WO2018210107A1 - 一种基于Wi-Fi物联网设备网络的定位方法和系统 - Google Patents

一种基于Wi-Fi物联网设备网络的定位方法和系统 Download PDF

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Publication number
WO2018210107A1
WO2018210107A1 PCT/CN2018/084186 CN2018084186W WO2018210107A1 WO 2018210107 A1 WO2018210107 A1 WO 2018210107A1 CN 2018084186 W CN2018084186 W CN 2018084186W WO 2018210107 A1 WO2018210107 A1 WO 2018210107A1
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subnet
positioning
information
node
target device
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PCT/CN2018/084186
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English (en)
French (fr)
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展睿
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乐鑫信息科技（上海）有限公司
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Priority to US16/489,877 priority Critical patent/US11310761B2/en
Publication of WO2018210107A1 publication Critical patent/WO2018210107A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • H04W64/006—Locating users or terminals or network equipment for network management purposes, e.g. mobility management with additional information processing, e.g. for direction or speed determination
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W64/00—Locating users or terminals or network equipment for network management purposes, e.g. mobility management
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0205—Details
    • G01S5/0221—Receivers
    • G01S5/02213—Receivers arranged in a network for determining the position of a transmitter
    • G01S5/02216—Timing or synchronisation of the receivers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/0284—Relative positioning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
    • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
    • G01S5/06—Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/01—Protocols
    • H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
    • H04L67/125—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks involving control of end-device applications over a network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/023—Services making use of location information using mutual or relative location information between multiple location based services [LBS] targets or of distance thresholds
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H04W56/0015—Synchronization between nodes one node acting as a reference for the others
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L67/00—Network arrangements or protocols for supporting network services or applications
    • H04L67/01—Protocols
    • H04L67/12—Protocols specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/30—Services specially adapted for particular environments, situations or purposes
    • H04W4/33—Services specially adapted for particular environments, situations or purposes for indoor environments, e.g. buildings
    • 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
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

Definitions

  • the invention relates to a (semi)distributed computing and centralized positioning information management positioning method and system based on Wi-Fi Internet of Things device network.
  • indoor positioning and its application have become a hot topic and have broad application prospects.
  • Various indoor positioning technologies emerge in an endless stream, and the application scenarios are also varied.
  • indoor positioning applications have two main aspects: indoor robotic device positioning navigation and indoor natural person positioning navigation.
  • Positioning and navigation of indoor robot equipment usually requires high positioning accuracy, equipped with various types and functions of detecting equipment, complicated algorithm requirements, high system requirements and high implementation cost.
  • Commonly used detection and positioning technologies include: robot vision positioning, ultrasonic radar, infrared detection, laser detection, radio frequency identification (RF-ID), SLAM technology.
  • RFID radio frequency identification
  • two or more positioning technologies are often used in combination to achieve precise positioning.
  • RSSI received signal strength
  • the device uses the TOA (time of arrival), TDOA (time difference of arrival), AOA (angle of arrival) and other information to perform positioning and navigation.
  • the positioning of this method has higher precision and the algorithm is simpler.
  • the UWB-based circuit customization design is complicated, the hardware cost is high, and the working frequency band is high, and the power consumption is large. Therefore, the positioning method has no way to achieve low-cost and low-power large-scale applications.
  • the positioning accuracy is much higher than the positioning accuracy requirement of indoor natural persons in general.
  • Wi-Fi IoT access is one of the most widely used, lowest cost, and most scalable IoT access methods.
  • Wi-Fi IoT devices access the network directly through a Wi-Fi Access Point (also known as a Wi-Fi hotspot or wireless router).
  • Wi-Fi Access Point also known as a Wi-Fi hotspot or wireless router.
  • Wi-Fi hotspot also known as a Wi-Fi hotspot or wireless router.
  • a large number of IoT devices In the case of covering a large physical range and having a large number of IoT devices, a large number of IoT devices generally use a certain topology (most commonly a tree structure) to implement interconnection, control, and data. Transmission, etc.
  • a certain topology most commonly a tree structure
  • Wi-Fi IoT environment monitoring facility network so the location of these IoT devices is more fixed than Wi-Fi access points, and the functions are relatively simple.
  • the data transmission and data processing resources of a single Wi-Fi IoT device are more redundant, and the device layout density is also Higher and has a stable power supply.
  • the prior art has not used these Wi-Fi IoT devices as positioning reference points, and uses redundant resources for indoor positioning navigation and tracking.
  • the invention utilizes the networking structure of the Wi-Fi Internet of Things device network, and realizes the real-time location monitoring of the large physical range and the large target number by using the T-OA information of the received signals between the sub-network devices through the Wi-Fi local sub-network synchronization method. Methods and systems.
  • one technical solution of the present invention is to provide a positioning method based on a Wi-Fi Internet of Things device network:
  • the spatial location information and the physical distance of each of the positioning monitoring nodes are known.
  • the target device to be located sends a data packet corresponding thereto;
  • All the positioning monitoring nodes in the subnet or all the positioning monitoring nodes except the subnet master node in the subnet receive the data packets sent by the same target device to be located in the range of information transmission and reception, and record corresponding
  • the data packet receives the clock information, and provides the data packet receiving clock information and the identification information of the data packet corresponding to the target device to be located to the subnet master node;
  • the sub-network master node uses the information provided by each of the plurality of positioning and monitoring nodes to receive the signal arrival time difference of the data packets of the same target device to be located, and calculates the target device to be located relative to the plurality of positioning monitoring nodes. The distance is poor and the location of the target device to be located in the physical coverage of the subnet is determined.
  • the subnet master node periodically broadcasts local clock information, or local clock information, and clock distance adjustment information of each positioning monitoring node to other positioning monitoring nodes of the subnet, so that the positioning monitoring node that receives the broadcast packet can clock
  • the deviation of the information is adjusted to ensure that all positioning monitoring nodes within the subnet have synchronized clocks.
  • the target device to be located sends the Beacon packet according to the set period in the SoftAP mode, where the MAC address of the target device to be located is included;
  • the target device to be located has two MAC addresses, and the Beacon packet including the first MAC address is sent in the set period by the SoftAP mode and the first MAC address, and the nearby Wi-Fi connection is connected through the STA mode and the second MAC address.
  • the IoT Central Control Unit of the Wi-Fi IoT device network Into the point to obtain information sent by the IoT Central Control Unit of the Wi-Fi IoT device network.
  • any one of the positioning monitoring nodes locally maintains a MAC address table of the target device to be located, and periodically updates the table through the subnet master node;
  • the positioning monitoring node receives the Beacon packet sent by the target device to be located and supports the MAC layer to adjust the sending period, and records the receiving time;
  • the positioning monitoring node provides information to the corresponding subnet master node in the MAC address table of the target device to be located in the positioning monitoring node;
  • the information includes the MAC address of the Beacon packet sender, the receiving time of the Beacon packet, the RSSI value of the Beacon packet receiving signal strength, or the MAC address of the Beacon packet sender, the receiving time of the Beacon packet, and the received signal strength RSSI value of the Beacon packet.
  • the detection information obtained by the sensing detection module of the target device to be located.
  • the period of sending the data packet by any target device to be located is adjusted according to the speed at which the target device to be located moves within the subnet, and/or according to the number of all target devices to be located in the subnet to avoid data. Collision and congestion of the bag.
  • the subnet master node groups the positioning monitoring nodes in the subnet by two, and the equidistance difference curves of the two positioning monitoring nodes in each group are:
  • d 1T and d 2T are the distances of the target device to be located to two positioning monitoring nodes in each group;
  • (t1, t2) is the subnet when each of the two positioning monitoring nodes in each group receives the data packet.
