A passive optical positioning system for detecting the position of a target

Abstract

The application discloses a positioning system for passively detecting target positions by using visible light, which comprises: a plurality of visible light transceiver nodes, which are installed and arranged at various set positions in a site, and are used for emitting narrow light beams with unique ID information to various set illumination areas in the site to perform illumination, receiving visible light reflected from a target, and adjusting relevant data information of the visible light; and a central information processing unit, which is connected with the visible light transceiver nodes in signal, and is used for performing positioning calculation according to the ID information of the visible light reflected from the target and adjusting the visible light, so as to obtain a positioned target position. The application utilizes visible light communication and reflection characteristics of a target surface to realize passive positioning of the target, and the application itself can provide a beneficial supplement for an existing indoor positioning system, and can play a more active role in some occasions with more restrictions, for example, a hospital where mobile phones are prohibited, and some areas in an airport.

Description

Technical Field

[0001] This application relates to the field of positioning technology, and in particular, to a positioning system for passive optical detection of target position. Background Technology

[0002] In the past decade or so, many researchers have been conducting cutting-edge research on a newly emerging and hot technology—Visible Light Communication (VLC). This new technology owes its existence to the maturity and rapid development of LED (Light Emitting Diode) technology. Simultaneously, LEDs, due to their high reliability, long lifespan, low heat loss, and high luminous efficiency, have rapidly expanded their market share in the lighting market, giving these cutting-edge researches a broad market prospect. LED light sources can be rapidly turned on and off; switching frequencies exceeding 300Hz are imperceptible to the human eye. Therefore, we can transmit data through changes in the switching state of LEDs. These changes in light can be detected by a photodiode or other photosensitive elements, and the receiving end demodulates the data, thus constituting visible light communication.

[0003] Besides continuously improving communication speeds to transmit more data in a shorter time, low-speed visible light communication, achieved simply using ordinary LEDs and low-cost microcontrollers, can also provide a novel solution to some existing technological problems in our daily lives and industries. All published visible light communication positioning system inventions require the target to be a smart device, such as a mobile phone or a specially designed smart terminal. The target must have the ability to receive and detect information contained in visible light to be detected. These can all be classified as active positioning, which is costly, complex, and difficult to promote. Summary of the Invention

[0004] This application provides a passive optical detection target location system to solve the technical problems of high cost, system complexity, and difficulty in promotion of existing visible light communication positioning systems.

[0005] The technical solution adopted in this application is as follows:

[0006] A passive optical target location detection system, comprising:

[0007] Several visible light transceiver nodes are installed and arranged at various designated locations within the site to emit narrow beams of light with unique ID information to various designated lighting areas within the site for illumination, receive visible light reflected from targets, and adjust the relevant data information of the visible light.

[0008] The central information processing unit is connected to each visible light transceiver node and is used to perform positioning calculations based on the visible light reflected from the target and adjust the ID information of the visible light to obtain the location of the target.

[0009] Furthermore, the visible light transceiver node includes:

[0010] The microcontroller outputs control pulses to control the LED to turn on and off, and performs ADC sampling on the output signal of the visible light detection circuit to demodulate the ID information contained in the visible light and determine which narrow beam the visible light comes from.

[0011] Several LEDs are connected to the GPIO interface circuit of the microcontroller through an LED driver circuit. They are used to provide multiple narrow beams with corresponding illumination distances according to the control pulses output by the microcontroller to jointly form the illumination area of ​​a node.

[0012] The visible light detection circuit is connected to the ADC sampling interface circuit of the microcontroller through the receiving circuit, and is used to receive visible light reflected from the target;

[0013] The serial transceiver circuit enables communication between the microcontroller of each node and the central information processing unit, allowing each node to accept the control of the central processing unit and send relevant visible light data information obtained from visible light communication to the central processing unit to complete the positioning function.

[0014] Furthermore, when the microcontroller outputs control pulses to control the LED's on / off state, differential pulse position modulation (DPPM) is used to adjust the visible light. Each pulse has the same amplitude and width. The interval between the falling edge of the previous pulse and the rising edge of the next pulse represents 1 or 0, with a short interval representing 1 and a long interval representing 0. When designing the ID information for each narrow beam, the ratio of 0 to 1 remains constant, and the average length is equal to the pulse interval length when the LED is not performing visible light communication. Assuming that the amplitude and width of the pulses remain constant when the LED is not performing visible light communication, the brightness is changed by adjusting the duty cycle, i.e., the pulse interval, which is t1. The short interval representing 1 is t2, and the long interval representing 0 is t3. Among the n numbers, the number of 1s is x. Then, the following formula must be satisfied:

[0015] t2 <t1<t3;

[0016]

[0017] Furthermore, the visible light detection circuit includes a photosensitive sensor, which is connected to the ADC sampling interface circuit of the microcontroller through a receiving circuit.

