Background technology
In the monitoring of mine environmental parameter, the monitoring of gas bearing capacity is the most important, and this is because of the harm maximum that gas explosion accident causes in coal production, so gas monitor accurately is the important leverage of mine safety and personnel in the pit's life security.Gas is the general name of multiple inflammable gas, and the main constituent of gas is methane CH4 in the mine of China.Therefore, gas detects and is essentially the methane detection.Methane detection alarming instrument is mainly used in the place that there is gas explosion danger in the colliery, locates as colliery roadway, getting working face, goaf, return aircourse, belt haulage drift, dynamo-electric chamber etc.,
But the portable methane detector device of part support of wireless communication generally uses non-contact RF ID (less radio-frequency identification) technology of low-frequency range to realize detecting address and testing staff's identification at present.Instrument uses the infrared communication technology to realize the communication of image data, is generated form and data and data demonstration and is transmitted by computing machine.There is following problem:
1. the methane detection mode is manual regional detection mode, and namely operating personnel are after methane concentration has manually been detected in the perform region;
2. the methane detection mode is the fixed point detection mode, detect density and limited by the rfid interrogator distribution density,, operating personnel need arrive RFID location card-reading apparatus and carry out position and identity validation, detecting data could be corresponding with the detection position, can not accomplish to detect in real time and the location;
3. detecting data can not real-time report, the detected data of checkout equipment adopt the infrared communication technical communication to report more, the collecting device support of pairing need be arranged, need operating personnel's manual operation to realize, so the data that detection system collects are historical data and non-real-time data.
Methane checkout equipment based on wireless sensor network mostly is fixed equipment, portable equipment is also arranged but since wireless sensor network have following problem can not realize substantially the location:
1. the down-hole mostly is the wire environment that the tunnel is formed, and is different from the plane positioning environment of clearing, and the installation site of radio communication router is subjected to space constraint;
2. the loss model of wireless signal is affected by environment huge.
3.Zigbee the hardware positioning engine of communication chip inside is applicable to that the plane positioning environment is as the criterion, bearing accuracy is subjected to radio communication router distribution space position and restricted number is installed;
4. because down-hole electrical equipment requirement of explosion proof is higher, so the installation quantity of radio communication router is restricted, but the Zigbee wireless communication distance is shorter, there is not the radio communication router of sufficient amount can't satisfy the system communication requirement of down-hole long span, so in concrete engineering construction, have difficulties;
" Ad hoc network " is that a kind of special self-organization of formulating of IEEE802.11 standard committee is to equation multi-hop mobile communications network, in the Adhoc network, node has the message transfer capability, the forwarding of a plurality of intermediate nodes is passed through in communication between node possibly, namely pass through multi-hop (MultiHop), this is Ad hoc network and other mobile networks' fundamental difference.Node is coordinated mutually by procotol and the distributed algorithm of layering, has realized automatic tissue and the operation of network.Therefore it is also referred to as multi-hop wireless net (MultiHop Wireless Network), self-organizing network (SelfOrganized Network) or infrastructureless network (Infrastructureless Network), and the module of WI-FI wireless network is supported Ad hoc network simultaneously mostly.
The utility model content
The utility model purpose is to provide a kind of down-hole methane monitoring and positioning system, but the methane concentration of optional position under the monitor well, the environment temperature of optional position under the monitor well synchronously; Monitor methane pick-up unit user of service's position and motion state in real time; Realization is to the real-time monitoring of each position production environment of mine; When down-hole meet accident accident or disaster, when the fixed communication facility can't operate as normal, the methane pick-up unit can be used as environment measuring equipment in the mine rescue and personnel's search and rescue device uses.The methane monitoring of described down-hole and positioning system realize by following scheme:
1. described down-hole methane monitoring and positioning system comprise: system server, monitor terminal, wire communication subsystem, radio communication base station, methane pick-up unit; The wire communication subsystem comprises optical fiber, optical splitter and wireless exchange board; Radio communication base station comprises explosion-proof tank, power supply, reserve battery, radio reception device, antenna isolator and antenna; The methane pick-up unit comprises: processor, wireless communication unit, button, storage chip, display screen, LED light, temperature sensor, motion detection circuit; Wireless communication unit comprises wireless communication module and antenna; Motion detection circuit adopts 3-axis acceleration sensor; The installation radio communication base station that keeps at a certain distance away in the down-hole, radio communication base station connects aboveground wireless exchange board and system server by optical fiber; The methane pick-up unit is communicated by letter by wireless mode with radio communication base station; The methane pick-up unit by 3-axis acceleration detection record user of service walk step number and the monitoring its vital movement feature; The methane pick-up unit is accurately located apart from realization based on the pacing of field intensity positioning combination meter.
