Research on simulation surveying and assembly experiment based on virtual reality

It is very important to combine the teaching theory with practice in the course of engineering drawing, especially to cultivate students' hands-on and innovative abilities. It is a course with strong theoretical and practical characteristics, so the experimental teaching link is crucial to learning this course well. Only by strengthening the practical teaching link can students truly understand and master the theoretical knowledge of the subject.

The teaching of engineering drawing courses is very specific and vivid. It focuses on the movement and action of the mechanism. Due to the lack of real feelings in theoretical teaching, students often feel boring and difficult to understand the content when listening to the lectures; the experimental equipment in mechanical courses is mostly expensive. In some cases, it cannot fully meet the corresponding experimental requirements, especially for each student. Student experiments are usually divided into groups. For some experiments, when there are few experimental equipment, there will be a lot of people in the group, so students will not have many opportunities to master the experiments; therefore, if virtual simulation experimental teaching can be carried out in teaching, it can not only make up for the lack of experimental resources to a certain extent, but also improve students' ability to observe, analyze and solve problems, so as to master a professional technical skill.

1 The practical significance of virtual simulation experiments in teaching

At present, most domestic colleges and universities still use the traditional method of experiment, that is, teachers explain and demonstrate, and then students do it themselves. However, foreign countries have switched from traditional experiments to a combination of physical experiments and virtual experiments, making full use of advanced computer equipment for virtual simulation experimental teaching, and have achieved good results.

The traditional teaching model is teacher-centered, and the transmission of knowledge mainly depends on the teacher's indoctrination of students. As the cognitive subject, students are in a passive state from beginning to end in the teaching process, and their initiative and enthusiasm are difficult to play, which is not conducive to the cultivation of students' divergent thinking, critical thinking and creative thinking, nor is it conducive to the cultivation of creative talents. Virtual simulation experiments break through the limitations of traditional teaching methods. Students operate by themselves and participate in the operation of the entire experimental process in person. By expressing the actual production process in a vivid form such as images and animations, students' perceptual understanding and learning interest are enhanced, the teaching effect is improved, and their practical ability, observation ability and inductive ability are well trained. Virtual experiment technology creates a humanized learning environment, enabling students to learn in a natural and interactive atmosphere. Based on the above thinking, an attempt is made to apply "virtual simulation experiment teaching" in the teaching of "Engineering Graphics" to explore teaching reform.

2 Design objectives of virtual simulation experiment

The development tools of virtual experiments are mainly network virtual reality modeling language (VRML) and 3D modeling software. VRML is a scene modeling language used to build real-world scene models or people's imaginary 3D worlds. The basic goal of VRML is to build interactive virtual objects, scenes, and 3D models on the Internet. Its basic features include distribution, 3D, interactivity, multimedia integration, and realistic scenes. It is currently the mainstream language for the production of 3D interactive websites based on "www" on the Internet.

The design of virtual reality system should achieve the following goals:

a) To make participants have a "real" experience. This experience is "immersion" or "devotion", that is, entering wholeheartedly. Simply put, it is an illusion in the virtual world. The ideal virtual environment should be difficult for users to distinguish between true and false, or even more "real" than the real thing. The significance of this sense of immersion is that it can enable users to concentrate their attention. In order to achieve this goal, it is necessary to have multi-sensory capabilities. The ideal virtual reality system should have all the perceptual abilities that humans have, including vision, hearing, touch, and even taste and smell.

b) The system should be able to provide convenient, rich, and mainly natural skill-based human-computer interaction methods. These methods enable participants to manipulate the virtual environment in real time, get feedback from the virtual environment, and help the system understand the location, state, deformation, and other data that the system needs to know about the key parts of the participants. Real-time performance is very important. If there is a large delay in the interaction, which is inconsistent with people's psychological experience, there is no natural skill interaction, and it is difficult to get a sense of immersion.

3. Virtual assisted teaching of component surveying and mapping practice

The course Engineering Graphics is a major technical foundation course for mechanical majors. It is a course with strong theoretical and practical characteristics. Therefore, the experimental teaching link is crucial to learning this course well. Only by strengthening the practical teaching link can students truly understand and master the theoretical knowledge of this subject. The implementation content of this project is mainly to use Inventor 2008, 3D Max, AutoCAD and VRML software systems to design a virtual experimental system, so that it can dynamically simulate the assembly of gear oil pumps (Figure 1), reducers (Figure 2), and vises (Figure 3). The dynamic simulation of the assembly process through vivid forms such as images and animations can give full play to the subjective initiative of students, which is conducive to students' rich perceptual understanding, stimulate students' interest in further raising questions and seeking solutions to problems, help broaden students' knowledge, and effectively support theoretical learning.

The practice of virtual assisted teaching technology for component surveying and mapping is to use the physical model as the basic element and the physical model surveying and mapping as the main line, and use the computer virtual reality method to create intuitive images mainly in the form of pictures and animations to analyze the shape structure and surveying and mapping process of the components.

The process of integrating virtual-assisted teaching into surveying and mapping practice teaching is: assigning surveying and mapping tasks; observing and analyzing physical models; teachers providing centralized guidance through virtual-assisted teaching courseware based on physical models; students independently surveying and mapping based on physical models and referring to virtual-assisted teaching courseware; and teachers conducting centralized commentary.

The main components of virtual assisted teaching are electronic documents mainly based on virtual images and a small amount of text description. They are: a drawing set that mainly uses animation to express the shape and structure of parts, a drawing set that mainly analyzes the shape and structure of parts and views, a drawing set that mainly guides the measurement and mapping methods and processes of parts, and a drawing set that mainly guides the dimensions, technical requirements, drawings, and work requirements.

4. Characteristics of Virtual Assisted Teaching Technology for Parts and Components Surveying and Mapping Practice

a) Virtual reality based on entities. Computer virtual reality and virtual 3D graphics are closely related to structural thinking and visual and visual psychology. Practice shows that without a physical model as a benchmark and without the support of structural thinking and visual and visual psychology, computer virtual reality and virtual 3D graphics will become meaningless works; on the other hand, without structural thinking and visual and visual psychological knowledge to guide the creation of computer virtual reality and virtual 3D graphics, good works cannot be obtained.

b) Selection of surveying and mapping objects (parts and components) based on graphics quality. Selecting good surveying and mapping objects is the primary condition to ensure the effectiveness of practical teaching of parts and components surveying and mapping. Both simplification and over-complication are undesirable and may harm the overall teaching of the university. The first factor in selecting surveying and mapping objects (parts and components) is to consider the requirements for cultivating students' graphics quality, and the second is to consider the needs of subsequent courses. Valves, pumps, fixtures (vises), and reducers are commonly selected surveying and mapping objects, and the main reason is that they are easy to teach. Considering the requirements for cultivating graphics quality, the surveying and mapping content of the selected parts and components should cover as many core contents of graphics as possible. For example, the expression method is typical and comprehensive, and the structure is representative. Considering the needs of subsequent courses, the surveying and mapping content of the selected parts and components should contain the main elements of subsequent courses.

5 Conclusion

The development of virtual surveying and assembly experiments for parts and components is to broaden the experimental teaching platform, improve surveying and mapping methods, improve surveying and mapping efficiency and quality, and reduce the teaching burden. The core of this teaching technology involves all aspects of traditional surveying and mapping, as well as deep theoretical and technical issues of modern educational technology. Of course, virtual simulation experiments cannot completely replace physical experiments, but they can be explored as a supplement to physical experiments and classroom theoretical teaching.