The motion planning problem consists in finding a control function which drives the system to a desired point. The motion planning algorithm derived with an endogenous configuration space approach assumes that the motion takes place in an arbitrary chosen time horizon. This work introduces a modification to the motion planning algorithm which allows to reach the destination point in time, which is shorter than the assumed time horizon. The algorithm derivation relies on the endogenous configuration space approach and the continuation (homotopy) method. To achieve the earlier destination reaching a new formulation of the task map and the task Jacobian are introduced. The efficiency of the new algorithm is depicted with simulation results.
The efficient protection (support reinforcement) of a wall and heading crossing ensures continuity of the production cycle, and that is a quick moving of the scraper conveyor to the wall. Using low or high bolting as a support reinforcement element in wall and heading crossings allows for the elimination of traditional methods of maintaining longwall-gate crossings, and therefore allows for the efficient use high performance modern wall complexes. The paper presents the long underground experience, of the Knurów–Szczygłowice mine of efficient support wall and heading crossing maintenance, which was bolted to the rock mass with the usage of two pairs of bolts, showing full technical and economical usefulness of this support reinforcement method. The article also highlights work safety and the increasingly common usage of endoscopies when specifying the range of crack areas which directly effects the proper choice in number, load-capacity and length of the used bolts. The underground studies the measurements of the reach of the zones of fracturing and roof stratification (using endoscopes and wire type stratification meters) and the laboratory tests (using the test stand) have allowed to determine the safety factor for maintenance of the longwall gangway crossing, directly resulting in the necessity to install additional reinforcement. The value of the safety factor Sbsc-ch greater than 1 is advantageous and safe, and the value less than or equal to 1 can lead to a significant deterioration of the conditions of maintenance of a wall and heading crossing which was bolted.
Caving in the excavation of mining galleries is a dangerous phenomenon, resulting in a threat to the health and life of humans, technological difficulties (transport, ventilation, etc.) and economic losses. Mining galleries list: design errors, runtime errors, errors and random causes among the causes of the caving occurring in recent periods in the excavation of underground coal mines. Examples in the recent period of caving in the excavation of mining galleries in coal mines indicated that one of the main causes of the situation was the loss of capacity and double timber technical wear caused by the corrosion of the profile. In practice, the caving that occur as a result of the technical wear can be divided into the breaking arc of a roof – bar, the loss of stability of one of the heading walls and a total heading collapse. On the basis of the carried out analysis of these cases, guidelines were proposed for improving the safe operation of the workings. The improvement of support stability may be achieved by applying additional supports, stabilizing the structure by bolting the support sets or by introducing a fiber-reinforced concrete coating with injection into the rock mass. Examples of caving occurring in the excavation, for which the preparatory selection of support does not match the geological-mining conditions, were also presented. The summary indicated the importance of diagnostics roadway in the safe and efficient conduct of mining that should be covered by the operational rules, and their scope and frequency should be adapted to the rank of the occurrence of hazard and support construction.
The paper presents the experience of using the ŁPrP, ŁPKO, ŁPSp, ŁPSpA i ŁPSp3R types of flattened supports for longwall entries in the conditions of the JSW S.A. Knurów-Szczygłowice coal mine. The article concentrates on the support solutions applied in the conditions of the mine and the results in terms of stability and usefulness of the structures of the supports. An analysis of the load bearing capacity and technological conditions has been conducted for various flattened supports solutions, with special consideration given to the ŁPSp and ŁPrPJ support sets. Comparing these two, the ŁPSp exhibits a load bearing capacity that is 21% higher while using 31% less steel mass. The experiment results allowed to determine that the ŁPSpA and ŁPSp3R support types are an advantageous solutions in case of longwall set-up rooms.