2. this system further comprises: methane pick-up unit and system server are realized two-way communication by wire communication subsystem and radio communication base station.
3. this system further comprises: the methane pick-up unit detects the place environment temperature by thermal sensing element or controller built-in temperature detecting unit, and temperature information is uploaded to system server together with accurate location information by communication.
4. this system also further comprises call device, the processor real-time monitoring human activity of described call device, when the processor certain hour does not detect any physical activity or then triggering warning automatically of button operation, outwards transmit warning by radio communication and acousto-optic mode, enter the calling for help state.
5. this system further comprises: the communication protocol built-in has system time when system server and methane pick-up unit downlink communication, the methane pick-up unit is adjusted internal clocking after the parsing time consistent with system time, the clock of all methane pick-up units is synchronous in the realization system, when reporting methane concentration and temperature, attaches the methane pick-up unit correct time simultaneously, even information communication is because link problem postpones, system also can obtain the historical record of methane concentration, temperature and position accurately.
6. this system further comprises: when the methane pick-up unit detects the warning value that the methane concentration in the environment surpass to set, sound and light alarm, and report to the police to system server by communication, just often upload in real time at communication link, when communication link is obstructed, the operation this time of communication subsystem record, communication link is just often uploaded automatically again by the time.
7. this system further comprises: the processor control wireless communication unit of methane pick-up unit is realized downlink communication, the communication with dispatch instructions that the receiving system server issues and information warning, and be stored in the storage chip, remind the wearer to read by acousto-optic hint simultaneously.
8. this system further comprises: the processor of methane pick-up unit control wireless communication unit realizes and the uplink communication of system server that the information content of uplink communication comprises: methane concentration, temperature, position and preset warning message.
9. this system further comprises: the methane pick-up unit presets warning message and comprises: fire, floods, gas are gushed out, roof accident, mechanical disorder, shipping accident, injury to personnel, request relief.
10. this system further comprises: the uplink information that the methane pick-up unit sends is just often uploaded in real time at communication link, and when communication link was obstructed, the processor for recording of methane pick-up unit is operation this time, and communication link is just often uploaded automatically again by the time.
11. this system further comprises: when cordless communication network lost efficacy, near other radio communication device the methane pick-up unit can be searched for.
12. this system further comprises: the methane pick-up unit can moment testing environment methane concentration in the search and rescue process.
Embodiment
Below in conjunction with the drawings and the specific embodiments the utility model is further described.
As shown in Figure 1, downhole monitoring system:
The methane monitoring of described down-hole and positioning system comprise: system server (1), wire communication subsystem, radio communication subsystem, methane pick-up unit (3).The wire communication subsystem is the backbone of total system, and the wire communication subsystem is main transmission medium with optical fiber.The wire communication subsystem also comprises optical splitter, wireless exchange board network management devices such as (5).Keep at a certain distance away in the down-hole radio communication base station (2) is installed, radio communication base station connects aboveground system server by optical fiber.The radio communication base station major function is the WI-FI wireless access, and radio communication base station comprises power supply, reserve battery, radio reception device and antenna.Radio reception device is called AP (Access Point) in standard WI-FI network, be responsible for wireless terminal device and insert wired ethernet, by radio communication base station the WI-FI WLAN (wireless local area network) is covered each tunnel.Each AP is assigned service set identifier SSID and different physical addresss, supervisory system is according to the different radio communication base station of sign difference of AP, radio communication base station is supported the trans-regional roaming of wireless terminal device, radio communication base station is used as location reference point when the computing of location simultaneously, the positional information of radio communication base station and identification information are stored in the storage subsystem of system server and methane pick-up unit, for the location computing provides foundation.The methane pick-up unit inserts the WI-FI WLAN (wireless local area network) as standard WI-FI terminal device and communicates by letter with aboveground system server.System server is responsible for system communication management, data storage and the information service of personnel and equipment is provided for monitor terminal.The production management personnel are by the real-time monitoring of monitor terminal (4) access system server realization to underground work personnel, subsurface environment and relevant device, monitor terminal has map and shows, location of personnel, staff's data show inquiry, the location of personnel statistics, historical position is followed the trail of functions such as inquiry, regional environment methane and temperature display alarm.Geographical information platform can use MapX mapable parts, and the mine map is the map vector of tunnel two dimensional cross-sectionization, and map file is the MapInfo form.
