CN112017341B - Thing networking access control system based on contrary reflective visible light communication - Google Patents

Thing networking access control system based on contrary reflective visible light communication Download PDF

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CN112017341B
CN112017341B CN202010695846.7A CN202010695846A CN112017341B CN 112017341 B CN112017341 B CN 112017341B CN 202010695846 A CN202010695846 A CN 202010695846A CN 112017341 B CN112017341 B CN 112017341B
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retro
access control
information
signal
mobile terminal
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CN112017341A (en
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许辰人
徐燮阳
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Peking University
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Peking University
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    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/20—Individual registration on entry or exit involving the use of a pass
    • G07C9/22—Individual registration on entry or exit involving the use of a pass in combination with an identity check of the pass holder
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/20—Individual registration on entry or exit involving the use of a pass
    • G07C9/27—Individual registration on entry or exit involving the use of a pass with central registration
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/70—Services for machine-to-machine communication [M2M] or machine type communication [MTC]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

The invention relates to an Internet of things access control system based on retro-reflection visible light communication, which at least comprises a mobile terminal and an access control terminal, wherein the mobile terminal or the access control terminal is provided with a configurable retro-reflection unit, the mobile terminal and/or the access control terminal passively receive optical signals through the retro-reflection unit and return the optical signals in a retro-reflection mode to be in a passive communication state, and the optical signals can provide energy for the mobile terminal and/or the access control terminal. Through the setting mode, one end needing to be configured can be always in passive work without power supply or independent communication link establishment, configurability for a specific object can be realized, and the method is particularly suitable for the authority management scene that one party is inconvenient to obtain power supply but needs to be configured independently.

Description

Thing networking access control system based on contrary reflective visible light communication
Technical Field
The invention relates to application in the field of visible light communication, for example, the visible light communication is applied to an access control system of the Internet of things.
Background
The Access Control System is in the field of intelligent buildings, means an Access Control System, means the prohibition authority of a door, and is used for guard and prevention of the door. The "door" herein refers to various passages that can be passed through, including a door for people to pass through, a door for vehicles to pass through, a door for goods storage, and the like. The access control authority management is mainly realized. With the rapid development of communication, computer and internet technologies, modern access control technologies integrate microcomputer automatic identification technologies and modern safety management measures, and relate to a plurality of new technologies such as electronics, machinery, optics, computer technologies, communication technologies, biotechnology and the like.
The existing access control system mainly comprises a password access control system, a card swiping access control system, a biological identification access control system and the like. Password access control systems have been under scrutiny due to their poor security and convenience. The biological identification access control system is an access control system which can identify the identity according to the difference of the biological characteristics of the human body. Common fingerprint access control systems, iris access control systems, face recognition access control systems and the like. The biological identification access control system has the defects of high cost, difficulty in wide deployment, low contrast speed and unsuitability for occasions with more personnel. The card-swiping access control system is divided into a contact access control system and a non-contact access control system. The contact access control system includes a contact Integrated Circuit Card (IC), a magnetic stripe Card, a barcode Card, and the like. The contact card is easy to wear, so that the use frequency is limited, the contact card is easy to copy, the safety is low, and the use range of the contact card is limited.
The non-contact access control system includes Radio Frequency Identification (RFID) technology, an inductive IC card, and the like. Due to the rapid development of sensor technology, radio frequency identification technology and embedded technology, the non-contact access control system can be combined with the internet of things technology so as to meet the actual requirements of modern access control technology. For example, documents [1] poplar stems, an access control system based on the internet of things research [ D ]. Tianjin university, an internet of things technology and an access control system are combined to construct a novel access control system based on the internet of things technology, a sensor technology in the internet of things technology is introduced, the physical state of an access control site can be sensed, the real-time condition of the site can be known and processed at a remote measurement and control end, for example, an infrared sensor, a laser scanner and the like are used for acquiring identity information, or a camera is used for a user to acquire an intuitive monitoring picture; through introducing the embedded technology in the thing networking, can increase access control system's integrated degree and stability, reduce the installation volume, reduce installation cost and power supply demand, extension life cycle etc.. By introducing the RFID technology in the Internet of things, the identities of people or objects such as cardholders, cardholders and vehicles can be effectively authenticated, and people or objects with strange identities are prevented from entering. However, radio frequency information based on the internet of things technology is easily interfered and broken, so that the radio frequency information is easily intercepted and copied, and information leakage and property loss are caused. The above contents all form the common general knowledge in the field of wireless networking technology of the internet of things. To avoid repetition, the present invention is hereby incorporated by reference to the extent that such references form a part of the present disclosure.
Most of the existing access control systems have the problem that the security and the system cost are difficult to be integrated, namely, the verification mode of the access control system is based on the traditional wireless mode, so that the transmission mode is uncontrollable and the confidentiality is poor. However, the Visible Light Communication technology (VLC) naturally has the natural advantages of strong transmission controllability and high security and security, and can effectively overcome the problems of low contrast efficiency and poor security of the existing access control system.
For example, document [2] Guo Yanqing, Internet of things access control system design based on visible light communication and implementation [ D ].2016, Nanjing post and Electricity university disclose an Internet of things access control system based on visible light communication, which combines visible light communication technology and wireless network access control technology to realize that a user can complete personal information verification of the access control system in a visible light mode, and forms a CS mode through Internet of things wireless networking technology to realize online matching of user access control authority and access control monitoring. The access control system comprises three parts, namely an optical secret key, an optical access control part and a background server. The optical key unit is responsible for encrypting and sending key information, visible light is used as carrier waves and sent to the optical access control unit, the optical access control unit receives the visible light carrier waves loaded with the encrypted key information and carries out photoelectric conversion and key decryption, then request information and state information of the access control are sent to the background monitoring unit through a wireless information receiving and sending module of the optical access control unit to carry out authority verification and state recording, and the background monitoring unit feeds back access enabling information to the optical access control unit. Among them, this document uses a light key unit instead of a magnetic wireless card, RFID, contact IC card, electronic password, fingerprint recognition, iris recognition, face recognition, etc., and realizes modulation of information using a change in the brightness of light emitted from the LED and transmits it to the light gate unit. The optical key unit adopts two implementation schemes, one is a portable optical key based on an embedded chip, and the other is an optical key connected with a Micro USB interface of the smart phone. The basic technical scheme is that information is processed, such as coding and the like, and is transmitted to a driving circuit of an LED, so that an LED lamp is driven to emit visible light with changed brightness, namely, the information is loaded on the visible light; the light entrance guard unit receives the visible light and demodulates the visible light to obtain information. The detection principle of the light access control unit on visible light is as follows:
the optical access control unit is provided with an optical sensor, such as a Photodiode (PD), which can sense an optical signal of a surrounding environment, thereby implementing photoelectric conversion. Due to strong interference of other ambient light around, such as a fluorescent lamp for lighting, visible light and ambient light transmitted by the optical key unit are mixed together, and electronic noise generated in the PD, such as thermal noise, shot noise, dark current noise, etc., also interferes with the conversion of the optical signal, so that noise isolation is required to be performed on the received visible light signal, thereby improving the signal-to-noise ratio. The signal is then amplified. Generally, two-stage amplification is adopted, wherein the first stage amplification mainly improves the signal-to-noise ratio of a signal, and the second stage amplification is the signal magnitude required by a subsequent recovery circuit for amplifying the signal. However, the operational amplifier will also amplify the noise, and the operational amplifier itself will also generate the noise, mainly from the inside of the chip, so that signal filtering is required to filter out the noise, so as to ensure the signal-to-noise ratio of the output signal. The amplification is followed by signal recovery. The principle of signal recovery is to sample and judge an analog signal according to the requirements of digital communication on an electric signal, and then recover a digital signal corresponding to a code rate, thereby playing a role of analog-to-digital conversion. And decoding and recovering the electric signal according to the rule of visible light modulation, and then forming a data frame which can be identified by the optical access control unit according to a serial port communication protocol defined by the system for the module.
