A kind of wireless sensor network Precise Position System and methodTechnical field
The present invention relates to communication technique field, particularly relate to a kind of wireless sensor network Precise Position System and method.
Background technology
In recent years, pinpoint demand increases day by day, although GPS can obtain good positioning precision, under indoor environment, gps signal decay is comparatively large, cannot accurately locate.In addition, GPS is also easy in outdoor be subject to the extraneous factor impacts such as weather, and the occasion thus cannot located at GPS needs to utilize other technical scheme to replace GPS, such as indoor accurate position.The indoor positioning market demand is comparatively large, typical apply such as underground coal mine is accurately located, Prison staff location, personnel's assets location, specific building etc.
For Trend of Underground Personnel Positioning System, the current intelligence of down-hole regional personnel should be able to be reflected to surface computer system by time, accurately, administrative staff are enable to grasp the distribution situation of personnel in the pit and the movement locus of each miner at any time, so that carry out more reasonably dispatching management.Especially, when a fault occurs, the data that rescue personnel also can provide according to personnel in the pit and equipment navigation system and figure, understand rapidly the situation of the relevant personnel, take in time to rescue measure accordingly, improves the efficiency of emergency management and rescue work.Therefore, country pays much attention to the construction of mine personnel positioning system.Before 6 years, coal academy of sciences Changzhou automation research institute just adopts the personnel positioning monitoring system of the RFID of 433M radio frequency, thereafter, multi-form navigation system is had again to come out, 2007, national security industry standard AQ6210-2007 " coal mine underground operators position monitoring and management system general technical specifications " and AQ1048-2007 " coal mine underground operators management system uses and management regulation " issues, as the policy paper that research and development, production and onsite application manage.Colliery equipment navigation system also has some years, and each department require different, as coal office of Shanxi Province just required before 3 years that all collieries must be equipped.No. (2010) 23, State Council's promulgated by the State Council " State Council is about the notice strengthening enterprise safety operation work further " requires " to force to carry out advanced and applicable technical equipment.Technical facilities in production standard be formulated and be implemented in colliery, non-coal mine will, monitoring and controlling system is installed, the technical equipment such as system and channel of communication is sued and laboured in Mine Personnel Positioning System, emergency hedge system, compressed-air self-help system, water supply, and completed within 3 years ".In August in the same year, national Work Safety Supervision Bureau safety supervision total coal dress (2010) No. 146 literary compositions require that " all collieries of central enterprise and State owned coal mine enterprise will complete the construction Perfect the work of Mine Personnel Positioning System; Before the end of the year 2011, other all collieries will complete the construction Perfect the work of Mine Personnel Positioning System." at present, the personnel location system of central enterprise and State owned coal mine enterprise completes installation, but national local mine also has more than 10,000 to locate, estimating at least over halfly also does not have location equipment.
At present, the domestic technical scheme realizing indoor positioning mainly contains:
1, radio-frequency card (RFID) attendance checking system:
This scheme is generally install a RFID card reader at entrance, the mode to RFID radio-frequency card reads is utilized to register personnel, and it can not be real-time the particular location of the personnel that report accurately, floor rank or room level can be navigated to, be in fact a kind of attendance checking system, be difficult to accomplish accurate location.
2, the personnel location system of 2.4GRFID technology is adopted
Adopt the manufacturer of this scheme many, the most high energy of its decipherment distance reaches 10-40 rice, and recognition speed is very fast, and the most outstanding advantage is low-power consumption, and wireless identification tag can normally work continuously when not changing battery more than 6 each moons.Positioning precision is directly proportional to the density of receiver, in order to realize higher positioning precision, just needs higher overall system cost, therefore poor expandability.
3, Zigbee radio network technique is adopted
The wireless identification distance of this scheme is 50 ~ 100m, and recognition speed is fast, can two-way communication, but the power dissipation ratio RFID of identification card is much bigger, is unfavorable for the use under special occasions.
Summary of the invention
The object of the embodiment of the present invention is for Problems existing in above-mentioned background technology, a kind of wireless sensor network Precise Position System and method are proposed, low to solve indoor position accuracy in prior art, or just need higher cost thus the lower problem of autgmentability to reach higher positioning precision.
