CN201803950U - Vegetation canopy structure parameter measuring device based on wireless sensor network - Google Patents

Abstract

The utility model provides a vegetation canopy structure parameter measuring device based on wireless sensor network. The device comprises a wireless sensor network and a data processing and node control system, wherein the wireless sensor network consists of canopy upper and lower measurement nodes and routing nodes which are distributed in a target area, and the data processing and node control system is formed by connecting sink nodes with a control terminal remote server; the measuring nodes collect the solar radiations above and below the canopy under the conditions of different solar elevation angles in one day to obtain vegetation parameter information and perform data transmission and localization through a wireless Ad-hoc network; the sink nodes upload the data of the individual measuring nodes to a control terminal through serial ports or GPRS, and the data processing system calculates vegetation structure parameters; and the control terminal sends commands to the individual nodes through the sink nodes to change the parameter settings. The vegetation canopy structure parameter measuring device has small size, low power consumption and low cost, is convenient for layout, is applied to the parameter measurement of the large-area vegetation with long growth cycle, and has higher practical value and application prospect in the technical fields of agriculture, ecology and wireless sensor networks.

Description

A kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network

(1) technical field

The utility model relates to a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network, and it is relevant with the data acquisition of vegetation canopy structure parameter, belongs to agricultural and ecology and wireless sensor network technology field.

(2) technical background

Vegetation canopy structure parameter is an important indicator of research vegetation growth developmental condition, also is an important relevant parameter of restriction land-atmospheric action process model.Therefore, accurately obtaining vegetation structure parameter is the active demand that promotes land surface model modeling and modelling verification.

Vegetation structure parameter described in the utility model is meant vegetation canopy leaf area index, and (Leaf Area Index is LAI) with leaf inclination angle probability density function.

The acquisition methods of vegetation structure parameter has direct measurement method and indirect measurement method, and wherein direct method comprises that destructive mensuration and manual original position measure and the fallen leaves method.Directly measurement result precision height can be used as the comparison reference of indirect measurement method ratio of precision.But the time-consuming consumption power of measuring process and can cause certain destruction to measuring sample ground, the numerical value that is difficult to use in the long-time sequence of large tracts of land obtains.

In the indirect surveying instrument to vegetation structure parameter, be by measuring vegetation canopy direction clearance rate, estimating these structural parameters according to the relation of clearance rate and leaf area index and leaf tilt profiles.The difference of these instruments is to obtain the method difference of clearance rate.Can have two types to the commercialization instrument that vegetation structure parameter is measured indirectly at present, first kind is to estimate the canopy transmitance by measuring the solar radiation quantity that sees through in the canopy, as the SunScan and the Australian Demon of Britain.Wherein SunScan is that 64 optical sensors come the disposable multi-level information of obtaining canopy structure information by dispose nearly in canopy bottom, and Demon moves along certain direction or track in the canopy bottom and reaches the purpose of once obtaining multi-angle information by driving (hand-held moving or motor driven) sensor.Another is to utilize the hemisphere imaging technique to obtain vegetation and background information in the visual field, method statistic pixel count separately by classification calculates direction clearance rate in the canopy, LAI2000 and patent " light transmission layered density determination method and camera " (patent No. 01128255.X) and " a kind of device that is used to measure light transmission layered density " (patent No. 01250965.5) as the U.S., in order to obtain vegetation canopy multi-angle image, they have adopted the fish eye lens of wide visual field angle to obtain canopy structure information.

The common feature of above surveying instrument is to realize measurement to the canopy structure parameter by the form of obtaining multi-angle canopy radiation profiles information at canopy bottom one-shot measurement.When in long-time sequence and large space scope, carrying out data acquisition, because need be at the bigger a plurality of surveying instruments of experiment place deploy, and need personnel repeatedly to measure to the scene, therefore, more than under instrument and method need expend huge data acquisition cost, comprise human cost and Instrument purchase cost.

