CN104809908B - Method of ZigBee network based vehicle positioning in indoor parking area environment - Google Patents

Abstract

The invention discloses a method of ZigBee network based vehicle positioning in indoor parking area environment. According to the method, a ZigBee wireless sensor network is established in an indoor parking area, the network is divided in a time division and zoning manner to calculate the distance between a to-be-positioned vehicle and a positioning terminal node, distance calculation precision is improved, further vehicle positioning precision is improved, and quick and accurate guide to the vehicles in the indoor parking area environment is realized beneficially.

Description

Vehicle positioning method based on zigbee network under the environment of parking garage

Technical field

The invention belongs to vehicle positioning technology field, more particularly, to it is based on zigbee network under a kind of environment of parking garage Vehicle positioning method.

Background technology

Intelligent transportation occupies very important status in City road traffic system, carries out reasonably for urban transportation Planning, control, monitoring and induction, to the efficiency improving urban road network and the living standard improving urbanite, have Important meaning.Vehicle positioning system is one of important support technology of intelligent transportation, and vehicle is as the just determination of mobile node Potential energy is enough intuitively and effectively observed to the running status of urban transportation and controls.

For realizing, under the environment of large-scale parking garage, vehicle is automatically led to purpose parking stall planned in advance, need head First solve vehicle indoors parking lot travel during orientation problem.Because, under parking lot environment indoors, navigator is connect The satellite-signal receiving is generally relatively fainter, reduces efficiency and the accuracy of vehicle positioning stop.Therefore, more and more interior is stopped Indoor parking to be realized from the wireless communication technology of multi-point in parking lot.At present, conventional wireless communication technology includes: bluetooth, Wifi, rfid, zigbee, ultra-wideband communications, gprs, 3g, 4g etc., considering cost, power consumption, operating distance, precision, network The many factors such as capacity, typically preferably adopt the vehicle location scheme based on zigbee technology of wireless sensing network.Based on zigbee The vehicle positioning technology of radio sensing network is to connect business-like zigbee module on the smart mobile phone of vehicle, in vehicle In moving process, this module is realized vehicle location is determined by carrying out communicating with the zigbee positioning terminal node of vehicle periphery Then positional information is passed to the navigation module in smartphone software by position, and navigation module utilizes current vehicle position information And the electronic chart in parking lot, finally realize the Route guiding to purpose parking stall.

According to the location technology theory based on received signal strength indicator rssi and transmission of wireless signals in Zigbee-technology Shadowing model in field, the intensity of receipt signal with transmitting-receiving internodal from relation be:

$p_l\left(d\right)=p_l\left(d_0\right)-10\mathrm{nlg}\left(\frac{d}{d_0}\right)+x_d$

Wherein, d is the distance between transmitting terminal and receiving terminal, and unit is m；d₀For reference distance, unit is m；p_lD () is to connect The received signal power of receiving end, unit is dbm；p_l(d₀) it is apart from d₀The received signal power at place, unit is dbm；x_dIt is to obey The stochastic variable of Gauss distribution, average is zero, and unit is dbm；N is path attenuation index, and it represents that rssi value increases with distance Plus and the speed of decay.When carrying out a large amount of, independent measurement, x can be made_d=0 (dbm), now has:Wherein,For receipt signal mean power, unit is dbm；A be away from send out The opposite number of the received signal power at sending end 1m, unit is dbm.For example: if put down in the receipt signal at transmitting terminal 1m All power is -30dbm, then the value of parameter a is 30, after above formula is deformed, can obtain:As can be seen here, if Known parameters a and the value of n, are averaged through multiple measurement and obtainAfterwards, you can calculate the distance between transmitting-receiving node, if tool There is the distance measure of more than 3, node to be positioned can be determined according to triangle centroid localization algorithm or Maximum Likelihood Estimation Method Coordinate.The precision of a and n is the key factor determining range finding or even positioning precision, the value of this two parameters not only with wirelessly Home environment during signal transmission is relevant, also can change in time, therefore brings very big difficulty to their measurement. Relatively more traditional method is empirical value method, that is, carry out substantial amounts of experiment measurement in positioning occasion before positioning, by linear regression Method determine the value of a and n.Specific implementation process is: in area to be targeted, the discharger of a fixation is installed first, Then put reception device, the distance between accurate measurement discharger and reception device at certain position, gather one group of rssi value And be averaging；Next, pressing mobile route planned in advance, reception device being moved to another location, repeating said process；This The measurement process of sample repeats down always, until whole region is finished by the mobile route institute " covering " of reception device.Corresponding Coefficient formulas are:

