CN113686341A

CN113686341A - LIFI-based indoor navigation method and system for visually impaired people

Info

Publication number: CN113686341A
Application number: CN202110970910.2A
Authority: CN
Inventors: 陈智刚; 陈健豪; 吴观华; 杨高强
Original assignee: China State Onstruction Lighting Co ltd
Current assignee: China State Onstruction Lighting Co ltd
Priority date: 2021-08-23
Filing date: 2021-08-23
Publication date: 2021-11-23

Abstract

The invention provides an LIFI-based indoor navigation method and system for visually impaired people, which comprises the following steps: the system comprises a local area network system, a remote central office, an optical coupler, a plurality of LED VAP units and a plurality of navigation devices; the local area network system, the remote central office, the optical coupler and the LED VAP units are sequentially in communication connection; the local area network system comprises a server, and the server comprises a shortest distance path algorithm program; the LED VAP units are distributed at corresponding indoor positions to provide position information and LIFI signals; and the navigation equipment is in communication connection with the LED VAP units and performs navigation according to the shortest distance path provided by the shortest distance path algorithm program. According to the invention, an exclusive indoor local area network is constructed by LIFI, position information is acquired by an optical sensor and fed back to the position of the visually impaired person through the LIFI local area network, so that a set of indoor navigation system is provided for the visually impaired person.

Description

LIFI-based indoor navigation method and system for visually impaired people

Technical Field

The invention relates to the technical field of indoor navigation, in particular to an LIFI-based indoor navigation method and system for visually impaired people.

Background

For outdoor environments, the Global Positioning System (GPS) provides better services such as locating, navigating and displaying ambient traffic conditions. For indoor environments, conventional GPS technology is not suitable because the satellite signals are severely attenuated when passing through a solid wall. In recent decades, several approaches have been proposed to achieve indoor positioning by means of ultra-wideband, wireless local area network, Radio Frequency (RF) Identification (ID), bluetooth, and cellular systems. Light Emitting Diode (LED) technology has developed very rapidly over the last several decades. The intelligent lighting system not only provides economical and efficient lighting and long service time for people, but also paves a road for intelligent lighting and visible light communication (LIFI). As a strong candidate for next generation high speed wireless networks, LIFI has many advantages over traditional RF communications.

The LIFI technology is one of optical communication technologies, and transmits information mainly by visible light. Visible light between 400THZ and 800THZ is used as a medium, and a rapid pulse is used as a wireless transmission mode. This is a fast and low cost telecommunications framework compared to Wi-Fi. Meanwhile, because of the non-penetrability of light and the general indoor existence of sufficient LED light sources, the LIFI technology is suitable for constructing a local area network with extremely high safety in an indoor space which is relatively closed. Meanwhile, the existing optical sensor and the laser radar provide a data acquisition scheme for acquiring indoor position information.

At the more and more huge present of indoor space, the continuous construction of each mill's workshop, shopping mall, office building, subway station, it is indispensable to the safety and the monitoring of personnel, object based on indoor navigation and location, and people's position service demand in the indoor environment has become showing day by day, and especially vision receives the sight barrier personage of influence, more needs can obtain accurate, reliable guide in the indoor of environment relatively complicated. At present, most indoor navigation positioning systems are realized based on proximity detection, triangulation, multilateral positioning and fingerprint positioning methods, or a combined positioning method is adopted to improve the precision. The data transmission mode generally adopts WIFI or Bluetooth, but due to the influence of multipath effect, the indoor environment is variable and complex, and a universal solution is not provided; therefore, how to improve the precision, the real-time performance and the safety, improve the expandability and reduce the cost is still a research hotspot, and how to lead the visually impaired people to acquire indoor position information anytime and anywhere in life or working environment and enjoy the convenience brought by the position-based service. The method is particularly important for improving the self-care ability of the visually impaired and lightening the burden of families and even the society.