[0018] Furthermore, the photosensitive sensor is a photodiode, and the receiving circuit is a photodiode receiving circuit.

[0019] Furthermore, the serial transceiver circuit adopts a wireless serial transceiver module or a wired serial transceiver module.

[0020] Furthermore, the wireless serial transceiver module includes WIFI, Bluetooth, and ZigBee.

[0021] Furthermore, the wired serial transceiver module includes RS422 and RS485 bus networks.

[0022] Furthermore, the central information processing unit employs a computer with a graphical user interface (GUI). The computer performs positioning calculations based on the visible light reflected from the target and adjusts the ID information of the visible light to obtain the target's location, which is then displayed on the GUI.

[0023] Furthermore, it also includes a reflective tag placed on the target object to reflect visible light from the visible light transceiver node.

[0024] Compared with the prior art, this application has the following advantages:

[0025] This application designs a passive optical target location detection system. By applying visible light communication technology, the visible light beam carries unique ID information, allowing it to be identified by the receiving end. For targets with high reflectivity and smooth surfaces, reflection enables and establishes a reliable visible light communication link. The data obtained from the communication can be used to further locate the target. This application also incorporates the original lighting function of indoor lighting systems. By adding low-cost hardware, the existing LED lighting source is modified to simultaneously provide both lighting and communication functions. The prototype developed based on this application has been experimentally verified to be feasible. The inherent characteristics of visible light and the specific requirements of the positioning system for the target can help this application find application environments in certain limited scenarios, such as locating cars in indoor parking lots or metal parts in warehouses. It can also play a more active role in situations with greater restrictions, such as in places where mobile phone positioning is inconvenient, such as hospitals and certain areas within airports where mobile phone use is prohibited. This greatly expands the scope of application. The system is low-cost, simple, and easy to promote, possessing broad market application prospects.

[0026] In addition to the purposes, features, and advantages described above, this application provides other purposes, features, and advantages. The application will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0028] Figure 1 This is a schematic diagram of the network connection principle of a passive optical target location positioning system according to a preferred embodiment of this application.

[0029] Figure 2 This is a functional block diagram of a visible light transceiver node according to a preferred embodiment of this application.

[0030] Figure 3 This is a schematic diagram of a visible light differential pulse position modulation waveform according to a preferred embodiment of this application.

[0031] Figure 4 This is a schematic diagram of a visible light communication link established by reflection from a target surface, according to a preferred embodiment of this application. Detailed Implementation

[0032] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] like Figure 1 The preferred embodiment of this application provides a passive optical target location detection system, comprising:

[0034] n visible light transceiver nodes (n is an integer greater than 1) are installed and arranged at various designated locations within the site. They are used to emit narrow beams with unique ID information to various designated lighting areas within the site for illumination, receive visible light reflected from targets, and adjust the relevant data information of the visible light.

[0035] The central information processing unit is connected to each visible light transceiver node and is used to perform positioning calculations based on the visible light reflected from the target and adjust the ID information of the visible light to obtain the location of the target.

[0036] Compared with the prior art, this embodiment has the following beneficial effects:

[0037] This embodiment designs a passive optical target location detection system. By applying visible light communication technology, the visible light beam carries unique ID information, allowing it to be identified by the receiving end. For targets with high reflectivity and smooth surfaces, reflection enables and establishes a reliable visible light communication link. The data obtained from the communication can be used to further locate the target. This embodiment also considers the original lighting function of an indoor lighting system. By adding low-cost hardware, the original LED lighting source is modified to simultaneously provide both lighting and communication functions. The prototype developed based on this embodiment has been experimentally verified to be feasible. The characteristics of visible light itself and the specific requirements of the positioning system for the target can help this application find application environments in certain limited scenarios, such as locating cars in indoor parking lots or metal parts in warehouses. It can also play a more active role in some restricted situations, such as in places where mobile phone positioning is inconvenient, such as hospitals and airport areas where mobile phone use is prohibited, greatly expanding the scope of application. It is low-cost, simple, easy to promote, and has broad market application prospects.

[0038] Preferably, such as Figure 2 As shown, the visible light transceiver node includes:

[0039] The microcontroller outputs control pulses to control the LED to turn on and off, and performs ADC sampling on the output signal of the visible light detection circuit to demodulate the ID information contained in the visible light and determine which narrow beam the visible light comes from.

[0040] Several LEDs are connected to the GPIO interface circuit of the microcontroller through an LED driver circuit. They are used to provide multiple narrow beams with corresponding illumination distances according to the control pulses output by the microcontroller to jointly form the illumination area of ​​a node.