For example, chinese patent publication No. CN106296896A discloses an access control system based on LED visible light communication, in which an intelligent handheld device of the access control system communicates with an access network server through a wireless network to obtain an access control pass code, and the pass code after being encoded uses an LED flash lamp of a mobile device to send information; the entrance guard network server builds an entrance guard data service system on a PC (personal computer) end through programming design to serve as an entrance guard management system, confirms the identity of a user requesting to log in the server, and transmits a login pass code to the intelligent handheld device which logs in successfully through a wireless network; the visible light receiving control unit supports communication with the PC end, and the decoding of transmitted information, serial port communication and the opening and closing functions of controlling an access control system are realized by carrying a single chip on a receiving circuit.
For example, chinese patent publication No. CN108734823A discloses an entrance guard authentication method, a key device, and an entrance guard device based on ultraviolet light communication, the entrance guard authentication method including: the key terminal sends the information containing the random bit verification code; the entrance guard end judges whether the bit number L of the random bit identifying code information is within a preset bit number range or not; the entrance guard end judges whether the arrangement serial number is consistent with the stored arrangement serial number M; the access control terminal judges whether the random verification code information is accurate or not; and opening the access control, and storing the M + L as a new sequence number. The access control authentication method needs to sequentially verify the bit number of the random bit verification code, the position of the random bit verification code in the verification sequence information and the random verification code information, has the characteristics of higher safety, ultraviolet short-distance transmission and partial penetration of barriers, is not easy to interfere in the verification process, and is difficult to copy or crack interactive information.
For example, chinese patent publication No. CN107492175A discloses a visible light security door lock, a system and an unlocking method, wherein the visible light security door lock includes an electronic door lock mechanism, an LED backlight panel for receiving a visible light signal, an LED backlight panel for sending the visible light signal, and a processor electrically connected to the electronic door lock mechanism, the LED backlight panel and the photodetector, and the processor stores a corresponding address code; when the device is used, the processor sends the address code after receiving the activation code, and calculates to obtain a check code by applying an RSA encryption algorithm according to the address code; and after the processor receives the unlocking code, the checking code and the unlocking code are compared, and the electronic door lock mechanism is controlled to unlock after the comparison is consistent. According to the invention, the access control card is replaced by the mobile terminal and the unlocking is verified by adopting double calculation, so that the defect of replicability of the access control card is overcome, a user can unlock the door only through the mobile terminal, and the safety and convenience of the access control system are further improved.
The access control system based on visible light communication disclosed in the above documents adopts a mobile terminal to actively transmit a light signal, and the access control terminal receives the light signal and verifies the identity information contained in the light signal, or is connected with a server through the internet of things or the internet to verify the identity information, and then opens or closes the access control; or remove the end and pass through the internet and be connected with the server, acquire corresponding key information and send to entrance guard terminal with the form of visible light, entrance guard terminal demodulates and generates corresponding check-up information according to the light signal that receives, then send to removing the end, remove the end demodulation and acquire corresponding check-up information and server and send the key information and verify, after verifying the pass again to entrance guard terminal transmission information of unblanking, entrance guard terminal verifies according to unblanking information and local information contrast, it unblanks to verify after succeeding in verification. Therefore, the access control system based on visible light communication actively emits visible light to transmit information no matter one-way communication or two-way communication is adopted. However, the light emitting range of a general LED or other general light emitting device and the corresponding angle range of the sensor for receiving an optical signal are limited, which requires that a mobile terminal and an access terminal need to be completely aligned to realize two-way communication, which poses a serious challenge to the Mobility (Mobility) of any device and the Scalability (Scalability) of one-to-many communication and many-to-many communication, and is difficult to be practically applied to an application scene with a large traffic volume. Secondly, from the viewpoint of design concept, economic cost, operation and maintenance, and wide deployment and use, the corresponding device should be miniaturized, have low power consumption, and even be passive. However, the energy consumption of communication emission based on the LED is usually several hundred milliwatts, and the effective electric energy converted by the solar cell of the size of the internet of things device is usually only several hundred microwatts, which results in poor mobility and high cost. Secondly, the active transmitting-receiving visible light mode is not only easily interfered by ambient light and poor in anti-interference capability, but also easily intercepted, and the safety is questioned. Finally, in order to improve the security of the access control system based on visible light communication disclosed in the above document, not only the mobile terminal and the access control terminal need to be connected to the corresponding server or the background management system through the internet, but also the verification procedure is complicated and complex, and the identity verification can be completed only by performing mutual bidirectional communication between the mobile terminal, the access control terminal and the server for many times.
Furthermore, on the one hand, due to the differences in understanding to the person skilled in the art; on the other hand, since the inventor has studied a lot of documents and patents when making the present invention, but the space is not limited to the details and contents listed in the above, however, the present invention is by no means free of the features of the prior art, but the present invention has been provided with all the features of the prior art, and the applicant reserves the right to increase the related prior art in the background.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an Internet of things access control system based on retro-reflective visible light communication, which at least comprises a mobile terminal, an access control terminal and a server connected with the mobile terminal or the access control terminal through Internet of things wireless networking technology. The mobile terminal can establish a visible light communication link with the access control terminal to transmit identity verification information, so that the identity verification information is authenticated by the server to open or close the access control terminal. The mobile terminal or the entrance guard terminal is provided with a configurable retro-reflection unit. The mobile terminal and/or the entrance guard terminal are in a passive communication state by passively receiving the light signals through the retro-reflection unit and returning the light signals in a retro-reflection mode. The optical signal can provide energy for the mobile terminal and/or the access terminal. In the process of bidirectional communication management authority, the end with the retro-reflecting unit is usually the end needing configuration, and the configuration involves two important aspects of signal transmission processing and power supply. In the invention, the configurable retroreflection unit utilizes the passive received light signal to realize configurability and returns the light signal in a retroreflection mode, namely the retroreflection unit of the invention can greatly reduce energy consumption in a retroreflection light signal mode, and simultaneously has the capabilities of collecting energy and processing the light signal, so that one end needing to be configured can be always in passive work without power supply and independent communication link establishment, and the configurability aiming at a specific object can be realized, and the invention is particularly suitable for an authority management scene that one party is inconvenient to obtain power supply but should obtain independent configuration. And moreover, the retroreflection unit adopts a retroreflection mode to establish the optical communication link, so that the optical communication link between the mobile terminal and the entrance guard terminal has good direction response characteristic, and the concentration of the reflection direction is ensured. In addition, the optical communication link established in a retro-reflection mode has high space orientation characteristics, communication information can be guaranteed not to be intercepted, and the safety of the access control system is further improved.
