Research On Multi-objective Optimization Method Of Displacement Sensors For Valves

LVDT(Linear Varizble Differential Transformer)is based on the principle of electromagnetic induction to measure displacement,with the advantages of high accuracy,large range,small volume,high pressure resistance,high temperature resistance,etc.It is widely used in the hydraulic system of construction machinery,and its performance has an important impact on the detection accuracy of the system.This paper takes displacement sensor for hydraulic valve as the research object,based on the performance requirements of small volume,long stroke and high accuracy of LVDT for orifice independent high flow hydraulic valve,multiobjective optimization study of displacement sensor for valve is carried out by improved NSGA-Ⅱ algorithm,and the optimization results are verified by simulation calculation and experimental test method.The results show that the linearity of the displacement sensor for valve designed by the improved NSGAⅡ algorithm reaches less than 0.2%with high sensitivity,which meets the requirements of high-precision high-flow orifice independent hydraulic control valve,the main research of this paper is as follows:For the problem of easy local convergence of the classical NSGA-Ⅱalgorithm,an improved NSGA-Ⅱ algorithm is proposed and used to solve the multi-objective optimization model of LVDT with its improvements,using a partitioning strategy for the parents and selective genetic operations for the parents after the partitioning;using an improved SBX crossover operator to introduce a new factor for the direction of variation.For the improved NSGAⅡ algorithm,the ZDT series test functions are used for experimental validation,and diversity,convergence,uniformity,and comprehensive performance metrics are selected to analyze its feasibility and effectiveness.A multi-objective optimization model of the LVDT for valve is established,and the optimized structural parameter matching group of the LVDT displacement sensor is obtained by applying the improved NSGA-Ⅱ algorithm with linearity and sensitivity as the optimization objectives and structural dimensional parameters as the constraints.According to the multi-objective optimization results of the improved NSGA-Ⅱ algorithm,Maxwell electromagnetic simulation software is applied to equivalently model the LVDT for valve,and the electromagnetic field simulation analysis is carried out between the optimized model and the original model to compare and analyze the magnetic field distribution and output characteristics of both,and the results show that the linearity of the optimized model becomes smaller and the sensitivity is improved,indicating that the design of the LVDT for valve by multi-objective optimization is more reasonable.The design of the LVDT with multi-objective optimization is more reasonable and the input and output indexes are good.Based on the research results,the prototype LVDT for valve was designed and prototyped,and experimental tests were conducted.A neural network is also used to correct the nonlinearity of the valve LVDT and optimize the output characteristics.The research results of this paper can provide some reference value for the optimized design of displacement sensors for valves.