In embodiment illustrated in fig. 2, methane pick-up unit hardware is formed and is comprised with the lower part:
1. processor (206) is selected the MSP430F147 single-chip microcomputer of TI company.This model is 16 risc architectures, has 32kFlash, 1kRAM; And 5 kinds of low-power consumption modes are arranged, abundant sheet inner peripheral module, plurality of advantages such as clock system flexibly.MSP430 can work under 1.8~3.6V low-voltage, and system adopts the 3.3V operating voltage.The built-in precision of MSP430F147 is the A/D converter of 12 200kps.1 non-linear differential error, 1 non-linear integral error, 4 kinds of analog to digital conversion patterns.
2.WI-FI communication (207) part comprises WI-FI communication module and antenna, the WI-FI communication module adopts and encrypts networking control chip CO2128 with the iChip series of ConnectOne company is the product of the scheme of core, and inside modules comprises radio-frequency module, communication interface modules, state control and detection module and storer; Antenna adopts flexible antennas.
3. button (204) control circuit is made up of 4 buttons, adopts independent button keyboard, in conjunction with the display interface of display screen, realizes the switching of each function and state.
4. storage (205) chip adopts 1 24C512, because described methane pick-up unit has only used a storage chip, chip select address need be set, so the sheet of 24C512 clicks the whole ground connection of pin.24C512 uses the I2C bus communication,, use two standard I/O interfaces to add and draw resistance to connect SCL and SDA pin, realize processor and storage chip Control on Communication.
5.LCD display screen (201) adopts two row dot matrix type LCD MODULE, have characteristics such as low in energy consumption, that the supply voltage range is wide, ken size: 60.5 * 18.0mm, 54.8 * 18.3mm, processor shows data by 8 I/O mouths to the Liquid Crystal Module transmission, drives the control Liquid Crystal Module by 4 I/O mouths in addition.
6.LED pilot lamp (202) adopts two paster LEDs, be respectively red and green, green as the system state indication, state comprises power supply indication and charging indication etc., red LED is indicated as information state, and state comprises information indication, warning indication and calls for help indication etc.
7. hummer (202) adopts passive hummer.
8. temperature sensor (211) hardware components comprises thermo-sensitive resistor and wheatstone bridge, thermo-sensitive resistor has good linearty, and precision height, good reliability, by the thermo-sensitive resistor resistance variations of wheatstone bridge measurement as temperature-sensing element (device), thermo-sensitive resistor directly is converted to the variation that bridge is pressed as one of them arm resistance with the changes in resistance amount.The module kernel of the ADC12 of MSP430147 shares, and finishes respectively by the analog switch of front end and gathers input.So the brachium pontis optional arbitrary mouth that connects 12 AD analog quantity inputs in thermo-sensitive resistor place is pressed for detection of bridge and is changed, and needs carry out software filtering by processor for detected signal.MSP430F147 Chip Microcomputer A/D changes the reference data voltage that reference data voltage can use outside input, and the reference data voltage that also can use internal reference voltage generator to produce can be finished A/D conversion setting by the ADC12CTL control register is set.Owing to use the single-chip microcomputer internal reference voltage can increase the power consumption of processor, consider for the Design of power saving of device, select external reference voltage for use, with the working time of assurance device.
9. motion detection circuit (210) uses the SMB380 3-axis acceleration sensor, the vibration that traditional mechanical type passometer adopts reed or elastic force bead to detect and goes on foot generation when the people walks judges that by internal processor electronic impulse realizes that meter goes on foot, adopt this mode can't distinguish walking and other movable vibration that produces, sensitivity and accuracy are not high.Use 3-axis acceleration sensor can measure three orthogonal axles and in the terrestrial attraction scope, keep static state and dynamic acceleration on the absolute direction, can detect the vibration that general physical activity produces, the signal of gathering is digital signal, and collection result is transferred to processor by the SPI interface.
10. serial communication (208) uses the MAX232 chip rs-232 standard serial ports single supply level transferring chip of TI company, use+5v single power supply, and interface uses the SMT2.5 socket, can use transit cable to connect computing machine 9 needle serial ports and realize communication.
