82 results about "Visible light positioning" patented technology

The invention discloses a visible light indoor adaptive positioning method fusing self-attention and a width learning network. The method specifically comprises the following steps: step 1, collecting pose information of received signal strength RSS and PD at different indoor space reference points; step 2, constructing a multi-dimensional feature fingerprint database containing reference point coordinates, RSS values and pose information; step 3, constructing an SA-BLS positioning model and carrying out training; 4, testing the positioning model trained in the step 3; and step 5, inputting the RSS and PD pose data at the target point to be positioned into the tested positioning model, calculating the coordinates of the target position, and outputting a positioning result. According to the invention, the problem that the existing positioning method is poor in precision due to the fact that the receiving end of the existing visible light positioning is in a fixed pose and the pose of the receiving end is dynamic and the RSS obviously fluctuates in practical application in the prior art is solved.

The invention discloses a multipath effect suppression method for indoor visible light positioning, relates to the technical field of indoor visible light communication and positioning, and aims to solve the problems in the prior art, the method comprises the following steps: constructing a fractional order chaotic signal generator and starting to generate a chaotic sequence signal; the chaotic sequence signals are modulated and loaded to an LED array and a driving circuit thereof, and optical signals carrying fractional order chaotic characteristics are generated and transmitted; after being propagated indoors, the optical signal is acquired by a photoelectric detector, is preprocessed and then is transmitted to a field FPGA (Field Programmable Gate Array); in the FPGA, based on a compressed sensing theory, modeling the received signal and constructing an adaptive sensing matrix to obtain a compressed observation signal; iteratively recovering sparse channel response from the compressed observation signal by adopting a path focusing guide orthogonal matching pursuit algorithm; and the FPGA extracts main path information from the reconstructed sparse channel response, and calculates a final positioning coordinate in combination with an arrival time positioning model. And in indoor visible light positioning, the method has a good capability of resisting a multipath effect.

The invention belongs to the technical field of visible light positioning, and relates to a visible light sparse fingerprint positioning method and system based on MLS-WKNN and a medium, and the method comprises the steps: collecting the received signal strength of a sampling point; fitting a received signal strength prediction value of each light source at the interpolation point through a moving least square method; constructing a dense fingerprint database through the received signal strength of the sampling points and the received signal strength predicted values of the interpolation points; collecting the real-time receiving signal intensity of the target point; and based on the real-time received signal strength and the dense fingerprint database, obtaining an accurate position estimation value of the target point through a weighted K-nearest neighbor algorithm. The sparse fingerprint database is subjected to MLS interpolation, the precision of sparse visible light fingerprint positioning is improved, and compared with an existing interpolation mode, the positioning precision is higher.

How to reduce the error of visible light positioning is the technical problem focused in the current positioning technology, and reduction of the positioning error by adopting the neural network technology is an important scheme for solving the problem. The invention provides a deep learning fusion system for visible light positioning and a method thereof, and aims to solve the problems of unstable model training effect, insufficient positioning precision and poor generalization ability caused by insufficient data acquisition amount in the prior art, or the problems of long training time caused by overlarge data scale and the like. According to the method, the corresponding small model neural network or large model neural network is selected for training and prediction according to the scale of the collected data volume in different operation stages of the system, and a dynamic judgment and periodical comparison mechanism is combined, so that quick and stable positioning output is realized when the data is limited; when the data is sufficient, a high-precision and high-robustness positioning effect is realized, so that the adaptability and reliability of the system in practical application are improved.

The invention discloses a visible light positioning method based on a single light source base station and double photosensitive position detectors. The method comprises: constructing a visible light positioning system; defining a world coordinate system, a PSD coordinate system and a PSD imaging coordinate system; calibrating two PSD internal parameters in the visible light positioning system by using a Zhang Zhengyou calibration method and an asymmetric dot calibration plate; the world coordinates of the LED light source and the external parameters of the PSD are calibrated; and determining the real-time coordinates of the mobile carrier in the world coordinate system. The method has the advantages that the double PSD receivers and the single light source base station are used for positioning the mobile carrier, positioning coordinate calculation can be carried out as long as the mobile carrier loaded with the double PSD receivers is located in the coverage area of one light source base station, operation is safe, easy and convenient, the degree of dependence on the light source density is reduced, and the applicability of the visible light positioning technology is enhanced.

