CN110913474A - Distance fingerprint data acquisition method in indoor positioning - Google Patents
Distance fingerprint data acquisition method in indoor positioning Download PDFInfo
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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
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- 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
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- 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
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Abstract
The invention discloses a distance fingerprint data acquisition method in indoor positioning, which comprises the following steps: selecting a starting point, and establishing a local rectangular coordinate system; step two, laying reference points in a grid mode with equal step length, and recording the coordinates of the reference points in the local rectangular coordinate system; measuring and obtaining the coordinates of the nearby wireless sensor access points under the local rectangular coordinate system according to the coordinates of the reference points under the local rectangular coordinate system; calculating to obtain the geometric distance between the reference point and the nearby wireless sensor access point according to the coordinates of the reference point and the nearby wireless sensor access point under the local rectangular coordinate system; and step five, storing the geometric distance between the reference point and the nearby wireless sensor access point into a position fingerprint database. The method can accurately obtain the geometric distance between the reference point and the access point without accurately measuring the absolute coordinates of the reference point and the access point, thereby enriching the information of the position fingerprint database, improving the performance of a matching algorithm and improving the indoor positioning precision.
Description
Technical Field
The invention relates to the field of service of internet of things, indoor positioning and based on positions. In particular to a method for establishing an indoor location fingerprint database.
Background
Location fingerprinting (Fingerprint) is an important type of indoor positioning method. The basic principle is to abstract and formalize the positioning environment, describe the position information in the environment by using the Received Signal Strength Indication (RSSI) of a plurality of wireless sensor (such as WiFi, Bluetooth and the like) access points, and collect the RSSI values on the ground reference point to establish a position fingerprint Database (Database); the user matches the RSSI measured value obtained by real-time measurement with the RSSI reference value in the position fingerprint database, selects a plurality of reference points with the best similarity with the RSSI measured value, and calculates the self position coordinate by using K-Nearest Neighbor (KNN), Weighted K-Nearest Neighbor (WKNN) and other algorithms.
Because a Global Positioning System (GPS) type trilateral distance intersection Positioning model is not required, the position fingerprint method can effectively avoid the influence of errors such as Non-Line of sight (NLOS) and multipath (Multi-path) of radio signals in an indoor environment, and simultaneously avoid the problem that the absolute position coordinates of the access point of the wireless sensor are difficult to accurately measure in the indoor environment. However, the RSSI value of the ap radio signal fluctuates and the measurement error is large in a complex indoor environment, so the location fingerprinting method can only obtain the actual positioning accuracy of several meters, and the performance needs to be improved.
Research shows that if the geometric distance from the ground reference point to the nearby access point can be accurately measured, the geometric distance and the RSSI value can be jointly used as fingerprint data for storage, so that a matching algorithm is optimized, and the positioning performance is further improved. According to a general understanding, to obtain an accurate distance from a ground reference point to a nearby access point, first, an accurate measurement is required to obtain absolute position coordinates of the reference point and the access point. However, since GPS cannot be used indoors, it is not easy to accurately determine the absolute position coordinates of the reference point and the access point (whether in a relatively geodetic coordinate system or an indoor local coordinate system), which causes a huge amount of work. Therefore, in indoor positioning, it is generally difficult to practically use the above-described method having more excellent performance.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a distance fingerprint data acquisition method in indoor positioning, which can accurately measure and calculate the geometric distance between a ground reference point and a wireless sensor access point without accurately measuring absolute position coordinates of the ground reference point and the wireless sensor access point, so that the geometric distance and the RSSI value measured on the reference point are used as fingerprint data to be stored and used for subsequent processing, the performance of a matching algorithm is optimized, and the positioning accuracy is improved.
On one hand, the embodiment of the invention provides a distance fingerprint data acquisition method in indoor positioning, which comprises the following steps: selecting a certain position in or near an indoor positioning area as a starting point, and establishing a local rectangular coordinate system; secondly, arranging reference points on the ground in the positioning area in a grid mode in an equal step length mode, and sequentially calculating and recording coordinates of the reference points under the local rectangular coordinate system; measuring and obtaining the coordinates of the wireless sensor access points near the reference points under the local rectangular coordinate system according to the coordinates of one or more reference points under the local rectangular coordinate system; calculating to obtain a geometric distance between the reference point and the nearby wireless sensor access point according to the coordinates of the reference point and the nearby wireless sensor access point under the local rectangular coordinate system; and fifthly, storing the geometric distance between the reference point and the nearby wireless sensor access point into a position fingerprint database.
