CN104280716A - Indoor positioning device and method - Google Patents
Indoor positioning device and method Download PDFInfo
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- CN104280716A CN104280716A CN201410416423.1A CN201410416423A CN104280716A CN 104280716 A CN104280716 A CN 104280716A CN 201410416423 A CN201410416423 A CN 201410416423A CN 104280716 A CN104280716 A CN 104280716A
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- 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
- G01S5/12—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 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
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- 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
- G01S5/0215—Interference
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Abstract
An indoor positioning system is composed of a controller, at least three base stations which are not on the same straight line and a plurality of tags to be positioned. The controller is composed of a synchronous control module and a signal processing module, the base stations can be in communication with the tags and the controller, the tags can transmit frequency modulated continuous waves to an indoor space after receiving signals transmitted by the base stations, and the synchronous signal transmission time delay of the controller is equal to that of the base stations. An indoor positioning method comprises the steps that the tags are positioned independently, and the distance differences, obtained by conducting subtraction in a pairwise mode on the pseudorange between the positioned tags and the base stations, between the tags and the base stations are calculated; an equation is solved based on a hyperbolic positioning principle, and the positions of the tags to be positioned are obtained according to plus-minus sign solving ambiguity of the distance differences. By means of the indoor positioning system and the indoor positioning method, the distance differences between the tags and the different base stations can be measured with high precision, and the tags are positioned with high precision based on the hyperbolic positioning principle.
Description
Technical field
The invention belongs to electronic communication field, relate to a kind of indoor positioning device and method.
Background technology
Along with the development of infotech and wireless communication technology is with universal, the demand of people to location and navigation increases day by day.GPS (GPS) is the location technology be most widely used at present, can meet the demand of people at outdoor positioning.But when GPS is in office work, signal intensity reduces greatly by the impact of buildings, and receiver cannot position.But along with the development of modern society, Development of China's Urbanization is accelerated, and heavy construction is increasing, and the time of people more than 80% is in indoor environment (containing underground, mine, tunnel etc.), in the indoor environment of complexity, the demand of people to indoor location service just increases sharply.And the field such as public safety, production safety, emergency management and rescue, Internet of Things, special population monitoring, large stadium management, smart city construction all needs to use indoor positioning information accurately
The indoor positioning technologies of current comparative maturity has radio-frequency (RF) tag (RFID) indoor positioning technologies, ultra broadband (UWB) indoor positioning technologies, purple honeybee (ZigBee) indoor positioning technologies, Wi-Fi indoor positioning technologies.Wherein the positioning precision of RFID indoor positioning technologies depends on the arranged in high density by reader number and reference label, and realizing meter level positioning precision based on this technology needs to lay a large amount of reference label, is difficult to realize applying on a large scale.UWB indoor positioning technologies mainly adopts the method based on time of arrival (toa) (TOA), although have very high precision, but the device wherein producing the device of ultra-broadband signal and the travel-time of measurement dual-mode antenna direct wave is very expensive, make UWB positioning system cost high, be difficult to large-scale application in the daily location of people.By contrast, the cost of ZigBee technology and Wi-Fi technology and complexity are all lower, and the indoor locating system based on these two kinds of technology is widely applied.But all adopt the localization method based on signal amplitude attenuation model (RSSI) due to these two kinds of positioning systems, positioning precision is larger by the impact of indoor multipath environment, and personnel walk about, the blocking reflection etc. positioning precision all can be caused to decline of body of wall/door, generally speaking positioning precision can only reach about 3 meters [indoor and outdoor hi-Fixs navigation white paper (2013)] [indoor positioning theory, methods and applications (Electronic Industry Press)], is difficult to the demand of satisfied indoor hi-Fix.
Summary of the invention
For overcoming the technological deficiency of existing indoor orientation method precision deficiency, the invention discloses a kind of indoor positioning device and the indoor orientation method based on this device.
Indoor locating system of the present invention, by controller, at least three base station on the same line and some labels to be positioned do not form, described controller is made up of synchronization control module and signal processing module, described base station can communicate with controller with label, described label can launch Continuous Wave with frequency modulation to the interior space after receiving the signal of Base Transmitter, and the synchronous transmission of signal time delay between described controller with each base station is equal.
Concrete, described base station is made up of base station communication module, antenna for base station, base station, frequency mixer, filter amplifier, AD converter, and signal flows to and is followed successively by antenna for base station-base station-frequency mixer-filter amplifier-AD converter-base station communication module.
Further, described base station also comprises the local oscillator be connected with frequency mixer.