According to a preferred embodiment, the retro-reflective unit comprises at least a modulation module, a first controller connected to the modulation module, a first optical sensor connected to the first controller, and energy storage means connected to the first optical sensor, the first controller and the modulation module, respectively. The first optical sensor is used for collecting energy and receiving optical signals with information, transmitting the collected energy to the energy storage device and transmitting the optical signals to the first controller. The first controller is configured to generate feedback information based on the information-bearing optical signal and to generate a driving signal to drive the modulation module based on the feedback information. One side of the modulation module is provided with a retro-reflection layer of retro-reflection light signals, so that the modulation module can modulate the feedback information on the retro-reflection light signals based on the driving signals in a manner of controlling the brightness change of the retro-reflection light signals of the retro-reflection layer.
The retroreflective elements are further configured to: and controlling the connection states of the first optical sensor and the energy storage device and the modulation module respectively through the first controller based on a pulse sequence, so that the mutual isolation and high-frequency switching of the energy collection state and the signal detection state are realized. Although the prior art may reduce the power consumption of the retroreflective elements by reducing the size or by using lower power consumption, additional means are still required to power the retroreflective elements. Furthermore, although an optical sensor like a solar cell may be used to collect the energy acquisition signal, for example, chinese patent publication No. CN106529645B discloses an automatic identification passive tag based on visible light communication, which discloses a power management system that converts light energy into electric energy using a solar cell and inputs the electric energy to the passive tag. The principle of signal acquisition using a solar cell disclosed in this patent document is: the solar cell converts the optical signal into the electrical signal and inputs the electrical signal into the capacitor, and the alternating current signal in the output of the solar cell can be obtained by reasonably selecting the capacitor due to the direct current and alternating current removing characteristic of the capacitor and is input into the optical receiver, so that the conversion from the visible light signal to the electrical signal is realized. However, the solar cell does not output an ac signal. In fact, the optical signal received by the solar cell includes an ambient light signal and an optical signal transmitted by the read-write unit, wherein the ambient light signal is in a continuous state with slowly changing amplitude most of the time, and the read-write unit transmits a discrete optical signal with interval states. The existence of the ambient light signal may possibly overwhelm the light signal sent by the read-write unit, and the electrical signal output by the solar cell may not output an alternating current signal with a partially intermittent characteristic due to the existence of the ambient light signal, so that the characteristic of removing direct current and alternating current of the capacitor is obviously unreliable to obtain the light signal sent by the read-write unit. Although the optical signal sent by the read-write unit can be detected and obtained by constructing a corresponding circuit through various electrical devices, the power and the volume of the retro-reflection unit are undoubtedly increased, and the energy provided by the solar cell cannot maintain the energy consumption of the retro-reflection unit, so the technical scheme disclosed in the patent cannot reliably detect the signal while the solar cell collects the energy. According to the invention, the energy collection state and the detection state of the optical signal are isolated from each other, namely the retro-reflection unit can not detect the optical signal sent by the read-write unit under the state of collecting energy, so that the reliable detection of the optical signal can be realized. According to the invention, the first controller controls the first optical sensor to be respectively connected with the energy storage device and the modulation module, so that the energy collection state and the signal detection state can be physically isolated, namely, under the condition that the first optical sensor is connected with the energy storage device, the retroreflection unit is in the energy collection state; when the first optical sensor is connected with the modulation module, the retro-reflection unit is in a signal detection state. In addition, the retro-reflection unit needs to timely and reliably identify the optical signal emitted by the mobile terminal or the entrance guard terminal in the energy collection state, which means that the retro-reflection unit needs to spend a certain amount of time to detect the signal, and although it can avoid that the retro-reflection unit misses the optical signal emitted by the mobile terminal or the entrance guard terminal, it may cause the energy collection time to be reduced, that is, the charging power is less than the power consumed by the retro-reflection unit due to the reduction of the charging time, so that the retro-reflection unit cannot normally operate, and therefore the energy collection state and the signal detection state are isolated and switched at high frequency by the first controller based on the pulse sequence. The high-frequency switching means that the duty ratio of the pulse sequence controls the connection of the first optical sensor with the energy storage device and the modulation module respectively, namely, the waveform obtained by the first optical sensor is collected at a short interval in a timing mode, so that the energy collection state and the detection signal state are alternately changed, the signal is detected in the shortest possible time, and the rest of the time is used for realizing energy collection. In fact, according to the nyquist sampling theorem, when the sampling frequency is greater than twice the frequency of the optical signal transmitted from the gate inhibition terminal or the mobile terminal, the first controller can still recognize the signal. Preferably, after the retro-reflection unit identifies the optical signal sent by the entrance guard or the mobile terminal, the retro-reflection unit directly accesses the modulation state, that is, the first controller demodulates the optical signal and generates the feedback information. The high frequency switching between the energy harvesting state and the signal detection state is re-entered until after the retro-reflective elements modulate the feedback information on the retro-reflected light signal. Moreover, under the authority management scene similar to entrance guard, the retro-reflecting unit is in a dormant state most of the time, namely in an energy collecting state, and the retro-reflecting unit can obtain enough energy through the arrangement. And the light signal is transmitted in a retro-reflection light signal mode, so that the retro-reflection unit only needs to supply power to the first controller and the modulation module with low power consumption, and the power consumption of the retro-reflection unit is extremely low, so that in a separately configured authority management scene, for example, a scene which needs to be configured to be connected with a server to verify information authority in a background or a scene which needs to be configured to be connected with a local storage system to verify information authority, no additional power supply device needs to be adopted for supplying power.
According to a preferred embodiment, in case the retro-reflection unit receives a light signal, the light signal enters the first optical sensor and the modulation module, respectively. The first controller is configured to: monitoring the light signal received by the first optical sensor, and in the event that an information-bearing light signal is identified, controlling the first optical sensor to disconnect from the energy storage device to exit a state of energy collection, and receiving the information-bearing light signal via the first optical sensor.
According to a preferred embodiment, the modulation module comprises at least a first and a second polarization device. The retroreflective layer is removably attached to the first polarizer. The second polarizer is configured to be disposed on the light emitting side of the first polarizer, and the polarization direction of the second polarizer can be changed with the driving signal generated by the first controller, so as to realize the brightness change of the optical signal. .
According to a preferred embodiment, the mobile terminal or the entrance guard terminal is further provided with a read-write unit for transmitting and receiving optical signals. The reading and writing unit is configured to actively send an optical signal at least comprising identity authentication information to the retro-reflecting unit and receive the retro-reflecting optical signal modulated and reflected by the retro-reflecting unit, so that information interaction between the mobile terminal and the access control terminal is realized.
According to a preferred embodiment, the read-write unit comprises at least a light emitting device, a second controller and a second optical sensor electrically connected in sequence. The second controller drives the light emitting device based on the authentication information and modulates the authentication information on the light signal in a manner of adjusting light brightness change. The second optical sensor is provided with at least one first polarizing device on an incoming light path thereof.
According to a preferred embodiment, in the case that the mobile terminal is provided with the read-write unit, the retro-reflection unit is arranged at the entrance guard terminal. The mobile terminal is configured to be connected with the server to acquire corresponding authentication information and actively send the authentication information to the access control terminal in the form of optical signals. The entrance guard end is configured to receive an optical signal through the retro-reflective unit. The entrance guard terminal verifies the authentication information carried by the optical signal based on the pre-stored information to generate feedback information at least comprising local information, so that the entrance guard is opened or closed based on the feedback information. The entrance guard terminal modulates the feedback information on a retro-reflection light signal reflected to the mobile terminal through the retro-reflection unit.
