| More and more attention has been paid to the inspection of hydraulic structures as the reservoir DAMS gradually age.Research and development underwater robots to replace divers in underwater observation,detection,diagnosis and maintenance is the key work of reservoir dam management.The underwater inspection robot is designed with the ability of swimming in the water and crawling on the floor,in order to move flexibly in the Stilling Basin and detect accurately at the fixed point in the specific area of Stilling Basin Slabs.Design hybrid Crawler-Flyer underwater vehicle according to the requirements of testing stilling basin bottom plate.Design all parts of underwater inspection robot using modular design idea.The robot uses tracked mobile mechanism to cover the floor of the underwater structure,and can swim with six degrees of freedom through eight-propeller layout underwater.According to the depth of water in the working environment of the robot,the dynamic seal is designed.There is silt on the bottom plate of the stilling basin,and the water is turbid.Therefore,a detection device is designed to remove the sludge to take videos and photos of the Stilling Basin Slabs.The control box which can bear certain water pressure is designed,and its pressure resistance performance is simulated and checked by ANSYS workbench.The control system of the robot is also introduced.The six degree of freedom floating motion of the underwater vehicle is modeled and simulated.According to the characteristics of the robot's body structure and considering its stress,the dynamic model of underwater floating motion is established and simplified.The dynamic model needs restoring force and moment vector,thrust and thrust moment vector,water damping matrix and inertia matrix.The restoring force and moment vector,thrust and thrust moment vector are obtained from the underwater gravity and buoyancy of the robot and the thrust of the propeller.Based on the computational fluid dynamics(CFD)theory,the damping force and moment of 6-DOF motion are calculated by FLUENT software,and the damping matrix is obtained by fitting the hydrodynamic coefficient.The inertia matrix is obtained by calculating the additional mass coefficient by dynamic meshes.The dynamic modeling and Simulation of the robot's underwater crawling motion are carried out.The stability of the robot is analyzed in three situations: running on the flat ground,climbing up the slope and climbing down the slope,and the buoyancy space of the robot in stable motion is obtained.Recur Dyn,a dynamic simulation software,is used to analyze the typical motion of the robot.The robot can walk stably on the underwater flat ground,climb and climb down the 15 deg slope stably,and the robot can turn over the obstacles with the height of 50 mm.Finally,a prototype is used to carry out experiments.The pressure resistance and sealing ability of key components were tested.After the robot is assembled,experiments are carried out on land and underwater crawling.The robot was tested at the stilling basin.The results show that the sealing index and pressure resistance of the robot meet the requirements.The climbing and obstacle surmounting ability of the robot meets the design requirements.When the robot works,it takes an image of the stilling basin floor.The research and development of the robot in this paper provides a new idea for the detection of hydraulic structures,and has reference value for further improving the efficiency and accuracy of underwater detection of stilling basin slabs. |
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