Design and optimization of the permanent magnet assembly for wall-climbing robots based on Halbach

SHEN Shunxi; CHEN Lizhi; TU Degui; CHEN Shudong; GUO Jinquan; ZHANG Liwei

doi:10.16579/j.issn.1001.9669.2025.11.016

Abstract：Aimed at the problems of unbalanced adsorption force and weight,severe magnetic flux leakage,and low adsorption efficiency of permanent magnet assemblies in traditional wall-climbing robots,to improve their magnetic adsorption performance on steel walls and meet the operation requirements in complex environments such as ships and tower drums,a study on the design and optimization of Halbach permanent magnet assemblies was carried out.N40M neodymium-iron-boron and Q235 steel were selected as the permanent magnet and yoke materials respectively,and a trapezoid-like Halbach permanent magnet assembly was designed.A yoke was added on the upper side to guide magnetic induction lines and reduce magnetic flux leakage,while no yoke was arranged on the side.Based on Maxwell's equations and the stress tensor method,a finite element simulation model of adsorption force was established.The control variable method was adopted to systematically analyze the influences of assembly length,width,thickness,and yoke thickness.Under size constraints,parameters were optimized via the nonlinear programming method of moving asymptotes(MMA)algorithm.Finally,a Shimadzu AGX-V2 tensile testing machine platform was built,loaded at a speed of 0.2 mm/s with equipment gravity deducted,to verify the simulation results.After optimization,the adsorption force was increased from 3 500.6 N to 3 755.3 N,with an increase of 7.28%.The test and simulation curves showed a consistent trend,and the maximum adsorption force deviation was 8.1%,which verified the accuracy of the simulation model and provided a basis for the optimization of the adsorption system of wall-climbing robots.