  • (x1, y1), (x2, y2) is the coordinates of two positioning monitoring nodes in each group;
  • (x, y) is the target device to be located The coordinates to be solved;
  • the sub-node master node coordinates the intersection points of the equal-distance difference curves of all the groups as the possible positions of the target device to be located; or the system group corresponding to the equidistance difference curve of all the groups of the sub-network master nodes. To calculate the solution value of (x, y) as the possible location of the target device to be located;
  • the positioning information is calculated using at least three equidistant handicap surfaces or at least three ternary equations obtained by grouping at least four positioning monitoring nodes.
  • a plurality of first positioning monitoring nodes including mutual distance information and spatial location information are known, and further comprising a plurality of second positioning monitoring nodes dynamically added;
  • the distance information between the second positioning monitoring node and the first positioning monitoring node is performed by performing the positioning method based on the Wi-Fi Internet of Things device network multiple times, and averaging the distance information obtained by multiple calculations. owned;
  • Each positioning of the second positioning monitoring node includes the following process:
  • the second positioning monitoring node sends a positioning data packet including the second positioning monitoring node identification information to the plurality of first positioning monitoring nodes based on the SoftAP mode;
  • Each first positioning monitoring node receives and records the receiving time of the positioning data packet, and provides the receiving time and the second positioning monitoring node identification information to the subnet master node of the subnet;
  • the sub-network master node receives the signal arrival time difference of the same positioning data packet by using the multiple first positioning monitoring nodes according to the information provided by the multiple first positioning monitoring nodes, and calculates the second positioning monitoring node and the first positioning monitoring node. Distance information between.
  • Another technical solution of the present invention is to provide a positioning system based on a Wi-Fi Internet of Things device network, which can perform any of the above positioning methods; the subnet described in the foregoing positioning method is a Wi-Fi Internet of Things device network. Any of several levels of subnets.
  • the positioning system based on the Wi-Fi IoT device network of the present invention for the Wi-Fi IoT device network, the multiple Wi-Fi IoT devices interconnected in a tree topology, according to each Wi-Fi Internet of Things The spatial distance between the device and the primary node of the corresponding primary subnet to divide the subnets of different depths;
  • the subnet master nodes of the other subnets are also the primary node of the subnet and one of the subnets of the upper subnet.
  • the control commands or data routed by the upper subnet are transmitted to the child nodes in the subnet, and the data information generated by the subnodes of the subnet is routed to the subnet master node of the upper subnet;
  • the child nodes of each level and the selected positioning monitoring nodes are all controlled Wi-Fi IoT devices.
  • the control commands related thereto the corresponding operations are performed, and the data is fed back through the subnet master node of the subnet. information;
  • the subnet master node of the subnet is processed and combined with the information provided by the positioning monitoring node in the subnet of the subordinate and the positioning information of the same target device to be located provided by the primary node of the subnet. Corresponding positioning information about the same target device to be located is provided to the subnet master node of the superior subnet.
  • a plurality of subnet backup master nodes are set in any one level subnet
  • the subnet backup primary node is one of the positioning monitoring nodes of the subnet; the relative location information of the positioning monitoring node in the subnet is stored locally in the subnode, or is stored in the primary node and subnet backup of the subnet.
  • Master node is one of the positioning monitoring nodes of the subnet; the relative location information of the positioning monitoring node in the subnet is stored locally in the subnode, or is stored in the primary node and subnet backup of the subnet.
  • the subnet backup primary node is also one of the child nodes of the upper subnet, and is connected to the primary node of the upper subnet; the subnet backup primary node takes over the completion of the current primary node of the subnet when the current primary node fails.
  • the information of the primary node of the network is bidirectional routing work.
  • a plurality of primary subnet master nodes of the Wi-Fi Internet of Things device network can directly communicate with the Internet of Things central control unit of the Wi-Fi IoT device network;
  • the Internet of Things central control unit performs control and maintenance of the Wi-Fi IoT device network, and aggregates, updates, and tracks the location information of all the target devices to be located in the physical range covered by the entire Wi-Fi IoT device network.
  • the Internet of Things central control unit performs any one of the following operations or any combination thereof:
  • the IoT central control unit enters the MAC address of the target device to be located, and sends it to all the positioning monitoring nodes in the Wi-Fi IoT device network through the multi-level subnet;
  • the IoT central control unit receives the detection information obtained by the sensing detection module of the target device to be located through the multi-level subnet, and monitors and detects the detection information; the sensing detection module treats the target The device itself and/or its surroundings are monitored and collected, and the obtained detection information is included in the data packet of the target device to be located for transmission;
  • the IoT central control unit generates real-time location navigation information or secure evacuation path information according to the location information of the target device to be located, which is aggregated from the sub-networks, and is provided to the target device to be located through each sub-network.
  • the positioning method and system of the present invention utilizes the data transmission and the calculated redundant resources of the devices in a large number of Wi-Fi Internet of Things, and realizes the target to be located and the reference sub-node of the sub-network through the timing synchronization of the devices in the sub-network.
  • the information of the signal arrival time difference (TDOA) is collected, and then the primary node of each Wi-Fi Internet of Things subnet performs preliminary processing of the positioning information in the subnet, and then the processed coarse positioning information is uploaded step by step; each level Based on the aggregated coarse positioning information, the network master node further refines and processes more accurate positioning information until the central positioning processing system of the entire Wi-Fi Internet of Things, centrally processes and maintains the location information of all the targets to be located and other collected information. Target information to be located, etc., and more monitoring, tracking and navigation services provided by the central positioning processing system.
  • TDOA signal arrival time difference
  • 1 is a system diagram of a Wi-Fi IoT device network.
  • FIG. 2 is a diagram showing an example of a two-dimensional plane positioning process of a sub-network master node to be positioned on a target device.
  • Wi-Fi IoT device network 1 is an example system of a Wi-Fi IoT device network.
  • the physical area covered by the Wi-Fi Internet of Things includes three floors, floor 1 to floor 3.
  • Each floor is equipped with a primary subnet master node (primary AP) P1 to P3 that communicates directly with the IoT central control unit.
  • primary AP primary subnet master node
  • all other controlled Wi-Fi IoT devices Sn are interconnected in a simple tree topology and connected to the IoT central control unit in the system through the primary subnets P1 to P3.
  • Controlled by the central control unit of the Internet of Things to implement basic Wi-Fi IoT control functions (such as lighting device switches, environmental detection information collection, etc.).
  • the network in this example uses a tree topology (but this is not a limitation of the topology used in the present invention).
  • the primary node of the primary subnet connects downwardly to several primary subnet nodes distributed in a certain spatial range, and the child nodes in the primary subnet are controlled by the primary node of the primary subnet; Some can be used as the primary node of the secondary subnet at the same time.
  • several secondary subnet nodes are connected and controlled to form a secondary subnet; similarly, with the coverage of the space Increase, subnet depth can be increased.
  • the numerous Wi-Fi IoT devices of the entire system are divided into several subnets of different depths according to the spatial distance from the primary node of the primary subnet.
  • the upper subnet can have several subnets. A special scenario is shown in Figure 1, that is, each upper subnet has only one subnet.
  • each Wi-Fi IoT subnet regardless of its network depth, has a subnet master node. Except for the primary node of the primary subnet, the current primary node of the subnet is both the primary node of the subnet and the subnode of the upper subnet. It is responsible for transmitting the control commands or data routed from the upper subnet to many child nodes in the subnet, and routing the data information generated by many subnodes to the primary node of the upper subnet.
