Study on precise control of coal caving mechanisms based on the kinematics of support structures

Precise control of the coal caving mechanism is a crucial foundation for realizing intelligent and unmanned top coal caving mining. The spatial relationship between the coal caving mechanism and the rear scraper conveyor, as well as the top coal influence of the hydraulic support's posture on this spatial relationship, is key to constructing a control model for the caving support. Using the ZF17000/27.5/42D low-position top coal caving support as the research object, this study explained the spatial relationship between the coal caving mechanism and the rear scraper conveyor under different pitch angles of the support's roof and base. Based on the control logic for the opening degree of the hydraulic support's coal caving mechanism, a support posture sensing system was established, and a method for kinematic analysis of the hydraulic support's coal caving mechanism was proposed. A kinematic model for the end of the low-position hydraulic support's coal caving mechanism based on the D-H matrix was developed, and a calculation model for the opening degree of the hydraulic support's coal caving mechanism was constructed. The average calculation error was only 1.71%, meeting the accuracy requirements for field applications. A closed-loop control method for the coal caving mechanism based on posture feedback was proposed, and the coal caving decision model developed from the opening degree calculation model was applied in the field. Application results showed that during automatic coal caving, the mean square deviation of the average caving time for each support was only 0.13 minutes, with an overall caving efficiency improvement of 20%-43.9% compared to manual caving. The top coal recovery rate reached 89%, and the load on the rear scraper conveyor was more balanced, with an overload rate of only 0.73%.