In order to realize aforementioned invention object, embodiments provide a kind of wireless sensor network Precise Position System, described system is realized by following technical scheme:
A kind of wireless sensor network Precise Position System, described system comprises:
One or more by localizing objects, described localizing objects comprises an identification card, for carrying out the mutual of information with one or more wireless card readers in wireless card reading base station that is arranged at, bilateral bidirectional ranging algorithm SDS-TWR is adopted to measure separately relative to the relative distance of each wireless card reader;
Server, for according to above-mentioned relative distance, adopts Semidefinite Programming algorithm to calculate the coordinate position determining each identification card.
Further preferably, described identification card specifically comprises:
Power management section, is used for carrying out Charge Management and/or power safety management;
Radio frequency control section, comprises output matching circuit, power monitoring, amplifier comparison circuit, receiving circuit, is used for sending ranging data bag to wireless card reader and receives packet from card reader to measure the distance with wireless card reader;
Processor unit, is used for coordinating radio frequency control section to carry out finding range, send/receive wireless data.
Further preferably, described receiving circuit comprises duplexer, filter, and described duplexer is used for controlling double antenna.
Further preferably, described identification card also comprises power saving management module, is used for according to the signal between identification card and wireless card reader strong and weak, automatically regulates the transmitting power of Subscriber Identity Module, realizes power saving management.
In order to realize aforementioned invention object, embodiments provide a kind of wireless sensor network accurate positioning method, described method is realized by following technical scheme:
A kind of wireless sensor network accurate positioning method, described method comprises:
Carried out the mutual of information by fixation and recognition card and one or more wireless card readers in wireless card reading base station that is arranged at, and adopt bilateral bidirectional ranging algorithm SDS-TWR to measure separately relative to the relative distance of each wireless card reader;
Server, according to above-mentioned relative distance, adopts Semidefinite Programming algorithm to calculate the coordinate position determining each identification card.
Further preferably, described employing bilateral bidirectional ranging algorithm SDS-TWR measures and specifically comprises relative to the relative distance of each wireless card reader separately:
Identification card sends first ranging data bag to wireless card reader, if wireless card reader proper reception of this packet, then returns hardware and replys to Subscriber Identity Module, and request produces transmission delay T1;
Identification card calculates transmission delay T1, these data is sent to wireless card reader simultaneously, and waits for the hardware response of wireless card reader;
Wireless card reader reads the relevant parameter sent of identification card, and to find range preparation for identification card and wireless card reader second time;
T2 by calculating process time delay T2, and is sent to identification card by wireless card reader;
Identification card receives the ranging data bag of wireless card reader, automatically sends hardware and replys to wireless card reader, and wireless card reader will calculate propagation delay T3 according to described hardware response;
Wireless card reader calculates propagation delay T3, and T3 is sent to identification card, and waits for the hardware response of identification card;
Identification card reads the T3 that wireless card reader sends, and calculates process time delay T4;
Identification card calculates the relative distance of identification card and wireless card reader according to T1, T2, T3, T4.
Further preferably, described server, according to above-mentioned relative distance, adopts Semidefinite Programming algorithm to calculate and determines that the coordinate position of each identification card specifically comprises:
Measure the identification card of movement and the paired distance between the mobile identification card that can communicate or fixed wireless card reader;
Paired distance between the node utilizing known wireless card reader or identification card position and measurement to obtain comes the position of the every other identification card of computing network.
Further preferably, the position that the paired distance between the described node utilizing known wireless card reader or identification card position and measurement to obtain carrys out the every other identification card of computing network specifically comprises:
If the set that mobile node and identification card set are N and stationary nodes and identification card or wireless card reader is A, the wherein position { a of stationary nodesk; K ∈ A} is given, the position { x of mobile nodei; I ∈ N} is unknown, according to measuring the paired distance obtained, is measured by following formula:
Wherein Eaand Enthe set of existing measuring distance between mobile node and stationary nodes and between mobile node and mobile node respectively.