Further, described local oscillator is made up of MCU, Direct Digital Frequency Synthesizers and upconverter, the input end of clock of described MCU is connected with the output terminal of clock of synchronization control module, the synchronous signal input end of MCU is connected with the synchronous signal output end of synchronization control module, MCU is connected with the frequency control input of Direct Digital Frequency Synthesizers, the output terminal of Direct Digital Frequency Synthesizers is connected with upconverter, and the output terminal of upconverter is connected with the local oscillator input end of frequency mixer.
Preferably, described label is made up of label communication module, Continuous Wave with frequency modulation generator, label amplifier and label antenna, and signal flows to as label communication module-Continuous Wave with frequency modulation generator-label amplifier-label antenna.
Preferably, by wired mode signal transmission between described controller and each base station, and controller is equal to the synchronous transmission of signal line transmission delay of each base station.
The invention also discloses a kind of indoor orientation method, based on indoor locating system as above, comprise several separate label positioning steps, described separate label positioning step comprises the steps:
SS1. controller sends label coding to each base station, and base station is forwarded to respective labels after receiving label coding; While label coding launched by controller, synchronous signal transmission is to each base station;
SS2. after label receives the label coding of base station forwarding, launch positioning signal, each base station receives positioning signal, utilizes frequency mixing technique that input signal is converted into digital medium-frequency signal, and transfers to controller; Described positioning signal is Continuous Wave with frequency modulation;
The synchronizing signal that controller is launched is synchronous or direct as local oscillation signal for carrying out local oscillation signal in the process being converted into digital medium-frequency signal;
SS3. the digital medium-frequency signal of controller to each base station received is handled as follows:
SS31 calculates the pseudorange between each base station and label to be positioned according to digital medium-frequency signal,
Pseudorange between SS32 label to be positioned and each base station makes the range difference that difference obtains between label and each base station between two;
SS33 is according to hyperbolic positioning principle, and solving equation also obtains the position of label to be positioned according to the sign ambiguity solution of range difference.
Preferably, all labels in controller determination locating area, totalize N to each label from 1 to N numbering, from first label, repeat described separate label positioning step, until whole label in traversal locating area.
Preferably, the Continuous Wave with frequency modulation in described step SS2 is linear frequency modulation continuous wave or stepped FMCW.
Preferably, when Continuous Wave with frequency modulation in described step SS2 is stepped FMCW, in described step SS31 to the computing method of pseudorange be: digital medium-frequency signal is done inverse Fourier transform, obtain one-dimensional range profile, therefrom choose the numerical value at image peak value place, utilize the pseudorange that k obtains between label and base station
In above formula, c is vacuum light speed,
for the step-length of step frequency, N is step frequency number;
When Continuous Wave with frequency modulation in described step SS2 is linear frequency modulation continuous wave, be: digital medium-frequency signal is obtained frequency spectrum do Fast Fourier Transform (FFT) from frequency spectrum, then find the maximum Frequency point of amplitude to the computing method of pseudorange in described step SS31
, utilize the pseudorange obtained between label and base station
In above formula, c is vacuum light speed,
for the maximum frequency deviation of transmitted tag frequency, T
mfor the frequency modulation cycle.
Compared with prior art, the invention has the beneficial effects as follows: the present invention adopts Continuous Wave with frequency modulation method to find range, and obtains high range resolution by large bandwidth, can effectively suppress multipath effect on the impact of distance accuracy.The present invention is by rational system and digital signal processing algorithm, the thick synchronous error that exists between base station and label can be eliminated on the impact of positioning precision, specifically comprise: design isochronous controller when system, a synchronizing signal is sent at regular intervals to each base station, this synchronizing signal can use the transmission line of identical time delay to each base station, to ensure each base station precise synchronization; When carrying out digital signal processing, by poor between two for the spacing of the label that calculates and each base station, realize the range difference of high-acruracy survey label and different base station, can position label accurately according to hyperbolic positioning principle accordingly.
Accompanying drawing explanation
Fig. 1 is the annexation figure of a kind of embodiment of indoor locating system of the present invention;
Fig. 2 is respective a kind of embodiment schematic diagram of label of the present invention, base station, controller;
Fig. 3 is that indoor locating system of the present invention carries out the embodiment process flow diagram of one-time positioning to all labels of locating area;
Fig. 4 uses triangular linear Continuous Wave with frequency modulation to transmit and the relation schematic diagram of Received signal strength in the present invention;
Fig. 5 uses stepped FMCW emission signal frequency to change schematic diagram in the present invention;
Fig. 6 is embodiment 1 locating area, locating device distribution schematic diagram;
Fig. 7 is the structural drawing of label and base station in embodiment 1;
Fig. 8 is one-time positioning sequential chart in embodiment 1;
Fig. 9 is one-time positioning result schematic diagram in embodiment 1;
Figure 10 is embodiment 2 locating area, locating device distribution schematic diagram;
Figure 11 is the structural drawing of label and base station in embodiment 2;
Figure 12 is one-time positioning sequential chart in embodiment 2;
Figure 13 is one-time positioning result schematic diagram in embodiment 2.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
As shown in Fig. 1 to 2, give the signal connected mode of indoor positioning device of the present invention and an embodiment of each component infrastructure.
