CN110856106A - Indoor high-precision three-dimensional positioning method based on UWB and barometer - Google Patents

Indoor high-precision three-dimensional positioning method based on UWB and barometer Download PDF

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CN110856106A
CN110856106A CN201911141192.7A CN201911141192A CN110856106A CN 110856106 A CN110856106 A CN 110856106A CN 201911141192 A CN201911141192 A CN 201911141192A CN 110856106 A CN110856106 A CN 110856106A
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base station
node
module
label
barometer
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CN110856106B (en
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刘期烈
丁升
洪婷
万志鹏
周文敏
何黄金
白逸轩
翁耀城
杨丰帆
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Chongqing University of Post and Telecommunications
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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
    • H04W4/021—Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
    • G01C5/06—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels by using barometric means
    • 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
    • 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

Abstract

The invention relates to the technical field of radio technology and indoor positioning, in particular to an NLOS (non line of sight) base station identification and indoor three-dimensional positioning system and method based on UWB (ultra wide band), wherein the system comprises a label node with unknown position, at least four base station nodes with known positions and an upper computer positioning terminal, each base station node at least comprises a main base station node and three auxiliary base station nodes, a label node module is installed on each label node, a main base station module is installed on each main base station, an auxiliary base station module is installed on each auxiliary base station, and each label node module comprises an ultra wide band transmitting and receiving module, a main control module, a vibration sensor module, a crystal oscillator circuit, a barometer module, a reset circuit and a power supply module which are connected with the; the NLOS base station identification method provided by the invention reduces errors generated by NLOS transmission to a large extent, so that the final ranging value is very close to a true value.

Description

Indoor high-precision three-dimensional positioning method based on UWB and barometer
Technical Field
The invention relates to the technical field of radio technology and indoor positioning, in particular to an indoor high-precision three-dimensional positioning system and method based on Ultra Wide Band (UWB) and barometers.
Background
In a wireless Positioning System, a Global Positioning System (GPS) has been widely used, the technology is quite mature, the coverage area is wide, the accuracy is high, the real-time performance is good, the outdoor Positioning accuracy can reach about ten meters, and the outdoor Positioning requirement is well met in an outdoor open environment. However, with the advance of modern construction of society, most people live and work in indoor environments such as high-rise buildings, positioning signals are seriously weakened due to shielding of buildings and generation of multipath effects, and positioning of the indoor environments cannot be carried out. The current indoor positioning technology plays more and more important roles in aspects such as superstores, fire-fighting, nursing homes, safety monitoring and the like.
The indoor positioning technology makes up the defect that the GPS cannot be used for indoor environment positioning because the signal is shielded by the building, and expands the positioning service from the outdoor space to the internal space of the building. Various indoor positioning technologies, such as indoor GPS positioning, bluetooth positioning, WIFI positioning, ultrasonic positioning, radio frequency positioning, infrared positioning, etc., are available at present, and various positioning technologies not only cause different positioning performances due to the characteristics of their own communication technologies, but also cause serious reduction in positioning accuracy due to non-line-of-sight (NLOS) transmission. In recent years, due to popularization of WIFI and low cost of WIFI, the WIFI positioning technology is developed rapidly, but the safety problem is more and more prominent, and not only is the anti-interference problem and the positioning accuracy not ideal.
In the existing wireless communication technology, ultra-wideband (UWB) signals have the advantages of high transmission rate, low power consumption, strong penetrability and anti-interference capability, and the like, so that when the technology is applied to a wireless positioning system, the technology has the advantage that other positioning technologies cannot exceed positioning accuracy, for example, the unique communication mechanism of the UWB positioning system can enable the positioning accuracy to reach centimeter level, and the UWB signals are not easily intercepted due to extremely low power consumption, so that the safety of signal transmission is improved, and in addition, the pulse has extremely low power spectral density, so that the system has extremely high time resolution and good anti-multipath capability. In summary, the UWB signal has many advantages, so that it is applied to the fields of indoor communication, position location, high-speed wireless local area network, radar, and the like, and most importantly, the communication technology can provide a solution with low complexity and high reliability for indoor accurate location.
At present, most UWB indoor positioning technology researches mainly focus on mobile node two-dimensional position resolving and positioning accuracy improvement, complexity of specific application scenarios is ignored, an actual indoor environment is often a mixed environment of LOS and NLOS rather than a single LOS or NLOS environment, and accordingly positioning accuracy is seriously affected. Several existing classical positioning algorithms, such as the time-based TOA/TDOA ranging method, have high requirements on the synchronization of devices, which results in increased complexity of the system. These factors hinder the popularization of the UWB positioning technology in practical applications, and therefore, the research on the high-precision positioning technology based on the UWB technology in a complex environment has a wide application prospect and a high practical value.
