  In this paper, we propose a multi-target image tracking algorithm based on
continuously apative mean-shift (Cam-shift) and unscented Kalman filter. We
improved the single-lamp tracking algorithm proposed in our previous work to
multi-target tracking, and achieved better robustness in the case of occlusion,
the real-time performance to complete one positioning and relatively high
accuracy by dynamically adjusting the weights of the multi-target motion
states. Our previous algorithm is limited to the analysis of tracking error. In
this paper, the results of the tracking algorithm are evaluated with the
tracking error we defined. Then combined with the double-lamp positioning
algorithm, the real position of the terminal is calculated and evaluated with
the positioning error we defined. Experiments show that the defined tracking
error is 0.61cm and the defined positioning error for 3-D positioning is 3.29cm
with the average processing time of 91.63ms per frame. Even if nearly half of
the LED area is occluded, the tracking error remains at 5.25cm. All of this
shows that the proposed visible light positioning (VLP) method can track
multiple targets for positioning at the same time with good robustness,
real-time performance and accuracy. In addition, the definition and analysis of
tracking errors and positioning errors indicates the direction for future
efforts to reduce errors.
