CN1862286B - Method for precisely positioning sensor node - Google Patents

Abstract

The present invention discloses a method for accurately locating a sensor node. The method includes the following steps: in a sensor network, configuring a plurality of sensor nodes meeting the conditions below as one cooperation node group, namely a ratio L/l of the distance L between any sensor node in the cooperation node group and a beaconing node or any sensor node in another cooperation node group and the distance l between any two sensor nodes in the cooperation node group beling larger than some aggregation degree parameter lc; obtaining the center of mass of the cooperation node group as a position for calculation; measuring a signal reaching angle of a signal sender of the beaconing node and the center of mass of the cooperation node group by measuring a time difference or a signal intensity difference when the signal reaches each sensor node in the cooperation node group, and obtaining the coordinate relation between each sensor node and the center of mass of the cooperation node group, wherein the signal reaching angle is an included angle of the direction of the signal reaching the center of mass and due north; locating a real position of the cooperation node group, thereby obtaining the accurate position of the sensor node.

Description

A kind of to the pinpoint method of sensor node

Technical field

The present invention relates to a kind of to the pinpoint method of sensor node.

Background technology

In sensor network, positional information is most important to monitoring.Position that incident takes place or the node location that obtains information are the important informations of node supervisory messages, do not have the supervisory messages of positional information often meaningless.Therefore, the node location of determining the position that incident takes place or obtaining information is one of basic functions of sensor network, it is used validity play key effect.

Have at present and proposed many targeting schemes pointedly.Wherein, TOA (time of arrival), TDoA (time of arrival is poor) based on time of arrival, AOA (angle of arrival) scheme based on the angle of arrival, utilized sound wave/hyperacoustic low-speed characteristic, obtain the higher air line distance of precision by measuring the travel-time, but, cost and energy expense have been increased owing to introduce extra hardware module; Particularly the AOA scheme requires each node all to be furnished with ultrasonic or aerial array, has limited application.Based on RSSI (indication of the received signal intensity) scheme of signal intensity, by setting up signal intensity in advance to the mapping relations of position or revise propagation model and position, the cost expense is not high, moderate accuracy.DV-Hop (jumping the segment distance vector) and Amorphous scheme replace air line distance to jump segment distance, and Centroid (barycenter) and APIT (point in the approximate polygon) scheme then with polygon barycenter and interior as the node actual position, positions; The low expense of these several scheme costs is little, and corresponding precision is not high yet.

Summary of the invention

At the problem that exists in the above-mentioned algorithm, the present invention proposes a kind of new targeting scheme, makes up the groups of nodes of cooperation, and as basic communication unit, by measuring and calculating difference time of arrival or received signal intensity, carries out estimating the location based on the cooperation angle of arrival of groups of nodes.

According to the present invention, provide a kind of to the pinpoint method of sensor node, comprise step:

(1) in sensor network, the a plurality of sensor nodes that meet the following conditions are configured to a cooperative node group, promptly in the cooperative node group in the distance L of any one sensor node any sensor node in beaconing nodes or another cooperative node group and the cooperative node group any two sensor nodes apart from the ratio L/l of l greater than a certain concentration class parameter lc;

(2) draw the barycenter of described cooperative node group, as the position of being convenient to calculate;

(3) arrive the mistiming or the difference in signal strength of each sensor node in the cooperative node group by measuring-signal, measure the signal angle of arrival of the signal sending end of beaconing nodes, and obtain the coordinate relation between the barycenter of each sensor node and described cooperative node group for the barycenter of described cooperative node group; Wherein, the described signal angle of arrival is that signal arrives the direction of described barycenter and the angle in positive north;

(4) physical location to described cooperative node group positions, thereby obtains the exact position of sensor node.

Preferably, described cooperative node group with the software and hardware resources of the sensor that it was had as available resources.

Preferably, the described signal angle of arrival is meant that signal arrives the direction of described barycenter and the angle in positive north.

Preferably, the middle measurement of step (3) transmitting terminal comprises for the step of the signal angle of arrival of the barycenter of described cooperative node group:

Arrive the mistiming or the difference in signal strength of each sensor node in the described cooperative node group by measuring-signal, measure the signal angle of arrival.

