Some embodiments of the disclosure provide an advance and retreat automatic control method based on hydraulic sensing conversion and an advance and retreat automatic control system based on hydraulic sensing conversion, which includes an automatic advance and retreat device based on hydraulic sensing conversion, a motor, an oil cylinder, and/or an electric generator. When the digging motor encountered an overlarge resistance force, a pressure on the digging motor is instantaneously increased and exceeds a setting pressure value, hydraulic oil enters a hydraulic operated directional valve and pushes a valve rod to make the walking motor is reverse and retreat, an ultrahigh pressure state of the digging motor is released to restore to a normal pressure value to make reciprocated impact, the valve rod of the hydraulic operated directional valve is reset, and the walking motor is forwards rotated for advancing.

Some embodiments of the disclosure provide an advance and retreat automatic control method based on hydraulic sensing conversion and an advance and retreat automatic control system based on hydraulic sensing conversion, which includes an automatic advance and retreat device based on hydraulic sensing conversion, a motor, an oil cylinder, and/or an electric generator. When the digging motor encountered an overlarge resistance force, a pressure on the digging motor is instantaneously increased and exceeds a setting pressure value, hydraulic oil enters a hydraulic operated directional valve and pushes a valve rod to make the walking motor is reverse and retreat, an ultrahigh pressure state of the digging motor is released to restore to a normal pressure value to make reciprocated impact, the valve rod of the hydraulic operated directional valve is reset, and the walking motor is forwards rotated for advancing.

A system and method for high wall bench mining, for example, of horizontal coal seams in mountains, includes a launch platform having two side-by-side tracks for guiding mining equipment, and utilizes two continuous miner machines and conveyor cars. Two side-by-side mine entries can be worked simultaneously, one miner advancing deeper into the coal seam and conveyor cars being added behind the miner at a first mine entry, and the mining completed and cars and miner retreating and being extracted from a second mine entry. As conveyor cars are being extracted onto one track from the mine entry that a string is retreating from, the cars are moved across the launch platform to the other track and are added behind the advancing miner machine launched from that track into the other mine entry.

A system and method for high wall bench mining, for example, of horizontal coal seams in mountains, includes a launch platform having two side-by-side tracks for guiding mining equipment, and utilizes two continuous miner machines and conveyor cars. Two side-by-side mine entries can be worked simultaneously, one miner advancing deeper into the coal seam and conveyor cars being added behind the miner at a first mine entry, and the mining completed and cars and miner retreating and being extracted from a second mine entry. As conveyor cars are being extracted onto one track from the mine entry that a string is retreating from, the cars are moved across the launch platform to the other track and are added behind the advancing miner machine launched from that track into the other mine entry.

A process for locating underground markers, including: transmitting signals through the ground between markers in the ground; and determining locations of the markers based on the transmitted signals.