Utility model patent " a kind of data collector of trees Canopy Analyzer " (publication number: CN101413875A) pass through at long 1.2-1.8m, the plane deploy of wide 0.6-1.0m reaches 14000 silicon light-sensitive cells or puts the solar radiation distribution that coupling element obtains the trees sylvan life, estimates the canopy structure parameter of trees indirectly by the variation mobile and solar radiation of the sun in a day.Its service condition of the described device of this patent is subject under the environment of forest land, and requires to have under the forest land bigger gap can place this equipment.And in short vegetation or continuous distribution vegetation, as crops, the meadow environment is next can't use.

(3) utility model content

1, purpose: at the problem of above equipment and technology existence, the purpose of this utility model is a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network, this device has that volume is little, cost is low, data are obtained automatically and the characteristics of wireless transmission, can realize under the unmanned situation for a long time, on a large scale, the automatic measurement and the transmission of many vegetation pattern canopy structure parameter.

2, technical scheme: for realizing above-mentioned advantage, the utility model is taked following technical scheme:

A kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network comprises:

By on the canopy that is distributed in study area with canopy under measured node and the wireless sensor network formed of routing node;

The data processing and the node control system that are connected to form by aggregation node and control terminal and remote server.

Wireless sensor network with the position annexation between data processing and the node control system is: wireless sensor network is by installing serial port module additional on its aggregation node, is connected by the RS232 Serial Port Line is in-plant with the node control system with data processing on the control terminal; Wireless sensor network is by installing the GPRS module additional on its aggregation node, be connected at a distance by the GPRS radio communication with the node control system with data processing on being positioned over breadboard remote server.

Wherein, described measured node by be used to measure canopy up and down the sun see through radiation optical sensor, be used for the ephemeral data storage data storage cell, be used to provide the real-time clock of acquisition time, acp chip and the power supply unit that is used to carry out wireless communication network and node control computing to form.Position annexation between them is: optical memory, real-time clock passes through I ²C is connected with acp chip, and data storage cell is connected with acp chip by SPI, and all unit all are connected with power supply unit.All components and parts are distributed in 10 * 4.5cm ²The node circuit plate on.

Wherein, described optical sensor is one 3 * 3mm ²Photoelectric commutator, employing be environment light sensor TSL2561 chip; Described data storage cell is to select M25P10 for use, the storer of 1Mbit; Described real-time clock is to select the timing of PCF8563 chip for use; Described acp chip is the high-power JN5139-Z01-M02R1 module that JENNIC company provides, and it has wireless communication network and Single-chip Controlling operation function simultaneously; Described power supply unit is relevant with the position that node is disposed, being deployed in node power under the canopy is two joint AA alkaline batteries, is deployed in node on the canopy and routing node and aggregation node power supply and is the combination of solar panel and standby two joint AA alkaline batteries.

Described routing node is the same on hardware is formed with measured node, and just the wireless communication protocol stack that calls on driver is different, and routing node can be realized the routing function of signal relay.

One aggregation node is set is used for gathering data, and the data transmission that will gather is given control terminal and remote server from all measured node.

Wherein, described aggregation node is to increase a GPRS wireless communication module and serial communication modular on the components and parts basis of measured node, the radio modem that is based on mobile 2.5G Hz GPRS network platform built-in Siemens MC35I/MC39I technical grade module that this GPRS module is selected for use, can be directly be connected, realize the GPRS data communication with host computer equipment such as industrial computer; It is good that serial communication modular selects for use JENNIC to support, the electrical level conversion chip SP3232 of low-power consumption; Being connected with remote server by aggregation node and control terminal, to form control device be data processing and node control system, transmits spatial positional information and data, and realize wireless telecommunications between the wireless sensor network; Described control terminal and remote server are Net-connected computer.Wherein, described measured node, routing node and aggregation node have all write the driver of autonomous establishment, the driver structural representation is seen Fig. 1. behind the power switch of opened nodes, at first carry out the initialization of each functional module, routing node can be set up wireless sensor network with other routing nodes and aggregation node by the mode of multi-hop ad hoc at once, in running order always then, wait for the access of measured node at any time.Measured node can be searched the wireless network of being made up of routing node, and behind the access network, measured node enters duty, according to pre-set time interval, gathers the storage data, and data are sent via wireless network.One time image data finishes, and enters dormant state, and wait is next constantly restarts interruption, so moves in circles.After a phase data collecting work is finished, can interrupt above-mentioned circulation at the timing node of setting, measured node enters long-time dormant state, waits for collecting work next time.