Disclosure of Invention
In order to obtain high-precision position information under the mixed environment of LOS and NLOS, the invention provides an indoor high-precision three-dimensional positioning system and method based on UWB and barometer, wherein the system comprises a label node with unknown position, at least four base station nodes with known positions and an upper computer positioning terminal, the base station nodes at least comprise a main base station node and three auxiliary base station nodes, the label node is provided with a label node module, the main base station is provided with a main base station module, the auxiliary base stations are provided with auxiliary base station modules, and the label node module comprises an ultra-wideband transmitting and receiving module, a main control module, a vibration sensor module, a crystal oscillator circuit, a barometer module, a reset circuit and a power supply module, wherein the vibration sensor module, the crystal oscillator circuit, the barometer module; the main base station module comprises an ultra-wideband transmitting and receiving module, a main control module, a WiFi module, a crystal oscillator circuit, a power supply module, a reset circuit and a barometer module, wherein the WiFi module, the crystal oscillator circuit, the power supply module, the reset circuit and the barometer module are connected with the main control module; the auxiliary base station module comprises an ultra-wideband transmitting and receiving module, a main control module, a crystal oscillator circuit, a reset circuit and a power module, wherein the crystal oscillator circuit, the reset circuit and the power module are connected with the main control module; wherein:
the ultra-wideband transmitting and receiving module is connected with the main control module through the SPI and is used for transmitting and receiving ultra-wideband signals;
the vibration sensor module is connected with the main control module through the I/O port and used for realizing the functions of awakening and sleeping the label node
The crystal oscillator circuit provides a clock signal for the master control system;
the barometer module is communicated with the main control module through I2C and is used for measuring the height difference between the base stations in real time;
the reset circuit is used for resetting the main control module to enter an initial condition;
the power module is used for providing power for the main control module.
The invention provides an indoor high-precision three-dimensional positioning method based on UWB and barometer, which is used for positioning in an indoor high-precision three-dimensional positioning system based on UWB and barometer under the mixed environment of line-of-sight communication and non-line-of-sight communication between base stations by the following steps, and comprises the following steps:
s1, correcting the positioning system before positioning;
s2, calculating the height difference between the main base station node and the label node by adopting a differential air pressure method, and taking the height difference as a height reference value;
s3, adopting a symmetrical bilateral two-way ranging algorithm to calculate the distances between the label node to be measured and the four base station nodes in real time, and simultaneously calculating the distance values between the base station nodes in real time in the last time slots of the ranging period;
s4, grouping the base stations, wherein each group takes 3 base stations, and the base stations have
Figure BDA0002280986920000031
Group, N is the number of base stations, C represents the operation of the combination number;
s5, calculating the real-time measuring height of each group by using a euler tetrahedron volume formula and a volume formula of a trigonal pyramid;
s6, screening out a value closest to a height reference value from the real-time measurement heights of each group, and taking three base stations corresponding to the value as reference base stations for measuring the label node to be measured;
s7, obtaining distance values calculated by the three reference base stations and the label nodes and distance values among the base station nodes;
s8, correcting the measured value in real time by adopting an enhanced pseudo-range differential method;
s9, transmitting the corrected measured value to an upper computer positioning terminal through a WIFI module on the main base station node by adopting a UDP (user Datagram protocol) protocol;
and S10, reducing the three-dimensional coordinates into two-dimensional coordinates for resolving according to the obtained distance measurement value and the height value measured by the barometer, and performing real-time position estimation on the to-be-detected label node by adopting a classical weighted least square positioning algorithm.
Further, calibrating the positioning system prior to positioning includes:
s11, confirming that the label node and the four base station nodes cannot be located on the same horizontal plane, wherein the four base station nodes must be located on the same horizontal plane, and the arrangement height of the base station nodes needs to be more than 1.5 meters;
s12, carrying out air pressure calibration on the label node and the barometer modules of the four base station nodes;
and S13, reading the air pressure values of the respective barometer modules in real time by the tag node and the main base station node, and smoothing the air pressure values by using Kalman filtering.
