Vibration Sensor for Horizon Control in Automated Longwall Mining. Final Technical Report.

摘要

The development of a Horizon Control Sensor for detecting the coal/rock interface during longwall mining with a shearer is described. The Sensor utilizes differences in the time or frequency characteristics of shearer vibrations,as sensed by an accelerometer mounted on the ranging arm,to discriminate the cutting of coal and rock. Laboratory tests established the basic principle of operation and vibratory characteristics of longwall cutting bits. Vibration data were collected from a variety of longwall shearers operating in mines having a variety of coal and rock types. A number of potential interface discriminants were investigated,both in the frequency domain and time domain. The best of each type was selected for further development and hardware implementation. The frequency domain Horizon Control Sensor,based on the vibration amplitudes at resonant frequencies,was found to be accurate and sensitive but requires fine-tuning for each model of shearer since the resonant frequencies depend on details of the drum design and bits. The time domain technique,based on the level of amplitude modulations in the vibration signal,is relatively independent of the shearer design. The time domain Horizon Control Sensor worked well on the collected field data yielding relatively few erroneous indications. It is expected to be useful in coal seams having friabilities and hardnesses sufficiently different from those of the surrounding rock. Four identical prototype time domain Horizon Control Sensors have been built and packaged in mine-permissible enclosures for further field evaluation. (ERA citation 04:012154)