| Large steel structures,such as steel frame Bridges,large storage tanks,ships and lifting machinery,are prone to loose connection,surface corrosion,fracture and other phenomena when they work under heavy loads in harsh environments for a long time,leading to capsizing and collapse.At present,the defect detection of large steel structures mainly relies on manual labor,but the work intensity of manual detection is high and there are safety risks.Therefore,it has become an inevitable trend to use wall-climbing robots to replace manual defect detection.Currently,there are few wall-climbing robots that can be put into use,and wall-climbing robots at home and abroad are still in the laboratory research and development stage.Most of the wall-climbing robots under development can only crawl on a single wall without wall transition ability,but there are many complex wall surfaces in the actual working environment of the robot.Secondly,most of the wall-climbing robots under development are difficult to achieve the unify of mobility and adhesion,and the adhesion force generated by the wall adhesion device will become the resistance of the robot.In view of the above problems,this paper proposes an electromagnet on-and-off circulation mechanism,and based on this mechanism,a crawler-type wall-climbing robot with transition ability is developed.The specific research is as follows:(1)Development of electromagnet on-and-off circulation mechanism and wall transition mechanism.In this paper,the development of an innovative electromagnet on-and-off circulation mechanism is carried out.By turning on-and-off of the electromagnetic adhesion unit,the robot can realize the unify of mobility and adhesion.A wall transition mechanism is also proposed.Through the meshing between spline gears and different internal gears,the robot can perform internal and external transitions.On this basis,this paper uses SOLIDWORKS three-dimensional modeling software to design the mechanical structure of the robot,and uses ANSYS finite element software to check the strength of key parts.(2)Force analysis of the wall-climbing robot.In the force analysis of the robot’s static state,by analyzing the robot’s working state at the critical point of sliding down,vertical overturning and lateral overturning,the minimum electromagnetic adhesion force generated by a single electromagnet is calculated to be 63.7N.In the force analysis of the robot’s motion state,by analyzing the robot’s upward crawling,internal transition and external transition motion,the minimum driving torque generated by the decelerating servo motor is calculated to be 13.84N·m.(3)Design and optimization of the electromagnet.First of all,empirical formulas are used to design the electromagnet,and the parameters of the electromagnet are determined preliminarily.Then COMSOL Multiphysics finite element software is used to simulate the electromagnetic field of the electromagnet,and the key parameters of the electromagnet are optimized.The electromagnetic adhesion force generated by the optimized electromagnet can reach 107.6N at most,which meets the design requirement.Based on the above research,a robot prototype is manufactured and the wall adhesion,steering and wall transition experiments of the robot are carried out.The wall adhesion experiment results show that the robot can be reliably adsorbed on different inclined steel walls,which proves that the electromagnetic adhesion force generated by the electromagnet meets the requirement of use.The results of steering and wall transition experiments show that the robot can steer flexibly and complete internal and external transitions,which verifies that the torque provided by the motor meets the requirement of use and the feasibility of the structure principle of each mechanism.In summary,the wall-climbing robot developed in this paper achieves the unify of mobility and adhesion,and is able to perform internal and external transitions.The robot will have good application value in the inspection of large steel structures. |
PDF Full Text Request