Further, the real-time correction of the measured value by using the enhanced pseudo-range differential method comprises:
s81, if the real distance between the base station i and the base station j is dijAnd a symmetric bilateral two-way distance measurement algorithm is adopted to calculate the distance measurement value between the base station i and the base station j in real time
Figure BDA0002280986920000042
S82, calculating an offset between the base station and the base station node, which is expressed as:
s83, respectively carrying out k iterations on the offset between two base station nodes, and respectively taking k groups
Figure BDA0002280986920000043
S84, finally, averaging all the offsets, which is expressed as
Figure BDA0002280986920000044
S85, useAnd (3) correcting the distance from the label node to the base station node in real time:
Figure BDA0002280986920000045
wherein r isiFor the corrected distance value between the label node and the base station node, ri cTo correct forMeasuring the distance between the previous label node and the base station node; n is the number of the base stations,
Figure BDA0002280986920000047
is the total number of distances between the N base stations,
Figure BDA0002280986920000049
distance measurement between nth base station and base station, dijnThe true distance between the nth base station and the base station; Δ dnkIndicating that the nth type offset is measured by k;representing the average of k offsets.
Further, step S10 specifically includes the following steps:
s101, if the distance between the label node and the base station node is ri, the horizontal distance li projected on a plane is represented as:
s102, establishing a two-dimensional coordinate equation of the label by using a two-dimensional weighted least square positioning algorithm, wherein the equation is expressed as:
s103, obtaining a two-dimensional coordinate of the to-be-detected label according to a weighted least square algorithm, and performing real-time position estimation on the to-be-detected label node by adopting a classic weighted least square positioning algorithm, wherein the expression is as follows:
Figure BDA0002280986920000053
wherein, (x.y) represents the location coordinates of the tag node; (x)0,y0)、(x1,y1)、(x2,y2) Is the coordinate of three secondary base stations, z1Δ H is the height value of the main base station, and Δ H is the height difference measured in real time.
The method for identifying the NLOS base station reduces errors generated by NLOS transmission to a large extent, and secondarily corrects the ranging value through the proposed enhanced pseudo-range difference method, so that the final ranging value is very close to a true value, and the position of the label node can be estimated by using a common weighted least square positioning algorithm.
Drawings
FIG. 1 is a flow chart of an indoor high-precision three-dimensional positioning method based on UWB and barometer of the invention;
FIG. 2 is a diagram of the architecture of a UWB high-precision three-dimensional positioning system of the present invention;
FIG. 3 is a schematic diagram illustrating a symmetric bidirectional bilateral ranging principle in an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating a deployment of a tag node and four base station locations in an application example according to an embodiment of the present invention;
FIG. 5 is a schematic space diagram of a tag node position solution principle in the embodiment of the present invention;
FIG. 6 is a block diagram of a tag node in an embodiment of the present invention;
FIG. 7 is a block diagram of a master base station node in an embodiment of the present invention;
fig. 8 is a block diagram of a secondary base station node in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides an indoor high-precision three-dimensional positioning system based on UWB and barometers, as shown in FIG. 2, the system comprises tag nodes with unknown positions, at least four base station nodes with known positions and an upper computer positioning terminal, wherein the base station nodes at least comprise a main base station node and three auxiliary base station nodes, the tag nodes are provided with tag node modules, the main base station is provided with a main base station module, the auxiliary base stations are provided with auxiliary base station modules, UWB communication technology is adopted between the base station nodes and the tag nodes, the main base station node transmits all measurement data to a background server for storage through WIFI communication, and then the upper computer positioning terminal acquires the data from a database and carries out position calculation;
fig. 6 to 8 are diagrams showing the block composition of the label node, the primary base station node, and the secondary base station node of the system, respectively, and mainly include a minimum system of STM32 for controlling the operation of other blocks; and the UWB signal transceiving module is used for transmitting and receiving UWB signals. It should be noted that only the master base station node includes the WIFI module, which is used to collect all data and upload the data to the server; only the main base station node and the label node comprise barometer modules for measuring the height difference in real time; only the label node comprises a vibration sensor and is used for realizing the functions of awakening and sleeping the label node and reducing the power consumption;
as shown in fig. 6, the tag node module includes an ultra-wideband transmitting and receiving module, a main control module, and a vibration sensor module, a crystal oscillator circuit, a barometer module, a reset circuit, and a power module connected to the main control module; as shown in fig. 7, the master base station module includes an ultra-wideband transmitting and receiving module, a master control module, and a WiFi module, a crystal oscillator circuit, a power module, a reset circuit, and a barometer module connected to the master control module; as shown in fig. 8, the auxiliary base station module includes an ultra-wideband transmitting and receiving module, a main control module, and a crystal oscillator circuit, a reset circuit and a power module connected to the main control module; wherein:
the ultra-wideband transmitting and receiving module is connected with the main control module through the SPI and is used for transmitting and receiving ultra-wideband signals;
the vibration sensor module is connected with the main control module through the I/O port and used for realizing the functions of awakening and sleeping the label node
The crystal oscillator circuit provides a clock signal for the master control system;
the barometer module is communicated with the main control module through I2C and is used for measuring the height difference between the base stations in real time;
the reset circuit is used for resetting the main control module to enter an initial condition;
the power module is used for providing power for the main control module.