According to some embodiments, wherein step three further comprises: and measuring by using a laser range finder or a measuring tape to obtain the vertical height from the wireless sensor access point to the ground, so as to obtain the elevation coordinate of the wireless sensor access point under the local rectangular coordinate system.
According to some embodiments, wherein step three further comprises: and according to the projection position of the wireless sensor access point in the ground grid, utilizing the coordinates of the reference point on the grid vertex under the local rectangular coordinate system to perform interpolation calculation to obtain the plane coordinates of the wireless sensor access point under the local rectangular coordinate system.
According to some embodiments, wherein said step four further comprises: when the geometric distance between the reference point and the nearby wireless sensor access points is calculated, the number of the reference points corresponding to a certain wireless sensor access point is determined by the effective coverage range of the wireless sensor access point signals and the arrangement precision of the grid coordinates of the reference points.
According to some embodiments, wherein step five further comprises: media Access Control (MAC) addresses of nearby wireless sensor Access points and RSSI values from the reference points to the nearby wireless sensor Access points are acquired at the reference points, and the MAC addresses, the RSSI values and Euclidean distances from the reference points to the nearby wireless sensor Access points are stored in a position fingerprint database together.
The invention provides a distance fingerprint data acquisition method in indoor positioning, which uses local coordinates of ground reference points to calculate local coordinates of nearby wireless sensor access points. Since the local coordinates of the ground reference point originally need to be calibrated and recorded, the local coordinates are used for measuring and obtaining the coordinates of the nearby access points without adding too much extra workload. More importantly, the error of the position coordinates of the reference point and the position coordinates of the access point obtained by the method is common, when the geometric distance between the reference point and the access point is calculated, the common error can be eliminated, the measurement of the geometric distance is not influenced, and therefore the accurate geometric distance value between the reference point and the access point can be obtained.
Drawings
FIG. 1 is a schematic diagram of establishing an indoor local coordinate system;
FIG. 2 is a schematic diagram of laying out reference points and calculating and recording local coordinates of the reference points in accordance with the present invention;
fig. 3 is a schematic diagram of obtaining local coordinates of nearby access points from local coordinate measurements of reference points, according to the present invention.
Detailed Description
For a better understanding of the technical aspects of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings. Embodiments of the present disclosure are described in further detail below with reference to the figures and the detailed description, but the present disclosure is not limited thereto.
The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word covers the element listed after the word, and does not exclude the possibility that other elements are also covered. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
All terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
In view of the above problems in the prior art, the inventor has noticed that, unlike the conventional thinking, the geometric distance from a reference point to a nearby access point needs to be acquired without accurately determining the accurate position coordinates of the reference point and the access point; on the contrary, the local coordinates of the access points can be synchronously obtained by using the local coordinates of the reference points only through simple operation, and then the distance between the access points and the local coordinates is calculated. Although the local coordinates of the reference points are subject to errors when laying out the ground reference points (and the errors may be accumulated and transmitted, the larger the coordinate error of the reference point farther from the origin), due to the fact that the local coordinates of the access points are measured according to the local coordinates of the nearby reference points, the errors of the local coordinates of the access points are common. When the geometric distance is calculated, common errors between the two can be eliminated, so that the calculation accuracy of the geometric distance is not influenced.
In view of the above, the present invention provides a distance fingerprint data collecting method in indoor positioning, including:
selecting a certain position in or near an indoor positioning area as a starting point, and establishing a local rectangular coordinate system;
secondly, arranging reference points on the ground in the positioning area in a grid mode in an equal step length mode, and sequentially calculating and recording coordinates of the reference points under the local rectangular coordinate system;
measuring and obtaining the coordinates of the wireless sensor access points near the reference points under the local rectangular coordinate system according to the coordinates of one or more reference points under the local rectangular coordinate system;
calculating to obtain a geometric distance between the reference point and the nearby wireless sensor access point according to the coordinates of the reference point and the nearby wireless sensor access point under the local rectangular coordinate system;
and fifthly, storing the geometric distance between the reference point and the nearby wireless sensor access point into a position fingerprint database.
