllers.The experimental results show that the bionic robotic fish steering dynamic model based on the data-assisted method and considering the head-yawing established in this thesis can effectively improve the model accuracy and perfect the system model.Moreover,the proposed DTSTC not only overcomes the nonlinear effects in the system,circumvents the drawback of traditional discrete-time sliding mode,but also increases response speed and control accuracy of the robotic fish system.