The Overall Structure Design And Swimming Simulation Analysis Of Amphibious Bionic Mechanical Crab With Underwater Gliding

With the further study of modern bionic robots,amphibious bionic robots have attracted much attention for their strong environmental adaptability.As a shoal amphibian,the biological sea-crab can crawl in land and swim in water,which has excellent sports ability.This work was supported by the National Natural Science Foundation of China,which taking sea-crabs as bionic objects to make a prototype of an amphibious bionic mechanical crab,with the premise of realizing the amphibious movement,which integrating the gliding function of the water.Current work includes overall structure design,underwater glide system research,underwater dynamic simulation and prototype experiments.The thesis carried out the following research work:First of all,according to the research and analysis of the physiological structure of biological crabs,the biological sea-crab have the underwater gliding structure,the paper is put forward the overall structural scheme of the amphibious bionic mechanical crab,including the detailed design and strength of the module such as the body,walking feet,swimming feet,waterproof electronic box,buoyancy adjustment system cabin Checked,and formulate an underwater sealing scheme for the mechanical crab to meet the waterproof effect under the target depth.The analysis of the degrees of freedom and stability of the mechanical crab are based on this scheme.After established a complete model of a mechanical crab by Solid Works,set the materials of each component,calculate its total weight and total buoyancy,and obtain the coordinate information of the center of gravity and the center of buoyancy,which have good guide-effect for further research and experiments.Secondly,the paper is put forward the design idea of amphibious bionic mechanical crab fusion underwater glide system,introduced the mechanism of mechanical crab underwater glide,and designed the scheme of underwater glide system.By comparing different buoyancy adjustment methods,the paper is put forward the detailed design and layout of the buoyancy adjustment system,and the simulink model was simulated according to the buoyancy adjustment scheme to obtain system parameters,then verified the stability of the system,and provided reference for further research and experiments.Put forward and discussed the feasibility of walking foot as the center of gravity adjustment mechanism and gliding wing at the same time.Analyzed the relationship between the pitch angle of mechanical crab and the rotation angle of walking foot.Through the analysis of the mechanical crab's stable glide motion under water,can obtain the relationship between the state parameters(angle of attack,pitch angle,glide speed,horizontal speed)and the controllable amount(offset of gravity center adjusted by walking foot,net buoyancy mass).Based on the mechanical crab prototype model,the situation of the swimming foot was analyzed,and the fluid simulation of the mechanical crab swimming was performed by using CFD numerical analysis software to obtain the flow field change of the mechanical crab swimming foot at the set 1Hz swing frequency.The slice method divides the flow field.Combined with the vorticity cloud map in the swinging cycle of the swimming foot,analyze the generation mechanism of the tail vortex structure on the hydrodynamic characteristics at different times,and the main cause of the mechanical crab's propulsive force from the perspective of fluid mechanics,then obtain the relationship between propulsion and lateral force.The simulation results show that the mechanical crab swims in the water in a straight line,which can obtain a continuous forward force,which is in keeping with the expected analysis results.Finally,on the basis of the above research,an amphibious bionic mechanical crab prototype was made,and an experimental platform was built to test the prototype structure,the buoyancy adjustment cabin tightness,the buoyancy adjustment system work,the horizontal and vertical movement of the land,the swimming situation in the water,and the switching between the water and land state.Experiments were carried out to verify the correctness of the theoretical and simulation analysis,combined with technical indicators to verify the prototype performance of the amphibious bionic mechanical crab,prepared for subsequent research.