In the first step, a set of coordinate reference bases for positioning and navigation is established mainly indoors where GPS signals cannot be normally received and used. The coordinate reference is formed by the origin of coordinatesOAnd coordinate axes pointing to a common definition. Origin pointOCan select a proper position point in the indoor area to play the role, and can further use the origin pointOIn the direction of the perpendicularZThe axis (pointing to the zenith is positive) and the meridian direction isXThe axis (pointing north is positive),Yshaft andX、Zthe left-hand rectangular coordinate system is established with the axis vertical (pointing to the east as positive) ((X、YThe rectangular plane coordinate system of the shaft components is consistent with the rectangular plane coordinate system in the measurement science). The local coordinate system thus established actually belongs to a perpendicular standing center rectangular coordinate system.
At the origin of a known local coordinate systemOIn the case of geodetic coordinates of (2), a conversion relationship between the indoor local coordinate system and the outdoor geodetic coordinate system may be established. In this case, the local area can also beOrigin of coordinate systemOSelecting a place which can normally receive and use GPS signals to carry out positioning at a place outside a window or nearby to conveniently and directly measure and obtain the origin of a local coordinate systemOThe geodetic coordinates of (a). Specifically, if the origin of coordinates is knownOCoordinates of earth's center
And latitude and longitude of geodetic coordinates
Then any point in spacePIn a manner thatOCoordinates in a local coordinate system as origin
Comprises the following steps:
wherein,
is a pointPThe geocentric coordinates of (a). Otherwise, if the point is knownPIn a manner thatOCoordinates in a local coordinate system as origin
Then point ofPCoordinates of earth's center
Comprises the following steps:
therefore, the conversion relation between the indoor local coordinate system and the outdoor geodetic coordinate system can be conveniently established.
In the second step, reference points are arranged on the ground of the positioning area in a grid mode in equal step length, and each reference point in the local rectangular seats is calculated and recorded in sequenceCoordinates under the standard system. As shown in figure 2 of the specification, origin of coordinatesOAnd is also typically the starting point for the ground reference point layout. Usually, the reference points are arranged in equal step length in a square grid mode, and the step length is set according to the required positioning precisionlDifferent values may be taken. Recording originOThe local area coordinate of the plane is (0, 0), then the reference point
Local area coordinates of plane
Comprises the following steps:
in actual work, tools and instruments such as a tape measure and a laser range finder are generally used for measuring the step length and laying reference points. However, whatever means is used, the measurement and operation precision is limited, and errors are brought to local coordinates of the reference points. The method has loose precision requirement on the local coordinates of the reference points and allows the local coordinates to have larger errors, so that a fingerprint database data acquisition personnel can use simpler tools and modes to measure and lay the reference points more quickly.
In the third step, the local coordinates of the peripheral access points are obtained by using the local coordinates of the reference points, which can be specifically divided into the acquisition of an elevation local coordinate and a plane local coordinate. As shown in fig. 3 for the access pointSLocal coordinates of elevation
The measuring instrument can be obtained by measuring with a laser range finder, a measuring tape or a plumb line and other tools; for access pointSLocal area plane coordinates of
The local area coordinate of a plurality of reference points on the vertex of the grid can be obtained by interpolation calculation according to the projection position of the grid on the ground. Specifically, if the access pointSGround projection of
4 vertexes away from the lattice point
、
、
And
are respectively at a distance of
、
、
And
the local area plane coordinates of the 4 vertexes are respectively
、
、
And
then an acquisition access pointSLocal area plane coordinates of
Simple interpolation ofThe method comprises the following steps:
thereby, the access point can be comprehensively obtainedSThree-dimensional local coordinates of
。
In the fourth step, after the local coordinates of the access point are obtained according to the local coordinates of the reference point, the geometric distance between the access point and the reference point can be calculated. The above access pointS4 vertices to grid points
、
、
And
geometric distance of
、
、
And
respectively as follows:
in theory, although all reference points to all reference points in the indoor positioning area can be obtained in the above mannerThe geometric distances between access points are stored as fingerprint data, but this is not generally recommended. This is due to the local coordinates of the respective reference points being from the originOAnd the sequential layout and calculation are started, so that the local coordinate error of the reference point can be transmitted and amplified due to the existence of the measurement error. Theoretically, the farther away from the origin of calculationOThe larger the error the local coordinates of the reference point may have. Therefore, when a reference point and an access point are far away from each other, the geometric distance error calculated in the above manner may be too large to be used as fingerprint data storage. Specifically, the number of the geometric distance values of the reference points corresponding to a certain access point is determined by the effective coverage area of the adopted wireless sensor access point signals and the arrangement precision of the grid coordinates of the reference points. When the effective coverage range of the wireless sensor is relatively large and the distribution precision of the grid coordinates of the reference points is relatively high, the geometric distance value between the wireless sensor and more nearby access points can be calculated on each reference point and stored; conversely, the number of geometric distance values from each reference point to nearby access points should be reduced.