Comprise some and at least three base stations of controller one, label to be positioned, wherein label to be positioned comprises communication module 1, Continuous Wave with frequency modulation generator 2, label amplifier 3, label antenna 4.After communication module 1 receive the order that transmits of the communication module 11 of base station, produce Continuous Wave with frequency modulation signal by Continuous Wave with frequency modulation generator 2, amplify through label amplifier 3, then via label antenna 4 to interior space radiation; Position because the present invention adopts hyperbolic localization method to offset thick synchronous error, need the hyperbolic curve that at least two different, therefore need at least three base stations, and these three base stations are not on the same line.
According to space size and shape determination base station number, three base stations are at least needed when applying of the present invention in two dimensional surface, the structure of each base station is identical, all comprise communication module and FM signal receiver, its structure comprises communication module 11, antenna for base station 5, base station 6, frequency mixer 7, local oscillator 8, filter amplifier 9, analog to digital converter (ADC) 10.The effect of base station comprises two parts.One is all label communications in the locating area of communication module and this base station, determines the sum of label and the label coding of each label, and is sent to controller and gathers, and is managed label by controller.In position fixing process, controller sends the label coding that is arranged in the label of locating area at every turn to base station, forward this label coding by the communication module of base station, and notice corresponding label starts to launch positioning signal.Another effect of base station is the positioning signal that FM signal receiver receives transmitted tag, specifically comprise: antenna for base station 5 receives the signal that label is launched, this signal amplifies through base station 6, then enter the local oscillation signal mixing that frequency mixer 7 and local oscillator 8 produce and obtain intermediate-freuqncy signal (radiofrequency signal reduces the signal after frequency through frequency mixer), intermediate-freuqncy signal after filtering amplifier 9 is carried out filtering and is converted digital signal to through ADC10 after amplifying process, exports to the signal processor 13 in controller.
Two parts are comprised: synchronization control module 12 and signal processing module 13 in controller.Synchronization control module carries out synchro control to the base station of all diverse locations at regular intervals, control mode has two kinds, one is that synchronization control module produces synchronizing signal, by waiting transmission line of time delay to give each base station, synchronous to the local oscillation signal in each base station; Another kind of mode is that isochronous controller directly produces local oscillation signal, is then divided into multichannel, by waiting transmission line of time delay to give each base station, as the local oscillation signal of frequency mixer, now can no longer need local oscillator 8 in base station.While carrying out synchro control to base station, synchronization control module sends the label coding being arranged in the label of locating area to base station, and is forwarded by the communication module in base station, thus controls the transmitted tag positioning signal in locating area.The function of signal processing module is processed by the digital medium-frequency signal of each base station received, and export positioning result, i.e. the position of label or coordinate.
The signal of transmitted tag to be positioned is generally high frequency radio signals, for meeting the ADC chip input signal sampling request of prior art, base station by the signal down of transmitted tag to be positioned to intermediate-frequency band.
In order to ensure the high-precision location of contrive equipment, in each base station, the local oscillation signal of mixer input requires stringent synchronization, therefore controller is needed to arrive the synchronizing signal propagation delay of each base station identical, when adopting wireless mode transmission of signal, require that controller is identical to the space length of each base station, when adopting wired mode transmission of signal, can require that controller arrives the signal transmssion line type of each base station all identical with length, obviously, employing wired mode is easier obtains equal synchronizing signal transmission time delay in the locating area of different structure shape.
Based on indoor locating system as above, the invention discloses a kind of indoor orientation method, comprise several separate label positioning steps, each separate label positioning step carries out one-time positioning to a label to be positioned, and described separate label positioning step comprises the steps:
SS1. controller sends label coding to each base station, and base station is forwarded to respective labels after receiving label coding, thick synchronous with what realize between base station with label; While label coding launched by controller, launch synchronizing signal to each base station, to ensure the stringent synchronization between base station;
SS2. after label receives the label coding of base station forwarding, launch positioning signal, each base station receives positioning signal, utilizes frequency mixing technique that input signal is converted into digital medium-frequency signal, and is emitted to controller; Described positioning signal is Continuous Wave with frequency modulation;
The synchronizing signal that controller is launched is synchronous or direct as local oscillation signal for carrying out local oscillation signal in the process being converted into digital medium-frequency signal;
SS3. the digital medium-frequency signal of controller to each base station received is handled as follows:
SS31 calculates the pseudorange between each base station and label to be positioned according to digital medium-frequency signal,
Pseudorange between SS32 label to be positioned and each base station makes the range difference that difference obtains between label and each base station between two;
SS33 is according to hyperbolic positioning principle, and solving equation also obtains the position of label to be positioned according to the sign ambiguity solution of range difference.