The invention discloses an indoor visible light cooperative positioning method based on multi-dimensional sampling vector compressed sensing, and relates to visible light positioning. A plurality of indoor light source LEDs are utilized to issue visible light signals to a target, a target end receives and extracts arrival time difference information among different LEDs through a PD, and a sparse positioning model is constructed. A plurality of groups of reference anchor points are introduced, time difference of arrival measurement vectors are collected from different dimensions, and a multi-dimensional sampling observation matrix with higher representation capability on sparse distribution of a target space is constructed. Redundant or repeated time difference of arrival measurement is eliminated in the model, calculation redundancy is reduced, and robustness of sparse recovery is enhanced. And solving a predicted value of the PD position coordinate through norm minimization, and calculating an error between the predicted value and a true value. Under the condition that accurate clock synchronization is not needed, multi-target cooperative positioning is effectively achieved, and centimeter-level positioning accuracy can be kept under various noise and deviation conditions. The method is suitable for typical indoor positioning scenes such as industrial Internet of Things, intelligent manufacturing and robot navigation.

The invention relates to the technical field of visible light positioning, and provides an end-to-end indoor visible light positioning method and system based on pilot frequency sequence characteristics, and the method comprises the following steps: transmitting a visible light signal through an orthogonal frequency division multiplexing and orthogonal amplitude modulation mode, and extracting a pilot frequency sequence; extracting local spatial features of the pilot signals and converting the local spatial features into sequence embedding features; time sequence modeling is carried out on the embedded features, and key features are extracted; performing full connection and nonlinear mapping on the key features, and retaining original features through residual connection; and a Kolmogorov-Arnold network is utilized to carry out positioning. Aiming at the problems of channel estimation dependence, high calculation complexity, high data demand, low signal-to-noise ratio, poor adaptability and the like in the existing indoor visible light positioning system, the real-time performance, the robustness and the calculation efficiency of the system are improved based on end-to-end deep learning indoor positioning of the pilot signal fusion LumiLocNet network.

The invention discloses an indoor multi-target visible light positioning method based on compressed sensing, and relates to the technical field of visible light communication.The method comprises the steps that visible light signals are converted into sparse vectors, and autocorrelation signal vectors in the multiple visible light signals are aggregated to obtain the total power of the signals; when the compressed sensing algorithm CS measures indoor visible light transmission, an observation matrix is formed, measurement power is given to the observation matrix based on the total power, and a plurality of sparse vectors are recovered by using the measurement power; aggregating cross-correlation measurement vectors in the plurality of visible light signals, reconstructing sparse vectors to obtain a plurality of positioning sparse vectors, identifying positions of non-zero elements in the positioning sparse vectors, and determining positions of a plurality of targets; according to the process, sparsity and cross correlation in multi-target visible light signals are mined, a multi-target positioning problem in a complex environment is converted into a sparse recovery problem by using a compressed sensing (CS) method, and multi-target signals are distinguished and identified by using sparse weak signals, so that high-precision multi-target positioning is realized.

The invention discloses an indoor high-precision visible light positioning method for a complex dynamic crowd environment, relates to the technical field of indoor visible light communication, and aims to solve the problems in the prior art. Performing initial position calculation based on a quadrilateral measurement method in combination with the phase and intensity information of the optical signal; optimizing the initial position of the receiving end by using a QPSO algorithm; an infrared sensor collects crowd density and dynamic changes in an area in real time and generates a thermodynamic diagram, the influence of crowd flow on a light field is predicted based on a hydromechanics eddy current model in combination with an RNN network, a crowd flow eddy current model is generated, optical signals of a receiving end are optimized through a CVPA algorithm, and signal characteristics are dynamically adjusted through the eddy current effect; the FPGA carries out accurate tracking and positioning updating on the position of the APD receiving end through an EKPF filter; the weights of the QPSO, the CVPA and the EKPF are adjusted in a self-adaptive mode; and the FPGA obtains the final accurate position coordinates of the receiving end through multiple iterations. The method is suitable for real-time positioning of high-density crowds.

