Directional drilling systems generate complex curved boreholes in the earth’s crust for the exploration and harvesting of oil, gas and geothermal energy. In practice, boreholes drilled with such systems often show instability-induced borehole spiraling, which negatively affects the borehole quality and increases drag losses while drilling. This paper presents a dynamic state-feedback controller...

The gas in a coal seam is clean energy source, but it also the main cause of accidents during mining mineral resources. There large pressure–relief influx upper and lower adjacent layers 1211 working face Wanfeng Coal Mine Jinhui, Shanxi Province, China. Based on evolution law overburden fractures, collaborative extraction mode “directional drilling gas-conducting fractured zone + staggered bur...