CN1862286A - Method for precisely positioning sensor node - Google Patents

Abstract

The invention discloses a method for precise positioning of sensor nodes, which includes the steps of: in the sensor network, constructing a plurality of sensor nodes satisfying the following conditions into a cooperative node group, that is, any sensor node in the node group to the signal The ratio L/l of the distance L of any sensor node in the target node or another node group to the distance l of any two sensor nodes in the node group is greater than a certain degree of aggregation parameter lc; the centroid of the cooperative node group is obtained as A position that is convenient for calculation; measure the signal arrival angle of the sending end for the centroid of the cooperative node group, and obtain the coordinate relationship between each sensor node and the centroid of the cooperative node group; carry out the actual position of the cooperative node group Positioning, so as to obtain the precise position of the sensor node.

Description

A Method for Accurate Positioning of Sensor Nodes

technical field

The invention relates to a method for precise positioning of sensor nodes.

Background technique

In sensor networks, location information is crucial to monitoring activities. The location where the event occurs or the location of the node that obtains the information is important information for node monitoring messages, and monitoring messages without location information are often meaningless. Therefore, determining the location of an event or the location of a node to obtain information is one of the most basic functions of a sensor network and plays a key role in its application effectiveness.

At present, many positioning schemes have been proposed specifically. Among them, TOA (Time of Arrival) and TDoA (Time Difference of Arrival) based on time of arrival, and AOA (Angle of Arrival) based on angle of arrival, use the low-speed characteristics of sound waves/ultrasonic waves to obtain high-precision straight-line distances by measuring propagation time, However, due to the introduction of additional hardware modules, the cost and energy overhead are increased; especially the AOA scheme requires each node to be equipped with an ultrasonic or antenna array, which limits the application. The RSSI (Received Signal Strength Indication) scheme based on signal strength performs positioning by pre-establishing the mapping relationship between signal strength and location or correcting the propagation model, with low cost and moderate accuracy. The DV-Hop (jump distance vector) and Amorphous schemes replace the straight-line distance with the hop distance, and the Centroid (centroid) and APIT (approximate polygon interior point) schemes use the polygon centroid and interior point as the real position of the node for positioning; this Several schemes have low cost and low overhead, and the corresponding accuracy is not high.

Contents of the invention

Aiming at the problems existing in the above algorithm, the present invention proposes a new positioning scheme, constructs a cooperative node group, and uses this as the basic communication unit, and performs cooperative angle of arrival estimation based on the node group by measuring the time difference of arrival or received signal strength position.

According to the present invention, there is provided a method for precise positioning of sensor nodes, comprising steps:

(1) In the sensor network, multiple sensor nodes satisfying the following conditions are constructed into a cooperative node group, that is, the distance L between any sensor node in the node group and the beacon node or any sensor node in another node group The ratio L/l of the distance l between any two sensor nodes in the node group is greater than a certain aggregation degree parameter lc;

(2) Obtain the centroid of the cooperative node group as a position convenient for calculation;

(3) measure the signal arrival angle of the transmitter for the centroid of the cooperating node group, and obtain the coordinate relationship between each sensor node and the centroid of the coordinating node group;

(4) Positioning the actual position of the cooperative node group, so as to obtain the precise position of the sensor node.

Preferably, the cooperating node group uses the software and hardware resources of the sensors it owns as available resources.

Preferably, the signal arrival angle refers to the angle between the direction in which the signal arrives at the centroid and true north.

Preferably, the step of measuring the angle-of-arrival of the signal at the sending end for the centroid of the coordinating node group in step (3) includes:

The angle of arrival of the signal is measured by measuring the time difference or the signal strength difference between the arrival of the signal at each sensor node in the cooperative node group.

Preferably, the step of obtaining the centroid in step (2) also includes:

When two sensor nodes form a cooperative node group, the position of the center of the connecting line of the two sensors is taken as the position of the centroid, and the mid-perpendicular line of the connecting line of the two sensors is taken as the orientation.