According to a preferred embodiment, in the case that the mobile terminal is provided with the retro-reflection unit, the read-write unit is arranged at the entrance guard terminal. The access control terminal is configured to acquire corresponding authentication information by being connected with the server, and actively send the authentication information to the mobile terminal in the form of optical signals. The movable end is configured to receive an optical signal through the retro-reflective unit. The mobile terminal verifies the authentication information carried by the optical signal based on the pre-stored information to generate feedback information at least comprising local information, and modulates the feedback information on the retro-reflected optical signal reflected to the mobile terminal through the retro-reflection unit. Under the condition that the entrance guard end receives the retro-reflected light signal, the entrance guard end is configured as: the feedback information is obtained through the read-write unit and is sent to the server so that the server can complete identity verification logic and generate confirmation information; and receiving confirmation information returned by the server to open or close the access control.
The invention also provides an Internet of things access control method based on retro-reflection visible light communication, which comprises the following steps: the method comprises the steps that a visible light communication link is established between a mobile terminal and an access control terminal to transmit identity verification information, and the identity verification information is authenticated through a server to open or close the access control terminal. The mobile terminal or the entrance guard terminal passively receives the optical signal through a configurable retroreflection unit arranged on the mobile terminal or the entrance guard terminal and returns the optical signal in a retroreflection mode to be in a passive communication state. The optical signal can provide energy for the mobile terminal and/or the access terminal.
According to a preferred embodiment, the method further comprises: the retro-reflective element identifies the optical signal with information during collection of the optical signal energy by switching between a state of collecting the optical signal energy and a state of detecting the optical signal.
Drawings
FIG. 1 is a block schematic diagram of a preferred embodiment of the present invention;
FIG. 2 is a block schematic diagram of another preferred embodiment of the present invention;
FIG. 3 is a schematic view of a preferred retroreflective optical communication of the present invention;
FIG. 4 is a schematic diagram of a preferred modulation module of the present invention;
FIG. 5 is a schematic diagram of another preferred modulation module of the present invention;
FIG. 6 is a schematic diagram of a preferred read/write unit according to the present invention; and
FIG. 7 is a schematic representation of the construction of a preferred retroreflective element of the present invention.
List of reference numerals
1: and the mobile terminal 2: entrance guard terminal
3: the server 4: retroreflection unit
5: the read-write unit 6: ambient light signal
7: optical signal with information 41: modulation module
42: the first controller 43: first optical sensor
44: retroreflective layer 45: energy storage device
46: the switch 47: detection circuit
48: DC-DC converter 51: light emitting device
52: the second control machine 53: second optical sensor
411: first polarizer 412: second polarizing device
Detailed Description
The following detailed description is made with reference to fig. 1 to 7.
Example 1
The embodiment discloses an access control system, which can be an internet of things access control system, an access control system based on visible light communication, or an internet of things access control system based on visible light communication, and can be realized by the system and/or other replaceable parts. For example, the method disclosed in the present embodiment is implemented by using various components in the system of the present invention. The preferred embodiments of the present invention are described in whole and/or in part in the context of other embodiments, which can supplement the present embodiment, without resulting in conflict or inconsistency.
Preferably, the existing access control technology based on visible light communication requires that a user is interconnected with a network on a mobile terminal to obtain a corresponding activation code, and the activation code is emitted by using an LED flash. Specifically, the prior art access control system based on visible light communication actively emits visible light to transmit information no matter one-way communication or two-way communication is adopted. However, the light emitting range of a general LED or other general light emitting device and the angle range of the light sensitivity of a corresponding sensor for receiving an optical signal are limited, which requires that the mobile terminal 1 and the access terminal 2 need to be completely aligned to realize two-way communication, which not only results in limited mobility of the mobile terminal 1 and the access terminal 2, but also presents a serious challenge in an application scenario of one-to-many communication or many-to-many communication, and is difficult to be practically applied to an application scenario with a large traffic volume, such as an access control system of a subway gate, an access control system of a railway station, an access control system of a bus station, and an access control system of an airport. Secondly, from the aspects of design concept, economic cost, operation maintenance and wide deployment and use, the existing access control equipment based on visible light communication is not small enough and does not have the characteristic of low power consumption. For example, the energy consumption of communication emission based on the LED is usually several hundred milliwatts, and the effective electric energy converted by the solar cell of the size of the internet of things device is usually only several hundred microwatts, resulting in poor mobility and high cost. Secondly, the active transmitting-receiving visible light communication mode is not only easily interfered by ambient light and poor in anti-interference capability, but also easily intercepted and captured, and the safety is questioned. Finally, in order to improve the security of the existing access control system based on visible light communication, not only the mobile terminal 1 and the access control terminal 2 need to be connected with the corresponding server 3 or the background management system through the internet, but also the verification procedure is complicated and complex, for example, the security of identity verification is ensured through a complex encryption algorithm, so that the mobile terminal 1 or the access control terminal 2 itself needs to have strong computing power, which results in the increase of hardware power consumption, cost and verification time of the device by times. Moreover, the mobile terminal 1, the access control terminal 2 and the server 3 need to perform mutual two-way communication for multiple times to complete the identity verification, thereby further increasing the expense of verification time. Based on the above reasons, this embodiment provides an thing networking access control system based on visible light communication, adopts one end initiative transmission, and two-way visible light communication link is established to the mode of the passive reflection of the other end to reduce the complexity, the consumption and the volume of equipment, increase the mobility of equipment, reduce the deployment degree of difficulty.
Aiming at the defects of the prior art, the invention provides an Internet of things access control system based on retro-reflection visible light communication, which at least comprises a mobile terminal 1, an access control terminal 2 and a server 3 connected with the mobile terminal 1 or the access control terminal 2 through Internet of things wireless networking technology. The mobile terminal 1 preferably refers to an apparatus capable of authenticating, which is used by an object requiring authentication information, such as a person or a vehicle. For example, a worker, a resident, or the like carries a mobile terminal (e.g., a mobile phone, a tablet computer, or the like) capable of authenticating identity, or carries an IC card, an RFID card, or the like capable of authenticating identity. The entrance guard terminal 2 is used for verifying the verification information carried by the optical signal emitted by the mobile terminal 1, and the entrance guard terminal 2 is required to be capable of establishing a visible light communication link with the mobile terminal 1 to transmit the authentication information. The access control end 2 further comprises a door lock mechanism, an access control drive for driving the door lock mechanism to open or close and a control module. The control module includes at least a processor and a memory. The memory is to store instructions. The processor is configured to store instructions by executing the memory. The Processor may be a Central Processing Unit (CPU), a general purpose Processor, a Digital Signal Processor (DSP), an Application-Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, transistor logic, hardware components, or any combination thereof. Preferably, in different embodiments, the mobile terminal 1 or the access control terminal 2 further needs a Wireless Module (RF Wireless Module) to implement network connection with the server 3. The wireless module can be a Wi-Fi module, an LTE module, a Bluetooth module, a Zigbee module and the like. Preferably, the mobile terminal 1 or the access control terminal 2 further includes a power supply module and a door lock detection module. The door lock detection module is used for detecting the running state of the door lock mechanism, timely finding problems and giving an alarm to process under the condition that the door lock has problems, and safety monitoring can be actively carried out. Preferably, the door lock detection module can adopt infrared wireless detection, video monitoring, sound monitoring, action detection and the like. Preferably, the server 3 is used for recording, verifying and managing access information, identity information and the like related to the current access control system. Preferably, the authentication information completes authentication via the server 3 to open or close the access terminal 2.
