English Classroom Immersive Teaching Based on Digital Twin Technology

. In order to improve the effect of English classroom teaching, this paper builds an immersive teaching model of English classroom based on digital twin technology. Moreover, in order to reduce the cost of the system, simplify the system structure, and enable learners to observe the stereoscopic display image with the naked eye, this paper builds an immersive hemispherical projection teaching system, designs the overall structure of the system and various components of the hardware, and studies the projection image predistortion algorithm. In addition, this paper uses the immersive experience between virtual reality technology and immersive teaching as a connection point to design an immersive teaching based on VR and apply it to teaching practice to test the effect of immersive teaching, and perfect the immersive teaching design model based on VR. Finally, this paper designs an experiment to verify and analyze the performance of the system. From the experimental results, it can be seen that the English classroom immersive teaching model based on digital twin technology constructed in this paper is effective.


Introduction
The rapid development of science and technology has a huge impact on people's production and lifestyle. In order to better adapt to the development of society and their own needs, the improvement of scientific literacy is particularly important. As the main way to improve scientific literacy, science education has become more and more important. Relevant departments have proposed that the reform needs to pay full attention to the vital role of information technology in the development of educational English teaching, accelerate the construction of educational informationization, and add high-quality resources and advanced technology to the current education system to promote the modernization of educational content, English teaching methods. Scientific spirit is one of the core qualities of talent training in the new century, and the study of science courses in colleges and universities is the first step to become scientific and technological talents. At present, China's science education has made a lot of progress in curriculum construction and practice. However, due to many reasons, Chinese science education still has problems in English teaching methods and English teaching content, which hinder the development of science education and the improvement of scientific literacy to a certain extent. Moreover, in the current social environment of rapid development of information technology, these problems are increasingly exposed [1]. Therefore, the use of advanced information technology to improve English teaching methods to make up for the deficiencies in traditional English teaching is becoming the research frontier in the field of educational English teaching. Moreover, the integration of immersive virtual reality technology into college science classrooms can enrich the English teaching situation and improve English teaching methods, thereby stimulating students' interest in learning and improving the quality of educational English teaching [2].
The current science curriculum lacks standard systemicity and completeness, and has high requirements for teachers. Therefore, science classrooms need to create a real English teaching environment for learners, and use learning resources to stimulate students' interest in learning. The traditional science classroom is mainly based on teachers' PPT courseware and video materials, and the English teaching form is single. It is difficult for students to master abstract scientific knowledge in the classroom, which leads to a decrease in interest in learning [3]. In addition, the smooth development of the experimental inquiry link largely determines the quality of English teaching in science courses, so the lack of experimental equipment is also a major problem in science education. In particular, due to insufficient education funds in remote areas, it is impossible to purchase the basic equipment needed for experiments, resulting in students not being able to experience the fun of scientific knowledge, thereby reducing their interest in learning. Therefore, due to the problems of English teaching methods and English teaching resources in the English teaching process of science courses in universities, the current level of science education in my country's universities is not high, which hinders the development of science education in my country. In order to better develop science courses and improve the shortcomings in traditional English teaching, education researchers gradually try to use new technical means to assist the development of learning activities. Virtual reality technology makes learners feel as if they are in the real world and get a real learning experience through various technical means such as computer three-dimensional technology, interactive technology, man-machine interface technology. The ease of operation of virtual courseware enables teachers to improve the English teaching methods of science courses and enrich courseware resources while effectively increasing students' interest in learning and completing English teaching content more efficiently.
Based on the above analysis, this paper uses digital twin technology to construct an English classroom immersive teaching model, analyzes the corresponding hardware and software structure, and combines experiments to verify it, so as to reform the traditional teaching model and improve the effect of college English teaching.

