Indoor Visible Light Positioning Technology Based On Stereo Vision

Location Services(LBS)is an important driving force for the development of unmanned driving,logistics management,and Internet of Things industries.The acquisition of location information is the basis of LBS.With the advancement of urbanization,a large number of people's production and life will be carried out indoors,and the demand for indoor positioning is also on the paper.The indoor positioning technology using light-emitting diodes(LEDs)as the transmitting end has attracted more and more attention due to its high positioning accuracy,low laying cost,wide use range,and environmental protection.It has become the focus of indoor positioning technology.In the current related research,the positioning method using photodetector(PD)as the receiving end is susceptible to external interference due to the influence of multipath effect;and the positioning method using image sensor(IS)as the receiving end is excellent in ideal positioning environment.However,in a non-ideal positioning environment(IS tilt or jitter),a large positioning error occurs.Solving the positioning error of non-ideal positioning environment is a key technical problem in indoor location of visible light and has important research value.The paper proposes a positioning technology scheme(Stereo-VLIP)combining stereoscopic and visible light communication,and corresponding methods and algorithms.The main innovations are as follows:(1)If the frame rate of IS is used as a reference,the positional constellation information is modulated onto the LED by the on-off key(OOK)method,which causes the LED to flicker visible to the human eye.Aiming at this problem,a binary amplitude keying modulation scheme based on rolling shutter exposure is designed.The experimental results show that the scheme can improve the communication speed while solving the LED flicker problem.(2)A visible light indoor positioning algorithm using a binocular camera as the receiving end is proposed.The algorithm can calculate the three-dimensional coordinates of the positioning point by using the distance information acquired by stereo vision and the position information of the LED imaging in IS.It shows that the positioning error in the area with a radius of 120cm is less than 4cm within two meters of the distance between the LED and the IS.In addition to high positioning accuracy and real-time performance,it can also reduce the number of LEDs used in the positioning environment and reduce costs.(3)In order to solve the influence of the tilt of the receiving end on the positioning,a pose estimation method combining stereo vision and perspective-n-points(PnP)is proposed,which can only be three in the positioning range.In the case of LEDs,the unique solution of the pose of the receiving end is obtained,and the anti-tilt is realized without excessively increasing the hardware cost and the calculation amount.The experimental results show that in the case of a small range of tilt,the positioning error does not exceed 7 cm,which ensures the centimeter--level positioning accuracy.The performance of Stereo-VLIP technology,in the experimental space of 240cm × 240cm × 200cm,the decoding quasi-power reaches 95%,the plane accuracy reaches 95%,the plane positioning maximum error does not exceed 7cm,and the spatial positioning maximum error does not exceed 10CM,achieving Centimeter-level positioning accuracy.