Design And Research On A Biomimetic Crucian Robot Actuated By SMA Wires

Compared with the traditional underwater robot driven by propeller, biomimetic fishes have higher efficiency, mobility and stability. However the current biomimetic robot fishes are noisy, angular and inefficient because of motors are widely adopted. With the advantages of simple structure, good flexibility, low noise, and easy to produce complex motion compared to the traditional motor, the adoption of smart material has become the development trend of robot fish driver.First of all, based on the research of morphology structure and swimming mechanism of crucian carp, we proposed an idea of biomimetic robot fish actuated by shape memory alloy(SMA) wires. According to the distribution of fish muscle we designed the driving structure of biomimetic robot fish. Then, the rigid front and flexible biomimetic tail of the robot fish are designed as a whole to realize the function of the biomimetic robot fish in the water.Furthermore, the control performance of biomimetic robotic fish can is analyzed theoretically, including mechanical analysis of flexible biomimetic tail bending. The relation equation between SMA wire bending stress, strain and the blending angle of fishtail are obtained through mechanics analysis, by introducing the SMA wire heating current thermodynamic equation and constitutive equation model used to describe SMA phase transition, the relation equation between maximum bending angle of fishtail and heating time, heating voltage, initial temperature.Finally, flexible tail fin and experimental platform are accomplished for flexible fishtail swing performance test. It includes swing angle test, symmetric test, blending time and recovering time test, heating mode test and propulsion force test. The result shows that when the swing angle is about 16° degrees the highest frequency can reach 1.4Hz, and when the swing angle is about 21°, the highest swing frequency is 0.8Hz and the maximum mean propulsive force is 0.041 N. Through the experimental comparison of the different frequency of the swing frequency, it is proved that the best performance of the swing frequency is 0.3Hz at swing degree of 25°. During swimming experiments, the maximum swimming speed is 0.28BL/s.