Synchronization control of multi-cylinder propulsion for autonomous walking of deep underground fluidized coal mining equipments

The shallow coal in China is gradually being exhausted, and mining resources from deep parts of the Earth has become an inevitable trend and national demand. Faced with the difficulty of deep coal mining beyond 2000 meters, an autonomous walking mechanism suitable for fluidized mining equipment was designed, and the focus was on the problem of multi-cylinder synchronous control in the hydraulic propulsion system of this mechanism. Firstly, based on the principle of fluidized mining technology and equipment composition, a resistance increasing step type autonomous walking mechanism was designed, which can achieve segmented autonomous walking of multiple compartments such as excavation, transformation, and output. Secondly, in response to the requirements of multi-cylinder synchronous control in hydraulic propulsion systems, four control strategies, namely master-slave control, adjacent cross-coupling control, deviation coupling control, and mean coupling control, as well as the advantages and disadvantages of proportional-integral-derivative control(PID) algorithm and automatic disturbance rejection controller (ADRC), were analyzed and compared. Control performance simulation tests were conducted under three working conditions: uniform load, sudden load, and time-varying load. Once again, the radar chart evaluation method was used to comprehensively evaluate the synchronization control performance under different control strategies, and the mean coupled control method based on ADRC was selected as the optimal synchronization control strategy. Finally, an autonomous walking mechanism test bench was developed and multiple hydraulic cylinder synchronization control experiments were conducted. The test results showed that when using the mean coupled synchronization control strategy based on ADRC, the maximum synchronization error of the four hydraulic cylinders under different working conditions can be maintained within ± 5 mm, and they have excellent robustness. It can meet the requirements of multi-cylinder synchronous propulsion for the autonomous walking mechanism of fluidized mining equipment.