The Mechanism Design And Hydrodynamic Analyze Of An Underwater Robotic Glider

As a new kind of underwater robot, underwater biomimetic glider combines the advantages of robotic fish and glider together, which makes it not only can swim for a long time but also can increase its maneuverability and location accuracy. These characteristic makes the application of underwater biomimetic glider in the field such as water quality monitoring of rivers and lakes, sampling of underwater cylindrical region, etc..This dissertation proposed a new biomimetic glider with a caudal fin, which can realized the spiraling motion with small radius and steady gliding motion by the translating and rotating of internal mass, expanding and contracting of external leather bag, and offsetting of caudal fin. On this basis, the hydrodynamic model is established for the proposed biomimetic glider and the equations of steady spiraling motion and steady gliding motion of it also is obtained by employing the fluid mechanics theory. Then, by analyzing spiraling motion,the relations are given between the turning radius & vertical speed and the parameters including the centroid position of pitching adjustment mechanism, offset angle of caudal fin, and centroid rotation angle of rolling adjustment mechanism. Meanwhile, the ranges of original values of the six output variables, which correspond to each of steady spiraling motion, are also obtained. The analyze of steady gliding motion reveals the relations between the input parameters including the movable mass displacements, the location of non-uniform stationary mass and net buoyancy and the output variables including the swimming speed and pitch angle. The following contributions have been made.1. The underwater biomimetic glider is designed, which can be propelled by the caudal fin or by the buoyancy changing device, or by them together.2. The hydrodynamic model is established for the proposed biomimetic glider. Firstly, the transformation matrix among the ground coordinates, body-fixed coordinate and speed coordinate is obtained. Secondly, the kinematical equation of biomimetic glider is derived by using this transformation matrix. Finally, the hydrodynamics of biomimetic glider is presented by analyzing the forces and moments excerted on the biomimetic glider.3. The dynamical behavior of the underwater biomimetic glider is analyzed. By the proposed hydrodynamic model, the performance indexes and the conditions of the spiraling motion and steady gliding motion are analyzed and obtained.