  • Each subnet can also select some sub-nodes with appropriate positions as the sub-backup master node. In case the current sub-network master node fails, it can take over the bidirectional routing function of the sub-master master node.
  • the sub-network sub-node that is the primary node of the subnet backup must be a sub-node of the sub-network of the upper-level subnet and can be connected to the primary node of the sub-network.
  • each node can be a controlled device.
  • the control instruction is completed, and the relevant information is fed back according to the protocol.
  • the Wi-Fi IoT system needs to add the following measures:
  • the selected reference subnet node must contain the primary node of the subnet and all subnet backup primary nodes. All the reference nodes in the selected subnet constitute a set of subnet location monitoring nodes.
  • the relative location information of the location monitoring node in the subnet may be stored locally in the child node, or may be stored only in the subnet master node and the subnet backup master node.
  • the clock synchronization between the monitoring nodes of the subnets in the subnet is implemented: the subnet master periodically broadcasts the local clock information to the other subnets of the subnet to locate the monitoring node. If the information of the subnet positioning monitoring node is only stored in the subnet master node, The broadcast packet also needs to be added with the clock distance adjustment information of each subnet positioning monitoring node, so that each subnet positioning monitoring node can adjust the synchronization clock deviation.
  • the subnet positioning monitoring node monitors the clock synchronization information of the master node, and adjusts the deviation of the latest received clock information according to the known physical distance between itself and the current subnet master node, so that all the positioning monitoring nodes in the same subnet Have a synchronized clock.
  • the MAC address of the target device to be located is recorded into the central control unit of the Internet of Things, and broadcasted to all the positioning monitoring nodes in the Wi-Fi Internet of Things through subnets at all levels.
  • the positioning monitoring node locally maintains a MAC address table of the target device to be located, and periodically updates the list through the subnet master node.
  • the target device to be located has only the SoftAP mode, and there is no need to establish and maintain a wireless connection with other Wi-Fi devices.
  • the period in which a normal AP sends a Beacon packet is about 100 ms. Since the natural person moves at a low speed, the period for sending the positioning Beacon packet can be lengthened. Therefore, according to the number of target devices to be located in the system, the period in which the Beacon packet is sent in SoftAP mode is appropriately lengthened in the system to reduce the collision and congestion of the Beacon packet in the air interface.
  • the MAC layer is added to increase the Beacon packet period, and the step size is increased by an integer multiple of 100 ms.
  • the Beacon package cycle can meet the indoor tracking and positioning requirements for natural person movement.
  • the target device to be located is in the normal working state, and the Beacon packet containing the MAC address of the device is sent according to the configured Beacon period.
  • other monitoring and collecting information of the device such as the body temperature, heartbeat, and blood pressure information of the simple medical monitoring device, may also be loaded according to the application protocol.
  • the positioning monitoring node of a subnet in the Wi-Fi Internet of Things receives a Beacon packet, it records the local subnet synchronization clock value corresponding to the packet. If the sending MAC address in the packet is in the MAC address table of the target device to be located locally in the positioning monitoring node, the positioning monitoring node will receive the MAC address, the receiving time of the Beacon packet, the received signal strength RSSI value of the Beacon packet, and others. The detection information sent by the Beacon packet is sent to the corresponding subnet master node.
  • the subnet master node After receiving the MAC address of the target device to be located and the receiving clock information of the Beacon packet sent by the subnet positioning monitoring node, the subnet master node can calculate the relative positioning of the target device to be located according to the information. The difference in distance between nodes and further determine its position in the physical coverage of the subnet.
  • the positioning of the target node to be located by the primary node is based on the signal arrival time difference (TDOA) of each positioning monitoring node receiving the same Beacon packet. Because the relative positions between the positioning monitoring nodes are precisely known, a simple geometric algorithm can be used. Obtaining more accurate positioning information of the target device to be located.
  • TDOA signal arrival time difference
  • FIG. 2 is a diagram showing an example of a two-dimensional plane positioning process of a sub-network master node to be positioned on a target device.
  • S1 is the subnet master node.
  • any point in the space can be selected as the two-dimensional coordinate origin, and the corresponding positioning monitoring node coordinate values (x1, y1) to (x5, y5) are obtained.
  • the red cross position in the figure is the position of the target device T to be located, and the unknown coordinate point is (x, y).
  • the target device T to be sent sends a Beacon packet, and S1 to S5 receive the Beacon packet and record the intra-subnet synchronization clock value when the packet is received locally, which is recorded as t1 to t5. Then, S2 to S5 receive the information of the target device T to be located, and the clock information t2 to t5 are sent to the sub-network master node S1. At this point, all subnet positioning monitoring nodes in the S1 are to be positioned to target the target device T. All information received.
  • S1 obtains (t1, t2, t3, t4, t5), and the TDOA information can be used to estimate the coordinate position (x, y) of the positioning target device T.
  • the distance between the target device T to be located and the subnet location monitoring nodes S1 to S5 is recorded as: d 1T , d 2T , d 3T , d 4T , d 5T .
  • the electromagnetic wave signal in the air propagates at the speed of light c.
  • the equidistance difference between S1 and S2 can be represented by one of the hyperbola:
  • the curve formed by the equidistance points between two points of the other subnet positioning monitoring nodes can be obtained, as shown in C14 and C15 in the figure. All available equidistant handicap curves, there may be one intersection point between the two (or the equations of all equations above have a solution of (x, y)), which is the possible position of the target device T to be located.
  • the intersection points of the different curves obtained above will not be the same point, but will be distributed in a certain range.
  • the more information about the subnet location monitoring node obtained by the subnet master node the more solutions the target location of the target device to be located is obtained.
  • At least three sub-network positioning monitoring node synchronization positioning information is required to form at least two equidistant difference point curves, and the intersection point is obtained.
  • at least four sub-network positioning synchronization node positioning information is required, and an equidistant difference point surface is formed between the two, and an intersection of three equidistant point surfaces (or a solution of three ternary equations), that is, A possible three-dimensional positioning coordinate point of the target device to be located.
  • the primary node of the subnet uploads the obtained positioning information step by step.
  • the master node of the upper level subnet knows more spatial structure information, such as more detailed space separation information. Therefore, the primary node of the upper-level subnet can use the different subnets to locate the same location information of the target device to be located for further processing. For example, the location information of each subnet and the RSSI information of each subnet can be combined to more accurately determine the cross-floor information or wall separation information of the target to be located.
  • the positioning information processing is dispersed in the main nodes of each subnet, which can greatly compress the amount of data that needs to be transmitted in the network, and reduce most of the primary positioning information processing required by the central control unit of the Internet of Things. burden.
  • the location monitoring information of the primary nodes of each subnet is finally collected to the central control unit of the Internet of Things.
  • the IoT Central Control Unit is responsible for maintaining location information updates, tracking and other services (such as target natural persons) for all target devices to be located within the physical scope of the entire Wi-Fi IoT coverage. Health monitoring).
  • the subnets can also be added to the new positioning monitoring node in the subsequent use.
  • the location of the newly added positioning monitoring node may be fixed or semi-fixed (unchanged timing), and the distance information between the newly added positioning monitoring node and the existing positioning monitoring node may not need to be manually measured, but based on the above-mentioned target device to be positioned.