In actual mechanical process, multiple label to be positioned is generally included in locating area, now can to circulate successively location to each tag number, be specially: all labels in controller determination locating area, totalize N numbering from 1 to N each label, from first label, repeat described separate label positioning step, until whole label in traversal locating area.
As shown in Figure 3, provide the embodiment utilizing indoor orientation method of the present invention to position N number of label,
Step 1: in each base station and locating area, all labels connect, and obtain its label coding, and are sent to controller, determine number of labels N(N >=1);
Step 2: initialization n=1;
Step 3: controller sends the label coding of label n to base station, forward this label coding notified tag n transmit by base station, simultaneously to each Base Transmitter synchronizing signal; When sending label coding and synchronizing signal, can launch according to certain hour gap periods.
Step 4: launch positioning signal after label n receives orders;
Step 5: base station 1, base station 2, base station 3 etc. receive the positioning signal of label n respectively;
Step 6: the positioning signal that base station 1, base station 2, base station 3 etc. dock receipts respectively processes, exports digital medium-frequency signal, and is all sent to controller and carries out digital signal processing;
Step 7: controller receives digital medium-frequency signal, and carry out digital signal processing: first calculate the pseudorange between each base station and label to be positioned according to digital medium-frequency signal, then the pseudorange between label to be positioned and each base station makes the range difference (distinguishing positive and negative) that difference obtains between label and each base station between two, last according to hyperbolic positioning principle, solving equation also obtains the position of label to be positioned, i.e. positioning result according to the sign ambiguity solution of range difference;
Step 8: controller exports positioning result;
Step 9: perform n=n+1, and judge whether n is greater than N, if so, one-time positioning terminates, otherwise, skip to the separate label positioning step that step 3 repeats to perform successively step 3 ~ step 9, until n is greater than N;
By above step 1 ~ step 9, the process of one-time positioning can be carried out label existing in locating area, repeat the real-time dynamic positioning that can realize label.
The signal waveform of transmitted tag to be positioned is Continuous Wave with frequency modulation, it can be linear frequency modulation continuous wave signal, also can be stepped frequency continuous wave signal, their frequency can periodically triangular wave or periodic serrations shape ripple change, the two difference is that sawtooth wave adopts mutational formats in the frequency decrease stage, triangular wave is then continuous gradual mode, and such as frequency control word Changing Pattern is 1-2-3-4-5-4-3-2-1-2-3-4-5 ... now DDS output waveform is triangular wave; If Changing Pattern is 1-2-3-4-5-1-2-3-4-5-1-2-... now DDS output waveform is zigzag wave.When adopting multi-form Continuous Wave with frequency modulation, disposal route corresponding in the digital signal processing module in controller is also different.
When adopt linear frequency modulation continuous wave signal time, according to linear frequency modulation continuous wave signal range measurement principle, if the frequency modulation cycle of FM signal be,
represent the speed that the light in vacuum is propagated.The signal transient frequency that bidding label are launched is
, its centre frequency is
, the maximum frequency deviation of transmission frequency modulation is
, the signal transient frequency that any two base stations receive is
,
,
,
be that the signal that receives of two base stations and local oscillation signal are respectively as the difference frequency that difference frequency obtains;
In real work, controller on the one hand by the local oscillation signal of of the same type and isometric transmission line synchronizing signal or homology to base station, send label coding on the one hand and launch positioning signal by base station forwards notified tag, because the airborne spread path of base station forwarding label coding is uncertain, random delay is there is between label and base station, be called thick synchronous error, be set to
, therefore the initial time of transmitting interrogation signals lags behind the initial time of the local oscillation signal in base station
.