Preferably, the step of obtaining the centroid in step (2) also includes:

When the cooperative node group is composed of three sensor nodes, the center of the circle determined by the three sensors is used as the centroid position, and the direction from the centroid to one of the nodes is taken as the orientation.

Preferably, the step of obtaining the centroid in step (2) also includes:

When the cooperative node group is composed of four sensor nodes, the diagonal intersection of the quadrilateral determined by the four sensors is used as the position of the centroid, and the direction from the centroid to one of the nodes is taken as the orientation.

Preferably, step (3) also includes the steps of:

Using the TDoA method or the theoretical model method of signal propagation to estimate the distance between each sensor node in the cooperative node group and the signal sending end;

For the multi-path signals sent by multiple nodes in the sending node group, the distance is estimated and averaged as the result;

Based on this, the Euclidean space composed of the sensor nodes in the node group, the centroid of the super node and the signal sending end is constructed, and the local angle of arrival of the signal at the sending end with respect to the centroid of the super node and the distance between each sensor and the centroid of the super node are obtained. coordinate relationship.

Preferably, in step (4), a triangulation method is used to locate the actual position of the coordinating node group.

Preferably, step (4) also includes the steps of:

Construct a polygon containing two beacon nodes and several adjacent cooperating node groups where the distances between sensor nodes are the same except for the distance between beacon nodes,

In the case of knowing the position and orientation of two beacon nodes, the position information of each cooperative node group is solved.

According to the basic idea of the present invention, before positioning starts, a cooperative sensor node group, ie, a super node, is constructed according to the distribution and aggregation status of the sensor nodes. The super node takes all software and hardware resources in the node group as available resources, takes a position in the node group that is easy to calculate as the centroid, and takes the angle between the direction of the signal arriving at the centroid and true north as the signal arrival angle. The angle of arrival of the signal can be estimated by measuring the time difference or signal strength difference between the arrival of the signal at each sensor node in the super node.

Simulation results prove that the angle of arrival estimation accuracy obtained by this method is acceptable. Based on this cooperative node group angle of arrival estimation method, two suitable positioning schemes are further proposed: one is a derivative version of the traditional angle of arrival estimation positioning scheme in a cooperative manner, and the other is an improved DV-Hop (mDV -Hop) program.

In the present invention, a plurality of gathered sensor nodes are used to form a transmitting and receiving array of a cooperative node group (super node) to estimate the virtual angle of arrival of the super node. This method effectively expands the application range of the positioning scheme based on the angle of arrival estimation.

Description of drawings

Fig. 1 shows the system model of the cooperative angle of arrival estimation positioning scheme according to the present invention;

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

Fig. 3 shows the method for calculating the global angle of arrival of the super node according to the present invention;

Fig. 4 has shown two sensors according to the present invention, three sensors, the centroid position of four sensor nodes, the definition of azimuth and corresponding signal arrival angle calculation method;

FIG. 5 shows the distribution of angle-of-arrival estimation errors according to the present invention.

Fig. 6 shows the distribution situation of the angle of arrival estimation error of two sensor super nodes according to the present invention and the relationship with the distance between the two sensors;

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

Detailed ways

In the present invention, it is assumed that the sensor network has N nodes, which are distributed with a certain aggregation degree. Among them, the beacon node knows its own position and has the ability to sense the angle of arrival of the signal.

According to the distribution and aggregation status of sensor nodes, the network establishes a topology structure with a node group containing several sensors as the basic unit. Among them, several sensor nodes gathered together are divided into the same node group, and such a node group is called a super node. The division is based on:

${\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; \}</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1,2</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ;</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; \&Element;</span><span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}<span\; class="notranslate">\; \}</span>$

s.t.