Preferably, the step that draws barycenter in the step (2) also comprises:

When constituting the cooperative node group, as centroid position, be the orientation with the perpendicular bisector of two sensors line with the position at two sensor line centers by two sensor nodes.

Preferably, the step that draws barycenter in the step (2) also comprises:

When constituting the cooperative node group, as centroid position, point to the direction of one of them node as the orientation by barycenter with the center of circle of the circle determined by three sensors by three sensor nodes.

Preferably, the step that draws barycenter in the step (2) also comprises:

When constituting the cooperative node group, as centroid position, point to the direction of one of them node as the orientation by barycenter with the tetragonal diagonal line intersection point determined by four sensors by four sensor nodes.

Preferably, step (3) also comprises step:

The theoretical model method that adopts TDoA method or signal to propagate is inferred the distance of each sensor node and signal sending end in the described cooperative node group;

To the multiple signals that send by a plurality of nodes in the cooperative node group, estimate the distance after ask on average as a result of;

Make up the Euclidean space of forming jointly by each sensor node, cooperative node group barycenter and signal sending end in the cooperative node group based on this, obtain transmitting terminal about the local angle of arrival of the signal of cooperative node group barycenter, and the relation of the coordinate between each sensor and the cooperative node group barycenter.

Preferably, the middle employing of step (4) triangulation is carried out the location to the physical location of described cooperative node group.

Preferably, step (4) also comprises step:

Construct a polygon that comprises two beaconing nodes and some adjacent cooperative node groups, wherein the distance between beaconing nodes, the distance between the sensor node is identical,

Under the situation of knowing two beaconing nodes positions, orientation, find the solution the positional information of each cooperative node group.

According to basic design of the present invention, before the beginning of location,, make up the sensor node group of cooperation according to the distribution or accumulation situation of sensor node, that is super node.This super node as available resources, is its barycenter with certain position of being convenient in the groups of nodes calculate with all software and hardware resources in the groups of nodes, and the direction that arrives this barycenter with signal is the angle of arrival of signal with positive northern angle.By the mistiming or the difference in signal strength of each sensor node in the measuring-signal arrival super node, can estimate the angle of arrival of signal.

The angle of arrival estimated accuracy that this mode of simulation result identity basis obtains is acceptable.Cooperative node group angle of arrival method of estimation in view of the above, two kinds of targeting schemes that further proposed to adapt with it: a kind of is that traditional angle of arrival is estimated the derived version of targeting scheme under cooperation mode, and a kind of is improved DV-Hop (mDV-Hop) scheme.

In the present invention, utilize a plurality of sensor nodes of assembling to constitute the transmitting-receiving array of cooperative node group (super node), carry out the virtual angle of arrival of super node and estimate that this method has been expanded the range of application of the targeting scheme of estimating based on the angle of arrival effectively.

Description of drawings

Fig. 1 shows the system model of estimating targeting scheme according to the cooperation angle of arrival of the present invention;

Fig. 2 shows the local angle of arrival method of estimation that comprises the super node A of two sensors according to of the present invention;

Fig. 3 shows the overall angle of arrival projectional technique according to super node of the present invention;

Fig. 4 shows according to the definition in the centroid position of two sensors of the present invention, three sensors, four-sensor node, orientation and the corresponding signal angle of arrival and asks method;

Fig. 5 shows according to angle of arrival evaluated error distribution situation of the present invention.

Fig. 6 show according to the angle of arrival evaluated error distribution situation of two sensors super node of the present invention and and two sensors between the relation of distance;

Fig. 7 shows according to m-DV-Hop localization method of the present invention.

Embodiment

In the present invention, suppose that sensor network has N node, distribute with certain concentration class.Wherein beaconing nodes is known self orientation and is had the ability of the sensing signal angle of arrival.