Therefore, a new solution is needed to overcome the shortcomings of the prior art.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides an LIFI-based indoor navigation system for visually impaired people.

In order to achieve the purpose, the invention adopts the following specific scheme:

the invention relates to an LIFI-based indoor navigation system for visually impaired people, which comprises:

the system comprises a local area network system, a remote central office, an optical coupler, a plurality of LED VAP units and a plurality of navigation devices;

the local area network system, the remote central office, the optical coupler and the LED VAP units are in communication connection in sequence, wherein the optical coupler and the LED VAP units are connected through optical fibers;

the remote central office adopts a core convergence exchanger or an industrial exchanger;

the optical coupler couples the input end signal to the output end by taking light as a medium to realize photoelectric conversion;

the LED VAP units are distributed at corresponding indoor positions to provide position information and LIFI signals;

the local area network system comprises a server;

the server comprises a main program, a shortest distance path algorithm program and a database;

the database stores position information of the LED VAP units and distance values between adjacent LED VAP units, and the position information comprises coordinates and position names;

taking the LED VAP unit at the current position as a starting point, taking the position of the LED VAP unit at a destination input by a user in the navigation equipment as an end point, taking the position information of the LED VAP unit and the distance value data between the adjacent LED VAP units from the database by the main program, and submitting the position information and the distance value data to the shortest distance path algorithm program to calculate the shortest distance path between the starting point and the end point;

the shortest distance path calculation process of the shortest distance path algorithm program is as follows: starting from the starting point to the end point, selecting the LED VAP unit with the shortest distance as the starting point of the next step each time, excluding the LED VAP units which do not pass through the compared paths, repeating the steps until the end point, thereby determining a shortest distance path from the starting point to the end point, and sending the information of the shortest distance path to the navigation equipment;

the navigation equipment comprises a human-computer interaction interface, is in communication connection with the LED VAP units, and guides the navigation equipment carrier to a destination according to shortest distance path information provided by a shortest distance path algorithm program.

Preferably, the LED VAP unit includes: the system comprises an LED emitter module, an LED receiver module, an LED VAP unit controller and a power supply module;

the LED VAP unit controller is respectively connected with the LED emitter module, the LED receiver module and the power supply module;

the LED VAP unit controller stores position information of an indoor place where the LED VAP unit is located as a fixed base station of the indoor position information;

the position information includes coordinates and a position name.

The LED VAP unit controller adopts an Arduino controller;

the Arduino controller adopts a voltage stabilizer as a power supply module and loads a program code of current position information.

Preferably, the LED emitter module is composed of an LED light source and a Tip122 darlington transistor;

the LED light source is an indoor lighting common lamp bead, and a stroboscopic instruction is sent out through the LED VAP unit controller, so that the LED light source sends out an LIFI signal;

the Tip122 Darlington transistor is connected between the lamp bead and the LED VAP unit controller, and plays a role in switching and signal amplification.

Preferably, the LED receiver module consists of an infrared receiver module and a crystal oscillator circuit module;

the infrared receiver module is connected to the LED VAP unit controller and used for establishing wireless connection with the navigation equipment, decoding and modulating the received infrared pulse signal and outputting the decoded infrared pulse signal to the LED VAP unit controller;

the crystal oscillator circuit module is directly connected to the LED VAP unit controller, provides clock parameters and provides oscillation frequency for receiving signals.

Preferably, the navigation apparatus includes: the device comprises a navigation equipment controller, a power supply module, a PIN receiver module, a distance measuring sensor module, a buzzer module, an infrared transmitter module, a voice broadcasting module and a three-axis magnetic field sensor;

the navigation equipment controller is respectively connected with the power supply module, the PIN receiver module, the distance measuring sensor module, the buzzer module, the infrared transmitter module, the voice broadcasting module and the three-axis magnetic field sensor;

the navigation equipment controller adopts the Arduino controller, and the Arduino controller adopts the stabiliser as power module to loaded navigation, the required program code of barrier early warning.