Wherein, in the described measured node, be positioned at that the sun sees through radiation under the canopy that measured node under the canopy is used for obtaining one day different sun altitude, be arranged in the total solar radiation that the measured node on the canopy is used for obtaining one day different sun altitude of study area, measure numerical value from above two and can extract vegetation canopy structure parameter information.

Wherein, between the described measured node, between measured node and the routing node, between routing node and the aggregation node, and aggregation node with the annexation of control terminal and remote server is: the measured node under the measured node on a plurality of (N＜=16) canopy and the canopy links to each other with routing node by the mode of radio communication; Between the routing node, and routing node is connected with the mode of aggregation node by wireless multi-hop ad hoc; Aggregation node also belongs to a routing node in itself, and still, difference is that aggregation node has serial communication modular and GPRS module with common routing node part.Aggregation node links to each other with control terminal or remote server with the GPRS wireless communication module by serial ports.

Wherein, between described measured node and the routing node, between routing node and the aggregation node, and the position of aggregation node and control terminal and remote server relation is: measured node is in the measured zone stochastic distribution, a routing node will be arranged at least as the signal relay point near per 16 measured node, maximum distance is no more than 200m between measured node and the routing node; Routing node adopts the mode of wireless multi-hop to connect, and will have a routing node coupled at least in the 200m scope around arbitrary routing node; Aggregation node can be positioned over around arbitrary routing node in the 200m scope; Aggregation node can use Serial Port Line to realize the closely data transmission of aggregation node and control terminal, also can use the GPRS module realization aggregation node of aggregation node and the remote data transmission of remote server.

Wherein, described data processing and node control system run on control terminal and remote server, when data from measured node via routing node, aggregation node, be ultimately delivered to after control terminal and the remote server, data processing and node control system can read and analyze data automatically, therefrom extract the vegetation canopy direction clearance rate under the different sun altitudes of each measured node, the clearance rate that utilization is extracted is finally inversed by the leaf area index and the leaf tilt profiles of this node place vegetation canopy, and result visualization is shown.Simultaneously, operating personnel can send order to measured node by data processing and node control system, change the parameter setting of measured node, thereby reach the control purpose.

3, advantage and effect: compared with prior art, the utility model is by measuring total solar radiation, measuring the sun in the canopy bottom and see through radiation and reach the purpose of calculating the canopy transmitance on canopy top, utilize that the variation of sun altitude realizes that the canopy clearance rate of multi-angle calculates among one day.And then, utilize the multi-angle clearance rate to calculate the structural parameters of canopy.The utility model utilizes the variation of sun altitude to replace the method that traditional fisheye camera once obtains multi-angle image, and, because the utility model has directly used the planar light sensor, can directly calculate the canopy clearance rate, need not observed object is carried out imaging, reduced image classification error in the Data Post.The utility model adopts wireless network to carry out data transmission, has reduced the data storage capacity of single-chip microcomputer, more helps being implemented in the big zone under the unmanned condition, the vegetation canopy parameter acquiring of long-time sequence.

(4) description of drawings

Fig. 1 is the utility model measured node driver structural representation

Fig. 2 is a measured node structural representation of the present utility model

Fig. 3 is the open-air synoptic diagram of disposing of the present utility model

Fig. 4 obtains the control algolithm structural representation for the utility model data

Symbol description is as follows among the figure:

1-measured node 2-routing node 3-aggregation node 4-Net-connected computer 5-Net-connected computer

(5) embodiment

A kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network of the utility model comprises the wireless sensor network of being made up of measured node 1 that is arranged in survey region canopy upper space and lower space and routing node 2; The data processing and the node control system that form by aggregation node 3 and control terminal and remote server.