Further preferably, described method comprises:
X is made to be all position vector x belonging to Ni; I ∈ N is as the matrix of row vector and Y=Xtx, Z=[I, X; Xt, Y], note eibe i-th component be 1, all the other components are the column vector of 0, then (5) and (6) two formulas are equivalent to
Now by Y=Xtx relaxes as Y>=Xtx; Or equivalently,
Z >=0 (i.e. Z positive semidefinite) (9)
The wireless sensor network Precise Position System of the embodiment of the present invention adopts location technology and the semi definite programming algorithm of SDS-TWR, have that good stability, positioning precision are high, fast operation and the advantage such as extensibility is strong, and can by precision controlling within 1M, in addition, because SDS-TWR location technology adopts linear frequency modulation spread spectrum, multi-path jamming, the RF noise jamming that may be able to exist in reduction system to greatest extent, adopt in method of measurement and come and go method of measurement, reduce the strict demand of location algorithm to system clock synchronization, semi definite programming algorithm uses method of convex programming to be similar to non-convex optimization problem simultaneously, it is high that system after optimization has positioning precision, the strong remarkable advantage of antijamming capability, therefore indoor accurate position is applicable to, such as underground coal mine is accurately located, Prison staff is accurately located, commercial building personnel assets are accurately located, (mine is searched and rescued in the scene of the accident, tunnel, building) etc., also outdoor positioning is applicable to, such as, location in Vehicular intelligent management, outdoor security guard patrol etc.
Accompanying drawing explanation
By the description carried out its exemplary embodiment below in conjunction with accompanying drawing, the above-mentioned feature and advantage of the present invention will become apparent and easy understand.
Fig. 1 is the framework schematic diagram of the embodiment of the present invention 1 Precise Position System;
Fig. 2 is that the one of the embodiment of the present invention is applied to downhole coal mine and accurately locates enforcement schematic diagram;
Fig. 3 is embodiment of the present invention wireless card reader block schematic illustration;
Fig. 4 is embodiment of the present invention Subscriber Identity Module block schematic illustration;
Fig. 5 is embodiment of the present invention SDS-TWR wireless distance finding work signaling scheme;
Fig. 6 is embodiment of the present invention SDS-TWR wireless distance finding method flow diagram.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail.
A kind of wireless sensor network Precise Position System, described system comprises:
One or more by localizing objects, described localizing objects comprises an identification card, for carrying out the mutual of information with one or more wireless card readers in wireless card reading base station that is arranged at, bilateral bidirectional ranging algorithm SDS-TWR is adopted to measure separately relative to the relative distance of each wireless card reader;
Server, for according to above-mentioned relative distance, adopts Semidefinite Programming algorithm to calculate the coordinate position determining each identification card.
Further preferably, described identification card specifically comprises:
Power management section, is used for carrying out Charge Management and/or power safety management;
Radio frequency control section, comprises output matching circuit, power monitoring, amplifier comparison circuit, receiving circuit, is used for sending ranging data bag to wireless card reader and receives packet from card reader to measure the distance with wireless card reader;
Processor unit, is used for coordinating radio frequency control section to carry out finding range, send/receive wireless data.
Further preferably, described receiving circuit comprises duplexer, filter, and described duplexer is used for controlling double antenna.
Further preferably, described identification card also comprises power saving management module, is used for according to the signal between identification card and wireless card reader strong and weak, automatically regulates the transmitting power of Subscriber Identity Module, realizes power saving management.
The embodiment of the present invention one is typically applied as colliery Precise Position System, further illustrates the workflow based on optimized algorithm Precise Position System below in conjunction with Figure of description 2.
As shown in Figure 2, its hardware is made up of following components: monitoring computer (industrial computer main frame and each one of guest machine), coffret, mining transmission substation, wireless card reading base station, Subscriber Identity Module (containing label), systems soft ware and tandem type data-signal lightning protection device form.Monitoring main frame installs system monitoring software and background data base, shows all monitoring informations; Subscriber Identity Module is worn by underground work personnel or moving target; Wireless card reading base station is arranged on to be needed to carry out in the tunnel following the tracks of and detect; Multiple stage wireless card reading base station in a series arrangement, is connected with substation by RS-485 bus or wireless transmission method.
