## 1 Introduction  
Industrial fabrics with extra-large width (12 m and above) have overall strength consistency, can enhance the protection of dams, mountains, and coasts, and can be used in fields such as flood resistance and tsunami resistance. High-speed weft insertion is a key prerequisite for the production of extra-large width fabrics. The existing regular size automatic weaving equipment is divided into two types: shuttle weft insertion and shutteless weft insertion. Compared with the shuttle weft insertion, the shutteless weft insertion does not need to fly with the weft clamp. It has the advantages of high weft insertion speed and low noise caused by the weft insertion movement. In the case of shutteless weft insertion, the loom can be divided into: air jet loom, water jet loom, rapier loom, and projectile loom. The first three looms have a width of 1.9 to 4.0 m [1, 2, 3]. The projectile loom has a wider door width, up to 5.4 m or more [4], but due to the limitation of the torsion shaft structure material, the weft insertion flight length is difficult to reach the requirement of extra-large width. Therefore, realizing the stability, reliability, and high-speed weft insertion of the extra-large width high-speed automatic loom is an urgent problem that needs to be solved in the high-speed weaving equipment of industrial textiles. In order to meet the needs of different weft insertion, much research has been carried out at home and abroad. For example, in order to reduce the energy consumption of air-jet looms, a new weft insertion method of main nozzle + weft insertion piece is proposed [5],as well as a new three-dimensional cylindrical fabric forming weft insertion method [6], and a magnetoelectric weft insertion device designed for the defects of shuttle looms [7]. In spite of the innovation and improvement of various weft insertion methods, in the weaving of extra-large width industrial textiles, the existing weft insertion methods cannot meet the requirements of long-distance weft insertion. In recent years, electromagnetic launch technology which has many characteristics such as good controllability, high safety and reliability, high energy utilization, and reusability, has been widely used in missile launches, take-off catapults, and industrial production, and is favored by many industries [8]. In the study of electromagnetic launch weft insertion mechanism, Japan proposed the electromagnetic shuttle insertion scheme of the loom in 1977 [9]. [PERSON] et al. explored the influence of launcher parameters on projectile velocity [10], and proposed an adaptive neuro-fuzzy system that can quickly calculate the dynamic parameters of the weft insertion process [11]. [PERSON] proposed a magnetic weft insertion system based on electromagnetic force, and designed and made a weft insertion model [12]. [PERSON] introduced a new weft insertion method that combines the advantages of traditional weft insertion methods while avoiding the problem of excessive energy consumption in the past. It is based on the principle of magnetic force to control the delivery of weft yams [13]. In the literature [14], we found that the launch performance is best when the length of the accelerating coil is the same as the length of the ferromagnetic weft gripper. During the acceleration process in a single coil, the electromagnetic force received by the ferromagnetic weft gripper shows a tendency to increase first and then decrease. In order to further improve the work done by electromagnetic force, this paper proposes a continuous acceleration electromagnetic weft insertion method. By changing the energization mode of the multi-stage segmented coil, the range of the peak electromagnetic force received by the ferromagnetic weft clamp is extended to realize high-speed weft insertion. This method has the potential to prepare extra-large width fabrics.