The invention also provides an indoor high-precision three-dimensional positioning method based on UWB and barometer, which is based on UWB and barometer, and carries out positioning by the following steps under the mixed environment of line-of-sight communication and non-line-of-sight communication between base stations, and comprises the following steps:
s1, correcting the positioning system before positioning;
s2, calculating the height difference between the main base station node and the label node by adopting a differential air pressure method, and taking the height difference as a height reference value;
s3, adopting a symmetrical bilateral two-way ranging algorithm to calculate the distances between the label node to be measured and the four base station nodes in real time, and simultaneously calculating the distance values between the base station nodes in real time in the last time slots of the ranging period;
s4, grouping the base stations, wherein each group takes 3 base stations, and the base stations have
Figure BDA0002280986920000071
Group, N is the number of base stations, C represents the operation of the combination number;
s5, calculating the real-time measuring height of each group by using a euler tetrahedron volume formula and a volume formula of a trigonal pyramid;
s6, screening out a value closest to a height reference value from the real-time measurement heights of each group, and taking three base stations corresponding to the value as reference base stations for measuring the label node to be measured;
s7, obtaining distance values calculated by the three reference base stations and the label nodes and distance values among the base station nodes;
s8, correcting the measured value in real time by adopting an enhanced pseudo-range differential method;
s9, transmitting the corrected measured value to an upper computer positioning terminal through a WIFI module on the main base station node by adopting a UDP (user Datagram protocol) protocol;
and S10, reducing the three-dimensional coordinates into two-dimensional coordinates for resolving according to the obtained distance measurement value and the height value measured by the barometer, and performing real-time position estimation on the to-be-detected label node by adopting a classical weighted least square positioning algorithm.
In this embodiment, the positioning system needs to be corrected before positioning, that is, before the system is positioned, it needs to be confirmed that the tag node and the four base station nodes cannot be located on the same horizontal plane, the four base station nodes must be located on the same horizontal plane, and the arrangement height of the base station nodes needs to be more than 1.5 meters, so as to ensure that LOS exists between all the base station nodes;
before the system is positioned, the barometer modules of the tag node and the master base station node need to be subjected to barometric calibration, and mainly errors caused by electrical differences among the barometers are reduced;
the barometer modules need to be calibrated, mainly because different modules have certain electrical differences, therefore, the height values measured by different barometers under the same condition have certain difference, the error causes the entry and exit of the barometers at the level of two meters, the normal use of the barometers is seriously influenced, therefore, calibration is needed before use, the main base station node and the tag node are placed at the same height under the same environment, meanwhile, collecting the air pressure value data of the main base station node and the label node within 10s, calculating the arithmetic mean difference of the air pressure of the main base station node and the label node as a deviation value, calibrating the barometer module of the label node by the deviation value, that is, the real-time measured air pressure value plus the deviation value is taken as the calibrated air pressure value, and the deviation value of the air pressure of the main base station node and the tag node is expressed as follows:
Figure BDA0002280986920000081
where Δ h represents the arithmetic mean pressure error value between the two, N1And N2Indicating barometer modules on the master base station node and the tag node, respectivelyThe number of data P respectively collected during the periodA(i) And PT(j) Respectively representing the air pressure values acquired by the master base station node and the label node at the ith moment and the jth moment;
before the system is positioned, the tag node and the main base station node need to read the air pressure values of the respective barometer modules in real time, and the air pressure values are smoothed by Kalman filtering.
