Control system for longwall face alignment

A control system for a longwal support having a plurality of hydraulically operated support units that are automatically arranged via a mining shield control system in the sense of robbing, advancing, and setting as a function of the position of a mining machine that travels along and removes rock from the longwall, the control system comprising:

• a position signaler carried by the mining machine and comprising:
• a rotatable measuring wheel that rotates in response to the mining machine traveling along the longwall and comprises electromagnetically detectable circumferential markings,
• a detector for sensing the electromagnetically detectable circumferential markings and providing a signal derived from the sensing,
• a microprocessor for receiving the signal from the detector and converting the signal from the detector into a processed signal, and
• a radio transmitter for transmitting the processed signal to the mining shield control system for use in the automatic arrangement of the hydraulically operated support units;
• and
• wherein the mining shield control system comprises:
• a plurality of radio receivers that are distributed along the length of the longwall for substantially directly receiving the transmitted processed signal, and the mining shield control system converts the processed signal received by at least one of the radio receivers into signals for rearranging the support units, and
• a plurality of control devices, wherein each of the control devices is connected to a respective one of the support units for controlling the respective support unit, each of the radio receivers is substantially directly connected to a respective one of the control devices for substantially directly passing signals received by any one of the radio receivers to its respective control device, and the control devices are connected to one another so that a signal received by one of the radio receivers is provided from its respective control device to all other of the control devices and the mining shield control system is operative to determine which of the support units are to be addressed by the signal.