# Magnetic Field Analysis and Optimization of the Gauge of Hybrid Maglev Needles
## 1 Introduction  
The computerized flat knitting machine is a very important textile equipment in the textile industry, mainly used for knitting sweaters and medical textiles. The needle drive system is an important part of it, which is related to the quality of textiles [1]. The traditional knitting machine uses a cam inside the machine head to push the needle in the needle slot to complete the knitting process [2]. During the operation of the equipment, the heel of the knitting needle often breaks due to poor lubrication, which in turn affects the quality of the fabric. In addition, the traditional cam drive needle has problems, such as vibration, noise, heating and wear. Therefore, some researchers have proposed a hybrid magnetic levitation needle array drive structure [3; 4; 5]. Hybrid magnetic levitation is a hybrid electromagnetic and permanent magnetic structure, which used an electric coil to generate an electromagnetic field. The repulsive force generated by the electromagnetic field and permanent magnet suspends the knitting needle. This structure can avoid the collision caused by mechanical transmission, so as to eliminate the related vibration, noise, and wear. However, the existing structure also has some defects. For example, when a hybrid magnetically levitated needle is driven, the spatial magnetic fields between the permanent magnet needles interfere with each other [6]. The smaller the gauge of the permanent magnet needle, the greater the magnetic disturbance; therefore, the permanent magnet needle drive cannot be stably controlled.  
Magnetic field interference situations are common in electronic devices [7; 8]. This can lead to energy loss, electromagnetic radiation, equipment that is difficult to control, etc. Shielding is the key to solving magnetic field interference [9; 10]. Magnetic field shielding is used in a wide range of applications, such as transmission circuits, electric vehicles,electronic components, and aerospace [11]. At present, with the development of material technology, some nano-materials with magnetic field shielding characteristics have been developed [12; 13; 14]. Woven products with electromagnetic shielding effects have also been developed in the textile field [15]. However, the cost of these materials is high.  
The driving structure of a hybrid magnetic levitation needle array has small needle spacing and a large number, which challenges the structural optimization of avoiding excessive magnetic interference between permanent magnetic needles. In this paper, through the analysis of the driving performance of a magnetic levitation needle array, the driving structure of the magnetic levitation needle array is optimized by using silicon steel, a high-permeability material, as the shielding material of the magnetic field. This material has the advantages of a low core loss, high magnetic induction strength, good insulating film performance, and low price. Finite element and experimental methods are used to analyze the effect of different silicon steel thicknesses on magnetic field shielding. The research results are of great significance in terms of enriching the design results of magnetic levitation needle array drive structures and proposing a more reasonable magnetic levitation needle array drive structure. The results of this paper can also provide a reference for the design of other similar projects.