| With the rapid development of Visible Light Communication(VLC)and Internet of Things(IOT),indoor positioning has attracted the attention and research of scholars all over the world.Visible Light Positioning(VLP)has the advantages of high positioning accuracy,no electromagnetic interference,abundant bandwidth,and low cost compared with traditional wireless positioning technology.However,most of the existing visible light positioning technologies are active positioning,requiring complex hardware receiving devices to be installed on the positioning objects,which are not suitable for real-time positioning in some specific scenarios.For example,the positioning of shopping cart in unmanned supermarket,the positioning of AGV car in warehouse,etc.In order to solve the above problems,this thesis introduces a light reflector to inversely beam the light back to the receiver on the ceiling to achieve high precision passive positioning in three-dimensional space.The formulas for the relationship between the received optical power and the position and Angle of the reflector under the direct link model and the reflector model are derived,and the rationality of the formulas is verified by ray tracing simulation.The main work and innovations of this thesis are as follows:1.This thesis designs a passive indoor visible light localization model based on reverse reflection.Studied the influence of reflectors on the receiving power at different directions and angles.By introducing the concept of effective reflection area and calculating the ratio of effective reflection area to maximum effective reflection area,the formula for receiving light power when the reflector is vertically upward is derived.Due to the fact that the reflector rotates with the movement of the object being tested,this thesis derives the expression for the received optical power when the reflector rotates.2.In order to verify the rationality of the derived formula,this thesis built an indoor visible light positioning system model using beam four software,and analyzed the impact of line-of-sight transmission channels and non line-of-sight transmission channels on light reflection in indoor environments.Verified the rationality of the power formula received by the reflector at different positions and directions.This thesis also studied the impact of different reflector movement steps and angles on the positioning performance of the system.Through comparative experiments,it was found that the optimal positioning accuracy is achieved when the reflector moves with a step size of 3m and a movement angle of 40 °.3.In order to reduce the number of receivers required for the positioning system,an indoor visible light positioning algorithm based on reflector position movement was designed.After simulation and experiment,it has been proven that at 4m × 4m × In a 3m positioning space,the average positioning error of this algorithm is 4.32 cm.Compared with the BP neural network algorithm,the average positioning accuracy of the algorithm proposed in this paper has been improved by 56.2%,and the average positioning time has been reduced by 25.2%.Has good robustness.4.Derived the expression for the received power in an indoor VLP model considering wall reflection.Propose a positioning algorithm that considers the reflection of the wall once,with an average positioning error of 3.53 cm.Compared to the positioning algorithm that does not consider wall reflection,its positioning accuracy has been improved by 18.3%.Analyzed the impact of direct and reflection on received power.The results show that the maximum received optical power of the direct link is 13.6m W,while the maximum received optical power of the primary reflection link is only 4.6m W. |
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