For the positive frequency modulation slope in triangular modulation linear frequency modulation continuous wave signal, as shown in Figure 4,1. the transmission frequency of label changes by the curve in Fig. 4, can be write as shown in the formula (1):
(1)
The receive frequency of two base stations as curve in Fig. 4 3. 4. shown in, can be write as following formula (2), (3):
(2)
(3)
Because there is thick synchronous error between base station and label, the local oscillation signal time of signal lag in base station of transmitted tag
, the local oscillation signal therefore in all base stations as the curve in Fig. 4 1. shown in, can be write as following formula (4):
(4)
Received signal strength in two base stations and the difference frequency signal of local oscillation signal are respectively as shown in the formula (5) (6):
(5)
(6)
The distance of outgoing label and two base stations can be obtained thus respectively such as formula (7), (8):
(7)
(8)
Wherein
,
for the measured distance of label and two base stations,
,
for the actual distance of label and two base stations.Will
,
differ from, the range difference obtaining label and two base stations is
(9)
Can see, owing to there is thick synchronous error in label and base station, the distance that formula (7) and formula (8) obtain is the pseudorange containing error, and the present invention adopts the mode making difference to obtain range difference to position, instead of directly utilizes the distance recorded to locate.From formula (9), although there is thick synchronous error between base station and label, the range difference measured by the present invention is exactly real range difference, and the present invention has the effect eliminating thick synchronous error.
Therefore, for linear frequency modulation continuous wave, disposal route in digital signal processor comprises: digital medium-frequency signal is made the frequency spectrum that Fast Fourier Transform (FFT) (FFT) obtains intermediate-freuqncy signal, then therefrom find prominent Frequency point, in corresponding (5), (6),
, and calculate apart from the pseudorange between label and base station according to formula (7), (8)
,
.Then will
,
the actual distance that work difference obtains label and two base stations is poor, can determine a hyperbolic curve thus.In position fixing process, owing to having the base station of three not conllinear at least, can obtain the pseudorange of label and three base stations, they be made between two difference and obtain range difference, recycling hyperbolic positioning principle calculates the positional information of label and exports.
When adopting stepped FMCW signal, if the signal of transmitted tag is
(10)
In formula
nfor step frequency number,
for the single-frequency point duration,
for the initial frequency of carrier frequency stepping,
for carrier frequency stepping-in amount,
,
, emission signal frequency change as shown in Figure 5.
Distance label is
base station received signal be
(11)
Wherein
.
Local oscillation signal in base station is
(12)
Wherein
for synchronous error.
Signal after Received signal strength and local oscillator mixing is
(13)
=R/c, c are the light velocity, and for the label of static (or slowly moving), the distance R between itself and base station is considered as constant, and synchronous error
be generally fixed value, therefore for static target
for constant, in formula (13), first exponential term is constant term, and second exponential term can regard the frequency-region signal of frequency linearity change as.Series of sub-pulses is to received signal sampled, and can obtain:
(14)
IFFT process is carried out to it, the range information of the target that can obtain.
(15)
In formula, k is the integer between 0 ~ N-1, is the frequency after discrete Fourier transform (DFT),
for the range value of corresponding frequency, from (15), when
time, the mould of above formula obtains maximal value.Therefore, by search
frequency corresponding to maximum of points can obtain k value, and then the range information between label and base station can be calculated:
(16)
Label can be obtained by above stepped FMCW range measurement principle to be respectively to the distance of two base stations
(17)
(18)
,
represent the frequency carried out after two base station received signals are sampled corresponding to the maximum amplitude after IFFT process respectively, wherein
,
for the measured distance of label and two base stations,
,
for the actual distance of label and two base stations.Will
,
differ from, the range difference obtaining label and two base stations is
(19)
With employing linear FM signal as transmitting in like manner, in real work, owing to there is thick synchronous error in label and base station, the distance surveyed is not the distance of real label and base station, and the distance by a label and two base stations of the present invention is made the technology that difference recycles location from range-difference measurements and can be overcome the impact of thick synchronous error on positioning precision.
Therefore, disposal route in digital signal processor comprises: digital medium-frequency signal is done inverse Fourier transform (IFFT), obtain one-dimensional range profile, then therefrom choose the frequency that image peak value place is corresponding, then through type (17) obtains the pseudorange between label and a base station
, in like manner through type (18) obtains the pseudorange of label and another base station
, then will
,
the actual distance that work difference obtains label and two base stations is poor, can determine a hyperbolic curve thus.In position fixing process, owing to having the base station of three not conllinear at least, can obtain the pseudorange of label and three base stations, they be made between two difference and obtain range difference, recycling hyperbolic positioning principle calculates the positional information of label and exports.
Below provide two specific embodiments.
