The Study On The Motion Control Of Bionic Robotic Fish With Two Degrees Of Freedom Pectoral-Fin And Tail-Fin

Biomimetic robotic fish has played an important role in the field of robot since it has wide prospects in many applications such as surveying the ocean,ecological monitoring,military surveillance,entertainment,etc..Up till now,the method of sinusoidal controller and the method based on the central pattern generator is one of the main control methods.Based on the CPG motion control,the control signal will not be mutated due to the modes switch softly.Because of the flexibility and stability,the method based on the CPG is widely used and in-depth researched in the field of the robotic fish.In this paper,the motion control of the bionic robot fish with two degrees of freedom pectoral-fin is studied.The main contents are as follows.(1)The CPG control network should be build based on the driving mechanism of the robot fish.The swimming models of swimming forward,swimming backward and swerving are come true.The velocity of swimming forward in resistant/lift model is 0.18m/s and 0.15m/s respectively.The angular velocity of swerving is 50°/s.Simulations and results of the experimental validate the feasibility of the CPG model and the gliding property of the CPG control methods.(2)The hydrodynamic analysis was performed to construct the hydrodynamic model based on the two degrees of freedom pectoral-fin.The hydrodynamic analysis results are used as the adaptive value function.In order to increase the moving capability,PSO is used to optimize the parameters of the fin's CPG controller.The linear speed can reach 0.2106m/s and the turning angular velocity can reach 87.40390/s.after the Optimization.The results of the hydrodynamic analysis and PSO are combined to analyze the effects of the CPG parameters on the robot fish.Experiments can verify the correctness of the optimization.(3)There are two main reasons for robot fish wall following direct swimming closed-loop control system can be build which can be used to control the direct swimming process of robot fish precisely.Firstly,the movements of the pectoral-fins and Tail-fin are independent,but effects of them can be superimposed on each other.Secondly,the method of CPG has the characteristics of smooth.The angle error and displacement error are used as feedback information which are collected by the MPU6050 gyroscope and HC-SR04 ultrasonic range finder.Feedback functions are build based on the feedback information.According to the experiment,the closed-loop control system is effective.The displacement error is within ±10cm,and the angle error fluctuates within ±20°.