Related work
Virtual Reality (VR for short) has gradually entered people's daily life and work, and Oculus-based immersive virtual reality has achieved fruitful application results in medical, construction, education, and entertainment applications [4]. In the next 2-3 years, virtual and remote laboratories will be the key technology to solve the contradiction of deep learning [5]. In the field of education and teaching, virtual reality technology breaks the traditional learning methods, enables students to interact with each other in a virtual environment, and makes up for the shortcomings of interactivity, contextuality, and immersion in traditional classrooms [6]. The idea of "virtual reality + education" is being realized step by step, and the new education and teaching mode V-1earning based on virtual reality technology is about to enter people's field of vision. Moreover, virtual reality has been continuously improved and developed in practice since its birth, and its application fields have gradually expanded. At the same time, virtual reality technology in the military, aerospace, and aviation fields can enable trainers to conduct military exercises as if they are in actual combat, thereby improving the ability of coordinated operations [7]. In terms of environmental industrial design and manufacturing, the use of virtual reality technology can provide technical support for various stages of product design and production, and determine the quality and performance of the product in a simulation environment, thereby saving a lot of manpower and material resources [8]. In addition, there are also signs of virtual reality in the entertainment and art fields such as virtual museums and virtual opera houses. With the widespread use of virtual reality technology, researchers and workers in the field of education have also begun to try to apply virtual reality technology to the field of education and teaching. According to existing research findings, virtual reality technology can improve learners' learning interest and learning motivation, and cultivate learners' practical operation and innovative thinking ability [9]. Moreover, the three characteristics of immersion, conception and interactivity of virtual reality technology can enable the experiencer to get the same feeling in the virtual reality environment as the natural environment [10]. The key technology of traditional virtual reality lies in data acquisition technology, modeling sensor technology, interactive technology and tracking technology. However, immersive virtual reality mainly uses environment modeling, stereo synthesis and stereo display technology, and it combines tactile feedback technology and positioning interaction technology in the new era to improve the user's sense of reality and presence [11]. Immersive virtual reality is a derivative of virtual reality technology. Users use virtual devices such as head-mounted displays, data gloves, and trackers to combine visual, auditory, and tactile senses to perform immersive experiences in simulated scenarios [12]. Immersive virtual reality technology can flexibly dispatch all sense organs of the user to interact with virtual objects in a variety of natural ways in real time to make up for the shortcomings in real life [13]. The teaching classroom based on immersive virtual reality technology combines the advantages of mobile learning and digital learning, and fully combines online learning resources and offline classroom teaching. Moreover, the intelligent learning environment it creates can break through the limitations of time and space, and improve the contextuality and intuitiveness of knowledge presentation. The application of immersive virtual reality technology to science curriculum education in colleges and universities aims to explore the characteristics of this teaching mode and give full play to its advantages to help students form scientific cognitive methods and correct scientific views, to enrich classroom learning methods, so as to stimulate students' enthusiasm for learning and develop students' creative potential [14]. In addition, the application of immersive virtual technology and equipment to science classrooms in colleges and universities can effectively solve many problems in the current classroom teaching, so that students can be immersed in a virtual science environment to intuitively understand scientific phenomena [15].

Analysis of immersive algorithms based on digital twin technology
This article uses English speech sounds to identify students, and introduces the extracted features and classification methods. We assume that the sample data of English speech sounds is [16]: The calculation formula for each feature is as follows: (1) Mean value: it represents the tie level of a certain set of data: (2) Standard deviation (SD): Standard deviation is the arithmetic square root of variance, which can be used to express the degree of dispersion of a set of data.
Among them,  is the mean of the sample.
(3) Coefficient of Variation (CV): The coefficient of variation of a random variable is used to describe the size of the standard deviation relative to the average.
(4) Kurtosis: The kurtosis of a random variable describes the height of the peak of the probability density distribution curve at the average value and reflects the sharpness of the peak.
(5) Skewness: The skewness of a random variable describes the direction and degree of skewness of the data distribution, and reflects the degree of asymmetry of the data distribution.
Interquartile range (IQR): It is an important statistical quantity that arranges a set of numbers from small to large, and divides the arranged numbers into four equal parts. The interquartile range is equal to the first quartile value minus the third quartile value [17]. 3 1 Among them, 1 Q is located in the   Since the result of classification is only two types of students and non-students, the method used in this paper to identify students is a two-class support vector machine. The essence of SVM is to minimize structural risk and maximize the geometric boundary between classes. Therefore, the larger the boundary, the better the classification effect. SVM has achieved good results in many practical learning problems, and its principles are as follows: First, we are given a training set [18]: Among them, the input is d i xR  , and its related output is x is transformed into a higherdimensional feature space F through the nonlinear mapping function   x  . If the training sample is linearly separable in a specific space F, there is a separation hyperplane corresponding to a vector F   and a scalar 0  , which is expressed as follows [19]: and: The separation boundary between the two classes is defined as 2 w , and the optimal separation hyperplane can be constructed for SVM by maximizing the boundary, that is, minimizing 2 T  under the constraints of the formula.
The optimal separating hyperplane is obtained by maximizing a quadratic programming problem, which constructs a Lagrangian formula, and then transforms it into a dual problem [20]: and 1 =0,0 , Among them,   12 = , , , n     is the Lagrangian multiplier and C is the regularization parameter.