  • the positioning method through the SoftAP mode, sends the Beacon packet containing its own information to the existing positioning monitoring node in the subnet by the newly added positioning monitoring node; and measures the relative position of the newly added node and the known node multiple times, By averaging, gradually approaching, the positioning accuracy of the node is improved.
  • the node may also join the positioning monitoring node autonomously and participate in the positioning monitoring of the target device to be located. .
  • the subsequent positioning monitoring node can increase the system redundancy, coverage and positioning accuracy by autonomously adding the autonomous measurement mode.
  • the method can greatly save the manpower required for the cloth setting position monitoring node, and makes the positioning network layout more convenient and quick.
  • the positioning system based on the Wi-Fi IoT device network is also highly robust.
  • the signal acquisition is rich, the positioning algorithm has a large amount of input information, and combined with the RSSI information, the influence of the non-line-of-sight positioning information can be eliminated, the self-correcting ability is strong, the positioning is accurate, and the algorithm design flexibility is higher and simpler.
  • TDOA signal reception time difference
  • the positioning system based on the above method can achieve positioning accuracy within one meter in a wide range of indoor spaces. For indoor natural person positioning navigation applications, this accuracy is sufficient. It should be noted that although the indoor positioning is taken as an example, if the Wi-Fi Internet of Things device network in the outdoor environment has the corresponding function and layout conditions (for example, the distance/position is accurate, the record is to be located.
  • the receiving time of the target device information, the data required for the positioning is sent to the sub-network master node, etc., but not limited thereto, the positioning method of the present invention can also be applied to the outdoor environment.
  • the application modes of the present invention can be mainly divided into two types:
  • One-way positioning information collection management such as hospital positioning management of patients, positioning of elderly people in nursing homes, nurseries, special nursing institutions, and positioning of workers' physical locations in large factory workshops.
  • the target device to be located needs only one Wi-Fi transmitting module that can support the SoftAP mode, which can be the simplest and lightest, does not increase the wearing burden of the positioned natural person, and does not need to be positioned by the natural person. Any interaction.
  • other functional modules can be integrated and loaded in the target device to be located.
  • the body temperature, heartbeat, blood pressure and other information collected by the health data monitoring module in the medical application can be returned to the central control unit of the Internet of Things together with the positioning information.
  • the central control unit of the Internet of Things can monitor the physical condition of patients and the elderly in real time according to the health monitoring information, provide early warning in real time, give positioning information, implement rescue in time, save a lot of nursing manpower, and greatly increase the system response speed and improve the system. Care and ambulance efficiency.
