## 1 Introduction  
China is the largest coal producer and consumer in the world according to the World Energy Annual Report in 2018. In 2017, China produced 3523 million metric tons of coal, accounting for 46% of the world's coal production, and China's coal consumption accounts for 51% of the world's coal consumption. This also led to China becoming the country with the most coal mine accidents and highest number of mining injuries and deaths, especially because \(>\)90% of China's coal is produced in underground coal mines [1]. In view of the above problems, China is implementing intelligent mining technology in coal mines nationwide [2; 3]. The goal of intelligent mining technology is to realize highly automated and efficient mining through intelligent sensing of the mining environment, intelligent decision-making, and automatic control of mining equipment [4; 5]. Through automated and intelligent technology, miners can be transferred from the dangerous working face to the roadway or to the ground to work during the mining process, thereby greatly reducing casualties [6]. Currently, mechanization of coal mining equipment has been realized in most coal mines in China, but the automation and intelligence level of coal mining needs to be improved [7; 8]. To achieve intelligent mining, it is necessary to deploy highly automated mining equipment at the working face [9]. The main equipment at the working face includes the shearer, hydraulic supports, and a scraper conveyor, with the shearer being the most important component. The shearer is the piece of equipment used for coal cutting and loading at the working face. During the mining process, the shearer runs on the track of the scraper conveyor, and the coal is transported to the roadway on the scraper conveyor. The hydraulic supports support the roof and isolate the goat to provide working space for the shearer and scraper conveyor. The equipment layout of a typical fully mechanized mining face is shown in Figure 1.  
Accurate position information of the shearer is the key to realizing automatic coal cutting and hydraulic support automatic shifting, and it is also the key to realizing shear memory cutting and adaptive cutting [10]. Therefore, precise positioning of the shearer is one of the most important technologies in intelligent mining. However, because most coal mines are underground in China, conventional ground positioning methods, such as radio navigation, satellite positioning, and astronomical navigation, cannot function [11; 12]. Conventional shearer positioning methods, such as infrared radiation, ultrasonic reflection, gear counting, and wireless sensor network methods, do not meet the accuracy requirements for automated mining [13; 14]. To achieve precise positioning of the shearer, a strapdown inertial navigation positioning method is proposed in this article. Strapdown inertial navigation system (SINS) is a navigation system in which inertial devices are directly fixed onto the running carrier. The angular velocity and acceleration of the running carrier are measured by a gyroscope and an accelerometer, respectively, and, when these are combined with the initial inertia information of the running carrier, navigation information such as the speed, position, course, and attitude can be obtained by calculation [15; 16]. SINS was developed on the basis of the platform inertial navigation system (PINS), which uses a mathematical platform instead of a physical platform, and has no complicated frame structure nor servo system. Compared with the traditional navigation system, SINS has the advantages of its light weight, small size, low cost, and high reliability [17]. Moreover, owing to the emergence of inertial devices such as laser gyros and fiber optic gyros, the rapid development of computer technology, and improvements in computational theory, the advantages of strapdown inertial navigation systems are more prominent. SINS can then be applied to the localization of the shearer in the coal mine environment [18]. [PERSON] et al.