Wherein, described measured node 1 by be used to measure canopy up and down the sun see through radiation optical sensor, be used for the ephemeral data storage data storage cell, be used to provide the real-time clock of acquisition time, acp chip and the power supply unit that is used to carry out wireless communication network and node control computing to form.Measured node 1 links to each other with routing node 2 by radio communication.Routing node 2 is identical with measured node 1 on hardware, the protocol stack difference of on driver, calling just, the protocol stack that routing node 2 uses can be realized the relaying to wireless signal, owing to this characteristics are arranged, can connect and form wireless sensor network by the multi-hop wireless communication mode between the routing node 2.The Jenie communication protocol of all using JENNIC company to provide is provided above-mentioned radio communication.This agreement is identical substantially with the protocol function of Zigbee, difference is that the agreement of Jenie takes up room littler, power consumption still less, its shortcoming is the Mesh network agile that does not have the Zigbee agreement, but fix for relative position, node can not move at any time, under the little situation of barrier influence, selects for use the agreement of Jenie to be more conducive to our network arrangement and network utilisation.Exchange in order to carry out data, an aggregation node 3 is set is used for gathering data, and the data transmission that will gather is given control terminal and remote server from all measured node with the external world.This aggregation node 3 is to have increased to be used for the serial communication modular and the GPRS module that are connected with control terminal and remote server on routing node 2 bases.

Wherein, optical sensor is one 3 * 3mm ²Photoelectric commutator, employing be environment light sensor TSL2561 chip, this chip has photoelectric converting function, directly passes through I ²C transmits the strong numerical information of light echo.Its concrete parameter is as follows:

Operating voltage 2.7-3.6V

Working temperature-30-70 ℃

Signal low level voltage-0.5-0.8V

Signal high level voltage 2.1-3.6V

Wherein, data storage cell is selected M25P10 for use, and the storer of 1Mbit, JENNIC are pointed out the good support to it in explanation.Its concrete parameter is as follows:

Memory space 1Mbit

Operating voltage 2.7-3.6V

Working interface SPI interface

Work maximum frequency 50MHz

Wherein, described acp chip, employing be the high-power JN5139-Z01-M02R1 module that JENNIC company provides, this module has wireless communication network and Single-chip Controlling operation function simultaneously.Its module parameter is as described below:

Physical parameter:

Transmission range＞1km

Module apparent size 18 * 41mm

Operating voltage 2.7-3.6V

Working frequency range 2.4GHz IEEE802.15.4 compatibility

Quiescent current (having wake-up timer)＜2.8uA

19dBm power, band SMA, uFI antenna connector

Receiving sensitivity :-100dBm

TX electric current:＜120mA

RX electric current:＜45mA

Interface parameters:

Five SPI interfaces

Two UART serial ports

Two programmable Timer timers

The I of two lines ²The C mouth

21 general IO mouths (part and UART are multiplexing)

Four road 12-bit, the ADC of 100ksps

The DAC that two-way is 11

A comparer

Temperature inside and voltage sensor

The processor parameter:

32 RISC CPU of 16MHz

·128KB?FLASH、64KB?ROM、96KB?RAM

Wherein, described real-time clock can provide year for the data of gathering, month, day, the time, dividing, PCF8563 is selected in the timing of second for use, and this chip power-consumption is very low, is applicable to the battery powered mode that we adopt.Its concrete parameter is as follows:

Crystal oscillator is 32.768KHz

Operating voltage 1.0-5.5V

Working current 0.25uA

Support I ²C interface

Wherein, it is good that described serial communication modular selects for use JENNIC to support, the electrical level conversion chip SP3232 of low-power consumption, and its concrete property is as described below:

Satisfy the EIA/TIA-232-F standard

Operating voltage is 3.0-5.5V

Fully loaded minimum data rate: 120Kbps

The low-power consumption shutdown mode of 1uA, receiver (SP3222E) is effective

Can use jointly with RS232, power supply is low to moderate+2.7V

Enhancement mode ESD standard:

± 15kV human body discharge mode

± 15kV IEC1000-4-2 bubble-discharge

± 8kV IEC1000-4-2 contact discharge

Wherein, the radio modem that is based on mobile 2.5G Hz GPRS network platform built-in Siemens MC35I/MC39I technical grade module that described GPRS module is selected for use can be directly be connected with host computer equipment such as industrial computer, realizes the GPRS data communication.Its concrete property is as described below:

Support EGSM900 and GSM1800 double frequency to support numeral, voice, short message and fax

Electric current is the transfer rate that 3mA supports three kinds of speech encodings when being in sleep state

The authentication of standard agreement, employing GSM Phase2/2+ standard

Operating voltage 3.3-5.5V

Frequency range: double frequency GSM900MHz and DCS1800MHz (Phase 2+)

Emissive power: 2W (GSM900MHz Class 4) 1W (DCS1800MHz Class 1)

SIM card connected mode: external

Antenna: connect exterior antenna by antenna connector

Temperature range: working temperature :-20-+55 ℃ storage temperature :-30-+85 ℃

Working current loss: call mode: 300mA (representative value .) idle pulley: 3.5mA (maximal value pattern: 100uA (maximal value)

Communication interface: RS232 (the two-way transmission of instruction and data)

Wherein, the composition of power supply unit is relevant with the position that node is disposed, being deployed in node power under the canopy is two joint AA alkaline batteries, is deployed in node on the canopy and routing node 2 and aggregation node 3 power supplys and is the combination of solar panel and standby two joint AA alkaline batteries.

Wherein, described control terminal and remote server are Net-connected computer 4,5.

One of advantage of the present utility model is to be fit to obtain large-area vegetation structure parameter, utilizes multi-hop connection between the routing node 2, the laying range expansion of measured node can be arrived 1km ²Perhaps bigger, measured node is concrete to be laid as shown in Figure 2, at first determine sampling policy according to the actual conditions of measured zone, determine to want to obtain each concrete point position of vegetation structure parameter according to sampling policy, place a measured node in the canopy lower space of each such measurement point position then, be used for measuring in one day that the vegetation canopy sun sees through radiation Q under the different sun altitudes _i(wherein i is the numbering of measured node under the canopy).In order to measure total solar radiation and sky radiation on the canopy, choose 2 point positions in addition, canopy upper space in each such measurement point position is placed a measured node, and therein one install shade disk above the node additional, be used for measuring in one day under the different sun altitudes total solar radiation Q on the vegetation canopy respectively ₀With sky radiation D ₀After laying 16 measured node, a routing node 2 need be set, the requirement of laying routing node 2 is that to make 16 measured node drop on these routing node 2 peripheral radiuses be in the circumference of 200m.It is a group node that 16 measured node 1 add a routing node 2, can arrange some group nodes at study area.Group with organize between be connected by routing node 2.After each group node arranges, select in arbitrary routing node 2 peripheral 200m scopes, an aggregation node 3 is set, it is in the nature a routing node 2 that has installed serial port module and GPRS module additional, aggregation node 3 is used for gathering the data of each measured node of wireless sensor network, and carries out exchanging of data with the external world.Each node is the power switch on the opened nodes after the arrangement of corresponding position fixes, and node is promptly started working.