  • the target device to be located needs to support two Wi-Fi modes at the same time, and uses two MAC addresses at the same time: SoftAP mode is used to send and locate Beacon packets; STA mode is used to connect to nearby Wi-Fi interfaces. Incoming point to obtain real-time location navigation information from the server/IoT central control unit, or to obtain the best secure evacuation path information from the server in an emergency, and so on.
  • the central control unit of the Internet of Things centrally manages and maintains positioning information, which facilitates rapid calculation of optimal evacuation, rescue plans and routes in emergency situations (such as fires), real-time monitoring of safe evacuation conditions, and facilitates the most effective rescue and safe evacuation of resources. arrangement.

Abstract

本发明涉及基于Wi-Fi物联网设备网络的定位方法及系统，子网中的定位监控节点各自在信息收发范围内对同一个待定位目标设备所发送的数据包进行接收，记录对应的数据包接收时钟信息，并将所述数据包接收时钟信息及待定位目标设备的识别信息提供给子网主节点；所述子网主节点利用多个定位监控节点接收同一个待定位目标设备的数据包的信号到达时间差，及定位监控节点相互的物理距离，计算待定位目标设备相对多个定位监控节点的距离差，并确定待定位目标设备在子网物理覆盖范围中的位置。本发明实现了大物理范围、大目标数量的实时定位监控。

Description

一种基于Wi-Fi物联网设备网络的定位方法和系统 技术领域
本发明涉及一种基于Wi-Fi物联网设备网络的(半)分布式计算、集中定位信息管理的定位方法和系统。
背景技术
近年来，室内定位及其应用已经成为一个热门话题，具有广阔的应用前景。各种室内定位技术层出不穷，应用场景也是五花八门。大体上，室内定位应用主要有两个方面：室内机器人设备定位导航和室内自然人定位导航。
对室内机器人设备的定位导航，基于室内机器人的不同工作要求，通常定位精度要求较高，配备的探测设备种类和功能较多，算法要求也较复杂，系统要求高，实现成本高。常用的探测定位技术有：机器人视觉定位、超声雷达、红外探测、激光探测、射频识别技术(RF-ID)、SLAM技术等。在实际应用中，常将两种或以上的定位技术综合使用，实现精确定位。
对室内自然人的定位导航，精度要求相对较低，多采用手持智能设备本地定位方式，使用方式繁琐，应用普及度很低，目前并不支持大目标数量的集中定位信息管理和导航服务。实际应用中，有几种常用方式：
1)基于多个通信基站或Wi-Fi接入热点的接收信号强度(RSSI)信息的定位算法。然而，通常通信基站或Wi-Fi热点的数量较少，且布设密度较低，加上无线信道衰减情况复杂，基于RSSI的定位方法算法复杂度高，可靠性差，误差很大。
2)基于UWB等技术，利用设备接收信号的TOA(time of arrival，到达时间)、TDOA(time difference of arrival，到达时间差)、AOA(angle of arrival，到达角度)等信息进行定位导航。这种方式的定位，精度较高，算法也较简单。不过基于UWB的电路定制设计较复杂，硬件成本很高，而且工作频段很高，功耗较大，因此该定位方式没有办法做到低成本低功耗大规模应用。而且，基于UWB技术的定位，其定位精度远远高于一般情况下室内自然人的定位精度需求。
通常，室内自然人的定位应用，需要在较大的室内物理范围内，进行大目标数量的集中定位。现有技术并没有提供能解决这种情况下的应用需求的 成本低、性能高的解决方案。
随着物联网时代的到来，市场上涌现出很多家用或商用的物联网设备。物联网设备之间，一般遵循某种无线连接技术实现互联。802.11Wi-Fi无线通信标准是目前应用范围最广的无线接入技术标准之一。在物联网领域，Wi-Fi物联网接入方式更是应用最广，成本最低，可扩展性最好的物联网接入方式之一。
通常，Wi-Fi物联网设备直接通过Wi-Fi接入点(Wi-Fi Access Point，也称Wi-Fi热点或无线路由器)接入网络。但是随着电子设备的集成度、运算处理能力的提高和设备生产成本的不断降低，越来越多的常用设备加载了Wi-Fi物联网功能，形成了规模可观的Wi-Fi物联网设备网。
在覆盖较大物理范围和拥有较大物联网设备数量的情况下，数量巨大的物联网设备之间，一般是采用某种拓扑结构(最常用的为树状结构)，来实现互联、控制和数据传输等。如较大范围公共区域内的Wi-Fi物联网照明设施网络，Wi-Fi物联网环境监测设施网络(烟雾、火警报警器)等。一般来说，这些物联网设备的位置相比Wi-Fi接入点更加固定，而且功能较简单，单个Wi-Fi物联网设备的数据传输和数据处理资源有较大冗余，同时设备布设密度较高，并且有稳定的电源供应。然而，现有技术还没有将这些Wi-Fi物联网设备作为定位参考点，将其冗余资源用来进行室内定位导航和追踪。
发明内容
本发明利用Wi-Fi物联网设备网络的组网结构，通过Wi-Fi局部子网同步的方法，利用子网设备间接收信号的TDOA信息，实现大物理范围、大目标数量的实时定位监控的方法和系统。
为了达到上述目的，本发明的一个技术方案是提供一种基于Wi-Fi物联网设备网络的定位方法：
从Wi-Fi物联网设备网络的任意一个子网的节点中选定多个定位监控节点，该子网的子网主节点是其中的一个定位监控节点；
所述定位监控节点各自的空间位置信息及相互的物理距离是可知的；
待定位目标设备发送与之对应的数据包；
该子网中的所有定位监控节点或者该子网中除子网主节点以外的其他所有定位监控节点，各自在信息收发范围内对同一个待定位目标设备所发送的 数据包进行接收，记录对应的数据包接收时钟信息，并将所述数据包接收时钟信息及数据包对应待定位目标设备的识别信息提供给子网主节点；
所述子网主节点根据多个定位监控节点各自提供的信息，利用多个定位监控节点接收同一个待定位目标设备的数据包的信号到达时间差，计算待定位目标设备相对多个定位监控节点的距离差，并确定待定位目标设备在子网物理覆盖范围中的位置。
优选地，子网主节点向所在子网的其他定位监控节点，定期广播本地时钟信息、或本地时钟信息及各个定位监控节点的时钟距离调整信息，使接收到广播包的定位监控节点能对时钟信息的偏差进行调整，以确保子网内的所有定位监控节点具有同步的时钟。
优选地，待定位目标设备通过SoftAP模式按设定周期发送Beacon包，其中包含该待定位目标设备的MAC地址；
或者，待定位目标设备具有两个MAC地址，通过SoftAP模式及第一MAC地址按设定周期发送包含第一MAC地址的Beacon包，以及通过STA模式及第二MAC地址连接附近的Wi-Fi接入点，以获取Wi-Fi物联网设备网络的物联网中央控制单元发送的信息。
优选地，任意一个定位监控节点在本地维护一个待定位目标设备MAC地址表，并通过子网主节点对该表进行定期更新；
所述定位监控节点接收待定位目标设备所发送的、支持在MAC层调整发送周期的Beacon包，并记录接收时间；
如果Beacon包中表示该Beacon包发送方的MAC地址，在该定位监控节点的待定位目标设备MAC地址表之内，则该定位监控节点向其对应的子网主节点提供信息；
该信息中，包含Beacon包发送方的MAC地址、Beacon包的接收时间、Beacon包接收信号强度RSSI值，或者包含Beacon包发送方的MAC地址、Beacon包的接收时间、Beacon包接收信号强度RSSI值、待定位目标设备的传感检测模块获得的检测信息。
优选地，任意一个待定位目标设备发送数据包的周期，根据该待定位目标设备在子网内移动的速度进行调整，和/或根据子网内所有待定位目标设备的数量进行调整以避免数据包的碰撞和拥堵。