[0041] The visible light detection circuit is connected to the ADC sampling interface circuit of the microcontroller through the receiving circuit, and is used to receive visible light reflected from the target;

[0042] The serial transceiver circuit enables communication between the microcontroller of each node and the central information processing unit, allowing each node to accept the control of the central processing unit and send relevant visible light data information obtained from visible light communication to the central processing unit to complete the positioning function.

[0043] In this embodiment, multiple LEDs can provide multiple narrow beams with long illumination distances to jointly form the illumination area of ​​a node. This ensures sufficient illuminance within the area while assigning unique ID information to each narrow beam. A photodiode (PD) has a large detection area and a sufficiently large field of view to receive visible light reflected from the target. The microcontroller outputs control pulses from the GPIO peripheral to control the LEDs to turn on and off, and performs ADC sampling on the output signal of the visible light detection circuit to demodulate the ID contained in the visible light, determining which narrow beam the visible light originates from. A serial transceiver circuit is used to enable communication between the control microcontroller (UART peripheral) of each node and the remote central information processing unit, allowing each node to accept control from the central processing unit and send data obtained from visible light communication to the central processing unit to complete the positioning function.

[0044] Preferably, to ensure constant and adjustable illuminance, we use Differential Pulse Position Modulation (DPPM) to adjust the visible light, as shown in the schematic diagram. Figure 3 When the microcontroller outputs control pulses to control the LED's on / off state, differential pulse position modulation (DPPM) is used to adjust the visible light. Each pulse has the same amplitude and width. The interval between the falling edge of the previous pulse and the rising edge of the next pulse represents 1 or 0, with a short interval representing 1 and a long interval representing 0. When designing the ID information for each narrow beam, the ratio of 0 to 1 remains constant, and the average length is equal to the pulse interval length when the LED is not performing visible light communication. Assuming that the amplitude and width of the pulses remain constant when the LED is not performing visible light communication, the brightness is changed by adjusting the duty cycle, i.e., the pulse interval, which is t1. The short interval representing 1 is t2, and the long interval representing 0 is t3. Among the n numbers, the number of 1s is x. Then, the following formula must be satisfied:

[0045] t2 <t1<t3;

[0046]

[0047] In this way, we can ensure that the duty cycle of the LED remains unchanged regardless of whether the LED is engaged in visible light communication, which means that the brightness of the LED remains unchanged. This ensures the stability of the lighting brightness and avoids changes in brightness that may affect the lighting effect and user experience.

[0048] Preferably, the visible light detection circuit includes a photosensitive sensor, which is connected to the ADC sampling interface circuit of the microcontroller through a receiving circuit. The photosensitive sensor is a photodiode, and the receiving circuit is a photodiode receiving circuit, which is low in cost and stable and reliable.

[0049] Preferably, the serial transceiver circuit employs a wireless serial transceiver module or a wired serial transceiver module. The wireless serial transceiver module includes WIFI, Bluetooth, and ZigBee. The wired serial transceiver module includes RS422 and RS485 bus networks.

[0050] In this embodiment, the selection of the serial transceiver circuit depends on the actual application. Mature wireless modules can be selected to form wireless local area networks such as WIFI, Bluetooth, and ZigBee, or bus networks such as RS422 and R485 can be built to meet the needs of different application scenarios, making it flexible and reliable.

[0051] Preferably, the central information processing unit is a computer with a graphical user interface (GUI). The computer performs positioning calculations based on the visible light reflected from the target and adjusts the ID information of the visible light to obtain the target location, which is then displayed on the GUI, allowing users to understand the positioning results in a timely and intuitive manner.

[0052] In this embodiment, the central information processing unit is typically a computer, such as a PC or laptop. It communicates with all visible light transceiver nodes via serial ports, remotely controls the LEDs through microcontrollers on the nodes, and receives data obtained from successfully established visible light communication links in each node's visible light detection circuit. Using this data, the PC can execute a positioning algorithm to obtain the target location and display it on the graphical user interface (GUI) of the computer screen. The network connection diagram is shown below. Figure 1 .

[0053] Preferably, the passive optical detection system for the location of a target also includes a reflective tag placed on the target object to reflect visible light from the visible light transceiver node, which facilitates the location of objects with poor surface reflectivity, such as objects with rough surfaces or objects with strong light absorption.

[0054] As a passive positioning method, this application does not require the target to actively participate in the positioning process by carrying electronic devices. However, in order to achieve reliable visible light communication and thus positioning by utilizing the reflective properties of the target surface, we require the target to have a smooth surface with high reflectivity and a sufficiently large surface area (greater than the effective area of ​​the photodetector). This invention can only locate this type of target. However, for objects that do not have a smooth surface with high reflectivity and a insufficient surface area, this embodiment facilitates the positioning of objects with poor surface reflectivity, such as objects with rough surfaces or strong light absorption, by setting reflective tags on the target object. This greatly expands the application scope of this application.