The PIN receiver module is connected to the navigation equipment controller, receives a visible light LIFI signal transmitted by the LED VAP unit, decodes and modulates the received LIFI signal and outputs the signal to the navigation equipment controller;

the infrared emitter module is connected to the navigation equipment controller, can convert the instruction that the navigation equipment controller sent into infrared ray signal, transmits LED VAP unit.

Preferably, the distance measuring sensor module is connected to the navigation equipment controller, detects the obstacle by using ultrasonic waves, and feeds back the distance between the navigation equipment and the obstacle to the navigation equipment controller in real time;

the buzzer module is connected to the navigation equipment controller, receives an obstacle early warning signal from the navigation equipment controller, and sends out vibration and buzzing early warning, wherein the closer the distance is, the higher the buzzing sound is, the more frequent the vibration is;

the voice broadcasting module is connected to the navigation equipment controller, receives the instruction of the navigation equipment controller and broadcasts the navigation instruction stored in the navigation equipment controller in advance;

the three-axis magnetic field sensor is connected to the navigation equipment controller, collects data of a magnetic field X axis, a magnetic field Y axis, a magnetic field Z axis and a course angle of the navigation equipment position, and transmits the data to the navigation equipment controller.

Preferably, the navigation device is also attached with a braille keyboard, and the user inputs the name of the position required to go to from the braille keyboard.

The invention also provides an LIFI-based indoor navigation method for the visually impaired, which comprises the following steps:

s1, arranging an indoor navigation system for the visually impaired based on LIFI indoors;

s2, storing the position information of all LED VAP units and the distance values between adjacent LED VAP units in a database in the server;

s3, using the LED VAP unit position information of the starting point position as the starting point position information, inputting the position name to be reached in the navigation equipment, providing the LED VAP unit position information of the corresponding position name by the database, and confirming the LED VAP unit position information as the terminal point;

and S4, calculating the shortest distance path through the shortest distance path algorithm, and performing voice navigation to the destination by the navigation equipment.

Preferably, the step S4 includes the steps of:

s41, taking each LED VAP unit as a node of one position, starting from the starting point and facing to the direction of the end point, comparing the distances from the starting point to the peripheral nodes, and finding out the node with the shortest distance from the starting point as a first node;

s42, starting from the first node, and facing to the direction of the terminal, comparing the distance from the first node to the peripheral nodes thereof, finding out the node with the shortest distance to the first node, and determining the node as the second node;

s43, excluding the nodes other than the second node participating in the distance comparison in step S42,

from the second node, towards the direction to the terminal point, comparing the distance from the second node to the peripheral nodes thereof, finding out the node with the shortest distance to the second node, and determining the node as a third node;

s44, repeating the step S43;

s45, determining the next node step by step through distance comparison, and eliminating redundant nodes until the path node is updated to the end point;

s46, determining that the path from the starting point to the first node to the second node and sequentially to the end point is the shortest distance path, and sending the information of the shortest distance path to the navigation equipment;

and S47, the navigation equipment navigates to the terminal point according to the shortest distance path.

Preferably, in step S4,

when the navigation equipment moves forward, the ultrasonic waves of the ranging sensor module detect the obstacles, the buzzer module sends out obstacle early warning signals, and the shortest distance path algorithm takes the current position as a starting point, calculates a new shortest distance path and sends the new shortest distance path to the navigation equipment.

By adopting the technical scheme of the invention, the invention has the following beneficial effects:

Drawings

FIG. 1 is a system architecture diagram of an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of an LED VAP unit according to an embodiment of the present invention;

FIG. 3 is a schematic circuit diagram of a navigation device in accordance with an embodiment of the present invention;

FIG. 4 is a diagram of a shortest distance path algorithm in accordance with an embodiment of the present invention;

FIG. 5 is a flowchart of an embodiment of a navigation method.

Detailed Description

The invention is further described below with reference to the following figures and specific examples.