优选地，子网主节点将子网内的定位监控节点两两分组，每个分组中两个定位监控节点的等距离差点曲线为：
d 1T-d 2T＝(t1-t2)c
Figure PCTCN2018084186-appb-000001
Figure PCTCN2018084186-appb-000002
其中，d 1T，d 2T是待定位目标设备分别到每个分组中两个定位监控节点的距离；(t1，t2)是每个分组中两个定位监控节点各自接收到数据包时的子网内同步时钟值；空气中的电磁波信号以光速c传播；(x1，y1)、(x2，y2)是每个分组中两个定位监控节点的坐标；(x，y)是待定位目标设备的待求解坐标；
子网主节点将所有分组的等距离差点曲线两两相交的交点坐标，作为待定位目标设备的可能位置；或者，子网主节点对所有分组的等距离差点曲线对应的方程组两个一组来计算(x，y)的解值，作为待定位目标设备的可能位置；
为确定待定位目标设备的二维定位信息，使用至少三个定位监控节点两两分组获得的至少两条等距离差点曲线或至少两个方程组来计算；或者，为确定待定位目标设备的三维定位信息，使用至少四个定位监控节点两两分组获得的至少三个等距离差点曲面或至少三个三元方程来计算。
优选地，任意一个子网中，包含相互距离信息和空间位置信息已知的若干第一定位监控节点，还包含动态加入的若干第二定位监控节点；
所述第二定位监控节点与第一定位监控节点之间的距离信息，是多次执行所述基于Wi-Fi物联网设备网络的定位方法计算，并对多次计算得到的距离信息进行平均而得到的；
其中对第二定位监控节点的每一次定位，包含以下过程：
所述第二定位监控节点，基于SoftAP模式向多个第一定位监控节点发送包含该第二定位监控节点识别信息的定位数据包；
各第一定位监控节点接收并记录定位数据包的接收时间，并将所述接收时间及第二定位监控节点识别信息提供给所在子网的子网主节点；
所述子网主节点根据多个第一定位监控节点各自提供的信息，利用多个 第一定位监控节点接收同一个定位数据包的信号到达时间差，计算第二定位监控节点与第一定位监控节点之间的距离信息。
本发明的另一个技术方案是提供一种基于Wi-Fi物联网设备网络的定位系统，能够执行上述任意一种定位方法；上述定位方法中所述的子网，是Wi-Fi物联网设备网络的若干级子网中的任意一级。
本发明所述基于Wi-Fi物联网设备网络的定位系统，对于所述Wi-Fi物联网设备网络中以树状拓扑实现互联的多个Wi-Fi物联网设备，根据各Wi-Fi物联网设备和与之对应的一级子网主节点之间的空间距离，来划分若干个不同级别深度的子网；
除了Wi-Fi物联网设备网络的若干个第一级子网主节点以外，其余各级子网的子网主节点同时是本级子网的主节点和上级子网的其中一个子节点，将上级子网路由下来的控制命令或数据传输给本级子网中的子节点，并将本级子网的子节点产生的数据信息路由至上级子网的子网主节点；
各级的子节点及从中选定的定位监控节点均是受控的Wi-Fi物联网设备，接收到与之相关的控制命令时执行对应操作，并通过所在子网的子网主节点反馈数据信息；
其中，结合本级子网内定位监控节点所提供的信息，以及下级子网的主节点提供的有关同一个待定位目标设备的定位信息，本级子网的子网主节点处理得到与本级对应的、有关该同一个待定位目标设备的定位信息，并将其提供给上级子网的子网主节点。
优选地，任意一级子网中设置有若干个子网备份主节点；
所述子网备份主节点是本级子网的其中一个定位监控节点；本级子网内定位监控节点的相对位置信息存储在子节点本地，或者存储于本级子网的主节点和子网备份主节点；
所述子网备份主节点同时也是上级子网的其中一个子节点，与上级子网的主节点连接；所述子网备份主节点在本级子网当前的主节点故障时，接替其完成子网主节点的信息双向路由工作。
优选地，所述Wi-Fi物联网设备网络的若干个一级子网主节点，能各自与所述Wi-Fi物联网设备网络的物联网中央控制单元直接通信；
所述物联网中央控制单元进行Wi-Fi物联网设备网络的控制维护，对整个 Wi-Fi物联网设备网络覆盖的物理范围内所有待定位目标设备的位置信息进行汇总、更新、追踪。
优选地，所述物联网中央控制单元还进行以下的任意一项操作或其任意组合：
所述物联网中央控制单元录入有待定位目标设备的MAC地址，并通过多级子网发送给Wi-Fi物联网设备网络中的所有定位监控节点；
所述物联网中央控制单元通过多级子网，接收由待定位目标设备的传感检测模块获得的检测信息，并对所述检测信息进行监控、预警处理；所述传感检测模块对待定位目标设备自身和/或其周边进行监控采集，并将获得的检测信息包含在所述待定位目标设备的数据包中发送；
所述物联网中央控制单元根据其从各级子网汇总得到的待定位目标设备的位置信息，生成实时定位导览信息或安全疏散路径信息，并通过各级子网提供给待定位目标设备。
本发明所述的定位方法和系统，利用大范围大数量Wi-Fi物联网中设备的数据传输和计算的冗余资源，通过子网内设备定时同步，实现待定位目标与子网参考子节点之间信号到达时间差(TDOA)的信息采集，然后在各个Wi-Fi物联网子网主节点进行子网内定位信息的初步处理，再将处理后的粗定位信息逐级上传；每一级子网主节点根据汇集的粗定位信息，进一步提炼处理更多更精确的定位信息，直至整个Wi-Fi物联网的中央定位处理系统，集中处理和维护所有待定位目标的位置信息及其他采集到的待定位目标信息等，并由中央定位处理系统提供更多监控、追踪和导航服务。
附图说明
图1是Wi-Fi物联网设备网络的系统示意图。
图2是一个子网主节点对待定位目标设备的二维平面定位过程示例图。
具体实施方式
以下结合附图，对本发明的具体实施方式进行说明。
图1为Wi-Fi物联网设备网络的一种示例系统。该Wi-Fi物联网所覆盖的物理区域包括三个楼层，楼层1到楼层3。每一个楼层均配有一个与物联网中央控制单元直接通信的一级子网主节点(主AP)P1到P3。在每一楼层中，所有其他的受控Wi-Fi物联网设备Sn以简单树状拓扑实现互联，并通过 一级子网主节点P1到P3，连接到本系统中的物联网中央控制单元，受物联网中央控制单元控制，实现基本的Wi-Fi物联网控制功能(如照明设备开关、环境检测信息采集等)。
本例中的网络采用树状拓扑(但这不是对本发明使用的拓扑结构的限制)。一级子网主节点向下连接分布在一定空间范围的若干一级子网子节点，该一级子网中的子节点，受一级子网主节点控制；一级子网子节点中的一些可以同时作为二级子网主节点，在一级子网覆盖空间边缘的延伸空间中，连接并控制若干二级子网子节点，构成二级子网；同理，随着空间覆盖范围的增大，子网深度可不断增加。整个系统的众多Wi-Fi物联网设备根据与一级子网主节点的空间距离，被划分为若干的不同级别深度的子网。上级子网可带若干下级子网。图1中所示为特殊情景，即每一个上级子网仅带一个下级子网。
以下为Wi-Fi物联网中节点的大概的基本功能描述，具体的功能视应用情况会有变动：
该Wi-Fi物联网中，每一个Wi-Fi物联网子网，不论其网络深度，都有一个子网主节点。除了一级子网主节点外，当前的子网主节点既是本级子网的主节点，也是上一级子网的一个子节点。它负责将上一级子网路由下来的控制命令或数据传输给本子网中的众多子节点，并将众多子节点产生的数据信息路由至上一级子网主节点。
每一个子网还可以选取一些位置合适的子节点兼作子网备份主节点，以备当前子网主节点故障时，接替其完成子网主节点的信息双向路由功能。作为子网备份主节点的本级子网子节点，必须为上一级子网的子节点，可以与上一级子网主节点相连。
该Wi-Fi物联网中，每个节点都可以为一个受控设备，当收到路由到该子节点的信息中有与自身相关的控制指令时，完成控制指令，并按协议反馈相关信息。
为了实现室内定位功能，本Wi-Fi物联网系统需要增加如下措施：
在每一个子网中选择一定数量、位置固定的子网节点，精确得到这些选定的参考节点之间的物理距离和空间位置信息。选定的参考子网节点一定包含该子网的主节点和所有子网备份主节点。所选定的该子网中所有的参考节 点，构成子网定位监控节点集合。子网内定位监控节点的相对位置信息可以存储在子节点本地，也可仅存储于子网主节点和子网备份主节点。
实现子网内子网定位监控节点之间的时钟同步：子网主节点定期广播本地时钟信息给所在子网的其他子网定位监控节点，若子网定位监控节点的信息仅存储于子网主节点，该广播包中还需要加入各个子网定位监控节点的时钟距离调整信息，以方便各子网定位监控节点调整同步时钟偏差。子网定位监控节点监听该主节点时钟同步信息，并根据自身与当前子网主节点间的已知物理距离，调整最新收到的时钟信息的偏差，以使同一子网中所有的定位监控节点拥有一份同步的时钟。