$\begin{array}{cc}\hat{n}=-\frac{\underset{i=1}{\overset{m}{\mathrm{\σ}}}(\lg d_i-\stackrel{\&overbar;}{\mathrm{lgd}})({\mathrm{rssi}}_i-\stackrel{\&overbar;}{\mathrm{rssi}})}{10\underset{i=1}{\overset{m}{\mathrm{\σ}}}{(\lg d_i-\stackrel{\&overbar;}{\mathrm{lgd}})}^2}& \hat{a}=-\stackrel{\&overbar;}{\mathrm{rssi}}-10\hat{n}\·\stackrel{\&overbar;}{\mathrm{lgd}}\end{array}$

In formula, m is the points of measurement, d_iFor the accurate distance between transmitter and i-th receiving point,For m distance value Meansigma methodss after taking the logarithm, rssi_iIt is the meansigma methodss of the rssi value obtaining in the multiple measurement that i-th receiving point is carried out,For m rssi_iThe meansigma methodss of value.Can be seen that from above-mentioned measurement process, the workload of traditional method is very big, and The change in time with space for a and n cannot be reacted.

As can be seen here, prior art awaits further improving.

Content of the invention

The present invention is the weak point avoiding above-mentioned prior art to exist, there is provided be based under a kind of environment of parking garage The vehicle positioning method of zigbee network.

The technical solution adopted in the present invention is:

Vehicle positioning method based on zigbee network under the environment of parking garage, the method comprises the following steps:

Step 1: zigbee wireless sensing network system, zigbee radio sensing network system are set in parking lot indoors System, including a zigbee network, one central node of setting, several router nodes and quantity in zigbee network More terminal nodes, terminal node is included for treating the positioning terminal node that positioning vehicle is positioned；Vehicle to be positioned Driver hold smart mobile phone, smart mobile phone is furnished with zigbee module, vehicle to be positioned sends positioning by smart mobile phone Request；

Step 2: according to the distribution of parking stall in parking garage, region division is carried out to above-mentioned positioning terminal node, is allowed to It is divided into the region of several non-overlapping copies, and each region is numbered, each region is triangular in shape or tetragon, positioning is eventually Leaf is arranged on each triangle or the summit of tetragon, in each region, each positioning terminal node and adjacent Two positioning terminal nodes carry out direction communication；

Step 3: the coordinate of each positioning terminal node in each region above-mentioned is carried out calculating adjacent two tops after accurate measurement Distance between point, and two undetermined constants drawing some positioning terminal node surrounding in region are calculated according to following formula a_i、n_i:

$\left\{\begin{array}{c}{\stackrel{\&overbar;}{\mathrm{rssi}}}_{i1}\left[\mathrm{dbm}\right]=-(a_i+10n_i\·\lg d_{i1})\\ {\stackrel{\&overbar;}{\mathrm{rssi}}}_{i2}\left[\mathrm{dbm}\right]=-(a_i+10n_i\·\lg d_{i2})\end{array}\right.$

Wherein, d_i1And d_i2For the 1st and the 2nd adjacent positioned terminal knot of i-th positioning terminal node and surrounding in region Distance between point,WithReceive around the 1st and the 2nd adjacent positioned for i-th positioning terminal node in region The mean power of terminal node signal transmitted；

Step 4: according to the distance value d calculating_i1And d_i2, and measured valueWithCalculate a_iAnd n_i, and A by positioning terminal nodes all in region_iAnd n_iTake the average value as a and n in this region, draw:

$\left\{\begin{array}{c}\stackrel{\&overbar;}{a}=\frac{1}{l}\underset{i=1}{\overset{l}{\mathrm{\σ}}}{a}_i\\ \stackrel{\&overbar;}{n}=\frac{1}{l}\underset{i=1}{\overset{l}{\mathrm{\σ}}}{n}_i\end{array}\right.$

Wherein,WithFor the meansigma methodss of two undetermined constants in this region, l is the individual of positioning terminal node in this region Number；

When the entrance in parking lot or exit have detected vehicle entrance or left, router is passed through by central node Node sends order to each positioning terminal node, and each positioning terminal node is communicated with neighbouring positioning terminal node, to a_iAnd n_i's Value is updated, and the undetermined constant again calculatingWithAfter vehicle to be positioned proposes Location Request, all with its at Positioning terminal node in energy direct communications range all can respond, and sends residing for positioning terminal node to vehicle to be positioned The meansigma methodss of a and n in region, because some positioning terminal nodes are generally divided to multiple regions, so this kind of positioning terminal knot Point can send the meansigma methodss of multiple a and n and the numbering in corresponding region, and the smart mobile phone of vehicle to be positioned receives neighbouring After positioning terminal node feedack, the region selecting numbering occurrence number most carries out next step；

Step 5: calculated between the vehicle to be positioned entering certain region and the positioning terminal node of selection area by following formula Apart from d,

$d_i={10}^{-\frac{(\stackrel{\&overbar;}{a}+\stackrel{\&overbar;}{{\mathrm{rssi}}_i})}{10\stackrel{\&overbar;}{n}}}$

Wherein, a and n takes the meansigma methodss in step 4,For receipt signal mean power.

Step 6: after calculating the distance between more than 3 above-mentioned vehicles to be positioned and positioning terminal node, by triangle Shape centroid localization algorithm or Maximum Likelihood Estimation Method calculate the coordinate of vehicle to be positioned.

It is provided with power amplifier module on each described positioning terminal node.

Terminal node in described step 1 also includes the monitoring terminal node for monitoring parking space state, and positioning terminal is tied Point no communicates between monitoring terminal node, between adjacent two monitoring terminal nodes；Described router node is arranged on several The center of the ring of encirclement of monitoring terminal node, router node is used for trunking traffic.

In described step 2, central node and router node adjacent thereto communicate, and central node is arranged on parking lot Porch or exit or center position.

Due to employing technique scheme, having the beneficial effect that acquired by the present invention

The invention provides timesharing subregional vehicle location algorithm under a kind of environment of parking garage, contribute to vehicle Quickly and accurately it is directed on target parking stall planned in advance, have that locating speed is fast, high precision, real-time are good etc. significantly Advantage.

Brief description

Fig. 1 is the overall structure diagram of the present invention.

Fig. 2 is the region division schematic diagram of the present invention.

Fig. 3 be do not consider a and n in time with spatial variations in the case of, the time dependent signal of maximum positioning error Figure.

Fig. 4 is not consider that a and n changes over, in the case of only considering a and n with spatial variations, maximum positioning error with The schematic diagram of time change.

Fig. 5 is both to consider that a and n changed over, it is further contemplated that in the case that a and n is with spatial variations, maximum positioning error with The schematic diagram of time change.

Specific embodiment

The present invention is described in further detail with specific embodiment below in conjunction with the accompanying drawings, but the present invention is not limited to These embodiments.

As depicted in figs. 1 and 2, the vehicle positioning method based on zigbee network, the method bag under the environment of parking garage Include following steps:

Step 1: zigbee wireless sensing network system, zigbee radio sensing network system are set in parking lot indoors System, including a zigbee network, one central node of setting, several router nodes and quantity in zigbee network More terminal nodes, central node and router node adjacent thereto communicate, and central node is arranged on entering of parking lot Mouthful place or exit or center position, terminal node includes tying for treating the positioning positioning terminal that positioned of vehicle Point；For reducing the laying amount of positioning terminal node, each described positioning terminal node is provided with power amplifier module, thus expanding The big direct communications range of positioning terminal node；Described terminal node also includes tying for the monitoring terminal monitoring parking space state Point, between positioning terminal node and monitoring terminal node, no communicates between adjacent two monitoring terminal nodes；Described router node It is arranged on the center of the ring of encirclement of several monitoring terminal nodes, router node is used for trunking traffic；Vehicle to be positioned Driver hold smart mobile phone, smart mobile phone is furnished with zigbee module, vehicle to be positioned sends positioning by smart mobile phone Request；