11. power circuit (209) part comprises battery, voltage transitions and battery management part; battery uses lithium-ions battery; lithium battery (group) should have anti-reverse function; have outside the internal protection circuitry; has outer holding circuit; possess anti-overcharge, prevented putting, functions such as overcurrent, short circuit, also have equalizaing charge, balanced discharge function.Voltage transitions adopts MAX1724 series power supply conversion voltage stabilizing chip, is converted to the stable operating voltage of 5V, 3.3V and 3V, is respectively LCD display, system and sensor power supply.Battery charger adopts the LM3658 chip of TI, 2.5~6V input voltage, and output current can be up to 1A, and the actual size of electric current can be regulated by external resistance, and built-in power fet can be adjusted charging current automatically according to environment temperature.
12. methane detects (methane transducer, testing circuit, amplifying circuit, A/D conversion) (212).Methane transducer adopts carrier catalyst element to comprise black element and white element, and black element is a kind of to the very sensitive carrier catalyst element of methane gas, and white element is compensating element,, to the methane gas Fails To Respond.Methane transducer is the key element that determines the detector precision, and it is selected according to mainly comprising working environment, stability, response speed, the linearity and power consumption etc.As shown in Figure 3, testing circuit is that methane transducer and resistance are formed resistance bridge, carrier catalyst element is two arms of electric bridge, during no methane gas, electric bridge is in equilibrium state, exothermic oxidation reaction takes place when methane gas enters the inherent thermocatalysis sensing element of sensor air chamber surface, the temperature of element is raise, resistance becomes big thereupon, the voltage output of electric bridge is uneven, according to the concentration of change in voltage detection methane gas, in certain methane concentration scope, produce the DC voltage change signal that is proportional to methane concentration.Amplifier circuit adopts the AD620 integrated operational amplifier, is responsible for the voltage signal of amplification sensor output.12 inner integrated ADC of MSP430 are used in the A/D conversion, and ADC12 selects inner 2.5V reference voltage.Be input to MSP430F147 after the weak voltage signal of electric bridge output is handled through operational amplifier and carry out the A/D conversion.Need the methane pick-up unit is calibrated when reality is used, concrete calibration process subsystem component below is introduced.
Among the embodiment, the system of methane pick-up unit forms and comprises as shown in Figure 4:
1. acquisition subsystem (401) is responsible for the collection of device input signal, comprising: temperature information collection, methane detection, the collection of motion detection signal, actuation of keys collection.
2. motion detection section is responsible for the acquisition process of 3-axis acceleration sensor signal, use the acceleration signal on three directions of buffer memory, X is the value of X-direction, Y is the value of Y direction, Z is the value of Z-direction, getting the axle of velocity variable maximum counts the step, according to the statistical measurement common people run per second be no more than 5 the step, low-speed running is not less than 1 step of per second, can be with the effective range of 0.5-5Hz as the signal in meter step, remove high frequency noise by low-pass filtering, data realize the accurately meter step through computing such as characteristic matching on reference to other axle.Use the method meter step not limited by methane pick-up unit wearing position, the user can be contained in the optional position with oneself with the methane pick-up unit, as the clothing pocket of packing into up and down, is fixed on the waistband or in the knapsack, is not subjected to all not influence accurate meter and goes on foot.By three data analysis, also can detect other human motion simultaneously.The filtering algorithm of temperature and methane signal adopts simple and effective limit filtration algorithm in conjunction with the arithmetic mean filtering algorithm, namely determines the maximum deflection difference value P that double sampling allows, x
nBe this collection value, x
N-1For collection last time value, as x
n-x
N-1Then this time the collection value is effective for≤P, otherwise abandons this sub-value, uses sub-value and replaces, be i.e. x
n=x
N-1, can effectively remove the impulse disturbances that accidentalia causes through limit filtration, carry out arithmetic mean filtering in the time of limit filtration, with x
1... x
nThe computing of averaging of n collection value
Then will go up the mean value x that obtains of step computing brings calibration equation into and asks actual value.
3. positioning subsystem (402), be responsible for gathering peripheral WI-FI access point to the signal strength of module from the WI-FI communication module, and according to the positional information of field intensity signal, access point, the step-length step number computing that is used in combination personnel obtains the position of methane pick-up unit, is uploaded to system server by communication subsystem.