The invention provides a positioning method and system based on a visible light communication technology, and particularly relates to the technical field of indoor visible light positioning. According to the method, a plurality of visible light emitters emit modulated light signals, the modulated light signals are received by a prismatic table phased array receiving terminal, the terminal is provided with a plurality of receiving surfaces, and each receiving surface comprises a plurality of light detection units. And multi-stage differential noise reduction processing is carried out on the electric signals output by the light detection units of the receiving surfaces, the multi-stage differential noise reduction processing comprises first-stage differential suppression of local noise in the receiving surfaces and second-stage differential suppression of reflected light interference between the receiving surfaces, and a light intensity response value is obtained. The distance between the terminal and each transmitter is calculated through filtering processing and a distance calculation model based on a light intensity response value, and then the position of the terminal is determined by using a multilateral positioning algorithm, so that centimeter-level precision positioning in an electromagnetic sensitive environment is realized, and electromagnetic interference and explosion-proof risks are avoided.

The invention discloses an indoor visible light positioning method and device based on environment dynamic adjustment, equipment and a storage medium, and relates to the technical field of optical information. According to the method, a preset reflection light model is established, parameters of the preset reflection light model are dynamically adjusted based on indoor environment changes, a propagation path of an optical signal in an indoor optical information environment is simulated according to the preset reflection light model, and the multipath effect and signal intensity distribution are evaluated. And a signal processing strategy is specifically designed at the rear end according to the condition of reflected light, for example, a filter model is designed to remove interference of a specific frequency, and the like, so that the reliability and accuracy of positioning are improved.

The invention discloses a visible light positioning method based on geometrical characteristics of a lamp, and belongs to the field of visible light communication in the technical field of communication. According to the method, firstly, a camera is used for capturing geometric features of a lamp, then, a normal vector of the lamp in an auxiliary coordinate system is calculated, in the process, the calculated normal vector has the problem of multiple solutions, the camera virtual offset technology is adopted, the uncertainty of the multiple solutions is effectively eliminated, and finally, through a single-view geometric method, the normal vector of the lamp in an auxiliary coordinate system is calculated. And the posture and the position of the camera are accurately determined, so that an accurate and efficient positioning technology is realized. Simulation results show that the positioning errors of the sample points are within 10cm.

The invention discloses an indoor passive visible light positioning system based on a perovskite cell and an implementation method thereof, and relates to the technical field of visible light positioning. According to the invention, during modulation, a PWM modulation method for carrying out digital coding on an analog signal level is adopted, so that the stable output power of a transmitter can be ensured, and light flickering caused by data transmission is prevented; when the receiving terminal solves the coordinates, the wave frequency is calculated through the counter, the counter is stopped immediately after the wave frequency is obtained, and the low-frequency analog-to-digital conversion module is stopped immediately after the sampling mean value is obtained, so that the power consumption of system operation is reduced to a certain extent, and the long-time operation of the system is ensured.

The invention relates to the technical field of indoor visible light positioning, in particular to a virtual light source positioning method based on indoor reflecting surface reconstruction. Comprising the following steps: establishing an indoor coordinate system, and collecting received signal strength and arrival time from a direct incidence path and a reflection path; judging a line-of-sight path and a non-line-of-sight path based on the RSS and the TOA, and preliminarily estimating a propagation distance; estimating plane equation parameters of the indoor main reflecting surface by using a constrained least square method; according to the estimated reflecting surface, performing mirroring operation on the position of the real light source, and reconstructing the position of a virtual light source; constructing a joint distance optimization model containing a real light source and a virtual light source, and solving an optimal coordinate of a receiving end by a weighted least square method; a self-adaptive dynamic updating mechanism is introduced, and joint state estimation and optimization are carried out on the position of the receiving end and the parameters of the reflecting surface; according to the method, the reflection path is converted into effective positioning constraint, the shielding problem in the NLOS environment is effectively solved, and the precision and robustness of a positioning system are remarkably improved.

The present invention relates to the fields related to optical camera communication technology and visible light positioning technology, and discloses a visible light positioning system based on a binocular vision algorithm, including a modulation transmitting end and a positioning receiving end; the system overcomes the disadvantage that a traditional direct line-of-sight visible light positioning system cannot locate under occlusion, and 3D positioning can still be achieved through an ambient reflection light system, and only one LED is required to achieve high-precision positioning, which greatly improves the environmental adaptability of the system; at the same time, compared with the traditional satellite positioning method, the system effectively improves the problem of poor indoor environmental signals and ineffective navigation.