Measured node 1 lay good after, once complete measuring process is, before The sun came up about 1 hour, when sky had only scattered light, measured node began to measure, and read a numerical value then at regular intervals at interval, stop to the sun surveying work that sets, thereby finish one-shot measurement.Canopy measurement up and down can obtain scattered light transmitance T before utilizing The sun came up _d, utilize in the sun altitude one day passing in time and the variation that takes place, by be distributed on the canopy with canopy down and the measured node of sheltering from heat or light on the canopy just obtained in one day the sun different sun altitude lower canopies under through radiation Q _i(i is canopy lower node numbering), the total solar radiation Q on the canopy ₀With sky radiation D ₀

Suitable measurement environment of the present utility model is sunny calm daytime, and weather cloudy or strong wind can make measurement result be full of noise and influence measuring accuracy, is not suitable for carrying out surveying work.Because the measured node under the canopy is used the alkaline battery power supply, stream time is limited, in order to realize that the study area long time period is measured, simultaneously also in order to improve the quality of measurement data, we have carried out following design, the one, each measured node 1 all has two state model, i.e. mode of operation and park mode.Measured node 1 is carried out data acquisition and is communicated by letter under the mode of operation, and measured node 1 enters deep sleep under the park mode, and electric quantity consumption drops to minimum point.Measured node 1 enters park mode at once after once gathering the storage end of transmission.Measured node 1 time of being in mode of operation in whole measuring period only accounts for very little ratio like this, thereby makes and can obtain measuring period prolonging.The 2nd, node when the weather of cloudy or strong wind having occurred in a measuring period, can make it enter park mode only being fit to carry out surveying work promptly sunny calm daytime in the time period of measuring by sending instruction to measured node 1.

Aggregation node 3 Measuring Time section by day gathers data from each measured node, and after the instruction of receiving the transmission data, aggregation node 3 can send to control terminal and remote server by serial port module and GPRS module with the data of being stored.

After the data processing of moving on control terminal or the remote server and node control system receive the data of aggregation node, begin to carry out data processing work, data processing and node control system are according to flow process shown in Figure 3, each node data is handled, because having many factors in the actual measurement process impacts measurement result, cause measurement result some noises to occur, so need carry out Filtering Processing earlier to measurement data, again because measured node 1 is numerical value of interval acquiring at regular intervals, so, need carry out interpolation processing to measurement data in order to obtain any sun altitude lower canopy sunshine transmitance.After the data pre-service finishes, use the inverting of following core algorithm realization to vegetation structure parameter:

Utilize the temporal information of real-time clock log on the measured node 1, each data acquisition can be scaled constantly corresponding sun altitude.By a threshold value constantly is set, measurement data can be divided into before sunrise data and sunrise data afterwards.

Data before sunrise, the sky radiation D ' that obtains by the measured node of not sheltering from heat or light on the canopy ₀The sky scattering that obtains with measured node under the canopy sees through radiation D ' ₁Form, can calculate the scattering transmitance by formula (1), promptly

$T_d=\frac{{\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HSA00000067098100021.png"\; state="\{\{state\}\}">D</figure-callout>}}_1^{\&prime;}}{D_0^{\&prime;}}---\left(1\right)$

Data after the sunrise, under the some time points that obtained by the canopy lower node, the canopy sun specific sun altitude under is through radiation Q _i(i is a canopy lower node label), under some time points that node obtains on the canopy, the total solar radiation Q under the specific sun altitude ₀Under the some time points that obtain with the node that shelters from heat or light on the canopy, the sky radiation D under the specific sun altitude ₀Form.Utilize this three amounts, can calculate direct light radiancy on the specific sun altitude lower canopy, promptly

E ₀＝Q ₀-D ₀ (2)

The scattered light transmitance T that obtains according to (1) formula _d, the sun that can calculate under the specific sun altitude lower canopy sees through radiancy

E ₁＝Q _i-D ₀×T _d (3)

Then the direct sunlight transmitance under specific sun altitude (h) can be expressed as

$T_s\left(h\right)=\frac{E_1}{E_0}=\frac{Q_i-D_0\&times;T_d}{Q_0-D_0}---\left(4\right)$

Formula (4) can further be transformed to

$T_s\left(h\right)=\frac{Q_i/Q_0-D_0/Q_0\&times;T_d}{1-D_0/Q_0}=\frac{T_Q-\mathrm{\&eta;}{T}_d}{1-\mathrm{\&eta;}}---\left(5\right)$

T wherein _QExpression built-up radiation transmitance, η is the ratio of skylight in built-up radiation, T _dBe the sky scattering light transmission rate.