The distribution of network based sensor node, gathering situation, setting up with the groups of nodes that comprises some sensors is the topological structure of base unit.Wherein, the some sensor nodes that flock together are divided in the same groups of nodes, claim that such groups of nodes is a super node.Divide according to being:

$S_k=\left\{n_{k_i}\right\},k=\mathrm{1,2},...M;n_{k_i}\∈\{n_1,n_2,...,n_N\}$

s.t.

min(L _ij/l _i，L _ij/l _j)≥l _c (1)

Wherein:

L _ij＝min[d(n _i，n _j)] n _i∈S _i，n _j∈S _j，i≠j

$l_k=\max \left[d(n_{k_i},n_{k_j})\right]{,n}_{k_i},n_{k_j}\∈S_k---\left(2\right)$

Parameter is described below:

S _k: cooperative node group k, k super node in the co-positioned network

: the node of sensor network, i node among the cooperative node group k

M: the number of the super node of structure

N: the number of sensor in the network

L _Ij: the minor increment of cooperative node group i and j

l _k: the ultimate range of any two nodes among the cooperative node group k

l _c: network concentration class parameter

Wherein the value of lc depends on the concentration class of sensor in the network, the application that the influence cooperation angle of arrival is estimated, and the value of lc is big more, and the concentration class of sensor is high more in the network, and the cooperation angle of arrival estimates that mode is meaningful more.

The super node that has made up, its physical parameter comprise available resources, centroid position, orientation (orientation), can correspondingly be derived by groups of nodes.The software and hardware resources of all the sensors in the groups of nodes is the available resources of super node.For the centroid position and the orientation of super node, should be chosen to be in principle and be convenient to position and the orientation calculated in the groups of nodes.For ease of explanation, in this realization, do following regulation:

1. for two sensors groups of nodes situation,,, be the orientation with the perpendicular bisector of two sensors line as centroid position with two sensors line center or other position of being convenient to calculate;

2. for three sensor node group situations,,, point to the direction of one of them node as the orientation by barycenter as centroid position with by the center of circle of the definite circle of three sensors or the position that other is convenient to calculate;

3. for four-sensor groups of nodes situation,,, point to the direction of one of them node as the orientation by barycenter as centroid position with tetragonal diagonal line intersection point or other position of determining by four-sensor of being convenient to calculate;

4. for other situation, with position and the direction of being convenient in the groups of nodes calculate, as centroid position and orientation.

Then, the angle of arrival of super node is done as giving a definition: signal is about the arrival direction of super node barycenter, with the angle in super node orientation be the local angle of arrival of signal, with the angle in positive north be the angle of arrival of signal.

On this basis, the signal angle of arrival on the super node is estimated.Adopt theoretical model method that TDoA method, signal propagate or other method to infer the distance of each sensor and signal sending end in the groups of nodes.To the multiple signals that send by a plurality of nodes in the sending node group, estimate the distance after ask on average as a result of.Make up the Euclidean space of forming jointly by each sensor node, super node barycenter and signal sending end in the groups of nodes based on this, obtain transmitting terminal about the local angle of arrival of the signal of super node barycenter, and the relation of the coordinate between each sensor and the super node barycenter.

Then, can be with triangulation or polygon method, the location of finishing super node.Division is as follows:

1. triangulation is equivalent to the virtual corporation groups of nodes that signal angle of arrival measurement capability is arranged in the sensor node alternative costs invention that signal angle of arrival measurement capability is arranged in traditional angle of arrival targeting scheme, that is super node, thereby can be regarded as the derived version of traditional angle of arrival targeting scheme under cooperation mode.Trigonometry is general to combine with the more accurate TDoA distance-finding method that compares, thereby has degree of precision.

2. polygon method is in particular the estimation of the cooperation angle of arrival and proposes, and has absorbed a targeting scheme of DV-Hop thought, is called the mDV-Hop scheme.Specific implementation such as Fig. 7, polygonal each interior angle can be derived by the signal angle of arrival of each node, thereby under the situation of knowing two beaconing nodes positions, orientation, the structure polygon can be found the solution the positional information of each super node easily, here suppose that the distance between beaconing nodes, the distance between the node is identical.Polygon method generally combines with the signal intensity telemetry, thereby precision is relatively poor.Particularly,

