One magnetic positioning system was deployed at the coal preparation plant, and positioning accuracy on floors 1–6 of the No. 2 main plant building was tested with the following procedure:
- Select key points along the test routes for positioning tests — 111 test points in total across floors 1–6. The key points on floors 1 and 3 are marked as shown in Fig. 13, and the actual coordinates of all test points are recorded.
- Testers wear the positioning terminals and walk along the predefined trajectories.
- Afterwards the positioning trajectories are extracted, the coordinates near each test point are compared with the actual coordinates, and the positioning error is computed.
Fig. 12 Magnetic positioning accuracy test routes
Fig. 13 Key test points (floors 1 and 3)
The positioning trajectory is shown in Fig. 14; results show the computed positions match the actual walking route. A real-scene vs. 3D comparison of reference point No. 44 is shown in Fig. 15.
Fig. 14 Positioning trajectory
Fig. 15 Real-scene and 3D comparison of reference point No. 44
The positioning errors of the 111 selected test points are shown in Fig. 16, and the cumulative error probability distribution in Fig. 17 — over 90% of points have errors below 1m.
Fig. 16 Positioning error results
Fig. 17 Cumulative error probability distribution
| Metric | Value |
|---|
| Total test points | 111 (floors 1–6) |
| Positioning error of 90%+ of points | < 1m |
| Mean positioning error (1σ) | Meets precision positioning requirements |
| Floors covered | 6-story main plant building |