The data of utilizing measured node 1 to record in one day can obtain n sun altitude lower canopy direct sunlight transmitance among a day, pass through following formula:

$T_s\left(h\right)=e^{-{\&Integral;}_0^{\frac{\mathrm{\&pi;}}{2}}k(\mathrm{\&theta;},h)\mathrm{LAId\&theta;}}---\left(6\right)$

Set up the relation between canopy direct sunlight transmitance and the vegetation structure parameter, wherein

k(θ，h)＝A(θ，h)g(θ) (7)

$A(\mathrm{\&theta;},h)=\left\{\begin{array}{cc}\cos \mathrm{\&theta;}& \mathrm{\&theta;}\&le;h\\ \cos \mathrm{\&theta;}[1+2(\tan {\mathrm{\&theta;}}_0-{\mathrm{\&theta;}}_0)/\mathrm{\&pi;}]& h<\mathrm{\&theta;}<\frac{\mathrm{\&pi;}}{2}\end{array}---\left(8\right)\right.$

Comprehensively (6)～(8), and formula (6) both sides are asked logarithm respectively, can obtain

$P\left(h\right)=-1n\left(T_s\left(h\right)\right)={\&Integral;}_0^{\frac{\mathrm{\&pi;}}{2}}A(\mathrm{\&theta;},h)g\left(\mathrm{\&theta;}\right)\mathrm{LAId\&theta;}---\left(9\right)$

With the leaf inclination angle [theta] in the canopy uniformly-spaced be divided into m interval, sunshine transmitance observation data under the canopy of n sun altitude obtaining of utilization under the condition of n＞m, can obtain the least square solution of LAI by the matrix linear operation like this.

Order $r\left(\mathrm{\&theta;}\right)=\frac{\mathrm{dL}}{\mathrm{d\&theta;}}=g\left(\mathrm{\&theta;}\right)\mathrm{LAI}---\left(10\right)$

R (θ) is a vegetation group structure parameter, can represent the leaf tilt profiles, can represent that also leaf area index changes.Thus, formula (9) can be written as

$P\left(h\right)={\&Integral;}_0^{\frac{\mathrm{\&pi;}}{2}}A(\mathrm{\&theta;},h)r\left(\mathrm{\&theta;}\right)\mathrm{d\&theta;}---\left(11\right)$

The leaf inclination angle is existed

Between be divided into M interval, each length of an interval degree is Δ θ, each interval leaf area index is L _i, the r (θ that each is interval _i) mean value be

$r_i=\frac{{\mathrm{LAI}}_i}{\mathrm{\&Delta;\&theta;}}---\left(12\right)$

Write formula (11) as discrete form, then

$P\left(h_j\right)=\underset{i}{\overset{m}{\mathrm{\&Sigma;}}}A({\mathrm{\&theta;}}_i,h_j)L_i---\left(13\right)$

As N observation was arranged in one day, each sun altitude is respectively h _j(j=1,2 ..., N), then formula (13) can be write as matrix form

P＝A×L (14)

P=(P wherein ₁, P ₂..., P _N) ^TBe N observation, A ^T=(A _Ij) _{M * N}, L=(L ₁, L ₂..., L _M) ^T

The least square solution of L is:

L＝(A ^TA) ^-1A ^TP (15)

In finding the solution the process of L, consider the influence of observation noise, for preventing singular value, increase a regularization amount H and parameters optimization λ, then

L＝(A ^TA+λH) ^-1A ^TP (16)

The value principle of H is

(i) H is a square formation

(ii) H master's diagonal element is 1 except that the upper left corner and the lower right corner, all is 2

(iii) adjacent with main diagonal angle element is-1

(iv) all the other elements are 0 in the square formation.