Construction of English classroom immersive teaching system based on digital twin technology
The immersive virtual reality system mainly refers to the system in which students enter the virtual environment through the use of special equipment during the learning process. As shown in Figure 1, it includes multiple devices [21]. Figure 1 The structure of the immersive virtual reality system Based on the view of activity theory, the elements in the activity system correspond to the design of learning activities. Figure 2 shows the structure diagram of the learning activity theory [22]. First, the subject of learning in learning activities is the subject of activity theory. Secondly, the learning objectives and learning content formulated according to the syllabus are the object elements in the activity theory. Third, a learning group composed of multiple learning subjects is a group element in activity theory, such as a learning collaboration group, a class, or a family. Fourth, the learning resources and learning tools used by the learning subject in the learning process are tool elements. Fifth, the collaboration rules in the learning group correspond to the rule elements in the theory, such as: collaboration rules and communication rules. Sixth, students learn task division and role assignment as the division of labor elements in the theory. In addition, based on the unique attributes of learning activities, the learning activity system should also have elements such as interaction design, teaching strategies, learning feedback, and learning evaluation. Each element in the learning activity model should be scientifically and reasonably arranged in a certain order, so as to promote the occurrence of efficient learning. The design mode of learning activities generally includes four stages: front-end analysis stage, teaching preparation stage, implementation stage and teaching evaluation stage.
As shown in Figure 3, the theory believes that the experience of doing is the most concrete, and it gradually transitions to the abstract experience. Various learning experiences are interrelated, and an effective education and teaching process should be full of concrete experience, and it also needs to extend to abstract experience with the help of teaching media. Dell's Tower of Experience Theory provides ideas on how to use network media technology in teaching and helps to find the teaching level of the media. With the continuous development of media technology, the way people learn is gradually changing. When Dell summed up the experience tower, multimedia technology has not yet been developed in the teaching field, so today's experience tower is facing a powerful challenge. Therefore, it is necessary to integrate high and new technology to form an "experience tower" in the network age. The emergence of immersive virtual reality technology has turned "doing experience" to "abstract experience" into a combination of traditional experience and network experience. Based on immersive virtual reality technology, users can experience the "doing experience" through various sense organs such as seeing, hearing and smelling in a simulated environment. Virtual reality technology is mainly used in teaching practice. Learners can be immersed in virtual teaching situations to simulate internship demonstrations or visit tours to gain "observational experience". The things in the virtual scene are composed of realistic threedimensional images, which make people feel immersive to observe the things. For abstract experience, virtual technology can create simulated teaching situations and concretize abstract concepts. Moreover, learners can use visual and intuitive simulation information to better obtain "abstract experience" in the learning process. In contrast, traditional teaching media can only provide two-dimensional text or images. However, the science classroom based on virtual reality technology can realize the organic integration of the three concepts in the "Tower of Experience" theory, so that learners can obtain rich sensory experience and optimize the teaching effect. As shown in Figure 4, the teaching design of immersive virtual reality mainly includes front-end stage, preparation stage, implementation stage and evaluation stage. In the front-end stage of learning, it is mainly to analyze learners and learning content. The learning preparation stage mainly includes the analysis of learning groups, learner characteristics, and learning tasks. The implementation stage is mainly about the teaching situation and learning resources. The learning evaluation stage is a combination of formative evaluation and summative evaluation. This article builds an immersion model that includes eight combinations of challenges and skills, as shown in Figure 5 below. Among them, challenges and skills are divided into three levels: high, medium, and low. Moreover, the two are combined into eight relationships: high challenge and high skill, high challenge and medium skill, high challenge and low skill, medium challenge and high skill, medium challenge and low skill, low challenge and high skill, low challenge and medium skill, low challenge and low skill. Among them, since personal ability is not enough to deal with challenges, high challenges and medium skills, high challenges and low skills, medium challenges and low skills can cause anxiety. Secondly, since the skills mastered by individuals are much higher than the current challenge level, medium challenge and high skill, low challenge and high skill, low challenge and medium skill will make people bored. In addition, because the personal skills are not high and individuals are not willing to challenge, low challenges and low skills make individuals indifferent. The model shows that only when high challenges are accompanied by high skills, a person enters and maintains a state of immersion, which is called "flow". This article refers to the "game immersive teaching model" to design a specific immersive teaching process, which removes game elements and adds elements of VR equipment. The specific teaching process design is divided into teacher activities and student activities. First, teacher activities include five parts: creating situations and asking questions; teacher-student communication and hypotheses; assisting students and immersing situations; teacher-student communication and testing conclusions; evaluation summary and reflecting on improving, as shown in Figure 6. Second, student activities include five parts: entering the situation and thinking about problems; communicating with students and proposing hypotheses; wearing VR glasses and exploring; trying to summarize and contrast hypotheses; reflecting on improving. Figure 6 Teacher activity framework and student activity framework VR-based immersive teaching meets the requirements of the new curriculum standard to return the classroom to students. Moreover, VR-based immersive teaching emphasizes the model of student-oriented and teacher-assisted, and its instructional design model is based on student activities and teacher-assisted students' meaning construction. The system constructed in this paper is perfected and developed on the basis of the learning-oriented teaching design model, and it fully considers the characteristics of immersive teaching and the reforms that VR technology brings to education. The final integrated VR-based immersive instructional design mainly includes three modules: pre-analysis, mid-term design and post-evaluation. The preliminary analysis includes four parts: analysis of learning needs, analysis of learning content, analysis of learner characteristics, and analysis of teaching objectives. The mid-term design includes four parts: VR teaching environment creation, classroom teaching, teacher activities, and student activities. The later evaluation includes two parts: learning effect evaluation and summary and reflection. The specific model is shown in Figure 7.

