Theoretical And Experiment Research On Magnetic Adhesion Device For Wall-climbing Robot Based On Halbach Array

For ferromagnetic surfaces, the adhesive ability of climbing robots with magnetic adhesion device is superior to the others. This kind of robots has the characteristics of energy conservation, no heat generation, noise free, simple configuration, safety and reliability, and low consumption. They are commonly in the applications such as nuclear industry, petrochemical industry, power plant, dockyard, etc., and perform the special tasks of manufacture and maintenance, which would gradually deal with these dangerous works instead of human beings. Therefore, they have a wide application value and have been provoking high attention by a variety of domestic and foreign research institutions. Magnetic adhesion mechanism is the core of climbing robots in magnetic adhesion solusion. In nowadays, the two issues are always existed as research hot spots and difficulties as follows:one is that how to increase the utilization ratio of magnetic materials by the reasonable design of magnetic circuit, and the other one is that how to solve the problem of large magnetic force easily to adhere to the surface but hard to detach from it. By taking the magnetic adhesion mechanism as the research object and the climbing robot in magnetic adhesion solution as the research background, the dissertation discusses in detail about the design of reasonable magnetic circuit, the establishment of mathematic model, the optimization analysis and the experiment research, which is in order to solve the two problems and provide theoretical and experimental basis for development of robot.Firstly, the basic structure model of wheeled climbing robot with non-contact magnetic adhesion is established on application purpose. This kind of robot has three characteristics as follows:Firstly, the structure of permanent magnetic adhesion mechanism is simple and its performance of adhesion is reliable. Secondly, the non-contact adhesion mode can decrease the motion resistance of robot, which can accordingly increase its motion flexibility. Thirdly, the wheel-driven locomotion is simple in structure, flexible in motion and easy for control. Then the rule of robot adhesion and movement on surface is analyzed by theoretical derivation and simulated calculation. In addition, the minimal allowable adhesion force of magnetic adhesion mechanism had to be provided and the general requirements of the reasonable design of adhesion device are obtained.Secondly, according to the requirements above mentioned, based on the magnetic congregate technique and requirements of magnetic route structure of magnetic adhesion mechanism on robot, and considering the advantages and disadvantages of Halbach array, the novel magnetic adhesion configuration with linear Halbach array is proposed in the dissertation. The novel configuration is composed of linear Halbach array, soft iron and rotating axis. The soft iron fixed on the cancelled side and two end sides of the array resolves the problems of non-zero flux on the cancelled side and ends effect. The operating and non-operating state is come into being when the enhanced and cancelled side of array is in the face of ferromagnetic surface respectively. The rotating axis can be rotated around the middle axle driven by motor so that the magnetic force could be adjustable.Thirdly, in order to considering the characteristic of materials and magnetic flux leakage, by using the finite element method, the two-dimensional magnetic field model is established and the rule of influence on magnetic adhesion performance by the structure parameters of soft iron, the segment number per wave length and the size of array is studied. Furthermore, by compared with pure linear Halbach array, traditional arrangement of magnets and adhesion mechanisms with adjustable magnetic force, it is shown that the performance of the novel configuration is the best.Fourthly, considering the convenience to solve the multi-objective optimization problem of magnetic adhesion device and the defect in existent immune genetic algorithm, a new improved immune genetic algorithm for multi-objective optimization (MOIIGA) is proposed. Then the optimal structure parameters of magnetic adhesion mechanism are obtained by using MOIIGA.Finally, the magnetic field in space and air gap of the adhesion device, the magnetic force and the adhesion performance of the climbing robot are measured. The results prove the correctness of theoretical analysis and optimization of the adhesion mechanism and the practical feasibility of the mechanism applied to the climbing robot.