Step 2: according to the distribution of parking stall in parking garage, region division is carried out to above-mentioned positioning terminal node, is allowed to It is divided into a, b, c, d ... and waits the region of several non-overlapping copies, each region is triangular in shape or tetragon, positioning terminal node It is arranged on each triangle or the summit of tetragon, in each region, each positioning terminal node and adjacent two are fixed Position terminal node carries out direction communication；

Step 3: the coordinate of each positioning terminal node in each region above-mentioned is carried out calculating adjacent two tops after accurate measurement Distance between point, and two undetermined constants drawing some positioning terminal node surrounding in region are calculated according to following formula a_i、n_i:

$\left\{\begin{array}{c}{\stackrel{\&overbar;}{\mathrm{rssi}}}_{i1}\left[\mathrm{dbm}\right]=-(a_i+10n_i\·\lg d_{i1})\\ {\stackrel{\&overbar;}{\mathrm{rssi}}}_{i2}\left[\mathrm{dbm}\right]=-(a_i+10n_i\·\lg d_{i2})\end{array}\right.$

Wherein, d_i1And d_i2For the 1st and the 2nd adjacent positioned terminal knot of i-th positioning terminal node and surrounding in region Distance between point,WithFor i-th positioning terminal node in region receive around the 1st and the 2nd adjacent fixed The mean power of position terminal node signal transmitted；

Step 4: according to the distance value d calculating_i1And d_i2, and measured valueWithCalculate a_iAnd n_i, respectively The positioning terminal node in region calculates a of oneself_iAnd n_iAfterwards, central node, central node meter are transferred to by router node It is transferred to each positioning terminal node, each positioning terminal node is in the data storage dress carrying after the meansigma methodss calculating each region a and n Put the meansigma methodss of middle storage oneself affiliated area (generally having multiple) a and n, draw:

$\left\{\begin{array}{c}\stackrel{\&overbar;}{a}=\frac{1}{l}\underset{i=1}{\overset{l}{\mathrm{\σ}}}{a}_i\\ \stackrel{\&overbar;}{n}=\frac{1}{l}\underset{i=1}{\overset{l}{\mathrm{\σ}}}{n}_i\end{array}\right.$

Wherein,WithFor the meansigma methodss of two undetermined constants in this region, l is the individual of positioning terminal node in this region Number；

After vehicle to be positioned proposes Location Request, all it is in positioning terminal node in energy direct communications range all with it Can respond, send the meansigma methodss of a and n in region residing for positioning terminal node to vehicle to be positioned, because of some positioning terminals Node is generally divided to multiple regions, so this kind of positioning terminal node can send meansigma methodss of multiple a and n and corresponding The numbering in region, after the smart mobile phone of vehicle to be positioned receives neighbouring positioning terminal node feedack, selects numbering The most region of occurrence number carries out next step；

Step 5: calculated between the vehicle to be positioned entering certain region and the positioning terminal node of selection area by following formula Apart from d,

$d_i={10}^{-\frac{(\stackrel{\&overbar;}{a}+\stackrel{\&overbar;}{{\mathrm{rssi}}_i})}{10\stackrel{\&overbar;}{n}}}$

Wherein, a and n takes the meansigma methodss in step 4,For receipt signal mean power.

