| With the continuous advancement of the "Made in China 2025" program and the rapid development of the Internet of Things technology,intelligent service robots that merging integrate information technology and intelligent manufacturing are also receiving more and more attention.At the same time,the robot needs to interact with the indoor environment during finishing tasks such as path planning,navigation obstacle avoidance and command communication.Therefore,an building an indoor positioning system which can provide intelligent device location information,and assist them in completing automation tasks that has been the Intelligent and personalized research hotspots.Because the wall of the house block the radio signal,global positioning system(GPS)is used to indoor environment,that will have problems such as large error and information loss.Therefore,it is necessary to construct an indoor positioning system of intelligent interactive to meet indoor positioning requirements.To this end,the researchers proposed two indoor positioning schemes for radiolocation and visible light communication(VLC):radio positioning is to arrange wireless signal transmitters such as WiFi and Bluetooth indoors,but its available frequency band is narrow,and electromagnetic interference is large,which limits its Application scenario;visible light communication is a method of assigning a light-emitting diode(LED)light source coded signal,obtaining an optical identifier(ID)and optical power information at a receiver,and analyzing a position coordinate.VLC having a large data bandwidth,a high rate,a green environment,and an anti-electromagnetic interference.Strong and other characteristics,so the research of VLC-based indoor positioning scheme has become one of the main directions of high-precision and high-reliability indoor positioning research.The VLC-based indoor positioning scheme needs to solve the two problems:LED's ID coding and the optimization of positioning algorithm.For this reason,this paper proposes two kinds of optical ID coding schemes are optimized:frequency division multiple access(FDMA)and code division multiple access(CDMA).Two indoor positioning algorithms are optimized:trilateral positioning algorithm and position fingerprinting algorithm,then,we designed and built based on the above scheme to test a set of VLC indoor positioning experimental system.The main research contents of this paper are as follows:(1)Firstly,the research background of the subject is introduced,and the positioning requirements of the intelligent service robot in the indoor environment are described.Secondly,the domestic and international research status of the indoor positioning scheme is described.Then the concept of visible light communication is introduced,and the indoor positioning scheme based on visible light communication is analyzed.Principles and characteristics;finally,the main contents and innovations of this paper are explained.(2)The spatial distribution model of LED light is introduced in detail,and then the principle of two kinds of optical ID coding schemes,that is frequency division multiple access(FDMA)and code division multiple access(CDMA),in visible light communication is analyzed:FDMA scheme will be LED The flicker frequency is transmitted as the optical ID,and at the receiver the mixed optical signal is separated by the Fourier transform to restore the optical ID;CDMA scheme convolves the source code of the LED ID with the Walsh code to form a spreading code to avoid inter-symbol interference.The receiver convolves the detected mixed optical signal with the spreading-code to restore the ID code.(3)The trilateral positioning algorithm based on K-means clustering and the location fingerprint algorithm based on modified weights are described.Aiming at the inefficiency of the trilateral positioning algorithm,multiple sets of data are sampled at the reference point,and the clusters are divided by K-means and the positioning points are optimized repeatedly.At the same time,in order to improve the accuracy of the location fingerprint algorithm,we add the correction weight before the fingerprint vector,which can increase the weight of the fingerprint vector with higher positioning,and improve the positioning effect of the fingerprint database.(4)Designing the experimental platform of VLC,introducing the design principle of the optical ID module and algorithm analysis module at the transmitting end,and expounding the experimental steps and design schemes of the two schemes of frequency division multiple access and code division multiple access,comprehensive theory and experimental findings:The positioning accuracy of FDMA scheme is 12±8cm,and the positioning accuracy of CDMA scheme is 8±6cm.Both schemes meet the requirements of high-precision indoor positioning,which proves the feasibility of the scheme.Finally,this paper transforms the indoor environment and builds a VLC indoor positioning system.the receiver module of optical signal is mounted on the intelligent service robot to realize the intelligent interaction between the robot and the positioning system.Under the guidance of the VLC system,the robot can acquire its own coordinates and complete intelligent tasks such as climbing,obstacle avoidance,and dispatching.The experimental results prove that the system scheme of this paper has great market application and promotion value. |
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