Specific embodiment one
Transmitted waveform adopts symmetric triangular linear frequency modulation continuous wave (STLFMCW).Locating device comprises label, base station, controller, and synchronization control module in its middle controller adopts and directly produces local oscillation signal and carry out base station synchronization by isometric transmission line to the mode of each base station.Communication module in label and base station adopts ZigBee module, adopt single-chip microcomputer (MCU) directly the to produce working method that frequency control word control DDS produces linear FM signal of the Continuous Wave with frequency modulation generator in label.For label 1 and base station 1, as shown in Figure 7, label comprises label antenna, label amplifier, upconverter, DDS(Direct Digital Synthesizer to the structure of label and base station, Direct Digital Synthesizer), MCU, ZigBee module; Base station comprises antenna for base station, base station, frequency mixer, filter amplifier, ADC, ZigBee module; Controller architecture comprises synchronization control module and signal processing module.ZigBee module in above base station is base station communication module, ZigBee module in label is label communication module, ZigBee is the low-power consumption LAN protocol based on IEEE802.15.4 standard, is the wireless communication technology of a kind of short distance, low-power consumption, is known to the skilled person.
Assuming that locating area is a length of side is the square room of 25 meters, 3 base stations are set in the present embodiment, position distribution as base station in Fig. 61, base station 2, base station 3, with Liang Tiao limit, room be X, Y-axis sets up rectangular coordinate system.Assuming that there are two labels in locating area, i.e. label 1 and label 2, position respectively in (5.5,15.6), (16.5,7.2), as shown in Figure 6.
In this implementation, first the synchronization control module in controller sends the tag addresses code of label 1 to base station 1, forwarded to locating area by the ZigBee module in base station, and the MCU that the ZigBee module in label 1 receives in rear abstract factory 1 starts working.MCU and DDS (direct synthesizer) forms Continuous Wave with frequency modulation generator, MCU produces frequency control word and is input to DDS, the required linear frequency modulated waveform of DDS synthesis, through upconverter, signal frequency is modulated in required frequency again, after amplifier amplifies, inputs antenna convert electromagenetic wave radiation to in space;
The address code of setting label is 24, when ZigBee module in base station forwards this address code, the length of Frame is 64, data transmission rate is 250kbps, data are transmitted the time consumed and are about 2.2 milliseconds, add acknowledgement frame (ACK) transmission time that data are transmitted and protocol stack processing time within a processor, make response from base station forwarding address code to label, about 4 milliseconds consuming time altogether;
Synchronization control module in controller also needs to produce local oscillation signal, and point three tunnels input base station 1, base station 2, base station 3, as the local oscillation signal of respective base station frequency mixer through the transmission line of equal length.Due to about 4 milliseconds consuming time of ZigBee module communication, in order to make the local oscillation signal in base station synchronous as far as possible with transmitting of label, so synchronization control module should postpone 4 milliseconds while the address code sending label 1 to base station 1 produce local oscillation signals to each base-station transmission;
The antenna of three base stations all receives the LFMCW signal of label 1 transmitting, input mixer and local oscillation signal mixing after amplifier amplifies, export intermediate-freuqncy signal, converted to digital medium-frequency signal by analog to digital converter ADC after amplifier process after filtering, transfer to controller respectively.
Controller receives the output signal of each base station, calculate the pseudorange of three base stations and label 1 respectively, then poor between two, obtain label 1 to base station 1 and label 1 to the range difference of base station 2, label 1 to base station 1 and label 1 to the range difference of base station 3, label 1 to base station 2 and the range difference of label 1 to base station 3, do in difference process, thick synchronous error is eliminated, and obtains real range difference, then obtains the exact position of label 1 by hyperbolic positioning principle.
After completing label 1 location, synchronization control module in controller sends the address code of label 2 again to base station 1, forwarded to locating area by the ZigBee module in base station, ZigBee module in label 2 is started working after receiving the address code of this label, the workflow of concrete location is identical with the positioning work flow process of above-mentioned label 1, locating device complete a secondary label 1, label 2 complete location sequential as shown in Figure 8; In Fig. 8, horizontal ordinate is time shaft, longitudinally represents the respective behavior of each base station in indoor locating system, controller and label.