待定位目标设备的MAC地址被录入到物联网中央控制单元，并通过各级子网，广播发送给Wi-Fi物联网中所有定位监控节点。定位监控节点在本地维护一个待定位目标设备MAC地址表，并通过子网主节点定期更新该列表。
为了降低待定位目标设备的功耗和物理尺寸，待定位目标设备仅具有SoftAP模式，无需与其他Wi-Fi设备建立和维持无线连接。正常的AP发送Beacon包的周期为100ms左右。由于自然人移动速度不高，发送定位Beacon包的周期可以加长。因此可以根据系统中待定位目标设备的数量，在系统中，将SoftAP模式下发送Beacon包的周期适当调长，以降低空口中定位Beacon包的碰撞和拥堵。Wi-Fi协议中，支持MAC层增加Beacon包周期，增加步长为100ms整数倍。该Beacon包周期，可以满足室内对自然人移动的跟踪定位需求。
待定位目标设备在正常工作状态下，按照配置的Beacon周期，发送包含该设备MAC地址的Beacon包。该包中，还可以按照应用协议，加载该设备的其他监控采集信息，比如简易医疗监控设备的体温、心跳、血压信息等。
处于该Wi-Fi物联网中某个子网的定位监控节点，如果接收到一个Beacon包，记录下接收到该包所对应的本地子网同步时钟值。如果包中的发送MAC地址在该定位监控节点本地的待定位目标设备MAC地址表中，则该定位监控节点将接收到的MAC地址、Beacon包的接收时间、Beacon包接收信号强度RSSI值以及其他Beacon包发送的检测信息，发送给其对应的子网主节点。
子网主节点在收到足够多的子网定位监控节点发送的某一个待定位目标设备的MAC地址和Beacon包接收时钟信息后，就可以根据这些信息，计算待定位目标设备相对多个定位监控节点之间的距离差，并进一步确定其在子网物理覆盖范围中的位置。
子网主节点对待定位目标设备的定位，是基于各定位监控节点接收同一个Beacon包的信号到达时间差(TDOA)，因为各个定位监控节点间的相对位置精确已知，利用简单的几何算法就可以得到较准确的待定位目标设备的定位信息。
图2为一个子网主节点对待定位目标设备的二维平面定位过程示例图。该子网中有5个定位监控节点，S1到S5，分布于一个二维平面。其中S1为子网主节点。根据定位监控节点间的相对空间位置，可以选取空间中任意点为二维坐标原点，并得到相应的定位监控节点坐标值(x1，y1)到(x5，y5)。图中红叉位置为待定位目标设备T位置，其未知坐标点为(x，y)。
待定位目标设备T发送一个Beacon包，S1到S5接收到该Beacon包并记录本地接收该包时的子网内同步时钟值，记为t1到t5。接着，S2到S5将自己接收到待定位目标设备T的信息，以及时钟信息t2到t5发送给子网主节点S1，至此，S1中有所有子网定位监控节点对待定位目标设备T的Beacon包接收的所有信息。
S1得到了(t1，t2，t3，t4，t5)，利用TDOA信息，可以对待定位目标设备T的坐标位置(x，y)进行估计。将待定位目标设备T与子网定位监控节点S1到S5之间的距离记为：d 1T，d 2T，d 3T，d 4T，d 5T。空气中的电磁波信号以光速c传播。
距离S1和S2的等距离差点，可以用双曲线中的一条表示：
d 1T-d 2T＝(t1-t2)c
如图中曲线C12所示，其中，
Figure PCTCN2018084186-appb-000003
同理，可以得到其他子网定位监控节点两点间的等距离差点构成的曲线，如图中的C14和C15。所有可以得到的等距离差点曲线，两两可能有一个交点(或如上所有等式构成的方程组两两会有一个(x，y)的解)，即为待定位 目标设备T的可能位置。
由于定时误差，非视距/多径传输等影响，以上得到的不同曲线交点并不会是同一个点，而是会分布于一定范围。子网主节点得到的不同子网定位监控节点信息越多，求得的待定位目标设备可能位置的解越多，越方便子网主节点排除偏离主要范围太远的不可靠点，提高待定位目标设备的定位精度。
二维定位信息的确定，需要至少三个子网定位监控节点同步定位信息，构成至少两条等距离差点曲线，求交点。三维定位信息的确定，则需要至少四个子网定位监控节点的同步定位信息，两两之间构成等距离差点曲面，三个等距离差点曲面的交点(或三个三元方程的解)，即为待定位目标设备的可能三维定位坐标点。
子网主节点将得到的定位信息逐级上传。上一级子网主节点知道更大的空间结构信息，如更详细的空间分隔信息等。因此，上一级子网主节点，可以利用不同子网对同一个待定位目标设备的定位信息，做进一步处理。比如可以结合各子网的定位信息与各子网的RSSI信息，更准确的确定待定位目标的跨楼层信息或墙壁分隔信息等。
将定位信息处理根据具体应用和监控空间的具体情况，分散在各个子网主节点，可以大大压缩网络中需要传输的数据量，减少了物联网中央控制单元的需要进行的大部分初级定位信息处理负担。
各级子网主节点的定位监控信息，最后汇集至物联网中央控制单元。物联网中央控制单元在基本的Wi-Fi物联网控制维护工作之外，负责维护整个Wi-Fi物联网覆盖物理范围内的所有待定位目标设备的定位信息更新、追踪以及其他服务(如目标自然人健康状况监控)。
各个子网中，除了Wi-Fi物联网初始布设时，已经精确得到相对距离信息和空间位置信息的定位监控节点之外，还可以在后续的使用中，自主加入新的定位监控节点。这些新加入的定位监控节点的位置可以固定，也可以为半固定(不定时变动)，其与已有的定位监控节点之间的距离信息，可以不必手动测量，而是基于上述对待定位目标设备的定位方法，通过SoftAP模式，由新加入的定位监控节点将包含其自身信息的Beacon包，发送给子网内已有的定位监控节点；多次测量新加入节点与已知节点的相对位置，通过平均，逐渐逼近，提高该节点的定位精度。当该子网的主节点的定位算法，确定该 节点的定位信息已经在定位监控节点的允许定位误差范围之内后，该节点也可作为自主加入定位监控节点，参与对待定位目标设备的定位监控。
在初始布设时，仅需人工测量最小数量的定位监控节点的空间位置信息，后续定位监控节点可以通过自主加入自主测量的方式，增加系统的设备冗余、覆盖范围和定位精度。该方法能够大大节省布设定位监控节点所需人力，使定位网络的布设更方便快捷。
由于Wi-Fi物联网设备网络中的设备数量大，布设密度高，因此系统的冗余度较高，基于该Wi-Fi物联网设备网络的定位系统的鲁棒性也很高。同时，信号采集丰富，定位算法输入信息数量大，结合RSSI信息，可以排除非视距定位信息影响，自纠错能力强，定位准确，算法设计灵活度更高更简单。
基于子网时钟同步，利用信号接收时间差(TDOA)的定位算法，其定位精度取决于用于同步的基带时钟。Wi-Fi信号带宽越大，基带时钟频率越高，定位精度越高。由于子网中定位监控设备数量较大，简单的定位算法就可以保证较好的定位精度。基于上述方法的定位系统，可以较简单的在大范围的室内空间中达到一米以内的定位精度。对于室内自然人定位导航应用，该精度已经足够。需说明的是，虽然文中以室内定位为例进行说明，但假如室外环境的Wi-Fi物联网设备网络中，定位监控节点具备相应功能及布设条件(如，距离/位置精确可知，记录待定位目标设备信息的接收时间，发送定位所需数据给子网主节点等，但不限于此)，则本发明的定位方法同样可以适用至室外环境。
本发明的应用方式，主要可以分为两种：
1)单向的定位信息汇集管理，如医院对病人的定位管理、养老院对老人的定位、托儿所、特殊护理机构、大型工厂车间对工人的物理位置的定位等。
在该应用方式中，待定位目标装置最低只需要一个可支持SoftAP模式的Wi-Fi发射模块，可以做到最简最轻，不会增加被定位自然人的穿戴负担，也不需被定位自然人的任何互动操作。
在特殊应用中，可以在待定位目标装置中集成加载其他功能模块，如医护应用中的健康数据监控模块采集的体温、心跳、血压等信息，可以与定位信息一起返回给物联网中央控制单元。物联网中央控制单元可以根据健康监 控信息，实时监控病人、老人的身体状况，实时做出预警，给出定位信息，及时实施救助，节省了大量看护人力，并大幅增加了系统反应速度，提高了看护和救护效率。
2)单向定位信息汇集管理，并将物联网中央控制单元处理得到的导航信息返回本地设备，如大型展览馆的室内低功耗手持/可穿戴导航导览设备等。
在该应用方式中，待定位目标设备需要同时支持两种Wi-Fi模式，同时使用两个MAC地址：SoftAP模式，用于发送定位Beacon包；STA模式，用于连接到附近的Wi-Fi接入点，以便从服务器/物联网中央控制单元获得实时定位导览信息，或在紧急状况下，从服务器获得推送的最佳安全疏散路径信息，等等。
物联网中央控制单元集中管理维护定位信息，有利于在紧急情况下(如火灾等)，快速计算最佳疏散、救援方案和路径，实时监控安全撤离状况，方便进行最有效的救援与安全疏散资源安排。