Preferably, the mobile terminal 1 or the access terminal 2 is provided with a configurable retro-reflective unit 4. The retro-reflection unit 4 passively receives the light signal and returns the light signal in a retro-reflection manner, so that the mobile terminal 1 or the entrance guard 2 is in a passive communication state. Preferably, the optical signal can provide energy for the mobile terminal 1 and/or the access terminal 2. Preferably, the retro-reflection unit 4 may be disposed at the mobile terminal 1, and the corresponding door 2 is provided with the read/write unit 5. Preferably, the retro-reflection unit 4 may be disposed at the door 2, and the corresponding mobile terminal 1 is disposed with the read/write unit 5. Preferably, the read-write unit 5 emits optical signals and receives optical signals. As shown in fig. 1 to 3, the read-write unit 5 is configured to actively send an optical signal including at least authentication information to the retro-reflection unit 4, and receive a retro-reflection optical signal modulated and reflected by the retro-reflection unit 4, so as to realize information interaction between the mobile terminal 1 and the gate terminal 2. Preferably, retroreflective means that light rays strike the surface of the retroreflective material and are reflected back toward the light source. This property is maintained when the direction of the incident light is varied over a large range. Preferably, the retro-reflective element 4 may be configured to provide power to the wireless module of the server 3 for connection, thereby enabling on-line matching of the authentication information. Through this setting mode, the beneficial effect of this embodiment is:
1. because the retro-reflection unit 4 realizes visible light communication between the mobile terminal 1 and the access control terminal 2 in a passive retro-reflection optical signal mode, the mobile terminal 1 and the access control terminal 2 do not need to be provided with all light emitters, for example, LEDs, LED driving circuits and the like, power consumption and cost are obviously reduced, miniaturization of equipment is facilitated, mobility is improved, and actual deployment is facilitated. For example, due to the low power consumption and miniaturization of the retroreflective elements 4, it can be easily integrated into a mobile terminal, such as a user's mobile phone, tablet computer, etc. Moreover, since the retro-reflecting unit 4 itself does not need to emit a light signal and the received light signal can be partially converted into electric energy, the retro-reflecting unit 4 does not need an additional power supply module, and has strong mobility and portability, thereby being capable of directly replacing the existing IC card, RFID card, and the like. Even in the case where the retroreflective unit 4 is disposed on the door 2, the first optical sensor 42 having a larger area can be provided, so that more energy is supplied to other electric devices of the door 2.
2. Benefit from contrary reflective unit 4 and adopt contrary reflective mode to establish optical communication link for the optical communication link between mobile terminal 1 and the entrance guard end 2 both has good direction response, has guaranteed the concentration of reflection direction again, and the outgoing direction of light is irrelevant with the incident angle of light promptly, makes and can wide angle both-way communication between mobile terminal 1 and the entrance guard end 2. In addition, the optical communication link established in a retro-reflection mode has high space orientation characteristics, communication information can be guaranteed not to be intercepted, and the safety of the access control system is further improved.
3. The method has good expansibility, and is particularly suitable for one-to-many communication or many-to-many communication scenes. Benefit from contrary reflective high space orientation characteristic and wide angle both-way communication, can realize that a plurality of removal end 1 are connected with entrance guard's end 2, perhaps remove end 1 and can be connected with a plurality of entrance guard's end 2, perhaps a plurality of removal end 1 can be connected with a plurality of entrance guard's end 2, under the great application scene of flow of people, can guarantee that the stream of people passes through fast, realize the seamless experience function of entrance guard.
4. The mobile terminal 1 or the access control terminal 2 provided with the retro-reflection unit 4 can realize the verification of identity information under the condition of not interacting with the server 3, so that the cost and the power consumption can be greatly reduced, the attack of malicious programs can be avoided, and the safety of an access control system is further improved. In addition, the complicated identity authentication method which requires multiple information interaction between the mobile terminal 1 and the access control terminal 2 can be avoided, so that the cost of authentication time can be reduced, unnecessary calculation cost can be avoided, and the complexity of local equipment is reduced.
Preferably, the preferred embodiment in which the mobile terminal 1 or the access terminal 2 provided with the retro-reflection unit 4 does not need to interact with the server 3 is as follows:
according to a preferred embodiment, in case that the mobile terminal 1 is provided with the read/write unit 5, the retro-reflection unit 4 is provided at the entrance 2, as shown in fig. 1. Preferably, the mobile terminal 1 is configured to connect with the server 3 to obtain corresponding authentication information, and actively transmit the authentication information to the access terminal 2 in the form of an optical signal. Preferably, as shown in fig. 1, the entrance guard 2 is configured to receive light signals through the retro-reflection unit 4. The access control terminal 2 verifies the authentication information carried by the optical signal based on the pre-stored information to generate feedback information at least including local information. Preferably, the pre-stored information is information previously stored regarding authentication. Preferably, the retro-reflection unit 4 can also update the stored information by the information sent by the read-write unit 5. Preferably, the local information at least includes time information, identity information, status information of entrance guard, and the like of the passing person. The state information of the access control system at least comprises an opening state, a closing state, an off-line state, an alarm state and the like. Therefore, the access control terminal 2 can open or close the access control according to the feedback information. Preferably, the entrance guard 2 modulates the feedback information on the retro-reflection light signal reflected to the mobile terminal 1 through the retro-reflection unit 4, so as to transmit the information to the mobile terminal 1. The mobile terminal 1 obtains the corresponding local information. Preferably, another embodiment can be verified in the following manner. Preferably, the mobile terminal 1 is configured to connect with the server 3 to obtain corresponding authentication information, and actively transmit the authentication information to the access terminal 2 in the form of an optical signal. The entrance guard terminal 2 is configured to receive the optical signal through the retro-reflection unit 4, verify the authentication information carried by the optical signal based on the pre-stored information to generate the feedback information including at least the local information, and modulate the feedback information on the retro-reflection optical signal reflected to the mobile terminal 1 through the retro-reflection unit 4. In the case where the mobile terminal 1 receives the retro-reflected light signal, the mobile terminal 1 is configured to acquire feedback information based on the retro-reflected light signal and send the feedback information to the server 3 to complete the authentication logic, thereby generating confirmation information. The mobile terminal 1 sends the confirmation information to the access terminal 2 through the read-write unit 5, so that the access terminal 2 opens or closes the access based on the confirmation information.
According to a preferred embodiment, in case that the mobile terminal 1 is provided with the retro-reflection unit 4, the read-write unit 5 is provided at the access terminal 2, as shown in fig. 2. The access terminal 2 is configured to acquire corresponding authentication information by connecting with the server 3, and actively transmit the authentication information to the mobile terminal 1 in the form of an optical signal. The mobile terminal 1 is configured to receive an optical signal through the retro-reflection unit 4. The mobile terminal 1 verifies the authentication information carried by the optical signal based on the pre-stored information to generate feedback information including at least local information, and modulates the feedback information on the retro-reflection optical signal reflected to the mobile terminal 1 through the retro-reflection unit 4. Under the condition that entrance guard's end 2 received the retro-reflection optical signal, entrance guard's end 2 configuration is: the feedback information is obtained through the read-write unit 5 and is sent to the server 3 so that the server 3 completes the identity verification logic and generates confirmation information; and receiving confirmation information returned by the server 3 to open or close the door.