4. communication subsystem (403) is responsible for communicating by letter of device and system and external device, comprises that the WI-FI radio communication controls the UART Control on Communication.The communication protocol of methane pick-up unit comprises two parts: first is external protocol, is the communication protocol between methane pick-up unit and system server; Second portion is internal agreement, is the processor of methane pick-up unit and the agreement of Wi-Fi module, and producer's difference of Wi-Fi module then this agreement is also different.Wherein first's agreement is the important component part of Design of Monitoring and Control System, can independently define, and it does not rely on concrete Wi-Fi equipment and module manufacturer.The based on network application layer of the realization of external protocol is on the tcp/ip layer, and data link adopts TCP or UDP mode, and the external communication protocol structure is divided into information header and the information content.Information header comprises frame head, device id, and frame total length (containing information header and imformosome), frame type, 4 contents of frame serial number take double byte length respectively.The external protocol content can be according to the functional requirement expansion of system.
5. display subsystem (404) is responsible for the driving of LCD screen of device and the demonstration of information.
6. control subsystem (405), hardware cells such as hummer, LED, the LCD that is responsible for control device is backlight, power supply are realized function separately.
7. storage subsystem (406) is responsible for communicating by letter between control device and the storage chip, realizes storage and the read operation of data.Canned data comprises positional information, methane concentration information and ambient temperature information etc.
In embodiment illustrated in fig. 5, the methane of methane pick-up unit and temperature detection workflow as shown in the figure:
The conversion value (501) that processor reads the A/D of methane concentration and temperature deposits internal memory in, change the conversion times of stipulating (502) as arriving after the multiple conversions, depositing A/D conversion value is carried out software filtering (503) filtering algorithm adopt the limit filtration algorithm in conjunction with the arithmetic mean filtering algorithm, detailed process subsystem component is in front described in detail; To bring the realistic border of calibration equation methane concentration value and temperature value (504) into through the value that the software filtering computing obtains, position computing (505), send display subsystem to show (506) methane concentration value and temperature value, deposit methane concentration value, temperature value, position and data acquisition time in storage chip (507); If methane concentration exceeds standard (508), then sound and light alarm (509) just uploads data to server (511) as communication link normal (510); As communication link not general rule continue gatherer process, when recovering to communication link institute's deposit data is not sent data and is sent to server.
In embodiment illustrated in fig. 6, methane pick-up unit communication process example is as follows:
The methane pick-up unit is set up TCP with the system server communicating pair in client-server end mode and is connected (601), pick-up unit is as client connected system server fixed ip address and port, system server terminal is that server side uses fixed ip address and fixed port, and up-downgoing information is transmitted based on the TCP link channel.When not having data transmission on the link channel, pick-up unit should send link detecting packet (603) every time S (602) and connect to keep TCP, system picks up counting, as receive that answer then resolves reply content and obtain system time information, according to system time calibration detection apparatus clock (607), after the link detecting packet sends overtime K, do not receive answer (604), send link detecting bag (603) immediately again; Do not receive yet that after continuously sending R time (605) answer judges that then link is invalid, data receiver initiatively disconnects this connection (608) repetition TCP connection procedure (601); If TCP fails successful connection, then reconnect network every time G (606).Parameter S, K, R, G can set according to link condition, with reference to value are: S=3min, K=30s, R=3, G=20s.
Fig. 7 is methane pick-up unit workflow diagram, behind the initialization system, pick-up unit is searched for other radio communication device (701) automatically, pick-up unit has Ad hoc networking function, when pick-up unit arrives the communication distance of other radio communication device, pick-up unit is other radio communication device distributing IP address (702), pick-up unit is accepted the connection (703) of other radio communication device, communication link (704) is set up in the open communication service, after the link establishment success, other radio communication device regularly detects the signal strength of pick-up unit, and other radio communication device sends field intensity information and the device number (705) of self by the communication link with the methane pick-up unit to the methane pick-up unit.The methane pick-up unit is resolved the signal strength that obtains the detected methane pick-up unit of other radio communication device after receiving the information that other radio communication device sends, with field intensity substitution experimental formula
Calculate the distance (706) of pick-up unit and other radio communication device; There is temperature sensor methane pick-up unit inside, has temperature detecting function, periodic monitor environment temperature (707); Show the ID (identity number) of other radio communication device of signal strength and the user's that other radio communication device is sensed last activity time by LCD screen, search and rescue person can this as reference of judging the captive active state; The methane pick-up unit is according to sending sound and the light (708) of different interval frequency with the distance of other radio communication device, the more short sound of distance and light flash frequency are more high, the user can not see LCD display, only namely know the distance of trapped personnel by listening or observation lamp optical flare situation, in order to improve search-and-rescue work efficient; LCD display shows real time temperature; The methane pick-up unit has time clock feature, can show the current time in real time, can make the user can grasp correct time in real time.The rescue worker can be shielded display reminding and operation push-button methane pick-up unit is set to upload recording status (709) by LCD, revise the WI-FI communication module in the communication subsystem of uploading methane pick-up unit processor under the recording status (710) are set, its duty is set to common WI-FI network terminal node mode, near the radio communication base station (711) of the operate as normal search of methane pick-up unit, as finding then to connect into automatically the WI-FI network, connected system server TCP serve port sends the searching record of not uploading (712) in the TCP mode, after whole records are uploaded, recover the WI-FI communication module automatically and change Ad hoc networking working method (713) over to, continue other radio communication device 701 of search).
