**6. Conclusions**

Based on the motion analysis of the shearer and drum-height adjustment, and with the drum movement law as the judgment knowledge, an automatic height-adjusting strategy of shearer was designed in the Unity3D engine, which integrates the information of the roof and floor fluctuation, coal seam inclination, and shearer fuselage inclination.

The modeling of the roof and floor was accomplished in the Unity3D engine using the mesh and LineRender components. The key cutting points could be read and the actual cutting curve drawn.

A real shearer height-adjusting model was developed, which can be controlled by the c# script. By measuring the position and posture of the scraper conveyor on real terrain, and constructing the

shape function of the scraper conveyor, the combined operation of the shearer and scraper conveyor was established. This provides theoretical support for shearer simulation on real terrain.

A conceptual idea is put forward: on the basis of geological exploration of coal seam, a virtual fine 3D coal seam is established. According to the production requirements of different enterprises, the pre-selected schemes and the decision-making are previewed in Unity3D, hence, digitized and visualized planning is carried out ahead of time. The entire production process can, therefore, be synchronously mapped in the production process, so as to obtain safe and efficient transparent mining.

**Author Contributions:** All authors (J.L.;Y.L.;J.X.;X.W.;X.G.) designed the project and participated in the experiments and the interpretation of the results. Conceptualization, J.L. and Y.L.; methodology, J.L.; software, J.X.; writing—original draft preparation, J.L.; writing—review and editing, J.L. and Y.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the Shanxi Province Nature Science Fund (201901D111056), the Shanxi province graduate education reform research topic (2019JG047), China Postdoctoral Science Foundation (No.2019M651081), and the Shanxi Youth Science and Technology Research Fund Project (201901D211022).

**Conflicts of Interest:** The authors declare no conflict of interest.