After the system is corrected, positioning is started, and when the system starts to be positioned, the height difference between the master base station node and the label node is obtained by adopting a differential air pressure method, and the height difference is used as a height reference value delta H which can be obtained along with environment self-adaptive calculation, so that the dependence on prior information of different scenes is reduced;
the air pressure value that single barometer gathered all probably changes at different moments, but under same environment, the air pressure difference that two barometers obtained is comparatively stable, can convert the air pressure difference into the difference in height through the high formula of laplace pressure, shows as:
Figure BDA0002280986920000091
where H is the height of the tag node measured at that time, H1Is the height of the master base station node measured at that time, T is the average temperature between the master base station node and the tag node, P1The measured air pressure value of the main base station node is P, and the measured air pressure value of the label node is P.
The height difference Δ H between the master base station node and the tag node is represented as:
Figure BDA0002280986920000092
the method adopts SDS-TWR (symmetric bilateral two-way ranging algorithm) to calculate the distance between the label node to be measured and four base station nodes in real time, and simultaneously calculates the distance value between the base station nodes in real time in the last time slots of the ranging period. Fig. 3 is a schematic diagram of the whole ranging process of the algorithm, which mainly includes the following steps:
s31, the label node sends a first message to the base station node at the time of T1, and the base station node receives the message at the time of T2;
s32, the base station node sends a second message back to the label node at the time of T3, and the label node receives the message at the time of T4;
s33, the label node sends a third message to the base station node at the time of T5, and the base station node receives the message at the time of T6;
s34, calculating the time of flight TOF between the label node and the base station node and the distance between the label node and the base station node according to the obtained time information, wherein the calculation is represented as follows:
Figure BDA0002280986920000093
S＝c×TOF；
wherein R isaThe total time taken for the tag node to begin sending the first message to receive the second message; rbA total time taken for the base station node to start sending the second message to receive the third message; daThe total time taken for the base station node to receive the first message and to send out the second message; dbThe total time taken for the tag node to receive the second message and to send out a third message; and c is the propagation velocity of the electromagnetic wave.
Grouping base stations, each group taking 3 base stations, having a total
Figure BDA0002280986920000104
Group, N is the number of base stations;
for each group, a real-time height H can be calculated from a formula derived from the Euler tetrahedral volume formula and the trigonal pyramid volume formulaiWherein
Comparison of Δ H and H, respectivelyiFind all H according to the magnitude relation ofiIn the value closest to Δ H, when H isiThe three base stations in the corresponding group can be used as reference base stations for measuring the label node to be measured next, the three base station nodes with the minimum NLOS influence are identified through the method, and the distance values calculated by the three identified base station nodes and the label node and the distance values between the base station nodes are obtained to participate in the next processing;
an NLOS base station identification method based on UWB fusion barometer, as shown in fig. 4, base station nodes are (x) respectivelyi,yi,zi) I is 0,1,2,3, and coordinates of the tag node are defined as (x, y, z), since the location of the base station node is known and LOS communication is performed, the true distance between any two base station nodes can be obtained:
Figure BDA0002280986920000101
the formula derivation is performed using the schematic shown in FIG. 5, r1,r2,r3,d01,d02,d12The 6 sides of the triangular pyramid are respectively shown in the figure, and the volume formula of the euler tetrahedron is as follows:
Figure BDA0002280986920000102
volume formula of triangular pyramid:
Figure BDA0002280986920000103
wherein S is a triangular plane formed by the nodes of the base stations A0, A1 and A2, and HiIs the height of a triangular pyramid.
The area of the triangular plane can be calculated using the Helen formula:
Figure BDA0002280986920000111
in the formula
Figure BDA0002280986920000112
From the above equation:
Figure BDA0002280986920000113
h calculated at this timeiAnd the height values of any other three base stations as a plane triangle can be calculated in real time in sequence, and then are compared with the reference height value delta H, and the base station combination closest to the delta H is found out to be used for the next operation. The reason why the comparison is possible is that if a certain base station is NLOS communication, the actually measured distance value becomes large, so that all errors are accumulated to the height under the condition that the base area is not changed, and the calculated height value is larger than the actual value, so that three base stations with the least influence of NLOS can be found as the reference base stations of the next step.
In the invention, one application example needs at least one label node and four base station nodes, and when the number of N is more, all LOS base stations can be found as far as possible to participate in ranging calculation, so that the influence caused by NLOS transmission can be eliminated.