The invention is explained in detail in connection with figures 1-5,

the invention provides an LIFI-based indoor navigation system for visually impaired people.

The system constructs a visible light wireless Access network consisting of a plurality of visible light Access points (VAPs), realizes high-speed wireless Access service for multiple points and multiple users in an indoor environment, and has a visible light communication transmission rate of 5 Gb/s.

The modulation mode of the system adopts an orthogonal frequency division multiplexing technology (OFDM modulation technology) to realize the dynamic bandwidth allocation and subcarrier multiplexing of the system. The specific scheme is that each visible light access point VAP is allocated with an OFDM sub-band with different center frequencies for signal transmission. And a Time Division Multiplexing (TDM) scheme is adopted in each VAP, and each user below the LED transmitter unit is allocated with a different time slot for visible light data transmission, so that visible light access of multiple users can be simultaneously realized in one VAP.

The optical fiber is the backbone of the network system link and is directly connected with the LED emitter unit to ensure that the system has enough bandwidth resources.

The downlink is a line for transmitting data to a user by the control center.

The remote Central Office (CO) may employ a core aggregation switch or industrial switch that functions to connect a number of LED transmitter units with a series of opto-couplers (OCs). Efficient switching is achieved. The remote central office can be connected into a local area network system to realize system interconnection and intercommunication, and the local area network system comprises a server.

The Optical Coupler (OC) takes light as a medium to couple input signals to output ends so as to realize photoelectric conversion, and one or more optical couplers can be arranged according to actual conditions.

In the downlink, signals belonging to different VAPs are first OFDM modulated in a remote Central Office (CO), upconverted to their pre-assigned sub-bands and then combined and transmitted over a fiber link. After reaching the access network, the downlink signal is first split by an Optical Coupler (OC), and the split optical signals are sent to the LED transmitter units of the VAPs, respectively. The LED transmitter unit is internally integrated with a fiber-optic transceiver device and a visible light transceiver device. Each VAP selects only its own subband signal by means of a bandpass filter and downconverts the bandpass signal to baseband using a mixer. The baseband downstream signal is further used to drive an LED transmitter unit to achieve visible light modulation. After indoor free space transmission, the downlink signal reaches the user terminal. The users under the LED emitter unit need to allocate the corresponding signal time slots in advance, and each user only needs to select the own downlink signal from the time slots allocated to the user in advance. Finally, the demodulation and recovery of the signals are realized through a navigation device receiver unit of the user side.

In the uplink, each user in the same VAP first modulates its own uplink OFDM signal onto an uplink infrared transmitter module, and then transmits the signal in a time slot previously allocated to itself. The signal is received by an infrared detector in the LED lamp on the ceiling, subsequently upconverted to a sub-band pre-assigned to the VAP, and the upconverted signal is modulated onto an optical carrier using a light intensity modulator and fed into an uplink optical fiber link. The uplink optical signals from different VAPs are combined by an optical coupler and finally reach a central office end through optical fiber transmission. And demodulating and recovering the data of each user by using down-conversion and filtering in the central office.

The LED VAP unit is arranged in each indoor room, can be a plurality of types of indoor light sources such as linear lamps and down lamps, and serves as an indoor lighting light source and a receiving and transmitting point of visible light signals. The LED VAP unit consists of an LED emitter module, an LED receiver module and an LED VAP unit controller 3,

the LED VAP unit controller is stored with position information (coordinates, position names, coordinates such as 1 and 6, and position names such as a cashier desk) of the indoor place where the LED VAP unit is located as a fixed base station of the indoor position information.

The LED VAP unit is connected with an Optical Coupler (OC) through an optical fiber

The electrical wiring diagram of the LED VAP unit is shown in figure 2:

the LED VAP unit controller adopts an Arduino controller, and the controller is an open-source electronic platform based on easy-to-use hardware and software. The Arduino controller has been pre-programmed with a boot loader to simplify the process of uploading the program to the controller's flash memory. In our model, the Arduino controller is loaded with program code regarding current location information through a serial connection to a computer.