Preferably, the retro-reflection unit 4 comprises at least a modulation module 41, a first controller 42, a first optical sensor 43 and an energy storage device 45. The first controller 42 is connected to the modulation module 41. The first optical sensor 43 is connected to the first controller 42. The energy storage device 45 is connected to the first optical sensor 43, the first controller 42 and the modulation module 41, respectively. The first optical sensor 43 is used to collect energy and receive the optical signal 7 with information and to transmit the collected energy to the energy storage device 45 and the optical signal to the first controller 42. The first controller 42 is configured to generate feedback information based on the information-bearing optical signal 7 and to generate a drive signal for driving the modulation module 41 based on the feedback information. One side of the modulation module 41 is provided with a retro-reflective layer 44 of a retro-reflective light signal, so that the modulation module 41 is able to modulate feedback information on the retro-reflective light signal based on the drive signal in such a way that the change in shade of the light signal retro-reflected by the retro-reflective layer 44 is controlled.
Preferably, the first controller 42 includes at least decoder, power management, and transmission and encoding logic. The first controller 42 may be selected from a microprogram control chip model MSP430G2403, which includes decoder, power management, and transmission and encoding logic. The first optical sensor 43 may be a solar cell or a solar panel. Preferably, the retro-reflection unit 4 further includes a driving circuit disposed between the modulation module 41 and the first controller 42. Preferably, retroreflective element 4 also includes detection circuitry 47. The detection circuit 47 comprises at least a comparator for amplifying the electrical signal received from the first optical sensor 43 and an amplifier for performing the digitization of the signal. Preferably, the energy storage device 45 may be a super capacitor. Preferably, the modulation module 41 comprises at least a first 411 and a second 412 polarization device. The second polarizer 412 is connected to the first controller 42. Preferably, the first polarizing device 411 is capable of achieving polarization of light. The first polarizing device 411 may be a polarizing device whose polarization direction is determined. Such as polarizing filters, etc. Preferably, the second polarizer 412 has a polarization direction that can be changed according to the driving signal generated by the first controller 42 to realize the brightness change of the optical signal. Preferably, the second polarizing device 412 may be a liquid crystal material. The liquid crystal material changes the polarization direction of light passing therethrough in the case where the voltage across the material changes. The second polarizer 412 is disposed on the light-emitting side of the first polarizer 411. When the polarization directions of the second polarization device 412 and the first polarization device 411 are the same, the optical signal can pass through all the light signals, and the brightness of the optical signal is large. When the polarization directions of the first polarizing device 411 and the second polarizing device 412 are different, the optical signal cannot pass through all the light signals, and the brightness of the optical signal is dark. In the case where the polarization directions of the first and second polarizing devices 411 and 412 are orthogonal, the optical signal cannot pass through. The setting mode can realize the light and shade change control of the optical signal, and further realize the modulation of information. Preferably, the second polarizer device 412 is connectable to the first controller 42. Preferably, the retro-reflective layer 44 is detachably connected to the first polarizing device 411. Preferably, the retroreflective layer 44 is made of a retroreflective material, such as glass bead-type or prism-type retroreflective material. Preferably, the detachable connection may be by means of adhesive, screw connection, or the like.
Preferably, the retroreflective elements 4 are further configured to: the connection state of the first optical sensor 43 with the energy storage device 45 and the modulation module 41, respectively, is controlled by the first controller 42 based on the pulse sequence, thereby achieving the isolation of the energy collection state and the signal detection state from each other and the high-frequency switching. In fact, in the case that the first optical sensor 43 is a solar cell, the optical signal it receives includes the ambient light signal 6 and the information-bearing optical signal 7 sent by the read-write unit 5, as shown in fig. 7. The ambient light signal 6 is in a continuous state with slowly changing amplitude most of the time, and the information-carrying light signal 7 sent by the read-write unit 5 is a discrete light signal with interval states. The existence of the ambient light signal 6 may possibly overwhelm the optical signal 7 with information sent by the read-write unit 5, and it is obvious that the electrical signal output by the solar cell will not output a signal with obvious intermittent characteristics due to the existence of the ambient light signal, so that the simple use of the characteristic of capacitance to go through and cross to obtain the optical signal sent by the read-write unit 5 is unreliable. Although the optical signal transmitted by the read-write unit 5 can be detected by constructing a corresponding circuit through various electrical devices, the power and the volume of the retro-reflection unit 4 are increased, and the energy provided by the solar cell cannot maintain the energy consumption of the retro-reflection unit 4. Therefore, the present invention can realize reliable detection of the optical signal by isolating the energy collection state and the detection state of the optical signal from each other, that is, the retro-reflection unit 4 does not simultaneously detect the optical signal transmitted from the read/write unit 5 in the energy collection state. Preferably, in case that the retro-reflection unit 4 receives the light signal, the light signal enters the first optical sensor 43 and the modulation module 41, respectively. The first controller 42 is configured to: the light signal received by the first optical sensor 43 is monitored and in case of identification of the information-bearing light signal 7, the first optical sensor 43 is controlled to disconnect the energy storage means 45 to exit the energy collecting state and to receive the information-bearing light signal 7 via the first optical sensor 43. The first controller 42 controls the connection of the first optical sensor 43 with the energy storage device 45 and the modulation module 41, so that the energy collection state and the signal detection state can be physically separated, that is, the retroreflective unit 4 is in the energy collection state when the first optical sensor 43 is connected with the energy storage device 45. When the first optical sensor 43 is connected to the modulation module 41, the retro-reflection unit 4 is in a signal detection state. Since the super capacitor, i.e. the energy storage device 45, may filter out part of the optical signal 7 carrying information, the first optical sensor 43 is connected to the energy storage device 45 and the detection circuit 47 via a switch 46, respectively. The switch 46 may be a low power single pole double throw switch. The energy storage device 45 provides stable DC power to the modulation module 41, the first controller 42, the switch 46 and the detection circuit 47 through the DC-DC converter 48, as shown in fig. 7. Preferably, the retro-reflection unit 4 needs to reliably identify the optical signal emitted by the mobile terminal 1 or the entrance guard terminal 2 in time in the energy collection state, which means that the retro-reflection unit 4 needs to spend a certain amount of time to detect the signal, and although it can avoid that the retro-reflection unit 4 misses the optical signal emitted by the mobile terminal 1 or the entrance guard terminal 2, it may cause the energy collection time to decrease, that is, the charging time decreases, the charging power is less than the power consumed by the retro-reflection unit 4, so that the retro-reflection unit 4 cannot normally operate, and therefore the energy collection state and the signal detection state are isolated and switched at high frequency by the first controller 42 based on the pulse sequence. The high-frequency switching means that the duty ratio of the pulse sequence controls the connection of the first optical sensor 43 with the energy storage device 45 and the modulation module 41 respectively, namely, the waveform obtained by the first optical sensor 43 is collected at a short interval in a timing mode, so that the energy collection state and the detection signal state are alternately changed, the signal is detected in the shortest possible time, and the rest of the time is used for realizing the energy collection. In fact, according to the nyquist sampling theorem, when the sampling frequency is greater than twice the frequency of the optical signal transmitted by the gate terminal 2 or the mobile terminal 1, the first controller 42 can still recognize the signal. Preferably, the manner of controlling the switching of the energy harvesting state and the detection signal state based on the duty cycle of the pulse train is: designing the duty cycle of the pulse sequence based on the frequency of the optical signal 7 with information and the parasitic capacitance and impedance employed; the logical values of the pulse sequence comprise "0" and "1", and when the pulse sequence is at the logical value "0", the first controller 42 controls the switch 46 to connect the first optical sensor 43 with the energy storage device 45, so that the retro-reflection unit 4 is in the energy collection state; when the pulse sequence is at a logic value of "1", the first controller 42 controls the switch 46 so that the first optical sensor 43 is connected to the detection circuit 47, thereby putting the retro-reflection unit 4 in a detection signal state. Preferably, the duty cycle may be a ratio between a time to maintain a logical value of "1" and a period. The value of the duty cycle is less than 1. Preferably, the value of the duty cycle can be set between 0.2 and 0.5. Preferably, after the retro-reflection unit 4 recognizes the optical signal transmitted by the access terminal 2 or the mobile terminal 1, the retro-reflection unit 4 directly switches to the modulation state, that is, the first controller 42 demodulates the optical signal and generates the feedback information. Until the retro-reflecting unit 4 re-enters the high frequency switching of the energy harvesting state and the signal detection state after modulating the feedback information on the retro-reflected light signal. Moreover, in the right management scene like entrance guard, the retroreflective unit 4 is in a dormant state, i.e. in an energy collecting state, most of the time, and the retroreflective unit 4 can obtain enough energy through the above arrangement. And the light signal is transmitted in a retro-reflective light signal mode, so that the retro-reflective unit 4 only needs to supply power to the first controller 42 and the modulation module 41 with low power consumption, and the power consumption of the retro-reflective unit 4 is extremely low, so that in a separately configured authority management scene, for example, a scene that is connected with the server 3 to verify information authority in a background mode needs to be configured, or a scene that is connected with a local storage system to verify information authority needs to be configured, and an additional power supply device does not need to be used for supplying power. Through the above arrangement mode, the retro-reflection unit 4 can acquire the authentication information according to the optical signal emitted by the read-write unit 5, and returns the verified feedback information to the read-write unit 5 according to the authentication information, so that the door lock mechanism can be opened and closed by the access control end 2 based on the information.