Evaluation of the effect of English classroom immersive teaching system based on digital twin technology
This paper constructs an English immersive teaching system based on digital twin technology. The system builds a virtual teaching environment based on digital twin technology to enable students to be immersed in the virtual teaching environment. The evaluation of the system effect in this paper is mainly launched from two aspects of system immersion reality and teaching effect. First of all, this paper evaluates the immersive reality of English classroom immersion teaching. It is carried out through experimental teaching methods, and quantitative analysis is carried out based on the scoring method of multiple groups of students, and the results obtained are shown in Table 1 and Figure 8 below.  From the above figure and table, it can be seen that the English immersive teaching system based on digital twin technology constructed in this paper has a good immersion effect, and students have a reality of teaching content in this teaching system. On this basis, this paper conducts an evaluation of the teaching effect of an English immersive teaching system based on digital twin technology. The results are shown in Table 2 and Figure 9.  Figure 9 Statistical diagram of the evaluation of the teaching effect of the English immersive teaching system based on digital twin technology From the above research results, it can be seen that the English immersive teaching system based on digital twin technology constructed in this paper can effectively improve the effect of English teaching.

Conclusion
This article innovates the traditional English classroom teaching model, analyzes the current situation of immersive teaching and the difficulties in the process of implementing immersive teaching. Moreover, this paper uses the immersive experience between virtual reality technology and immersive teaching as a connection point to carry out immersive teaching design based on VR. In addition, this paper applies it to teaching practice to test the effect of immersive teaching, and perfect the VR-based immersive teaching design model to provide practical and theoretical references for VR-based immersive teaching research. Further, this paper constructs an English immersive teaching system based on digital twin technology. The system builds a virtual teaching environment based on digital twin technology, so that students can be immersed in the virtual teaching environment. After building an English classroom immersive teaching model based on digital twin technology, this paper verifies the performance of the model. From the research results, it can be seen that the system constructed in this paper has a certain effect.

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