The utility model discloses a visible light positioning device based on irregular LED arrangement, which comprises a light detection processing all-in-one machine and at least one LED light source, and the LED light source is arranged at any position in a room. The optical detection processing all-in-one machine is arranged on an object to be positioned, and a circuit board is arranged in the optical detection processing all-in-one machine; the optical detection and processing all-in-one machine comprises a shell, and a spiral hole used for installation and fixation is formed in the shell. A cavity is formed in the rear side of the shell; an electric disc is arranged at the bottom of the cavity, a telescopic mechanism is arranged on the electric disc, a light detector is arranged on the telescopic mechanism, and the electric disc, the telescopic mechanism and the light detector are all electrically connected with the circuit board. According to the utility model, the flexible arrangement of the LED lamp source can be realized, the system can adapt to more indoor scenes, and the positioning performance is higher.

The invention discloses an indoor visible light pedestrian positioning method based on improved unscented Kalman filtering, and belongs to the technical field of visible light communication positioning. The method comprises the following specific steps: initializing a loop count value, positioning an initial coordinate and setting an initial covariance; collecting inertial navigation motion parameters and resolving visible light positioning position coordinates; dynamically adjusting a non-line-of-sight threshold according to received signal strength data within a period of time so as to judge whether visible light positioning data is adopted or a visible light and inertial navigation fusion algorithm is adopted; setting an improved extended Kalman filtering parameter, and introducing a self-adaptive Huber threshold value into a fusion filtering algorithm, so as to obtain a filtered carrier position; further obtaining a fusion positioning position coordinate at the moment k; judging whether the cycle count value reaches the maximum value or not to determine whether the positioning method is completed or not; according to the method, the problem of precision reduction caused by fusion under the sight distance is effectively solved, the positioning precision under the NLOS is remarkably improved, and good stability and reliability are achieved.

The invention discloses a visible light positioning method based on data enhancement and a neural network, and relates to the technical field of visible light positioning. The method is an indoor visible light positioning technology based on deep learning. According to the invention, a single LED lamp is installed in an indoor space to be positioned as a light source, a plurality of photoelectric detectors on a receiver are used for obtaining optical signals, and a trained deep learning model is used for analyzing the optical signals, so that the positioning of the receiver is completed.

The present invention discloses a method for finding extreme values ​​of correlation values ​​in a visible light communication and positioning system based on CDMA. Based on CDMA technology, in an indoor visible light communication and positioning system, the method assigns a highly correlated optical address code to the reserved undefined portion of the VLC frame to be transmitted by each LED light. At the receiving end, the local address code is used to continuously perform correlation operations on the received signal using a sliding window method to obtain a number of correlation values. The extreme values ​​and extreme value points of the correlation values ​​are then used for synchronous detection to determine the position of the address code in the VLC frame, and these extreme values ​​are used for positioning. The present invention can be used to separate positioning and communication signals in a combined visible light positioning and communication system, achieving simultaneous communication and positioning, and performing synchronous detection on signals with asynchronous arrival times.

The invention discloses an indoor combined positioning method utilizing environment perception, and particularly relates to the technical field of indoor positioning, which comprises the steps of S1, theoretical analysis, S2, algorithm design and S3, algorithm verification. By constructing an adaptive federated filtering architecture, the fusion of binocular vision, visible light positioning and an inertial navigation system is realized, a strapdown inertial navigation system is taken as a main reference system, visible light and a binocular camera are combined to serve as auxiliary reference systems, a sub-filter based on a maximum correlation entropy criterion is designed, and the visual positioning precision is improved. According to the method, the weight of each sub-filter is dynamically adjusted by introducing a self-adaptive information distribution mechanism, simulation and experimental verification show that the accuracy and robustness of indoor positioning can be effectively improved, compatibility of various sensors is supported, and the method is suitable for indoor high-precision navigation application of service robots, AR / VR equipment and the like.