Because LOS communication is carried out between the base stations, in order to further reduce errors such as multipath interference, measurement errors, hardware errors and the like among the distance values, the measurement values are corrected in real time by adopting an enhanced pseudo-range differential method which is innovatively proposed; for a traditional differential correction positioning algorithm, a nearest base station node needs to be found near a to-be-detected label node to serve as a differential reference node, and then the positioning coordinates of the to-be-detected label node are corrected by positioning the differential reference node through other reference nodes. But only one differential reference node is selected
The decision right for coordinate correction of the node to be detected is too large, and a reference node closest to the node to be detected needs to be selected, which is generally not easy to meet under the actual condition.
The invention provides an innovative enhanced pseudo-range differential method by utilizing the conditions that base station nodes are all in the LOS condition, the positions of the base station nodes are all known and the like, and the method mainly comprises the following steps:
s81, if the real distance between the base station i and the base station j is dijAnd a symmetric bilateral two-way distance measurement algorithm is adopted to calculate the distance measurement value between the base station i and the base station j in real time
Figure BDA0002280986920000121
S82, calculating an offset between the base station and the base station node, which is expressed as:
Figure BDA0002280986920000122
s83, respectively carrying out k iterations on the offset between two base station nodes, and respectively taking k groups
Figure BDA0002280986920000123
S84, finally, averaging all the offsets, which is expressed as
Figure BDA0002280986920000124
S85, use
Figure BDA0002280986920000125
And (3) correcting the distance from the label node to the base station node in real time:
Figure BDA0002280986920000126
wherein r isiFor the corrected distance value between the label node and the base station node, ri cThe distance measurement value between the label node and the base station node before correction is obtained; n is the number of the base stations,
Figure BDA0002280986920000127
is the total number of distances between the N base stations,
Figure BDA0002280986920000128
distance measurement between nth base station and base station, dijnThe true distance between the nth base station and the base station; Δ dnkIndicating that the nth type offset is measured by k;
Figure BDA0002280986920000129
representing the average of k offsets.
When the total number of distances between N base stations is 4, for example, it means that there are four base stations in total, and the distances between the base stations include 6 distances between base stations 1 and 2, base stations 1 and 3, base stations 1 and 4, base stations 2 and 3, base stations 2 and 4, and base stations 3 and 4; dijnIs the real distance between the nth base station and the base station, and the value of n is
Figure BDA00022809869200001211
I.e. n represents one of the 6 distances; Δ dnkRepresenting the n-th type of offset by k, e.g. Δ dn1Indicating that the 1 st offset takes k, i.e. the data between base station 1 and base station 2 takes k, Δ dn2It is indicated that the 2 nd offset takes k, that is, the data between the base station 1 and the base station 3 takes k, and so on.
And collecting all the corrected distance measurement values to a main base station node, and then transmitting data to an upper computer positioning terminal by adopting a UDP (user Datagram protocol) through a WIFI (wireless fidelity) module on the main base station node.
Reducing the three-dimensional coordinate into a two-dimensional coordinate for resolving according to the obtained distance measurement value and the height value measured by the barometer, and then estimating the position of the to-be-detected label node in real time by adopting a classic weighted least square positioning algorithm, wherein the distance value r between the label node and the base station nodeiAnd i is 1,2,3, and the horizontal distance projected on the plane is:
Figure BDA0002280986920000131
wherein Δ H is the height difference measured by the barometer in step 4). r isiThe distance value between the label node and the base station node after being corrected in the step 9).
Now that the three-dimensional space is reduced to a two-dimensional plane, the two-dimensional coordinates of the tag can be estimated by using a two-dimensional weighted least squares positioning algorithm, and the following nonlinear equation is established according to the relationship between the distance and the coordinates:
Figure BDA0002280986920000132
and subtracting the third row from the first row and the second row of the equation set respectively and rewriting the result into a matrix form to obtain:
Figure BDA0002280986920000133
wherein the content of the first and second substances,
Figure BDA0002280986920000134
constructing the above matrix form into a linear system of equations:
Y＝AX
wherein the content of the first and second substances,
Figure BDA0002280986920000135
the solution for X can be found from a weighted least squares algorithm as:
XWLS＝(ATWA)-1ATWY
w is a weighted weight, and the weighting method adopted here is that W is the reciprocal of the ranging noise variance, so that the contribution of data with larger ranging results to positioning can be ensured to be small.
And finally, obtaining the three-dimensional estimation position of the to-be-detected label as follows:
Figure BDA0002280986920000136
namely, it is
Figure BDA0002280986920000137
Wherein z is1Δ H is the height value of the main base station, and Δ H is the height difference measured in real time.