If the modulation period transmitted
t r =1ms, centre carrier frequency
f 0 =10.525GHz, modulating bandwidth
b=1.2GHz, if signal sampling rate
f s =1MHz, FFT count and increase to N=2 by zero padding
16, signal to noise ratio (S/N ratio) 10dB, considers multi-path influence.According to workflow of the present invention, Fig. 9 is shown in by schematic diagram.Positioning result is as follows:
The range difference that label 1 arrives base station 2 to base station 1 and label 1 is-8.4496(rice)
Label 1 is 5.6248(rice to base station 1 and label 1 to the range difference of base station 3)
The coordinate of label 1 is (5.4877,15.5847), and positioning error is 0.0196(rice);
Label 2 is 6.9485(rice to base station 1 and label 1 to the range difference of base station 2)
The range difference that label 2 arrives base station 3 to base station 1 and label 1 is-6.1760(rice)
The coordinate of label 2 is (16.5613,7.2691), and positioning error is 0.0924(rice)
Specific embodiment 2
The present embodiment is another kind of way of realization of the present invention, the present embodiment difference from Example 1 is: Continuous Wave with frequency modulation signal adopts stepping frequency-modulated form, between base station with base station, synchronous employing controller sends the mode of synchronizing signal, and therefore base station is different with the structure of the Continuous Wave with frequency modulation signal generator in label.The structure of controller, label and base station as shown in figure 11.Label construction is identical with the label in specific embodiment 1; Base station comprises antenna, amplifier, frequency mixer, filter amplifier, ADC, upconverter, DDS, MCU, ZigBee module; Controller architecture comprises synchronization control module and signal processing module.Suppose that locating area is identical with the locating area in embodiment 1,3 arrangement of base stations are also identical simultaneously.Setting label number in this embodiment is 1, i.e. label 1, and position is (10.5,9.8), and arrangement of base stations and label position are as shown in Figure 10.
In the present embodiment, first controller sends the address code of label 1, is forwarded to locating area by the ZigBee module in base station, and the MCU after the ZigBee in label receives address signal in abstract factory starts working.MCU 5 directly produces frequency control word and is input to DDS, the required stepping fm waveform of DDS synthesis, then is modulated in required frequency through upconverter by signal frequency, inputs antenna and convert electromagenetic wave radiation to in space after amplifier amplifies; Wherein, ZigBee module communication same embodiment one consuming time is 4 milliseconds.
Controller postpones 4 milliseconds after sending the address code of label 1 and produces a synchronization pulse, and this synchronization pulse divides three tunnels through the transmission line input base station 1 of equal length, base station 2, base station 3.Same treatment is done after receiving synchronization pulse in each base station: the MCU in base station carries out a clock synchronous after receiving the synchronization pulse of controller, and synchronization pulse is produced the starting point of frequency control word as MCU, the frequency control word that MCU produces is input to DDS, and the Step Frequency waveform that DDS produces is input to the local oscillation signal of frequency mixer as frequency mixer after upconverter; The antenna of base station receives the SFCW signal of transmitted tag, input mixer and local oscillation signal mixing after base station amplifies, export intermediate-freuqncy signal, converted to digital medium-frequency signal by ADC after amplifier process after filtering, digital medium-frequency signal transfers to controller.
Digital signal processing method in the present embodiment is different from embodiment 1, and corresponding distance measurement method is stepped FMCW telemetry, and instructions summary of the invention part has detailed introduction, no longer repeats here.The intermediate-freuqncy signal transferring to controller obtains the pseudorange of label 1 to 3 base stations after digital signal processor processes, then poor between two, obtain label 1 to base station 1 and label 1 to the range difference of base station 2, label 1 to base station 1 and label 1 to the range difference of base station 3, label 1 to base station 2 and the range difference of label 1 to base station 3, do in difference process, thick synchronous error is eliminated, obtain real range difference, then obtain the exact position of label 1 by hyperbolic positioning principle.Locating device completes the sequential of the complete location of a secondary label 1 as shown in figure 12, and in Figure 12, horizontal ordinate is time shaft, longitudinally represents the respective behavior of each base station in indoor locating system, controller and label.
The present embodiment arranges the modulation period transmitted
t r =1ms, stepping frequency modulation points N is 500, centre carrier frequency
f 0 =10.525GHz, modulating bandwidth
b=1GHz, signal to noise ratio (S/N ratio) 10dB, IFFT count and increase to N=2 by zero padding
20, consider multipath effect impact.According to workflow of the present invention, positioning result is as follows, and Figure 13 is shown in by schematic diagram:
The range difference that label 1 arrives base station 2 to base station 1 and label 1 is-3.1747(rice)
The range difference that label 1 arrives base station 3 to base station 1 and label 1 is-4.1506(rice)
The coordinate of label 1 is (10.4786,9.7762), and positioning error is 0.0321(rice).
The method that in the present invention, the disclosed embodiments describe or the software module that the step of algorithm can directly use hardware, processor to perform, or the combination of the two is implemented.Software module can be placed in the storage medium of other form any known in random access memory (RAM), internal memory, ROM (read-only memory) (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.