[0055] The positioning principle of the above embodiments will be briefly explained below.

[0056] Once we have deployed the visible light transceiver nodes, each node emits multiple narrow beams. One of these beams illuminates the target surface, is reflected, and is detected by a specific visible light transceiver node. The geometric relationship is shown in [the diagram]. Figure 4 Nodes i and j are the transmitting and receiving nodes for visible light communication, respectively. The thick black line segment on the ground represents the target surface, which is large enough and has high reflectivity to ensure the reliability of the visible light communication link after reflection. The information detected by each node is ultimately transmitted to the PC via serial communication. Figure 4 From successful visible light communication, we can draw a simple conclusion: the target is located within a known narrow beam of light. On a PC, we can aggregate information from all visible light transceiver nodes. If we have multiple successful visible light communication links, or if we know the tilt angle of the target surface or the target's historical movement trajectory, we can apply positioning algorithms to calculate the target's location more accurately.

[0057] In summary, this application constructs a positioning system by arranging multiple sets of visible light communication (VLC) transmitting and receiving nodes. Each transmitting node ensures that its emitted beam has unique ID information. By rapidly switching LEDs on and off, the ID information is modulated into the beam. When a target with a smooth surface enters the positioning area, its smooth surface reflects the modulated beam onto the receiving node, forming an optical communication path. The ID information demodulated by the receiving node reveals the area covered by the beam that the target is located within. By rationally designing the transmitting and receiving nodes and appropriately arranging their placement, a loosely coupled area positioning technology can be achieved.

[0058] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0059] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A positioning system for passive optical detection of a target position, characterized in that include: Several visible light transceiver nodes are installed and arranged at various designated locations within the site to emit narrow beams of light with unique ID information to various designated lighting areas within the site for illumination, receive visible light reflected from targets, and adjust the relevant data information of the visible light. The central information processing unit is connected to each visible light transceiver node and is used to perform positioning calculations based on the visible light reflected from the target and adjust the ID information of the visible light to obtain the location of the target. The visible light transceiver node includes: The microcontroller outputs control pulses to control the LED to turn on and off, and performs ADC sampling on the output signal of the visible light detection circuit to demodulate the ID information contained in the visible light and determine which narrow beam the visible light comes from. Several LEDs are connected to the GPIO interface circuit of the microcontroller through an LED driver circuit. They are used to provide multiple narrow beams with corresponding illumination distances according to the control pulses output by the microcontroller to jointly form the illumination area of ​​a node. The visible light detection circuit is connected to the ADC sampling interface circuit of the microcontroller through the receiving circuit, and is used to receive visible light reflected from the target; A serial transceiver circuit enables communication between the microcontroller of each node and the central information processing unit, allowing each node to receive control from the central processing unit and send relevant visible light data obtained from visible light communication to the central processing unit to complete the positioning function. When the microcontroller outputs control pulses to control the LED's on / off state, differential pulse position modulation (DPPM) is used to adjust the visible light. Each pulse has the same amplitude and width. The interval between the falling edge of the previous pulse and the rising edge of the next pulse is used to represent 1 or 0, with a short interval representing 1 and a long interval representing 0. When designing the ID information for each narrow beam, the ratio of 0 to 1 is kept constant, and the average length is equal to the pulse interval length when the LED is not performing visible light communication. Assuming that the amplitude and width of the pulses remain constant when the LED is not performing visible light communication, the brightness is changed by adjusting the duty cycle, i.e., the pulse interval, which is t1. The short interval representing 1 is t2, and the long interval representing 0 is t3, and so on. n The number of 1s in the given numbers is x Then the following formula must be satisfied: ； ； It also includes reflective tags placed on the target object to reflect visible light from the visible light transceiver node.

2. The passive optical target location detection system according to claim 1, characterized in that: The visible light detection circuit includes a photosensitive sensor, which is connected to the ADC sampling interface circuit of the microcontroller through a receiving circuit.

3. The passive optical target location detection system according to claim 2, characterized in that: The photosensitive sensor is a photodiode, and the receiving circuit is a photodiode receiving circuit.

4. The passive optical target location detection system according to claim 1, characterized in that: The serial transceiver circuit uses either a wireless serial transceiver module or a wired serial transceiver module.

5. The passive optical target location detection system according to claim 4, characterized in that: The wireless serial transceiver module includes WIFI, Bluetooth, and ZigBee.

6. The passive optical target location detection positioning system according to claim 5, characterized in that: The wired serial transceiver module includes RS422 and RS485 bus networks.

7. The passive optical target location detection system according to claim 1, characterized in that: The central information processing unit uses a computer with a graphical user interface (GUI). The computer performs positioning calculations based on the visible light reflected from the target and adjusts the ID information of the visible light to obtain the target's location, which is then displayed on the GUI.

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