Fig. 1. Model of visible light positioning system in coal mine

Fig. 2. Safety helmet receiver model. (a) Top view; (b) stereogram

Fig. 3. Network unit structure of SRU

Fig. 4. Neural network structure

Fig. 5. Error accumulation histogram. (a) Receiver A; (b) receiver B; (c) receiver C

Fig. 6. Error accumulation distribution

Fig. 7. Effect of receiver's height on SRU positioning. (a) z =0.13 m; (b) z =0.5 m; (c) z =1 m; (d) z =1.5 m

Fig. 8. Effect of x-axis position change on SRU positioning of LED lamp

Fig. 9. Effect of LED lamp's power change on SRU positioning performance

Fig. 10. Experimental scene. (a) Positioning system; (b) receiving device

Fig. 11. Experimental error distribution