S _i ∩ S _j = , i≠j

min(L _ij /l _i ，L _ij /l _j )≥l _c (1)

in:

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

${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; max</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; \&Element;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

The parameters are introduced as follows:

S _k : cooperative node group k, the kth super node in the collaborative positioning network

n _ki : node of the sensor network, the i-th node in the cooperative node group k

M: the number of super nodes built

N: the number of sensors in the network

L _ij : the minimum distance between cooperating node groups i and j

l _k : the maximum distance between any two nodes in the cooperative node group k

l _c : network aggregation parameter

The value of lc depends on the concentration of sensors in the network, which affects the application of cooperative angle of arrival estimation. The larger the value of lc, the higher the concentration of sensors in the network, and the more meaningful the collaborative angle of arrival estimation method is.

The constructed super nodes, whose physical parameters include available resources, centroid positions, and orientations, can be derived from node groups accordingly. The software and hardware resources of all sensors in the node group are the available resources of the super node. For the position and orientation of the centroid of the super node, in principle, it should be selected as the position and orientation that are convenient for calculation in the node group. For ease of description, the following provisions are made in this implementation:

1. For the case of two sensor node groups, take the center of the connection line between the two sensors or other positions that are convenient for calculation as the centroid position, and take the perpendicular line of the connection line between the two sensors as the orientation;

2. For the case of a three-sensor node group, the center of the circle determined by the three sensors or other positions that are easy to calculate are used as the position of the centroid, and the direction from the centroid to one of the nodes is taken as the orientation;

3. For the case of a four-sensor node group, take the intersection of the diagonals of the quadrilateral determined by the four sensors or other positions that are convenient for calculation as the position of the centroid, and the direction from the centroid to one of the nodes as the orientation;

4. For other situations, the position and orientation of the node group that are convenient for calculation are used as the position and orientation of the center of mass.

Then, the angle of arrival of the super node is defined as follows: the direction of arrival of the signal with respect to the centroid of the super node, the angle between the direction of the signal and the azimuth of the super node is the local angle of arrival of the signal, and the angle between the angle with the true north is the angle of arrival of the signal.

On this basis, the signal arrival angle on the super node is estimated. The TDoA method, the theoretical model method of signal propagation or other methods are used to estimate the distance between each sensor in the node group and the signal sending end. For the multi-path signals sent by multiple nodes in the sending node group, the distance is estimated and averaged as the result. Based on this, the Euclidean space composed of the sensor nodes in the node group, the centroid of the super node and the signal sending end is constructed, and the local angle of arrival of the signal at the sending end with respect to the centroid of the super node and the distance between each sensor and the centroid of the super node are obtained. coordinate relationship.

Then, triangulation or polygon method can be used to complete the location of the super node. The breakdown is as follows:

1. The triangulation method is equivalent to replacing the sensor node with the signal angle of arrival measurement capability in the traditional angle of arrival positioning scheme with the virtual cooperative node group with the signal angle of arrival measurement capability in the present invention, that is, the super node, so it can be regarded as It is a derivative version of the traditional angle-of-arrival positioning scheme in a collaborative manner. The triangulation method is generally combined with the relatively accurate TDoA ranging method, so it has high accuracy.

2. The polygon method is specially proposed for the cooperative angle of arrival estimation, and it is a positioning scheme that absorbs the idea of DV-Hop, called mDV-Hop scheme. The specific implementation is shown in Figure 7. Each internal angle of the polygon can be derived from the signal arrival angle of each node. Therefore, in the case of knowing the position and orientation of the two beacon nodes, the position information of each super node can be easily calculated by constructing the polygon. It is assumed here that the distances between nodes are the same except for the distance between beacon nodes. The polygon method is generally combined with the signal strength ranging method, so the accuracy is poor. specifically,

f(d′;  ₁ ,...,  _k )=d

${\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; ij</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; |</span>{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; d</span>}}^{<span\; class="notranslate">\; \&prime;</span>}& \mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; k</span>}\\ \mathrm{<span\; class="notranslate">\; d</span>}& \mathrm{<span\; class="notranslate">\; else</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

in:

 _i = n _i

${\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; |</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

i<j; i, j=1,...,k (3)-2

in

n _i is the vertex of the polygon, its coordinates are ( _xi , y _i ), and n ₁ , n _k are two beacon nodes with known coordinates;

 _i is the interior angle of the polygon with n _i as the vertex;

d _ij is the side length with n _i and n _j as endpoints in the polygon, except for the side length with two beacon nodes as endpoints is d′, the other side lengths are all equal to d;

The formula f(d';  ₁ ,...,  _k )=d is the relationship between known internal angles and known side lengths of polygons

Then the only unknown variable value d=f(d′;  ₁ ,...,  _k ) can be obtained from this formula, and the coordinate values of each vertex can be further obtained.

Finally, according to the previously obtained coordinate relationship between each sensor of the super node and the centroid of the super node, the position of the sensor is calculated.

Claims (10)

1. A method for precise positioning of sensor nodes, comprising steps: (1) In the sensor network, multiple sensor nodes satisfying the following conditions are constructed into a cooperative node group, that is, the distance L between any sensor node in the node group and the beacon node or any sensor node in another node group The ratio L/l of the distance l between any two sensor nodes in the node group is greater than a certain aggregation degree parameter lc; (2) Obtain the centroid of the cooperative node group as a position convenient for calculation; (3) measuring the signal arrival angle of the sending end for the centroid of the cooperating node group, and obtaining the coordinate relationship between each sensor node in the cooperating node group and the centroid of the cooperating node group; (4) Positioning the actual position of the cooperative node group, so as to obtain the precise position of the sensor node. 2. The method according to claim 1, wherein the cooperative node group uses the software and hardware resources of the sensors it owns as available resources. 3. The method according to claim 1, wherein the signal arrival angle refers to the angle between the direction in which the signal arrives at the centroid and true north. 4. The method according to claim 3, wherein the step of measuring the angle-of-arrival of the signal at the sending end for the centroid of the coordinating node group in step (3) comprises: The angle of arrival of the signal is measured by measuring the time difference or the signal strength difference between the arrival of the signal at each sensor node in the cooperative node group. 5. The method according to claim 1, wherein the step of obtaining the centroid in step (2) also includes: When two sensor nodes form a cooperative node group, the position of the center of the connecting line of the two sensors is taken as the position of the centroid, and the mid-perpendicular line of the connecting line of the two sensors is taken as the orientation. 6. The method according to claim 1, wherein the step of obtaining the centroid in step (2) further comprises: When the cooperative node group is composed of three sensor nodes, the center of the circle determined by the three sensors is used as the centroid position, and the direction from the centroid to one of the nodes is taken as the orientation. 7. The method according to claim 1, wherein the step of obtaining the centroid in step (2) also includes: When the cooperative node group is composed of four sensor nodes, the diagonal intersection of the quadrilateral determined by the four sensors is used as the position of the centroid, and the direction from the centroid to one of the nodes is taken as the orientation. 8. The method according to claim 1, wherein step (3) further comprises the steps of: Using the TDoA method or the theoretical model method of signal propagation to estimate the distance between each sensor node in the cooperative node group and the signal sending end; For the multi-channel signals sent by multiple sensor nodes in the sending node group, the distance is estimated and averaged as the result; Based on this, the Euclidean space composed of the sensor nodes in the node group, the centroid of the super node and the signal sending end is constructed, and the local angle of arrival of the signal at the sending end with respect to the centroid of the super node and the distance between each sensor and the centroid of the super node are obtained. coordinate relationship. 9. The method according to claim 1, wherein in step (4) triangulation is used to perform positioning of the actual location of the group of cooperating nodes. 10. The method according to claim 1, wherein step (4) further comprises the steps of: Construct a polygon containing two beacon nodes and several adjacent cooperating node groups where the distances between sensor nodes are the same except for the distance between beacon nodes, In the case of knowing the position and orientation of two beacon nodes, the position information of each cooperative node group is solved.

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