In the embodiment, by constructing a spatial coordinate system, and according to the spatial relationship, the WLS is solved to have two position coordinates, one of which is reasonably selected as the position estimation coordinate.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (9)

1. An indoor high-precision three-dimensional positioning system based on UWB and barometer comprises a label node with unknown position, at least four base station nodes with known positions and an upper computer positioning terminal, wherein the base station nodes at least comprise a main base station node and three auxiliary base station nodes; the main base station module comprises an ultra-wideband transmitting and receiving module, a main control module, a WiFi module, a crystal oscillator circuit, a power supply module, a reset circuit and a barometer module, wherein the WiFi module, the crystal oscillator circuit, the power supply module, the reset circuit and the barometer module are connected with the main control module; the auxiliary base station module comprises an ultra-wideband transmitting and receiving module, a main control module, a crystal oscillator circuit, a reset circuit and a power module, wherein the crystal oscillator circuit, the reset circuit and the power module are connected with the main control module; wherein:
the ultra-wideband transmitting and receiving module is connected with the main control module through the SPI and is used for transmitting and receiving ultra-wideband signals;
the vibration sensor module is connected with the main control module through the I/O port and used for realizing the functions of awakening and sleeping the label node
The crystal oscillator circuit provides a clock signal for the master control system;
the barometer module is communicated with the main control module through I2C and is used for measuring the height difference between the base stations in real time;
the reset circuit is used for resetting the main control module to enter an initial condition;
the power module is used for providing power for the main control module.
2. An indoor high-precision three-dimensional positioning method based on UWB and barometer is characterized in that in an indoor high-precision three-dimensional positioning system based on UWB and barometer, under the mixed environment of line-of-sight communication and non-line-of-sight communication between base stations, positioning is carried out through the following steps, including:
s1, correcting the positioning system before positioning;
s2, calculating the height difference between the main base station node and the label node by adopting a differential air pressure method, and taking the height difference as a height reference value;
s3, adopting a symmetrical bilateral two-way ranging algorithm to calculate the distances between the label node to be measured and the four base station nodes in real time, and simultaneously calculating the distance values between the base station nodes in real time in the last time slots of the ranging period;
s4, grouping the base stations, wherein each group takes 3 base stations, and has C3NGroup, N is the number of base stations, C represents the operation of the combination number;
s5, calculating the real-time measuring height of each group by using a euler tetrahedron volume formula and a volume formula of a trigonal pyramid;
s6, screening out a value closest to a height reference value from the real-time measurement heights of each group, and taking three base stations corresponding to the value as reference base stations for measuring the label node to be measured;
s7, obtaining distance values calculated by the three reference base stations and the label nodes and distance values among the base station nodes;
s8, correcting the measured value in real time by adopting an enhanced pseudo-range differential method;
s9, transmitting the corrected measured value to an upper computer positioning terminal through a WIFI module on the main base station node by adopting a UDP (user Datagram protocol) protocol;
and S10, reducing the three-dimensional coordinates into two-dimensional coordinates for resolving according to the obtained distance measurement value and the height value measured by the barometer, and performing real-time position estimation on the to-be-detected label node by adopting a classical weighted least square positioning algorithm.
3. The UWB and barometer based indoor high precision three dimensional positioning method of claim 1, wherein the correcting the positioning system before positioning comprises:
s11, confirming that the label node and the four base station nodes cannot be located on the same horizontal plane, wherein the four base station nodes must be located on the same horizontal plane, and the arrangement height of the base station nodes needs to be more than 1.5 meters;
s12, carrying out air pressure calibration on the label node and the barometer modules of the four base station nodes;
and S13, reading the air pressure values of the respective barometer modules in real time by the tag node and the main base station node, and smoothing the air pressure values by using Kalman filtering.
4. The UWB and barometer based indoor high-precision three-dimensional positioning method of claim 1 wherein the barometric calibration of the tag node and the barometer modules of the four base station nodes comprises: place main base station node and label node same height under same environment, gather the atmospheric pressure value data of main base station node and label node in 10s time simultaneously, calculate the arithmetic mean difference of main base station node and label node atmospheric pressure as the offset value, calibrate the barometer module of label node with this offset value, the atmospheric pressure value that will measure in real time is added this offset value as the atmospheric pressure value after the calibration, the offset value of main base station node and label node atmospheric pressure expresses as:
Figure FDA0002280986910000031
where Δ h represents the arithmetic mean pressure error value between them, N1And N2Respectively represents the number P of data collected by barometer modules on the master base station node and the label node in the period of timeA(i) And PT(j) And respectively representing the air pressure values acquired by the main base station node and the label node at the ith moment and the jth moment.