Previously described is each preferred embodiment of the present invention, preferred implementation in each preferred embodiment is if not obviously contradictory or premised on a certain preferred implementation, each preferred implementation can stack combinations use arbitrarily, design parameter in described embodiment and embodiment is only the invention proof procedure in order to clear statement inventor, and be not used to limit scope of patent protection of the present invention, scope of patent protection of the present invention is still as the criterion with its claims, the equivalent structure change that every utilization instructions of the present invention and accompanying drawing content are done, in like manner all should be included in protection scope of the present invention.
Claims (10)
1. indoor locating system, it is characterized in that, by controller, at least three base station on the same line and some labels to be positioned do not form, described controller is made up of synchronization control module and signal processing module, described base station can communicate with controller with label, described label can launch Continuous Wave with frequency modulation to the interior space after receiving the signal of Base Transmitter, and the synchronous transmission of signal time delay between described controller with each base station is equal.
2. indoor locating system as claimed in claim 1, it is characterized in that, described base station is made up of base station communication module, antenna for base station, base station, frequency mixer, filter amplifier, AD converter, and signal flows to and is followed successively by antenna for base station-base station-frequency mixer-filter amplifier-AD converter-base station communication module.
3. indoor locating system as claimed in claim 2, it is characterized in that, described base station also comprises the local oscillator be connected with frequency mixer.
4. indoor locating system as claimed in claim 3, it is characterized in that, described local oscillator is made up of MCU, Direct Digital Frequency Synthesizers and upconverter, the input end of clock of described MCU is connected with the output terminal of clock of synchronization control module, the synchronous signal input end of MCU is connected with the synchronous signal output end of synchronization control module, MCU is connected with the frequency control input of Direct Digital Frequency Synthesizers, the output terminal of Direct Digital Frequency Synthesizers is connected with upconverter, and the output terminal of upconverter is connected with the local oscillator input end of frequency mixer.
5. indoor locating system as claimed in claim 1, it is characterized in that, described label is made up of label communication module, Continuous Wave with frequency modulation generator, label amplifier and label antenna, and signal flows to as label communication module-Continuous Wave with frequency modulation generator-label amplifier-label antenna.
6. indoor locating system as claimed in claim 1, is characterized in that, by wired mode signal transmission between described controller and each base station, and controller is equal to the synchronous transmission of signal line transmission delay of each base station.
7. indoor orientation method, is characterized in that, based on the indoor locating system as described in Claims 1-4 any one, comprise several separate label positioning steps, described separate label positioning step comprises the steps:
SS1. controller sends label coding to each base station, and base station is forwarded to respective labels after receiving label coding; While label coding launched by controller, synchronous signal transmission is to each base station;
SS2. after label receives the label coding of base station forwarding, launch positioning signal, each base station receives positioning signal, utilizes frequency mixing technique that input signal is converted into digital medium-frequency signal, and transfers to controller; Described positioning signal is Continuous Wave with frequency modulation;
The synchronizing signal that controller is launched is synchronous or direct as local oscillation signal for carrying out local oscillation signal in the process being converted into digital medium-frequency signal;
SS3. the digital medium-frequency signal of controller to each base station received is handled as follows:
SS31 calculates the pseudorange between each base station and label to be positioned according to digital medium-frequency signal,
Pseudorange between SS32 label to be positioned and each base station makes the range difference that difference obtains between label and each base station between two;
SS33 is according to hyperbolic positioning principle, and solving equation also obtains the position of label to be positioned according to the sign ambiguity solution of range difference.
8. indoor orientation method as claimed in claim 7, is characterized in that, all labels in controller determination locating area, totalize N numbering from 1 to N each label, from first label, repeat described separate label positioning step, until whole label in traversal locating area.
9. indoor orientation method as claimed in claim 7, it is characterized in that, the Continuous Wave with frequency modulation in described step SS2 is linear frequency modulation continuous wave or stepped FMCW.
10. indoor orientation method as claimed in claim 7, is characterized in that,
When Continuous Wave with frequency modulation in described step SS2 is stepped FMCW, in described step SS31 to the computing method of pseudorange be: digital medium-frequency signal is done inverse Fourier transform, obtain one-dimensional range profile, therefrom choose the numerical value at image peak value place, utilize the pseudorange that k obtains between label and base station
In above formula, c is vacuum light speed,
for the step-length of step frequency, N is step frequency number;
When Continuous Wave with frequency modulation in described step SS2 is linear frequency modulation continuous wave, be: digital medium-frequency signal is obtained frequency spectrum do Fast Fourier Transform (FFT) from frequency spectrum, then find the maximum Frequency point of amplitude to the computing method of pseudorange in described step SS31
, utilize the pseudorange obtained between label and base station
In above formula, c is vacuum light speed,
for the maximum frequency deviation of transmitted tag frequency, T
mfor the frequency modulation cycle.
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