Step 6: after calculating the distance between more than 3 above-mentioned vehicles to be positioned and positioning terminal node, by triangle Shape centroid localization algorithm or Maximum Likelihood Estimation Method calculate the coordinate of vehicle to be positioned；In the different time periods, with parking The factor such as turnover of vehicle in, if two undetermined constants in all regions can change it is clear that relatively frequently in time They are updated with the positioning precision it is ensured that to vehicle, but the power consumption by the obvious summit increasing and forming each region.For This, only when the entrance in parking lot or exit have detected vehicle entrance or left, pass through router by central node Node sends order to each positioning terminal node, and each positioning terminal node is communicated with neighbouring positioning terminal node, to a_iAnd n_i's Value is updated, according to recalculating the undetermined constant drawingWithVehicle to be positioned and positioning terminal can be calculated Between node apart from d, and then calculate the coordinate of vehicle to be positioned.

It should be noted that the zigbee module that on vehicle to be positioned, smart mobile phone connects, the broadcast letter of its Location Request After breath sends, router node does not forward this information, is only in the positioning in node energy direct communications range to be positioned eventually Leaf can receive this information and respond；Treat positioning vehicle when being positioned, positioning terminal node can be by the essence of oneself In true coordinate and this region, the meansigma methodss of a and n are sent to the zigbee module of smart mobile phone, are provided with position solution in smart mobile phone Calculate software, calculate the real time position of vehicle to be positioned.Afterwards, smart mobile phone is according to the internal map in built-in parking lot and meter The vehicle location calculating, vehicle is directed to step by step target parking stall.

Positioning precision can be improved for the designed algorithm of checking, set some parameters on the basis of Fig. 2, and utilize Computer simulator write in matlab language.The design parameter being used is as shown in table 1:

The parameter that table 1 matlab simulation program is used

In addition to listed parameter in table 1, set signal to noise ratio as 30；In each region be calculate certain positioning terminal node with Distance value between node to be positioned, the pendulous frequency being carried out is 100 times.

Fig. 3 be do not consider a and n in time with spatial variations in the case of (that is: formula in using step 5 calculate away from From during, the unified meansigma methodss using the 3rd row and the 4th row in table 1 of a and n in each region), a to k totally 11 regions in Fig. 3 Maximum positioning error in 0 to 100 hour is over time.It is seen that error amount is very big, maximum error is Reach 35m.

Fig. 4 is only to consider the change with space for a and n, but does not consider that they (that is: are utilizing in the case of changing over During formula computed range in step 5, a and n in each region, take corresponding row the 3rd row of this region in table 1 and the 4th respectively The value of row), in Fig. 3, totally 11 regions maximum positioning error in 0 to 100 hour is over time for a to k.With Fig. 4 phase Error has reduced ratio, but maximum error still reaches nearly 30m.

Fig. 5 be both considered a and n with the change in space it is also considered that they change in the case of (that is: using step During formula computed range in rapid 5, a and n in each region, take the instant measured value of current time a and n respectively), Fig. 3 Totally 11 regions maximum positioning error in 0 to 100 hour is over time for middle a to k.It is seen that error shows Write and reduce, substantially control within 2m, achieve ideal locating effect.

As can be seen here, the localization method in the present invention considerably improves the vehicle location essence under the environment of parking garage Degree, contributes to quickly and accurately guiding vehicle to target parking stall planned in advance.

The part do not addressed in the present invention using or use for reference prior art can achieve.

Specific embodiment described herein is only the spiritual example explanation to the present invention.Belonging to the present invention Those skilled in the art can make various modifications or supplement or using similar to described specific embodiment Mode substitutes, but the spirit without departing from the present invention or surmount scope defined in appended claims.

Claims (4)

1. under the environment of parking garage the vehicle positioning method based on zigbee network it is characterised in that: the method includes following Step:

Step 1: zigbee wireless sensing network system, zigbee wireless sensing network system, bag are set in parking lot indoors Include a zigbee network, one central node of setting, several router nodes and more in zigbee network Terminal node, terminal node includes for treating the positioning positioning terminal node that positioned of vehicle；The driving of vehicle to be positioned The person of taking advantage of holds smart mobile phone, and smart mobile phone is furnished with zigbee module, and vehicle to be positioned sends Location Request by smart mobile phone；