As shown in Figure 2, first according to mine operational environment, along roadway direction, arrange wireless card reading base station in same side, tunnel and sustained height, the concrete coordinate in wireless card reading base station just can be measured when installation.The layout of wireless card reading base station needs the length considering tunnel, and the crossing instances in tunnel, angle of inclination, tunnel etc., between two wireless card reading base stations, ultimate range is no more than 400m.Adopt RS485 bus to connect between two wireless card reading base stations or wireless network connection, wireless network connection operating frequency is 2.4G, RS485 bus Configuration of baud rate is 9600bps.
After the staff wearing label card enters tunnel, first handshake exchange information is carried out between wireless card reading base station and label card, then distance is between the two measured, uploaded onto the server measuring the data obtained by RS485 bus in wireless card reading base station, server end passes through optimized algorithm, data are processed, obtains the accurate position coordinates of the relative wireless card reading base station of label card.Finally by the relative position coordinates between the known coordinate of wireless card reading base station and base station label card, calculate the exact position of label card in tunnel.
Be illustrated in figure 3 the composition schematic diagram of wireless card reading base station 2 in embodiment of the present invention Precise Position System.In Fig. 3, power management section 27, can be depressured to the operating voltage required by processor 26 by the intrinsic safety electric source of mine employing LDO.Under intrinsic safety electric source closes (or other is abnormal) situation, power management section 27 is automatically by above electrical source exchange to LiMn2O4 chargeable pond.In addition, power management section 27 can carry out Charge Management for lithium manganate battery, specifically comprises:
Charging current controls, and when cell voltage is less than 3V time, adopt precharge, charging current is 100mA; When cell voltage be greater than 3V be less than 4.1V time, adopt constant current charge, charging maximum current be 800mA, software can regulate charging current; When cell voltage be greater than 4.1V be less than 4.2V time, adopt constant voltage charge, last lithium manganate battery voltage reaches 4.2V.In addition power management section 27 also can too high for the charging voltage that may occur in charging process, rush the abnormal conditions such as electric current is too small, cell voltage is too high, cell voltage is too small and protect.
Processor unit 26 Main Function carries out swap data with control unit 25, thus realize wireless card reader and Subscriber Identity Module is directly found range, and sends broadcast message, the functions such as transmission time information.Processor unit 26 is realized by RS485 bus and transmits sub-station communication, and processor unit 26 is also compatible in addition, and Ethernet interface prepares against subsequent expansion.Charged by USB interface, the functions such as data download.
Control unit 25 is made up of microprocessor STM8L151G6, is communicated by UART with processor unit 26, and radio frequency control section 24 carries out Control on Communication by spi bus.
Duplexer logic is controlled by radio frequency control section 24, antenna 22 and antenna 21 form, these two antennas are all omni-directional, but under practical circumstances, current antenna is difficult to accomplish absolutely omnidirectional, therefore system double antenna, double antenna main purpose is the impact that measuring distance reduces, certainty of measurement is deteriorated eliminated RF blind area and reduce because wireless card reading base station and label card relative position bring.
Be illustrated in figure 4 the fundamental block diagram of Subscriber Identity Module 3 in embodiment of the present invention Precise Position System.In Fig. 4, power management section 36 mainly manages lithium manganate battery, comprises Charge Management, power safety management etc.Processor unit 35 Main Function be coordinate radio frequency control section 34 to carry out finding range, the operation such as transmission and reception wireless messages, power saving management, wherein, power saving management comprises:
For the signal power (RSSI of main monitor user ' identification card) between Subscriber Identity Module and wireless card reader, automatically regulate the transmitting power of Subscriber Identity Module, the maximum transmission power of Subscriber Identity Module is 16dbm, and having 64 grades can adjust; The PA mode of operation of Subscriber Identity Module is burst mode, and default setting is sleep 3 seconds, work 1 second of then wakeing up, periodic duty, and the concrete length of one's sleep and operating time software can freely be arranged; When Subscriber Identity Module does not communicate with wireless card reader for a long time, the length of one's sleep will lengthen gradually, such as, sleep 30 seconds, work 1 second of then wakeing up.