Preferably, as shown in fig. 4, the second polarizing device 412 is located between the two first polarizing devices 411. Preferably, the optical signal is polarized after passing through the first polarizer 411 to become polarized light. The control of the polarization direction of the optical signal passing through the second polarizer 412 is achieved by controlling the voltage variation of the second polarizer 412, so that the polarization direction of the retro-reflected optical signal changes after passing through the second polarizer 412, and the light intensity of the retro-reflected optical signal becomes weaker when the changed polarization direction is the same as the polarization direction of the first polarizer 411. Only when the changed polarization direction is the same as the polarization direction of the first polarizing device 411, the light intensity of the retro-reflected light signal is unchanged. Through the arrangement mode, the optical signal can be modulated.
According to a preferred embodiment, the read-write unit 5 comprises at least a light emitting device 51, a second controller 52 and a second optical sensor 53 electrically connected in sequence. Preferably, the light emitting device may be an LED, or a flash of a mobile phone, a head lamp of an automobile, or the like. Preferably, the second controller 52 may be identical to the first controller 51. Preferably, the second optical sensor 53, like the first optical sensor 43, may be a photodetector. Preferably, the second controller 52 drives the light emitting device 51 based on the authentication information and modulates the authentication information on the light signal by adjusting the light brightness variation. . Preferably, the read-write unit 5 is provided with a corresponding drive circuit for driving the light emitting device 51, thereby enabling the second controller 53 to drive the light emitting device 51.
Example 2
This embodiment is a further improvement of embodiment 1, and repeated contents are not described again. Preferably, the retroreflective elements 4 are structured as shown in fig. 5, and unlike the retroreflective elements 4 of embodiment 1, the second polarizing device 412 is not disposed between two first polarizing devices 411, but at least one first polarizing device is disposed only between the second polarizing device 412 and the retroreflective layer 44. Through the setting mode, the visible light communication between the mobile terminal 1 and the entrance guard terminal 2 is flicker-free.
Preferably, retroreflective element 4 is provided with at least one first polarizer 411 that is polarized only when light is entering. Preferably, the first polarizing device 411 may be a polarizing filter, or the like. With this arrangement, the optical signal received by the retro-reflecting unit 4 is a polarized optical signal, which facilitates the subsequent retro-reflecting unit 4 to modulate the polarization state of the optical signal by using the second polarization device 412. Preferably, the retro-reflection unit 4 modulates the optical signal emitted by the read-write unit 5 by means of back polarization. The rear-polarization means that the state of on or off of the light signal of the retro-reflection unit 4 occurs on the read-write unit 5 in a rear-mounted manner, so that the light signal between the read-write unit 5 and the retro-reflection unit 4 is transmitted in a temporally and/or spatially continuous manner. Preferably, as shown in fig. 6, the second optical sensor 53 is provided with at least one first polarization device 411 on its light incoming path, so that the read-write unit 5 can realize on/off or brightness change of the optical signal through the first polarization device 411 or other devices capable of sensing polarization change. Preferably, the prior art basically adopts OOK modulation or other amplitude-dependent modulation methods, so that the light signal modulated by the retro-reflection unit 4 is in a state of alternating light and dark, thereby causing a problem of light flicker. The problem of light flicker is that since human vision is very sensitive to moving objects and flickering objects, the flickering retroreflective elements 4 are likely to be distracting to the driver at the mobile terminal 1, and especially in the case of the mobile terminal 1 being a vehicle, not only distracting to the driver, but also causing dizziness and headache of the driver. In fact, other modulation techniques that do not cause flicker may be used, but not only are power consuming and costly. On the other hand, human eyes cannot perceive light flicker by increasing the modulation frequency of on/off keying (OOK), but this method needs to increase the response speed of the driver, so it needs to build and maintain the VLBC system at high cost, and it does not conform to the design concept of low power consumption, low cost and large-scale deployment of the internet of things access control system. According to the invention, through post-polarization, the light and shade alternation of the light caused by the retro-reflection unit 4 adopting OOK modulation or other amplitude-related modulation modes is post-arranged on the read-write unit 5, and the retro-reflection unit 4 can modulate the information into the optical signal only by modulating the polarization direction of the optical signal through the second polarization device 412, so that the optical signal transmitted from the retro-reflection unit 4 to the read-write unit 5 is continuous in time and/or space. By temporally and/or spatially continuous is meant that the intensity or amplitude of the light signal reflected by the retro-reflecting element 4 is not modulated, i.e. does not change regularly and continuously, so that the spatial amplitude or light intensity of the light signal changes continuously with time within a certain time range, and the change amplitude is small and can be approximately constant. Through this mode of setting up, because the unable perception light polarization direction of people's eye, the unchangeable light of consequently intensity can not produce the scintillation, because reading and writing unit 5 and contrary reflective unit 4 set up respectively at removal end 1 and entrance guard end, consequently can realize removing the no scintillation visible light communication between end 1 and the entrance guard end 2.
Example 3
The embodiment discloses an access control method, which can be an access control method based on the internet of things, an access control method based on visible light communication, or an internet of things method based on the visible light communication, and the method can be realized by the system and/or other replaceable parts. For example, the method disclosed in the present embodiment is implemented by using various components in the system of the present invention. The preferred embodiments of the present invention are described in whole and/or in part in the context of other embodiments, which can supplement the present embodiment, without resulting in conflict or inconsistency.