The invention belongs to the technical field of solid waste recycling and intelligent sorting equipment, and discloses a waste plastic high-speed sorting method based on multispectral fusion and element screening, which is suitable for online separation of general-purpose plastics such as PP (polypropylene), PE (polyethylene), PVC (polyvinyl chloride) and PET (polyethylene terephthalate). Aiming at the problems of difficulty in black plastic identification, insufficient PVC / halogen-containing risk discrimination and wrong sorting caused by industrial drift in traditional near-infrared sorting, a link of visible light positioning, near-infrared main identification, intermediate infrared / medium-wave infrared reinspection, X-ray fluorescence element discrimination, multi-modal fusion decision-gas injection separation is adopted, grading detection is triggered through confidence, and the sorting accuracy is improved. A risk priority rule and an online self-calibration compensation strategy are combined, and a two-stage sorting framework is matched. According to the method, high-risk PVC particles are preferentially removed, black plastic is accurately recognized, the separation purity is improved while high productivity is guaranteed, the industrial operation stability and expandability are enhanced, and the waste plastic recycling benefit is remarkably improved.

The invention relates to the technical field of indoor visible light positioning, in particular to an RSS fingerprint reconstruction method applied to visible light positioning, which comprises the following steps: constructing a visible light RSS data acquisition method for eliminating the influence of natural light, and eliminating the influence of the natural light by using a real-time RSS difference value of a high level and a low level; the method comprises the following steps: constructing a visible light RSS fingerprint reconstruction method without coefficient calibration, and reconstructing an RSS vector of each interpolation position by using an RSS matrix of a training position; and combining the RSS matrix of the training position and the RSS matrix of the interpolation position to form a dense visible light RSS database, and completing reconstruction and updating of the visible light RSS fingerprint. According to the technology, the labor cost and the time cost for constructing the RSS database are greatly reduced on the premise that the positioning precision similar to that of an actual dense RSS database is obtained. The RSS fingerprint reconstruction method provided by the invention does not need coefficient calibration, is not influenced by natural light, and can be well applied to RSS fingerprint reconstruction of visible light positioning.

The application provides a CSI-based adaptive iterative visible light positioning method and system, and the method comprises the following steps: receiving positioning light signals sent by a plurality of LED light sources, and processing each positioning light signal to obtain a channel impulse response vector; estimating a line-of-sight path distance between each LED light source and a receiver according to the channel impulse response vector, and obtaining a first horizontal distance between each LED light source and the receiver according to each line-of-sight path distance; constructing an initial position set by using a cyclic least square method according to the first horizontal distance between each LED light source and the receiver, and obtaining a final estimated position of the receiver according to the initial position set and a preset position weight threshold. The application can fully utilize positioning information, effectively reduce the influence of nonlinear error in the least square positioning application based on CSI, improve positioning accuracy and stability, support complex indoor positioning scenes, and has high application value.

The invention discloses a light source RSSI (Received Signal Strength Indicator)-based selective weighted positioning method, which is realized by adopting an FPGA (Field Programmable Gate Array), and the positioning process mainly comprises the following steps of: screening four signals with the maximum power from different light sources from numerous received signals, selecting any three light sources from the four light sources, ensuring that the three light sources are not collinear, and then selecting one light source from the screened four light sources. Every three light sources form one group, four position coordinates of a receiving end are calculated through an RSSI triangulation positioning algorithm for correcting the weight of the four groups of light sources, and finally the coordinates of the receiving end are accurately estimated through centroid weighting. According to the method, positioning errors caused by light source reflection interference and transmission distance errors in actual use of visible light positioning can be reduced, the influence of environmental factors on signal fluctuation is reduced, the positioning precision is improved, and the method can be implemented on an FPGA hardware platform and has practicability.

The invention discloses a software platform system suitable for visible light positioning communication, which is applied to a server, is realized by adopting a B / S (Browser / Server) architecture, and comprises a front-end module and a rear-end module, the rear-end module is constructed by adopting a SpringBoot framework, and data interaction transmission is performed between the rear-end module and a lamp by adopting a TCP / IP (Transmission Control Protocol / Internet Protocol) communication protocol; the rear-end module is used for receiving lamp data, and the lamp data contains personnel attribute information received by the lamp from the user side; the rear-end module is used for analyzing and processing the lamp data, transmitting an analysis and processing result to the front-end module, and performing data storage and data read-write processing; wherein the lamp adopts a visible light communication technology to communicate with the rear-end module and the user side; and the front-end module uses a preset front-end framework to build a page and is used for displaying the analysis processing result on a pre-stored place three-dimensional stereogram so as to realize different display functions. According to the invention, stable, efficient and accurate data transmission can be realized, personnel positioning can be realized, and operation and management are facilitated.