The PA part of radio frequency control section 34 is made up of output matching circuit, power monitoring, amplifier comparison circuit etc., can by maximum for the NA5TR1 power output 16dbm that adjusts to; The receiving circuit of radio frequency control section 34 is made up of duplexer, filter etc., and peak response is-95dbm.Antenna 31 and antenna 32 are controlled by duplexer 33, and it acts on the double antenna of similar wireless card reader.
As the ranging process that Fig. 5 and Fig. 6 is in embodiment of the present invention Precise Position System between wireless card reading base station (wireless card reader) and label card (Subscriber Identity Module).Ranging process is exactly mainly the process of a SDS-TWR (bilateral bidirectional ranging, SymmetricDoubleSide-TwoWayRanging).
In Fig. 6, preparatory stage 51 condition is: system is in non-ranging state and wireless card reader, Subscriber Identity Module are all successfully completed initialization.
Incipient stage 52, Subscriber Identity Module 3 will send packet to the wireless card reader of specific address (MAC Address appointment), if wireless card reader proper reception of this packet, wireless card reader will return hardware and reply to Subscriber Identity Module, and request produces transmission delay T1.
1 stage 53 of replying is divided into following steps:
A1. Subscriber Identity Module will call RangingCallback_Ack () to calculate transmission delay T1, these data are sent to wireless card reader by Subscriber Identity Module simultaneously, and wait for the hardware response of wireless card reader, if all do not replied more than 10ms wireless card reader, just think that this finds range unsuccessfully, need to restart.
B1. wireless card reader calls RangingCallback_Rx (), reads the relevant parameter that Subscriber Identity Module sends, and is that Subscriber Identity Module and wireless card reader second time are measured ready.
C1. wireless card reader is by calculating process time delay T2, and this parameter is passed to Subscriber Identity Module by RangingMode ().
In Fig. 5, Fig. 6,2 stages 54 of replying can be divided into following steps:
A2. Subscriber Identity Module receives the packet of wireless card reader, automatically will send hardware and reply to wireless card reader, and wireless card reader will calculate propagation delay T3 according to this response.
B2. wireless card reader utilizes RangingCallback_Ack () to calculate propagation delay T3, and these data are sent to Subscriber Identity Module, and waits for the hardware response of Subscriber Identity Module.
C2. Subscriber Identity Module utilizes the parameter that RangingCallback_Rx () reading wireless card reader passes over, and calculates T4.
D2. wireless card reader is by calling RangingMode (), and transmission delay T3 is sent to Subscriber Identity Module.
E2. Subscriber Identity Module obtains T3 by calling RangingCallback_Rx (), and end user calculates the distance of Subscriber Identity Module and wireless card reader by T1, T2, T3, T4.
F2. the time error that hypothesis optimization card brings due to crystal deviation is ea, assumed wireless card reader due to the time error that crystal error is brought be eb, then the flight time ideally between wireless card reader and Subscriber Identity Module is Tt:
G2. the crystal error of Subscriber Identity Module and wireless card reader is considered:
H2. T is supposed2=T4+ δ and Ttδ, then
I2. the words of twice range measurement principle are adopted:
By contrast: adoptmethod of measurement, compareshave a clear superiority in.
After received server-side to the distance value between identification card and wireless card reading base station, calculated the position of label card (Subscriber Identity Module) by semi definite programming algorithm.In computing network, the position of mobile node and Subscriber Identity Module is determined by two processes.
First process measures mobile node and the paired distance between the mobile node that can exchange or fixed-node (anchor point).The RF transceiver of the wireless sensor network supplier of the utilization obedience IEEE-802.15.4 standard of corresponding transducer has the ability of the spacing measuring adjacent mobile node.Each sensor collection range data and these data are sent to engine of positioning to do the location of the second process.
The location of second process utilizes known anchor point position and the distance measured in pairs between the node that obtains comes the position of the every other node of computing network.Above, the WSN orientation problem of the second process is the orientation problem that a multistep is transmitted.It is belong to mathematically with calculate on problem.Simple triangulation or polygon method of measurement cannot meet the demand of real application systems to Position location accuracy and coverage rate.A feasible method is the distance not only utilizing neighbouring anchor point, but also uses the neighbouring distance that can obtain other nodes of signal, and cause the orientation problem that so-called multistep is transmitted, it can improve Position location accuracy in a large number.