In embodiment illustrated in fig. 8, the implementation procedure of personnel positioning is as follows:
In system's initial procedure of methane pick-up unit, at first the height record T according to the methane pick-up unit user of service who stores obtains its actual step size (801) by following formula:
N=1.85(T-132)
The field intensity (802) that methane pick-up unit periodic monitor and each radio communication base station transmit, when the personnel in the pit carries the walking of methane pick-up unit near radio communication base station, field intensity is to peaking, with the position of this radio communication base station current location as the methane pick-up unit, as once reliably locating storage radio communication base station numbering, this position as when prelocalization reference point (803), is begun the meter step simultaneously.The step number M of methane pick-up unit real time record personnel through walking behind the radio communication base station multiply by the methane pick-up unit user of service's who self stores individual step-length, can obtain the distance (804) of personnel and prelocalization reference point; If step number is M, step-length is N, and then the methane pick-up unit with the distance L of working as the prelocalization reference point is:
L=MN
Direction is judged (805), as shown in Figure 9, judge personnel in the pit's (904) direct of travel according to the reliable locator data of the last time of recording, the radio communication base station of accurately locating as last time is A (901), this time accurately the radio communication base station of location is B (902), and the direct of travel that then can judge personnel is to be moved to wireless base station B direction by radio communication base station A; Also can judge direction according to the field intensity variation tendency of the detected radio communication base station of methane pick-up unit (3), detect the field intensity of two adjacent wireless base stations when the methane pick-up unit, as the field intensity variation tendency that detects radio communication base station B (902) is to diminish gradually, and the field intensity variation tendency of radio communication base station C (903) is to become big gradually, judges that then direct of travel is to be moved to radio communication base station C direction by radio communication base station B; Error judgment (806), according to the next one location reference point on methane pick-up unit user of service's the direct of travel judgement moving direction, greater than when the distance between prelocalization reference point and the next location reference point, illustrate then that there is error in this distance value as the value of distance L, as with reference to being worth; Detect the signal strength value Rd1 when prelocalization reference point place radio communication base station (902) and next location reference point place radio communication base station (903), Rd2 (807); Calculate distance (808) according to field intensity, with field intensity bring into the following formula of substitution obtain methane pick-up unit and radio communication base station (902) and (903) apart from d1, d2.
A is that signal is propagated the power that 1m receives signal when far away in the formula;
N is that propagation factor is also referred to as loss index, and its numerical values recited depends on the propagation of wireless signal environment;
The signal intensity of the radio communication base station that Rd receives for other radio communication device, i.e. RSSI value;
X
δGaussian distribution normal random variable for zero-mean
As shown in figure 10, get d1, d2, the value at three public parts of distance common factor of L center is as the d (809) of methane pick-up unit with the distance of working as prelocalization reference point place radio communication base station (902); The methane pick-up unit is arrived the curvilinear equation of tunnel on map apart from d substitution two radio communication base station places of working as prelocalization reference point place radio communication base station (902), can obtain the current coordinate (810) of methane pick-up unit, as shown in Figure 9, the tunnel of establishing two radio communication base station places is respectively (x for line endpoints always
1, y
1), (x
2, y
2), will apart from d and two point form straight-line equation solve an equation namely obtain other radio communication device coordinate (x, y)
, the position computing is finished in conjunction with map vector data by system server.