The present invention provides a binocular positioning method with unconstrained arrangement of light sources, which belongs to the field of computer vision positioning. It is a visible light positioning method that uses an unscented Kalman filter to fuse data from an inertial sensor and data from a binocular camera. The present invention first establishes a process equation in the framework of an unscented Kalman filter algorithm to predict the position and attitude angle of a target object in three-dimensional space, and then establishes a measurement equation based on the pixel image of the binocular camera to correct the position and heading angle of the visible light feature points of the target object calculated in the process equation. The position and attitude angle of the visible light feature points of the target object calculated by the present invention can maintain high accuracy even when the data accuracy of the six-axis inertial sensor is low and the position recognition noise of the visible light feature points in the pixel image is large; it has wide applicability and strong stability.

This application discloses a visible light positioning and communication method, apparatus, and system, belonging to the field of visible light positioning and communication. It involves driving an LED lamp to emit a light signal with a preset modulation frequency. A receiving sensor receives the spectrum, extracts the chip's native blue light spectrum, and then decodes the spectral information carried by the spectrum based on the hardware parameters of the receiving sensor to obtain digital information. Positioning and communication are then performed based on this digital information. This application's solution completely eliminates physiological flicker perceptible to the human eye by employing high-frequency modulation at a preset frequency. Simultaneously, receiving only the native blue light spectrum effectively removes the afterglow effect of phosphors, ensuring clear high-frequency signals and significantly improving decoding success rate. Adaptive decoding, combined with the receiving sensor's hardware parameters, solves the frequency offset problem caused by hardware differences between different devices, enhancing cross-device compatibility. This achieves high-precision, high-reliability visible light positioning and communication, applicable to indoor navigation, communication, and other scenarios.

The utility model discloses a modulator for visible light positioning, which relates to the technical field of acoustic optical modulators, and comprises a modulator main body, one end of the modulator main body is provided with a first connecting end, the other end of the modulator main body is provided with a second connecting end, and the front end of the modulator main body is provided with a radio frequency interface; the modulator comprises a modulator body and further comprises a limiting groove formed in the corner of the lower surface of the modulator body, a moving groove is formed in one side of the limiting groove, a limiting frame is arranged in the limiting groove and moves along the limiting groove, and a fixing base is arranged at one end of the limiting frame; according to the scheme, the acousto-optic modulator solves the problems that the position of a fixing seat of an existing acousto-optic modulator is fixed, when the acousto-optic modulator is installed, due to the fact that the position of an installation hole does not correspond to the position of the fixing seat, the acousto-optic modulator cannot be installed, holes need to be punched again, time and labor are wasted, installation is inconvenient, and flexibility is poor.

The invention provides a positioning method based on visible light, which realizes a communication and positioning integrated system by sending a positioning signal by using a subcarrier in orthogonal frequency division multiplexing (OFDM). The system uses a visible light communication technology, and data transmission is carried out through visible light sources such as an LED. Meanwhile, the OFDM technology is utilized to divide the frequency spectrum into a plurality of subcarriers, and part of the subcarriers are selected for positioning. The specific subcarriers can provide high-precision position information during positioning. The method has the advantage that a more efficient and accurate communication and positioning integrated solution is provided for a user by combining visible light positioning and a high-spectrum-efficiency OFDM technology. The method not only improves the performance of a communication system, but also has a wide application prospect in the field of positioning.

The invention discloses a light source design-based false light source identification method in visible light positioning, and belongs to the technical field of navigation positioning. A plurality of light sources with different radiuses are adopted as a group of light source arrays, the light sources are circularly arranged clockwise or anticlockwise to form a polygonal dot matrix, and the size sequence relation of each sub-light source in each group of light sources according to clockwise or anticlockwise sorting is recorded; in the receiving process, after the light source ID is confirmed by identifying the feature sequence point light source, whether the clockwise or anticlockwise arrangement sequence of the sub-light sources in the light source array is consistent with the preset recorded arrangement sequence is analyzed to judge the authenticity of the light source; if the arrangement relation of the neutron light sources in the light source array is consistent with that during installation, determining that the light source is a real light source; otherwise, judging the light source as a mirror image light source. IDs between the sub light sources do not need to be distinguished by stripes, the identification can be carried out according to the arrangement sequence of the sub light sources in each group of light source array, the identification method is simple and easy to calculate, the identification precision and speed are improved, the identification can be effectively carried out, and the light source design is simple.