The Arduino controller of the LED VAP unit adopts a voltage stabilizer as a power supply module, the input voltage of the voltage stabilizer is 12V-24V, and the voltage stabilizer is matched with the voltage of a common indoor lamp. The voltage regulator is configured to generate a stable circuit output voltage in response to changes in input voltage conditions, thereby acting to regulate the voltage in the transmitter.

The LED emitter module of the LED VAP unit is composed of an LED light source and a Tip122 Darlington transistor.

LED light source is lamp pearl commonly used for the indoor lighting, sends the stroboscopic instruction through Arduino controller, makes the LED light source send the LIFI signal.

Tip122 darlington transistor is connected between lamp pearl and Arduino controller, and its collecting electrode rated current is about 5A, and the gain is about 1000, and its collecting electrode also can bear about 100V's voltage, plays switch and signal amplification effect.

And the LED receiver module of the LED VAP unit consists of an infrared receiver module and a crystal oscillator circuit module.

The infrared receiver module is connected on the Arduino controller, can decode, mediate the back with received infrared signal and export the Arduino controller.

The crystal oscillator circuit module is directly connected to the LED VAP unit controller, can provide clock parameters and provides stable oscillation frequency for receiving signals.

The navigation apparatus is composed of: the device comprises a navigation equipment controller, a power supply module, a PIN receiver module, a distance measuring sensor module, a buzzer module, an infrared transmitter module, a voice broadcasting module and a three-axis magnetic field sensor. As shown in figure 3 of the drawings,

the navigation equipment controller adopts the Arduino controller, and the Arduino controller adopts the stabiliser as power module, and stabiliser input voltage is 12V-24V. The voltage regulator is configured to generate a stable circuit output voltage in response to changes in input voltage conditions, thereby acting to regulate the voltage in the transmitter.

The navigation device controller adopts an Arduino controller, which is an open source electronic platform based on easy-to-use hardware and software. The Arduino controller has been pre-programmed with a boot loader to simplify the process of uploading the program to the controller's flash memory. In our model, the Arduino controller loads the relevant program code required for navigation, obstacle warning, etc. through a serial connection to a computer.

The three-axis magnetic field sensor is connected to the navigation equipment controller, collects data of a magnetic field X axis, a magnetic field Y axis, a magnetic field Z axis and a course angle of the navigation equipment carried by the visually impaired people, and transmits the data to the navigation equipment controller.

The distance measuring sensor module is connected to the navigation equipment controller, and can feed back the distance between the navigation equipment and the obstacle to the navigation equipment controller in real time by adopting ultrasonic waves to detect the obstacle.

The buzzer module is connected to the navigation device controller, can receive the obstacle early warning signal from the controller, sends vibration and buzzing early warning, and the nearer the distance the buzzing sound is higher, and the vibration is more frequent, plays the role of providing obstacle early warning for the visually impaired people, and avoids being stumbled by the obstacle.

The PIN receiver module is connected to the navigation equipment controller, can receive a visible light LIFI signal emitted by the LED VAP, decodes and modulates the received LIFI signal and outputs the decoded and modulated LIFI signal to the navigation equipment controller.

The infrared emitter module is connected to the navigation equipment controller, can convert an instruction sent by the navigation equipment controller into an infrared signal, and transmits the infrared signal to the LED VAP unit through the indoor space.

The voice broadcast module is connected to the navigation equipment controller, can receive the instruction of the navigation equipment controller, and broadcasts the navigation instruction stored in the controller in advance.

The navigation equipment is also provided with a man-machine interaction interface and a Braille keyboard, and a user inputs a position required to be reached from the Braille keyboard.

The local area network system comprises a server;

The shortest distance path algorithm demonstrates, as shown in fig. 4:

to select the best path between two nodes, the algorithm must first analyze the metrics (distances) assigned in each link (path between two nodes) and calculate the distance metrics for all possible paths. Based on the calculated value, the path with the smallest distance is classified as the optimal path.