尽管本发明的内容已经通过上述优选实施例作了详细介绍，但应当认识到上述的描述不应被认为是对本发明的限制。在本领域技术人员阅读了上述内容后，对于本发明的多种修改和替代都将是显而易见的。因此，本发明的保护范围应由所附的权利要求来限定。

Claims (10)

  1. 一种基于Wi-Fi物联网设备网络的定位方法，其特征在于：
    从Wi-Fi物联网设备网络的任意一个子网的节点中选定多个定位监控节点，该子网的子网主节点是其中的一个定位监控节点；
    所述定位监控节点各自的空间位置信息及相互的物理距离是可知的；
    待定位目标设备发送与之对应的数据包；
    该子网中的所有定位监控节点或者该子网中除子网主节点以外的其他所有定位监控节点，各自在信息收发范围内对同一个待定位目标设备所发送的数据包进行接收，记录对应的数据包接收时钟信息，并将所述数据包接收时钟信息及数据包对应待定位目标设备的识别信息提供给子网主节点；
    所述子网主节点根据多个定位监控节点各自提供的信息，利用多个定位监控节点接收同一个待定位目标设备的数据包的信号到达时间差，计算待定位目标设备相对多个定位监控节点的距离差，并确定待定位目标设备在子网物理覆盖范围中的位置。
  2. 如权利要求1所述的定位方法，其特征在于，
    子网主节点向所在子网的其他定位监控节点，定期广播本地时钟信息、或本地时钟信息及各个定位监控节点的时钟距离调整信息，使接收到广播包的定位监控节点能对时钟信息的偏差进行调整，以确保子网内的所有定位监控节点具有同步的时钟。
  3. 如权利要求1所述的定位方法，其特征在于，
    待定位目标设备通过SoftAP模式按设定周期发送Beacon包，其中包含该待定位目标设备的MAC地址；
    或者，待定位目标设备具有两个MAC地址，通过SoftAP模式及第一MAC地址按设定周期发送包含第一MAC地址的Beacon包，以及通过STA模式及第二MAC地址连接附近的Wi-Fi接入点，以获取Wi-Fi物联网设备网络的物联网中央控制单元发送的信息。
  4. 如权利要求1或2或3所述的定位方法，其特征在于，
    任意一个定位监控节点在本地维护一个待定位目标设备MAC地址表，并通过子网主节点对该表进行定期更新；
    所述定位监控节点接收待定位目标设备所发送的、支持在MAC层调整发送周期的Beacon包，并记录接收时间；
    如果Beacon包中表示该Beacon包发送方的MAC地址，在该定位监控节点的待定位目标设备MAC地址表之内，则该定位监控节点向其对应的子网主节点提供信息；
    该信息中，包含Beacon包发送方的MAC地址、Beacon包的接收时间、Beacon包接收信号强度RSSI值，或者包含Beacon包发送方的MAC地址、Beacon包的接收时间、Beacon包接收信号强度RSSI值、待定位目标设备的传感检测模块获得的检测信息。
  5. 如权利要求1或2或3所述的定位方法，其特征在于，
    任意一个待定位目标设备发送数据包的周期，根据该待定位目标设备在子网内移动的速度进行调整，和/或根据子网内所有待定位目标设备的数量进行调整以避免数据包的碰撞和拥堵。
  6. 如权利要求1或2或3所述的定位方法，其特征在于，
    子网主节点将子网内的定位监控节点两两分组，每个分组中两个定位监控节点的等距离差点曲线为：
    d 1T-d 2T＝(t1-t2)c
    Figure PCTCN2018084186-appb-100001
    Figure PCTCN2018084186-appb-100002
    其中，d 1T，d 2T是待定位目标设备分别到每个分组中两个定位监控节点的距离；(t1，t2)是每个分组中两个定位监控节点各自接收到数据包时的子网内同步时钟值；空气中的电磁波信号以光速c传播；(x1，y1)、(x2，y2)是每个分组中两个定位监控节点的坐标；(x，y)是待定位目标设备的待求解坐标；
    子网主节点将所有分组的等距离差点曲线两两相交的交点坐标，作为待定位目标设备的可能位置；或者，子网主节点对所有分组的等距离差点曲线对应的方程组两个一组来计算(x，y)的解值，作为待定位目标设备的可能位置；
    为确定待定位目标设备的二维定位信息，使用至少三个定位监控节点两两分组获得的至少两条等距离差点曲线或至少两个方程组来计算；或者，为确定待定位目标设备的三维定位信息，使用至少四个定位监控节点两两分组获得的至少三个等距离差点曲面或至少三个三元方程来计算。
  7. 如权利要求1或2或3所述的定位方法，其特征在于，
    任意一个子网中，包含相互距离信息和空间位置信息已知的若干第一定位监控节点，还包含动态加入的若干第二定位监控节点；
    所述第二定位监控节点与第一定位监控节点之间的距离信息，是多次执行所述基于Wi-Fi物联网设备网络的定位方法计算，并对多次计算得到的距离信息进行平均而得到的；
    其中对第二定位监控节点的每一次定位，包含以下过程：
    所述第二定位监控节点，基于SoftAP模式向多个第一定位监控节点发送包含该第二定位监控节点识别信息的定位数据包；
    各第一定位监控节点接收并记录定位数据包的接收时间，并将所述接收时间及第二定位监控节点识别信息提供给所在子网的子网主节点；
    所述子网主节点根据多个第一定位监控节点各自提供的信息，利用多个第一定位监控节点接收同一个定位数据包的信号到达时间差，计算第二定位监控节点与第一定位监控节点之间的距离信息。
  8. 一种基于Wi-Fi物联网设备网络的定位系统，执行权利要求1-7中任意一项所述的定位方法，其特征在于，
    权利要求1-7中所述的子网，是Wi-Fi物联网设备网络的若干级子网中的任意一级；
    对于所述Wi-Fi物联网设备网络中以树状拓扑实现互联的多个Wi-Fi物联网设备，根据各Wi-Fi物联网设备和与之对应的一级子网主节点之间的空间 距离，来划分若干个不同级别深度的子网；
    除了Wi-Fi物联网设备网络的若干个第一级子网主节点以外，其余各级子网的子网主节点同时是本级子网的主节点和上级子网的其中一个子节点，将上级子网路由下来的控制命令或数据传输给本级子网中的子节点，并将本级子网的子节点产生的数据信息路由至上级子网的子网主节点；
    各级的子节点及从中选定的定位监控节点均是受控的Wi-Fi物联网设备，接收到与之相关的控制命令时执行对应操作，并通过所在子网的子网主节点反馈数据信息；
    其中，结合本级子网内定位监控节点所提供的信息，以及下级子网的主节点提供的有关同一个待定位目标设备的定位信息，本级子网的子网主节点处理得到与本级对应的、有关该同一个待定位目标设备的定位信息，并将其提供给上级子网的子网主节点。
  9. 如权利要求8所述的定位系统，其特征在于，
    任意一级子网中设置有若干个子网备份主节点；
    所述子网备份主节点是本级子网的其中一个定位监控节点；本级子网内定位监控节点的相对位置信息存储在子节点本地，或者存储于本级子网的主节点和子网备份主节点；
    所述子网备份主节点同时也是上级子网的其中一个子节点，与上级子网的主节点连接；所述子网备份主节点在本级子网当前的主节点故障时，接替其完成子网主节点的信息双向路由工作。
  10. 如权利要求8或9所述的定位系统，其特征在于，
    所述Wi-Fi物联网设备网络的若干个一级子网主节点，能各自与所述Wi-Fi物联网设备网络的物联网中央控制单元直接通信；
    所述物联网中央控制单元进行Wi-Fi物联网设备网络的控制维护，对整个Wi-Fi物联网设备网络覆盖的物理范围内所有待定位目标设备的位置信息进行汇总、更新、追踪；
    优选地，所述物联网中央控制单元还进行以下的任意一项操作或其任意组合：
    所述物联网中央控制单元录入有待定位目标设备的MAC地址，并通过多级子网发送给Wi-Fi物联网设备网络中的所有定位监控节点；
    所述物联网中央控制单元通过多级子网，接收由待定位目标设备的传感检测模块获得的检测信息，并对所述检测信息进行监控、预警处理；所述传感检测模块对待定位目标设备自身和/或其周边进行监控采集，并将获得的检测信息包含在所述待定位目标设备的数据包中发送；
    所述物联网中央控制单元根据其从各级子网汇总得到的待定位目标设备的位置信息，生成实时定位导览信息或安全疏散路径信息，并通过各级子网提供给待定位目标设备。
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