But, even if the network transmitted a very little multistep, accurately and expeditiously determine that the position of node is a difficult computational problem position.Employing Semidefinite Programming algorithm can with two wireless card readers with regard to energy consumer positioning identification card position.
Concrete methods of realizing is:
If mobile node set N and fixed-node (anchor point) set A, the wherein position { a of anchor pointk; K ∈ A} is given, the position { x of mobile nodei; I ∈ N} is unknown, needs, according to measuring some distance obtained in couples, to be determined by certain mode.
Wherein Eaand Enthe set of existing measuring distance between mobile node and anchor point and between mobile node and mobile node respectively.Present target will utilize formula (5) and (6) to determine the position { x of mobile node exactlyi; I ∈ N}.This problem is geometrically being seen, is the friendship of a lot of hypersphere, is proved to be np hard problem, there is not the algorithm with polynomial-time complexity.When the scale of problem becomes larger, solving of it just becomes very difficult.
In order to make a good approximate solution of trying to achieve former problem at short notice, the embodiment of the present invention introduces following matrix, and to attempt it to relax be a semi definite programming problem.
X is made to be all position vector x belonging to Ni; I ∈ N is as the matrix of row vector and Y=Xtx, Z=[I, X; Xt, Y], if we remember eibe i-th component be 1, all the other components are the column vector of 0, and so (5) and (6) two formulas are equivalent to
Now by Y=Xtx relaxes as Y>=Xtx; Or equivalently,
Z >=0 (i.e. Z positive semidefinite) (9)
(7)-(9) can by setting up semi definite programming, solve at polynomial time with softwares such as sedumi again, obtain an approximate solution of former orientation problem, compare traditional multiple didactic algorithm, it is high that semi definite programming algorithm has solving precision, the clear superiority that antijamming capability is strong.
Because label card is compared in wireless card reading base station, construct more complicated, therefore price also wants much expensive.Under some specific occasion, such as, between two wireless card reading base stations, under there are at least two label card situations, system can, by one of them label as base station process, utilize semi definite programming algorithm to orient position simultaneously.Particularly when in the more situation of wireless identification tag card, such as tens, system will select some label card as base station, measure with other label cards, which decrease the computational complexity of system, abandon the value that some obviously departs from simultaneously, improve the accuracy of system location.
The wireless sensor network Precise Position System of the embodiment of the present invention adopts location technology and the semi definite programming algorithm of SDS-TWR, have that good stability, positioning precision are high, fast operation and the advantage such as extensibility is strong, and can by precision controlling within 1M, in addition, because SDS-TWR location technology adopts linear frequency modulation spread spectrum, multi-path jamming, the RF noise jamming that may be able to exist in reduction system to greatest extent, adopt in method of measurement and come and go method of measurement, reduce the strict demand of location algorithm to system clock synchronization, semi definite programming algorithm uses method of convex programming to be similar to non-convex optimization problem simultaneously, it is high that system after optimization has positioning precision, the strong remarkable advantage of antijamming capability, therefore indoor accurate position is applicable to, such as underground coal mine is accurately located, Prison staff is accurately located, commercial building personnel assets are accurately located, (mine is searched and rescued in the scene of the accident, tunnel, building) etc., also outdoor positioning is applicable to, such as, location in Vehicular intelligent management, outdoor security guard patrol etc.
One of ordinary skill in the art of the present invention are appreciated that; the above embodiment of the present invention is only one of the preferred embodiments of the present invention; for length restriction; here can not all execution modes of particularize; any enforcement that can embody the claims in the present invention technical scheme, all in protection scope of the present invention.
It should be noted that; above content is in conjunction with concrete execution mode further description made for the present invention; can not assert that the specific embodiment of the present invention is only limitted to this; under above-mentioned guidance of the present invention; those skilled in the art can carry out various improvement and distortion on the basis of above-described embodiment, and these improve or distortion drops in protection scope of the present invention.