The method comprises the following specific steps:

1. starting from the starting point, comparing the shortest distances of all the neighbors (starting point → starting point), and finding out the neighbor node A;

2. starting from the neighbor node A, calculating the distances from the node A to all the neighbor nodes, comparing, recording the smaller distance, and updating the path point B;

3. then removing the nodes of all the neighbors which are already calculated, finding out the node with the minimum distance from the remaining nodes which are not scratched, calculating the distances from the node to all the neighbors of the node from the node, comparing, recording the smaller distance, and updating the path point C;

4. repeating step 3;

5. and updating the path point to the end point until all the nodes are scratched out, ending and outputting the shortest distance path.

The working principle of the system is as follows: the method comprises the steps that an indoor exclusive local area network is constructed through visible light communication (LIFI), LED VAP units are used as visible light signal receiving and transmitting points and position information fixing base stations, each LED node provides a unique ID, and when a visually impaired person holds navigation equipment to enter an indoor signal receiving range, the visually impaired person firstly adds description of a destination (node ID) through a Braille keyboard. An algorithm is used to identify the best route based on the destination given by the user from the keypad. The LED VAP transmits the corresponding navigation information to the navigation equipment of the visually impaired people, and broadcasts the distance and the advancing mode of the LED VAP with the shortest distance from the place where the visually impaired people are located through the voice broadcasting module, so that the visually impaired people can acquire the position information of the visually impaired people in the room in real time.

Meanwhile, an ultrasonic sonar distance sensor on the navigation equipment senses the distance between obstacles around the visually impaired people in real time, and when the distance is too short and the visually impaired people are influenced to move, the buzzer vibrates to give an alarm to generate continuous buzzing sound to inform the user of the distance between the obstacles in front. The closer the distance, the higher the beep, the more frequent the vibration.

The three-axis magnetic field sensor adopts an HMC5883L module which is compatible with the existing system, and the HMC58 5883L module adopts the current position and direction and calculates the direction in which a user should be positioned after rotating. The HMC5883L module will then continue to check for changes in the user's orientation until the user turns to the direction given by the system. When the user reaches the correct position the HMC5883L module will detect the correct direction, the system will issue a voice command prompting the user to stop the turn and continue the path.

The technical effects are as follows:

the invention constructs the indoor local area network by utilizing LIFI, provides a new solution for constructing the indoor local area network, and the local area network adopts visible light as a communication signal, can realize the highest transmission rate of 3Gbit/s, and improves the transmission rate by 57 times compared with the highest transmission rate (54Mbp/s) of the traditional WIFI signal.

The signal transmission mode of the invention provides unregulated and infinite bandwidth for visible light and infrared bands and a plurality of bands, and is used as a practical solution for the problem of the current spectrum tension.

The invention adopts a multi-node server system, each node is provided with an optical coupler, so that the LIFI signals are ensured to be fully covered indoors, the indoor cross-room use is realized, and meanwhile, the information can be prevented from being leaked outdoors.

The LIFI technology adopted by the invention takes light waves as a signal transmission medium, and because the light waves can not generate any electromagnetic interference, the LIFI can be widely applied to a plurality of environments sensitive to radio frequency, such as mines, power plants and hospitals.

The signal transmission of the invention is based on the visible light communication technology (LIFI), and the scheme of the invention can be used as long as the lighting infrastructure exists, thereby reducing the hardware cost;

the invention adopts visible light as a signal transmission medium for a downlink (LED VAP-navigation equipment), adopts infrared rays as a signal transmission medium for an uplink (navigation equipment-LED VAP), and allocates different time slots to downlink channels for the uplink, thereby minimizing the mutual interference between the uplink and the downlink and ensuring the effectiveness of signal transmission.

