A complex stratum formed due to the influence of internal and external dynamic geological processes will lead to extremely complex mining conditions in deep exploration and development of oil, gas, coal and other resources, processes mainly threatened by disasters such as coal and gas conflict, mine water inrush, and rock burst. Combined with formation identification and measurement while drilling technology, the drilling level of underground drilling robot in coal mines is constantly developing. In order to prevent coal mine accidents and achieve safe and efficient mining, efficient and accurate drilling is the key, and should be based on research on the influence of complex stratum on the drilling trajectory. In order to comprehensively and systematically summarize the research on the influence of a complex stratum on drilling tool mechanics, this paper describes the history and current situation of complex stratum exploration, measurement while drilling technology, borehole bending conditions, stress analysis of complex coal seams on drilling tools, formation force theory and method, and geosteering drilling technology. In addition, the research and application of directional drilling technology in gas control, water hazard prevention and geological anomaly detection are also discussed.

During the operation of the guide rail pair, the accuracy of the guide rail pair is decreased by friction and wear, and the overall performance of the machine tool is directly affected. The influence of surface micro-features of the slider raceway on the dynamic friction factor of the guide rail pair is analyzed in this paper. The relationship between the geometric characteristics of the surface micro-features and the dynamic friction factor is studied, and a prediction model of the dynamic friction factor is established. Meanwhile, the correctness and rationality of the predicted model is verified by the orthogonal experiments of the friction force. It is found that the dynamic friction factor increases with the increase of the groove depth, the height of the peaks and peak–valleys on the surface of the slider raceway. The above research provides a basis for the study of the friction and wear characteristics of guide rail pairs and lays a foundation for improving its friction and wear performance.