λ is a positive constant, can adjust according to precision as a result when calculating, until the optimum solution that obtains L.

After LAI finds the solution, can try to achieve leaf tilt profiles function g (θ) according to formula (12) and (14).

The sun that measures of each node under the canopy is seen through radiation Q _i(i is canopy lower node numbering) above-mentioned core algorithm of substitution just obtains laying node leaf area index and leaf tilt profiles one to one down with canopy.Utilize each measured node 1 and aggregation node 3 relative position spatially,, just can calculate the absolute spatial position of each measured node, have the inversion result visualization display of spatial information the most at last in conjunction with the spatial orientation information of aggregation node 3.All nodes all can carry out the initialization setting before laying, comprise the mode of operation time point, the park mode time interval, and the wireless self-networking time period, survey crew can utilize data processing and node control system as shown in Figure 3, to aggregation node 3 transmitting control commands, order is issued to the initial setting up that each node is revised node by control terminal or remote server, makes it satisfy measurement requirement by wireless sensor network.

Claims (10)

1. vegetation canopy structure parameter measuring apparatus based on wireless sensor network is characterized in that: it comprise by on the canopy that is distributed in study area with canopy under measured node and the wireless sensor network formed of routing node; The data processing and the node control system that are connected to form by aggregation node and control terminal and remote server;

Wireless sensor network with the position annexation between data processing and the node control system is: wireless sensor network is by installing serial port module additional on its aggregation node, is connected by the RS232 Serial Port Line is in-plant with the node control system with data processing on the control terminal; Wireless sensor network is by installing the GPRS module additional on its aggregation node, be connected at a distance by the GPRS radio communication with the node control system with data processing on being positioned over breadboard remote server;

Described measured node by be used to measure canopy up and down the sun see through radiation optical sensor, be used for the ephemeral data storage data storage cell, be used to provide the real-time clock of acquisition time, acp chip and the power supply unit that is used to carry out wireless communication network and node control computing to form; Position annexation between them is: optical memory, and real-time clock is connected with acp chip by I2C, and data storage cell is connected with acp chip by SPI, and all unit all are connected with power supply unit; Above-mentioned all components and parts of this measured node are installed on the node circuit plate;

Described routing node is the same with measured node on hardware is formed.

2. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1, it is characterized in that: this optical sensor is one 3 * 3mm ²Photoelectric commutator, its chip model is TSL2561.

3. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1, it is characterized in that: this data-carrier store is the M25P10 storer of a capacity 1Mbit.

4. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1, it is characterized in that: this real-time clock is to select the timing of PCF8563 chip for use.

5. a kind of vegetation canopy structure parameter measuring apparatus according to claim 1 based on wireless sensor network, it is characterized in that: the acp chip that this is used to carry out wireless communication network and node control computing is the JN5139-Z01-M02R1 module that JENNIC company provides.

6. a kind of vegetation canopy structure parameter measuring apparatus according to claim 1 based on wireless sensor network, it is characterized in that: the composition of this power supply unit is relevant with the position that node is disposed, being deployed in node power under the canopy is two joint AA alkaline batteries, and the power supply that is deployed in node on the canopy and routing node and aggregation node is the combination of solar panel and standby two joint AA alkaline batteries.

7. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1 is characterized in that: this GPRS module is a radio modem based on mobile 2.5G Hz GPRS network platform built-in Siemens MC35I/MC39I technical grade module.

8. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1 is characterized in that: this serial communication modular is that JENNIC supports good electrical level conversion chip SP3232.

9. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1, it is characterized in that: this control terminal and remote server are Net-connected computer.

10. a kind of vegetation canopy structure parameter measuring apparatus based on wireless sensor network according to claim 1, it is characterized in that: all components and parts of this measured node are distributed in 10 * 4.5cm ²The node circuit plate on.

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