Fig. 1. Calibration board example and effect image of circle center extraction algorithm

Fig. 2. Image pyramids

Fig. 3. Effect images of proposed algorithm and spot detection algorithm

Fig. 4. Flow chart of PCB visual calibration and positioning method

Fig. 5. Calibration board and PCB sample images

Fig. 6. Experimental apparatus

Fig. 7. Diagrams of positioning results

Fig. 8. Divide sample 1 into 5 regions

Fig. 9. Average positioning error curve for 5 positioning regions

Fig. 10. Positioning error scatter plots for sample 2, sample 3, and sample 4