The invention also provides an Internet of things access control method based on retro-reflection visible light communication, which comprises the following steps: a visible light communication link is established between the mobile terminal 1 and the access control terminal 2 to transmit the authentication information, so that the authentication information is authenticated by the server 3 to open or close the access control terminal 2. Preferably, the method further comprises that the mobile terminal 1 or the entrance guard terminal 2 passively receives the light signal through the configurable retroreflection unit 4 arranged on the mobile terminal 1 or the entrance guard terminal 2 and returns the light signal in a retroreflection manner to be in a passive communication state, and the light signal can provide energy for the mobile terminal 1 and/or the entrance guard terminal 2. According to a preferred embodiment, the method further comprises: the retro-reflective element 4 provides a configurable source of energy for the retro-reflective element 4 by enabling identification of the optical signal 7 with information during collection of optical signal energy by switching between a state of collecting optical signal energy and a state of detecting the optical signal. Preferably, the mobile terminal 1, the access control terminal 2 and the retro-reflection unit 4 disclosed in embodiments 1 and 2 are adopted in the access control method of the internet of things provided by this embodiment, and repeated contents are not described again.
It should be noted that the above-mentioned embodiments are exemplary, and that those skilled in the art, having benefit of the present disclosure, may devise various arrangements that are within the scope of the present disclosure and that fall within the scope of the invention. It should be understood by those skilled in the art that the present specification and figures are illustrative only and are not limiting upon the claims. The scope of the invention is defined by the claims and their equivalents.

Claims (9)

1. The utility model provides an thing networking access control system based on contrary reflective visible light communication includes at least: a mobile terminal (1) and an entrance guard terminal (2),
it is characterized in that the preparation method is characterized in that,
the mobile terminal (1) or the access terminal (2) is provided with a configurable retro-reflection unit (4), wherein,
the mobile terminal (1) or the entrance guard terminal (2) is in a passive communication state by passively receiving the light signal through the retro-reflection unit (4) and returning the light signal in a retro-reflection manner, wherein,
the optical signal is capable of providing energy to the mobile terminal (1) or the access terminal (2), wherein,
the retro-reflection unit (4) comprises at least a modulation module (41), a first controller (42), a first optical sensor (43) and an energy storage device (45), wherein,
the retroreflective unit (4) is configured to: the connection state of the first optical sensor (43) with the energy storage device (45) and the modulation module (41) is controlled by the first controller (42) based on the pulse sequence, so that the mutual isolation and the high-frequency switching of the energy collection state and the signal detection state are realized.
2. The IOT access control system of claim 1, wherein the retro-reflective unit (4) comprises at least a modulation module (41), a first controller (42) connected to the modulation module (41), a first optical sensor (43) connected to the first controller (42), and energy storage devices (45) connected to the first optical sensor (43), the first controller (42), and the modulation module (41), respectively,
the first optical sensor (43) is used for collecting energy and receiving optical signals with information, transmitting the collected energy to the energy storage device (45) and transmitting the optical signals to the first controller (42),
the first controller (42) is configured to generate feedback information based on the information-bearing optical signal and to generate a drive signal for driving the modulation module (41) based on the feedback information,
one side of the modulation module (41) is provided with a retro-reflective layer (44) of a retro-reflective light signal, so that the modulation module (41) can modulate the feedback information on the retro-reflective light signal based on the drive signal in a manner of controlling the brightness change of the light signal retro-reflected by the retro-reflective layer (44).
3. The internet of things access control system of claim 1 or 2, wherein, in case the retro-reflecting unit (4) receives a light signal, the light signal enters the first optical sensor (43) and the modulation module (41), respectively, and the first controller (42) is configured to: -monitoring the light signal received by the first optical sensor (43), and-in case an information-carrying light signal is identified-controlling the first optical sensor (43) to disconnect from the energy storage means (45) to exit the energy collecting state and to receive the information-carrying light signal via the first optical sensor (43).
4. The IOT access control system of claim 2, wherein the modulation module (41) comprises at least a first polarization device (411) and a second polarization device (412), wherein,
the retroreflective layer (44) is detachably connected to the first polarizer (411),
the second polarizing device (412) is configured to be arranged on the light emitting side of the first polarizing device (411), and the polarization direction of the second polarizing device can be changed along with the driving signal generated by the first controller (42) so as to realize the light and shade change of the optical signal.
5. The IOT access control system according to claim 1, wherein the mobile terminal (1) or the access control terminal (2) is further provided with a read/write unit (5) for transmitting and receiving optical signals, wherein,
the reading and writing unit (5) is configured to actively send an optical signal at least comprising identity authentication information to the retro-reflecting unit (4) and receive the retro-reflecting optical signal modulated and reflected by the retro-reflecting unit (4), so that information interaction between the mobile terminal (1) and the entrance guard terminal (2) is realized.
6. The IOT access control system according to claim 5, wherein the read/write unit (5) comprises at least a light emitting device (51), a second controller (52) and a second optical sensor (53) which are electrically connected in sequence,
the second controller (52) drives the light emitting device (51) based on the authentication information and modulates the authentication information on the light signal by adjusting the light brightness change.
7. The IOT access control system according to claim 1, wherein the retro-reflection unit (4) is provided at the access control end (2) in case that the mobile end (1) is provided with a read-write unit (5), wherein,
the mobile terminal (1) is configured to be connected with the server (3) to acquire corresponding authentication information and actively send the authentication information to the access control terminal (2) in the form of optical signals;
the entrance guard terminal (2) is configured as follows:
receiving an optical signal through the retro-reflective unit (4);
and verifying the authentication information carried by the optical signal based on the prestored information to generate feedback information at least comprising local information, thereby opening or closing the entrance guard based on the feedback information, and modulating the feedback information on the retro-reflecting optical signal reflected to the mobile terminal (1) through the retro-reflecting unit (4).
8. The IOT access control system according to claim 1, wherein a read-write unit (5) is provided at the access control end (2) in case the mobile end (1) is provided with the retro-reflective unit (4), wherein,
the entrance guard terminal (2) is configured as follows: the mobile terminal is connected with the server (3) to obtain corresponding identity authentication information, and the identity authentication information is actively sent to the mobile terminal (1) in the form of optical signals;
the mobile end (1) is configured to receive an optical signal through the retro-reflective unit (4);
verifying the authentication information carried by the optical signal based on the pre-stored information to generate feedback information at least comprising local information, and modulating the feedback information on the retro-reflected optical signal reflected to the mobile terminal (1) through the retro-reflection unit (4); wherein the content of the first and second substances,
under the condition that the entrance guard end (2) receives the retro-reflected light signal, the entrance guard end (2) is configured to:
the feedback information is obtained through the read-write unit (5) and is sent to the server (3) so that the server (3) completes identity verification logic and generates confirmation information;
and receiving confirmation information returned by the server (3) to open or close the access.
9. An internet of things access control method based on retro-reflective visible light communication is characterized by comprising the following steps:
the mobile terminal (1) or the entrance guard terminal (2) passively receives the optical signal through a configurable retroreflection unit (4) arranged on the mobile terminal and returns the optical signal in a retroreflection mode to be in a passive communication state, wherein,
the optical signal can provide energy for the mobile terminal (1) or the entrance guard terminal (2);
the retro-reflection unit (4) realizes the identification of the optical signal with information in the process of collecting the optical signal energy by switching between the state of collecting the optical signal energy and the state of detecting the optical signal.
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