5. The UWB and barometer based indoor high-precision three-dimensional positioning method of claim 1 wherein the calculating the height difference between the master base station node and the tag node using a differential barometric method comprises:
Figure FDA0002280986910000032
Figure FDA0002280986910000033
where H is the height of the tag node measured at that time, H1Is the height of the master base station node measured at that time, T is the average temperature between the master base station node and the tag node, p1The measured air pressure value of the main base station node, p the measured air pressure value of the label node and delta H the height difference between the main base station node and the label node.
6. The indoor high-precision three-dimensional positioning method based on the UWB and barometer according to claim 1, wherein the step S3 specifically comprises:
s31, the label node sends a first message to the base station node at the time of T1, and the base station node receives the message at the time of T2;
s32, the base station node sends a second message back to the label node at the time of T3, and the label node receives the message at the time of T4;
s33, the label node sends a third message to the base station node at the time of T5, and the base station node receives the message at the time of T6;
s34, calculating the time of flight TOF between the label node and the base station node and the distance between the label node and the base station node according to the obtained time information, wherein the calculation is represented as follows:
Figure FDA0002280986910000041
S＝c×TOF；
wherein R isaThe total time taken for the tag node to begin sending the first message to receive the second message; rbA total time taken for the base station node to start sending the second message to receive the third message; daThe total time taken for the base station node to receive the first message and to send out the second message; dbThe total time taken for the tag node to receive the second message and to send out a third message; and c is the propagation velocity of the electromagnetic wave.
7. The UWB and barometer based indoor high precision three dimensional positioning method of claim 1, wherein the real time measured height of the ith packet in step S5 is represented as:
Figure FDA0002280986910000042
wherein d is01,d02,d12Are respectively the lengths of triangles formed among the three base stations, and 0,1 and 2 respectively represent three auxiliary base stations; r is0,r1,r2The lengths of the connecting lines of the three auxiliary base stations and the label nodes are respectively; d is an intermediate parameter expressed as
Figure FDA0002280986910000043
E is radix Ginseng IndiciNumber, is shown as
Figure FDA0002280986910000044
F is an intermediate parameter expressed as
Figure FDA0002280986910000045
8. The UWB and barometer based indoor high precision three dimensional positioning method of claim 1, wherein the real time correction of the measured values using the enhanced pseudorange differential method comprises:
s81, if the real distance between the base station i and the base station j is dijAnd a symmetric bilateral two-way distance measurement algorithm is adopted to calculate the distance measurement value between the base station i and the base station j in real time
Figure FDA0002280986910000046
S82, calculating an offset between the base station and the base station node, which is expressed as:
Figure FDA0002280986910000047
s83, respectively carrying out k iterations on the offset between two base station nodes, and respectively taking k groups
S84, finally, averaging all the offsets, which is expressed as
Figure FDA0002280986910000049
S85, use
Figure FDA0002280986910000051
And (3) correcting the distance from the label node to the base station node in real time:
Figure FDA0002280986910000052
wherein r isiFor the corrected distance value between the label node and the base station node, ri cThe distance measurement value between the label node and the base station node before correction is obtained; n is the number of the base stations,
Figure FDA0002280986910000053
is the total number of distances between the N base stations,distance measurement between nth base station and base station, dijnThe true distance between the nth base station and the base station; Δ dnkIndicating that the nth type offset is measured by k;
Figure FDA0002280986910000055
representing the average of k offsets.
9. The indoor high-precision three-dimensional positioning method based on UWB and barometer according to claim 1, characterized in that step S10 specifically comprises the following steps:
s101, if the distance between the label node and the base station node is ri, the horizontal distance li projected on a plane is represented as:
Figure FDA0002280986910000056
s102, establishing a two-dimensional coordinate equation of the label by using a two-dimensional weighted least square positioning algorithm, wherein the equation is expressed as:
Figure FDA0002280986910000057
s103, obtaining a two-dimensional coordinate of the to-be-detected label according to a weighted least square algorithm, and performing real-time position estimation on the to-be-detected label node by adopting a classic weighted least square positioning algorithm, wherein the expression is as follows:
Figure FDA0002280986910000058
wherein, (x.y) represents the location coordinates of the tag node; (x)0,y0)、(x1,y1)、(x2,y2) Is the coordinate of three secondary base stations, z1Δ H is the height value of the main base station, and Δ H is the height difference measured in real time.
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