The navigation equipment is provided with the ultrasonic sensor, and can perform early warning on obstacles influencing the actions of the visually impaired people by matching with the buzzer, so as to provide guidance for timely avoiding the obstacles for the visually impaired people.

The invention sets up the far-end Central Office (CO), in the central office, reuse down conversion and filtering to realize demodulation and recovery to each user's data, the far-end central office can be connected with host computer of the computer in series, process, program the data, and issue the navigation command. Therefore, the system can have better compatibility with the existing indoor machine room, and the hardware setting cost at the upper end is reduced.

The invention adopts a three-axis magnetic field sensor HMC5883L module with good system compatibility as a forward direction sensing module of the visually impaired, and by comparing the difference between the set direction of the path and the forward direction of the visually impaired, the steering instruction is broadcast by a voice broadcaster in time until the visually impaired returns to the direction specified by the system.

The invention establishes a tree diagram in a database, stores the coordinates of the indoor key positions, the distance of the adjacent points and the path information in the database, selects the optimal path through an optimal path algorithm, and broadcasts the path navigation information to the visually impaired through a voice broadcast module by a system calling. Compared with the traditional method of storing the indoor map in the database as the navigation basis, the method reduces the development cost of the database and increases the adjustability of the path.

The invention provides a set of complete solution for the visually impaired people, so that the visually impaired people can acquire indoor position information at any time and any place in the living or working environment, the obstacle avoidance and self-care capacity of the visually impaired people in the room is improved, the living level of the visually impaired people is improved, and the public service cost of the society for the visually impaired people is reduced.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The utility model provides a look barrier personage's indoor navigation based on LIFI which characterized in that includes:

the local area network system comprises a server;

the shortest distance path calculation process of the shortest distance path algorithm program is as follows: and starting from the starting point to the end point, selecting the LED VAP unit with the shortest distance as the starting point of the next step each time, excluding the LED VAP units which do not pass through the compared paths, repeating the steps until the end point, determining a shortest distance path from the starting point to the end point, and sending the information of the shortest distance path to the navigation equipment.

2. The LIFI-based visually impaired indoor navigation system of claim 1,

3. The LIFI-based visually impaired indoor navigation system of claim 1,

the LED VAP unit includes: the system comprises an LED emitter module, an LED receiver module, an LED VAP unit controller and a power supply module;

the position information comprises coordinates and a position name;

the LED VAP unit controller adopts an Arduino controller;

the Arduino controller adopts a voltage stabilizer as a power supply module and loads a program code of current position information;

the LED emitter module consists of an LED light source and a Tip122 Darlington transistor;

4. The LIFI-based visually impaired indoor navigation system of claim 3,

the LED receiver module consists of an infrared receiver module and a crystal oscillator circuit module;

5. The LIFI-based visually impaired indoor navigation system of claim 1,

the navigation apparatus includes: the device comprises a navigation equipment controller, a power supply module, a PIN receiver module, a distance measuring sensor module, a buzzer module, an infrared transmitter module, a voice broadcasting module and a three-axis magnetic field sensor;

the navigation equipment controller adopts an Arduino controller, the Arduino controller adopts a voltage stabilizer as a power supply module, and program codes required by navigation and obstacle early warning are loaded;

6. The LIFI-based visually impaired indoor navigation system of claim 5,

the distance measuring sensor module is connected to the navigation equipment controller, detects the obstacle by adopting ultrasonic waves, and feeds back the distance between the navigation equipment and the obstacle to the navigation equipment controller in real time;

7. The LIFI-based visually impaired indoor navigation system of claim 1,

the navigation equipment is also attached with a Braille keyboard, and a user inputs a position name required to go to from the Braille keyboard.

8. An indoor navigation method for visually impaired people based on LIFI is characterized by comprising the following steps:

9. The LIFI-based indoor navigation method for visually impaired people according to claim 8,

the step S4 includes the following steps:

s44, repeating the step S43;

10. The LIFI-based visually impaired indoor navigation method of claim 8,

in the step S4, in step S4,