Study On The Movement Characteristics Of Diving Beetle's Hind Leg And Design & Simulation Of The Bio-imitated Paddle Propulsion Mechanism

Micro-UUV is not only play an important role in civil field,such as marine disaster rescue,environmental information detection,marine geography research and etc.,but also has irreplaceable application value in military affairs.The bionic unmanned underwater vehicles through completely or partially imitating the shapes and motion patterns of aquatic organisms have become the research highlights at the recent years.They have the characteristics of high efficiency,low noise,flexible turning and good maneuverability.In nature,some smaller aquatic insects have evolved unique structures and motion patterns,and have extraordinary advantages in mobility,concealment,and flexibility,such as diving beetles,they are excellent bionic model for researching micro underwater vehicles.In this paper,we took the Cybister bengalensis with lager size as the research object,analyzed its configuration,structural features and its motion characteristics in the free-water environment.In combination with the joint mechanism of the hind leg of diving beetle,a simple bionic paddling mechanism was designed and the kinematics simulation was performed.The studies have been carried out as follows:The biological surface characteristics of the diving beetles were analyzed by stereo microscope and the ratio between the length of each joint of each leg and the length of the trunk of diving beetles was measured and calculated.F-test and T-test showed that the body structure of the diving beetle is symmetrical,and there is no significant difference in the length of each joint corresponding to the hind leg of the male and female diving beetles.An experimental environment was set up for testing the movement of diving beetles.We used two high speed camera systems and 3D motion image analysis system(Simi Motion)to study the motion characteristics and joint kinematics of the diving beetles in free water environment.During swimming,the forelegs and the middle legs produce almost no thrust and the thrust is mainly produced by the two powerful hind legs.It was found by analysis that in the process of the forwarding and retreating motion,the diving beetles simultaneously use both hind legs,and the movement of the hind legs is symmetrical.During turning,the movement of the two hind legs is not synchronized and the direction of rotation is determined by the hind leg which plays a major role.The angle of rotation is determined by the amplitude of the oscillation of the two hind legs.The femur has the largest range of changes in angles,and the angles of all parts of the tarsus are the same and the range of change is small.X-ray three-dimensional microscopy and mimics image reconstruction software were used to study the connection mechanism between the joints of the hind legs of the diving beetles and fond that they are mostly rotational joints.Neglecting the forelegs and the middle legs and simplifying the hind leg,a single leg mechanism was designed according to the diving beetle's movement pattern and the connection mechanism between the joints of the hind leg.Imported the three-dimensional model into ADAMS for motion simulation and fond that there is no problems such as interference between the rods occurred during the simulation process.Comparison of the trajectory obtained by simulation with the trajectory obtained by biological experiments showed that they have a high degree of similarity,which verified the rationality and feasibility of the design.Using a three-dimensional scanner and reverse engineering software to establish a biological model.A torso shape with a turbulent streamline was designed by extracting and optimizing the torso characteristic curve of the biological model.The complete machine with two legs arranged symmetrically was designed based on the symmetry of the diving beetle's body structure.Using ADAMS software to verify the feasibility and rationality of the whole machine that established by CATIA.