The surroundings of underground mining machines still constitute an unsafe area for miners due to bad visibility conditions. In this paper, we present a novel acoustic position estimation system for safety applications in such hazardous environments. Our system is based on a pulse compression technique and utilizes linear (LFM) and hyperbolic (HFM) frequency-modulated signals in the frequency range of 5-20 kHz. As the miners are moving, we incorporated a means of Dopplershift compensation. This system not only provides the positions of moving targets but also their velocity and direction. In stationary measurements, we evaluated LFM signals at noisy conditions both in an indoor laboratory environment and in the vicinity of a mining machine. The movement of a miner has been emulated in dynamic laboratory measurements at constant speeds up to 1 m/s using both LFM and HFM signals. Our results show that the acoustic signal can be evaluated down to a low signal-to-noise ratio of −30 dB. The results of the dynamic measurements clearly demonstrate the insensitivity of the HFM signals to Doppler-shifts both with regard to the estimated position and estimated velocity.

Precise and accurate position estimation has become crucial to solving many technical problems. This contribution gives an overview of the LPM local positioning measurement system, which is based on the frequency-modulated continuouswave radar principle. LPM uses two active transponders within each measurement cycle: one acts as a time reference for all base stations, while the other is mounted on the object whose position is to be determined. By evaluating the time-difference of arrival at several base stations surrounding the measurement field, the position can be precisely estimated. We demonstrate this using measurement data.

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