Step 2: according to the distribution of parking stall in parking garage, region division is carried out to above-mentioned positioning terminal node, is allowed to divide Become the region of several non-overlapping copies, and each region is numbered, each region is triangular in shape or tetragon, positioning terminal is tied Point is arranged on each triangle or the summit of tetragon, in each region, each positioning terminal node and adjacent two Positioning terminal node carries out direction communication；

Step 3: the coordinate of each positioning terminal node in each region above-mentioned is carried out calculating after accurate measurement between adjacent two summits Distance, and calculated according to following formula and draw two undetermined constant a of some positioning terminal node surrounding in region_i、n_i:

$\left\{\begin{array}{c}{\stackrel{\&overbar;}{rssi}}_{i1}\[dbm\]=-(a_i+10n_i\·\lg d_{i1})\\ {\stackrel{\&overbar;}{rssi}}_{i2}\[dbm\]=-(a_i+10n_i\·\lg d_{i2})\end{array}\right.$

Wherein, d_i1And d_i2For i-th positioning terminal node in region and surrounding the 1st and between the 2nd adjacent positioned terminal node Distance,WithReceive around the 1st and the 2nd adjacent positioned terminal for i-th positioning terminal node in region The mean power of node signal transmitted；

Step 4: according to the distance value d calculating_i1And d_i2, and measured valueWithCalculate a_iAnd n_i, and by area The a of all positioning terminal nodes in domain_iAnd n_iTake the average value as a and n in this region, draw:

$\left\{\begin{array}{c}\stackrel{\&overbar;}{a}=\frac{1}{l}\underset{i=1}{\overset{l}{\σ}}{a}_i\\ \stackrel{\&overbar;}{n}=\frac{1}{l}\underset{i=1}{\overset{l}{\σ}}{n}_i\end{array}\right.$

Wherein,WithFor the meansigma methodss of two undetermined constants in this region, l is the number positioning terminal node in this region；

When the entrance in parking lot or exit have detected vehicle entrance or left, router node is passed through by central node Send order to each positioning terminal node, each positioning terminal node is communicated with neighbouring positioning terminal node, to a_iAnd n_iValue enter Row updates, and the undetermined constant again calculatingWithAfter vehicle to be positioned proposes Location Request, all it is in energy with it Positioning terminal node in direct communications range all can respond, and sends region residing for positioning terminal node to vehicle to be positioned A and n meansigma methodss, because some positioning terminal nodes are generally divided to multiple regions, so this kind of positioning terminal node meeting Send the meansigma methodss of multiple a and n and the numbering in corresponding region, the smart mobile phone of vehicle to be positioned receives neighbouring positioning After terminal node feedack, the region selecting numbering occurrence number most carries out next step；

Step 5: the distance between the vehicle to be positioned entering certain region and the positioning terminal node of selection area is calculated by following formula d_i,

$d_i={10}^{-\frac{(\stackrel{\&overbar;}{a}+\stackrel{\&overbar;}{{\mathrm{rssi}}_i})}{10\stackrel{\&overbar;}{n}}}$

Wherein, a and n takes the meansigma methodss in step 4,For receipt signal mean power；

Step 6: after calculating the distance between more than 3 above-mentioned vehicles to be positioned and positioning terminal node, by triangle form quality Heart location algorithm or Maximum Likelihood Estimation Method calculate the coordinate of vehicle to be positioned.

2. the vehicle positioning method based on zigbee network, its feature under the environment of parking garage according to claim 1 It is: on each described positioning terminal node, be provided with power amplifier module.

3. the vehicle positioning method based on zigbee network, its feature under the environment of parking garage according to claim 1 Be: the terminal node in described step 1 also includes the monitoring terminal node for monitoring parking space state, positioning terminal node with Between monitoring terminal node, no communicate between adjacent two monitoring terminal nodes；Described router node is arranged on several monitorings The center of the ring of encirclement of terminal node, router node is used for trunking traffic.

4. the vehicle positioning method based on zigbee network, its feature under the environment of parking garage according to claim 1 It is: in described step 1, central node and router node adjacent thereto communicate, and central node is arranged on parking lot Porch or exit or center position.