Regulating Control And Experimental Researches On Propulsion For Bionic Robotic Fish

The caudal fin propulsion modes represented by amberfish are of great significance for developing the bionic underwater vehicles. By choosing the crucian as the bionic experimental subject, the studies in this paper observe the crucians’ different gestures in different water flow environment and are inspired by the modes switching. This paper puts forward the methods for controlling the modes switching of the present propulsion equipment based on the bionic inspiration. By analyzing the motion control, researching of modulating algorithm and performance optimization and experimental verification, this paper develops the following achievements and progress:1. The observation experimental system in which the water flow environment can be tuned was built; and the observation experiment on the bionic subject was performed by setting different water flow environment; and then, motion characteristic parameters related to changeable environment were extracted. The experimental phenomenon shows that there were different swimming behaviors of crucian in different environment; and the extracted parameters verified the results from the observation experiments. The experiment phenomenon and the data analysis showed that there were the adaptive behaviors of fish in different water flows and it’s a smooth and soft switching process between different modes, which supplied the evidence to improve the multi-joint equipment’s motion in complex water flow environment.2. In connection with the bionic inspiration from the soft switching process of fish, this paper studied the disadvantages existing in the equipment. By choosing the example of four-joints robotic fish, the study brought forward the forward and back ward motion model. The relative algorithms for two models, keeping the wave and signals smooth and continuous, were proposed from the aspect of motion control. The simulation results verified the effectiveness of the adapting algorithm and set up the basis of controlling the multi-joints robotic fish.3. From the point of view from the biological neuron, a bionic neural network was proposed based on the Hopf oscillators to realize the motion control of the robotic fish. The proposed model had the advantages of easy adjacent relationship and convenient engineering applications which needed the smooth transition between different modes. Analysis was done about the influence of the parameters in the model on the switching speed. Based on the characters of fishes’ physical mechanism, a bionic neural network composed of coupled oscillators was built up to mimic the tail swing behavior, pectoral fin swing behavior and the cooperating behavior of two fins. Simulation results show that the networks based on the oscillators can produce the needed smooth and continuous signals.4. The pre-existing multi-joints robotic fish and the simulated robotic fish designed were carried out to verify the switching process of different modes. Experiments verified the effectiveness of modulating algorithms from three aspects of wave, driven signals and the bionic networks. The algorithms improve the abrupt phenomenon of joint during changing the motion parameters.All the above works and achievements offer the significant exploration about the robotic fish adapting to the complex environment and set up basis of realizing the function of robotic fish sensing the environment and automatic control.