And in the fifth step, storing the acquired geometric distance between the reference point and the access point into a fingerprint database for subsequent processing. Although fingerprint matching location of a user position can be realized by only utilizing geometric distance fingerprint information, most algorithms need to combine geometric distance fingerprint data with traditional RSSI fingerprint data to obtain significantly better location performance. Therefore, in order to fully exert the function of the geometric distance fingerprint data, the geometric distance fingerprint data and information such as the access point MAC address and the RSSI value acquired at the reference point are often stored in the position fingerprint database together and provided for a subsequent matching algorithm to use.
By using the distance fingerprint data acquisition method in indoor positioning provided by the invention, the local coordinates of nearby access points are obtained by using the local coordinate measurement of the ground reference point, and the geometric distance between the two is further obtained by using the local coordinates of the two. The method has the main advantages that firstly, local coordinates of nearby access points can be easily measured and obtained by using the local coordinates of the ground reference points, and not too much workload is additionally increased; and secondly, the error between the obtained local coordinate of the reference point and the local coordinate of the access point is public, and the calculation of the geometric distance between the local coordinate of the reference point and the local coordinate of the access point is not influenced, so that the accurate geometric distance between the local coordinate of the reference point and the local coordinate of the access point can be calculated under the condition that both the local coordinate of the reference point and the local coordinate of the access point have errors (even larger errors). Therefore, the problem that distance fingerprint data information is difficult to acquire efficiently and accurately in the current indoor position fingerprint positioning is effectively solved, the performance of a matching algorithm is optimized, and the indoor positioning precision is improved.
While the embodiments of the present invention have been described in detail, the present invention is not limited to these specific embodiments, and those skilled in the art can make various modifications and modifications of the embodiments based on the concept of the present invention, which fall within the scope of the present invention as claimed.
Claims (5)
1. A method of range fingerprint data acquisition in indoor positioning, the method comprising:
selecting a certain position in or near an indoor positioning area as a starting point, and establishing a local rectangular coordinate system;
secondly, arranging reference points on the ground in the positioning area in a grid mode in an equal step length mode, and sequentially calculating and recording coordinates of the reference points under the local rectangular coordinate system;
measuring and obtaining the coordinates of the wireless sensor access points near the reference points under the local rectangular coordinate system according to the coordinates of one or more reference points under the local rectangular coordinate system;
calculating to obtain a geometric distance between the reference point and the nearby wireless sensor access point according to the coordinates of the reference point and the nearby wireless sensor access point under the local rectangular coordinate system;
and fifthly, storing the geometric distance between the reference point and the nearby wireless sensor access point into a position fingerprint database.
2. The method for collecting distance fingerprint data in indoor location according to claim 1, wherein said step three further comprises:
and measuring by using a laser range finder or a measuring tape to obtain the vertical height from the wireless sensor access point to the ground, so as to obtain the elevation coordinate of the wireless sensor access point under the local rectangular coordinate system.
3. The method for collecting distance fingerprint data in indoor location according to claim 1, wherein said step three further comprises:
and according to the projection position of the wireless sensor access point in the ground grid, utilizing the coordinates of the reference point on the grid vertex under the local rectangular coordinate system to perform interpolation calculation to obtain the plane coordinates of the wireless sensor access point under the local rectangular coordinate system.
4. The method for distance fingerprint data collection in indoor location according to claim 1, wherein said step four further comprises:
when the geometric distance between the reference point and the nearby wireless sensor access points is calculated, the number of the reference points corresponding to a certain wireless sensor access point is determined by the effective coverage range of the wireless sensor access point signals and the arrangement precision of the grid coordinates of the reference points.
5. The method for distance fingerprint data collection in indoor location according to claim 1, wherein said step five further comprises:
and acquiring the MAC address of a nearby wireless sensor access point and the RSSI value from the reference point to the nearby wireless sensor access point, and storing the MAC address, the RSSI value and the Euclidean distance from the reference point to the nearby wireless sensor access point into a position fingerprint database.
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Cited By (2)
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| CN112996110A (en) * | 2021-04-25 | 2021-06-18 | 刘成 | RSSI position fingerprint positioning method based on chain transfer constraint |
| CN114353803A (en) * | 2022-01-04 | 2022-04-15 | 刘成 | Indoor and outdoor positioning coordinate reference frame conversion method |
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