$d_{\mathrm{ij}}=\left|n_i{n}_j\right|=\left\{\begin{array}{cc}{d}^{\′}& i=1,j=k\\ d& \mathrm{else}\end{array}\right.---\left(3\right)-1$

Wherein:

$\left|n_i{n}_j\right|=\sqrt{{(x_i-x_j)}^2+{(y_i-y_j)}^2}$

i＜j；i，j＝1，...，k (3)-2

Wherein

n _iBe polygonal summit, its coordinate is (x _i, y _i)), and n ₁, n _kTwo beaconing nodes for known coordinate;

Be with n in the polygon _iInterior angle for the summit;

d _IjBe with n in the polygon _i, n _jBeing the length of side of end points, is that the length of side of end points is that d ' is outer divided by two beaconing nodes wherein, and other length of side equates to be all d;

Formula Relational expression for known each interior angle of polygon and the known length of side

Then can solve only known variables value by this formula

And can further draw each apex coordinate value.

At last, according to the relation of the coordinate between each sensor of the super node that had before drawn and the super node barycenter, extrapolate the sensor position.

Claims (8)

1. one kind to the pinpoint method of sensor node, it is characterized in that described method comprises step:

(1) in sensor network, the a plurality of sensor nodes that meet the following conditions are configured to one first cooperative node group, in the promptly described first cooperative node group in the distance L of any one sensor node any sensor node in beaconing nodes or another the second cooperative node group and the described first cooperative node group any two sensor nodes apart from the ratio L/l of l greater than a certain concentration class parameter lc;

(2) draw the barycenter of the described first cooperative node group, as the position of being convenient to calculate;

(3) arrive the mistiming or the difference in signal strength of each sensor node in the described first cooperative node group by measuring-signal, measure the signal angle of arrival of the signal sending end of described beaconing nodes, and obtain the coordinate relation between the barycenter of each sensor node in the described first cooperative node group and the described first cooperative node group for the barycenter of the described first cooperative node group; Wherein, the described signal angle of arrival is that signal arrives the direction of described barycenter and the angle in positive north;

(4) physical location to the described first cooperative node group positions, thereby obtains the exact position of sensor node.

2. method according to claim 1 is characterized in that, the described first cooperative node group with the software and hardware resources of the sensor that it was had as available resources.

3. method according to claim 1 is characterized in that, the step that draws barycenter in the step (2) also comprises:

When constituting the described first cooperative node group by two sensor nodes, as centroid position, be the orientation with the perpendicular bisector of two sensors line with the position at two sensor line centers.

4. method according to claim 1 is characterized in that, the step that draws barycenter in the step (2) also comprises:

When constituting the described first cooperative node group by three sensor nodes, as centroid position, point to the direction of one of them node as the orientation by barycenter with the center of circle of the circle determined by three sensors.

5. method according to claim 1 is characterized in that, the step that draws barycenter in the step (2) also comprises:

When constituting the described first cooperative node group by four sensor nodes, as centroid position, point to the direction of one of them node as the orientation by barycenter with the tetragonal diagonal line intersection point determined by four sensors.

6. method according to claim 1 is characterized in that, step (3) also comprises step:

The theoretical model method that adopts TDoA method or signal to propagate is inferred the distance of the signal sending end of each sensor node and described beaconing nodes in the described first cooperative node group;

To the multiple signals that send by a plurality of sensor nodes in the described first cooperative node group, estimate the distance after ask on average as a result of;

Make up the Euclidean space of forming jointly by the signal sending end of each sensor node, cooperative node group barycenter and described beaconing nodes in the described first cooperative node group based on this, obtain the signal angle of arrival of transmitting terminal about cooperative node group barycenter, and the relation of the coordinate between each sensor and the cooperative node group barycenter.

7. method according to claim 1 is characterized in that, the employing triangulation is carried out the location to the physical location of the described first cooperative node group in the step (4).

8. method according to claim 1 is characterized in that, step (4) also comprises step:

Construct a polygon that comprises two beaconing nodes and some adjacent cooperative node groups, wherein the distance between beaconing nodes, the distance between the sensor node is identical,

Under the situation of knowing two beaconing nodes positions, orientation, find the solution the positional information of each cooperative node group.

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