Underground coal mine accurate personnel positioning method based on asynchronous time-measuring

The existing underground coal mine personnel positioning methods always have a large positioning error,and it is difficult to meet the needs of coal mine accident rescue,transportation,and electromechanical accident prevention and control. To improve the accuracy of underground coal mine personnel positioning,an underground coal mine accu- rate personnel positioning method based on asynchronous time-measuring was proposed:some locating substations are installed at certain distance in the underground roadway to ensure that the two neighboring locating substations can communicate with each other wirelessly and the positioning card can communicate with two neighboring locating sub- stations at the same time. Any one initial locating substation sends a ranging signal to the positioning card and the neighboring locating substation in the communication range. The neighboring locating substation receives the ranging signal and at the same time it sends a ranging signal to the positioning card. The positioning card replies response sig- nals to the initial locating substation and the neighboring locating substation separately. After receiving the response signal replied from the positioning card,the initial locating substation calculates the time between sending and receiv- ing the ranging signal. After receiving the response signal replied from the positioning card,the neighboring substation calculates the time between sending and receiving the ranging signal,and sends the time to the initial locating substa- tion. According to the time between sending and receiving the ranging signal calculated by the initial locating substa- tion and the neighboring substation separately,and the distance and signal transmission speed between the initial loca- ting substation and the neighboring substation,the initial locating substation calculates the distance between the posi- tioning card and the initial locating substation and the distance between the positioning card and the neighboring sub- station. Measuring distance using the underground coal mine accurate personnel positioning method based on asyn- chronous time-measuring is only related to the time of sending and receiving ranging signal from the substation and not related to the signal strength. The accuracy of positioning is not affected by the signal transmission power,receiving sensitivity and signal transmission attenuation. The underground coal mine accurate personnel positioning method based on asynchronous time-measuring is not related to the clock of the positioning card,which greatly reduces the complexi- ty and cost of positioning cards,eliminates the need for synchronization between locating substations,and reduces the complexity and cost of locating substations. The main performance indicators of the underground coal mine accurate personnel positioning method based on asynchronous time-measuring are superior to other underground coal mine posi- tioning methods. Simulation experiments show that under the same experimental conditions such as the same clock fre- quency offset,the positioning error of other underground coal mine accurate personnel positioning methods such as TWR and SDS-TWR is more than twice of the positioning error of the underground coal mine accurate personnel posi- tioning method based on asynchronous time-measuring.