Method for Selecting Sensor Nodes

• US 20120166155A1
• Filed: 08/08/2011
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: National Tsing Hua University
• Original Assignee: National Tsing Hua University
• Inventors: Tseng, Yu-Chee, Chen, Po-Yu, Chen, Wen-Tsuen
• Granted Patent: US 8,687,058 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: G01B 11/022 by means of tv-camera scanning
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G06V 20/52 Surveillance or monitoring of activities, e.g. for recognising suspicious objects recognising microscopic objects G06V20/69
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

The present invention relates to a method for selecting sensor nodes, the method is adopted for calculating the value of a contribution function for a plurality of objects contributed by a plurality of sensor nodes, wherein the contribution function value is calculated by way of determining a coverage level of the objects made by the sensor nodes, or by means of arranging a sub sensor node group capable of sensing covering an object group and calculating the value of the contribution function for the objects contributed by the sensor nodes; Therefore, through the method, the sensor nodes having maximum contribution to the objects can be selected and arranged in a specific environment, and the sensing direction of those sensor nodes can be adjusted for making the sensor node group performs the best efficiency.

Claims

1. A method for selecting sensor nodes, comprising steps of:

(1) determining a sensor node group S={s₁, s₂, . . . , s_i} and an object group O={o₁, o₂, . . . , o_j};

(2) determining a coverage level o_j.level of a plurality of objects o_j in the object group O, respectively;

(3) calculating a first contribution function of a plurality of sensor nodes s_i in the sensor node group S;

(4) selecting the sensor node s_i having the maximum first contribution function value;

(5) directing the sensor node s_i toward a sensing direction α

_i;

(6) changing the state of the sensor node s_i to a fixed state;

(7) removing the sensor node s_i in the fixed state from the sensor node group S;

(8) determining whether all of the sensor nodes s_i are in the fixed state, if yes, proceeding to step (9), otherwise, repeatedly proceeding to the step (2);

(9) determining whether the value coverage level of all objects in the object group is equal to a default value k, if yes, proceeding to step (10), otherwise, repeatedly proceeding to the step (2); and

(10) determining whether there are no sensor nodes s_i in an undecided state can make the contributions to the coverage level o_j.level of the plurality of objects o_j, if yes, ending the step, otherwise, repeatedly proceeding to the step (2).

2. The method for selecting sensor nodes of claim 1, wherein the step (2) further comprises the steps of:

(21) defining the object group O={o₁, o₂, . . . , o_j};

(22) setting the sensing direction α

_i=dir({right arrow over (s_io₁)})+θ

in the include angle formed by X-axis and a vector {right arrow over (s_io_j)}, of the sensor node s_i and the object o_j;

(23) rotating the sensing direction α

_i counterclockwise and making the α

_i=α

_i+θ

′

;

(24) defining a sub sensor node group C′

={s₁, s₂, . . . , s_x} of the sensor node group S;

(25) choosing a sensing node s_x from the sub sensor node group C′

;

(26) rotating a vector dir({right arrow over (o_js_x)}) of the sensing node s_x and the object o_j;

(27) determining whether a sensing node s_x+1 is met capable of making the included angle formed by the sensing node s_x, the object o_j and the sensing node s_x+1 larger than 90°

, if yes, proceeding to step (28), otherwise, proceeding to step (2A);

(28) including the sensing node s_x+1 into the sub sensor node group C′

;

(29) letting s_x+1=s_x, and repeatedly proceeding to the step (26);

(2A) determining whether there are no sensor nodes s_x+1 can be include into the sub sensor node group C′

, if yes, proceeding to step (2B), otherwise, repeatedly proceeding to the step (26);

(2B) getting the object'"'"'s coverage level o_j.level=|c′

|;

(2C) determining whether the sensing direction α

_i=α

_i+θ

, if yes, proceeding to step (2D), otherwise, repeatedly proceeding to the step (23);

(2D) determining whether the included angle formed by the last sensor node s_x+1, the first sensor node s_x, and the object o_j is larger than 90°

, if yes, proceeding to the step (3), otherwise, proceeding to step (2E); and

(2E) getting the object'"'"'s coverage level o_j.level=|c′

|−

1.

3. The method for selecting sensor nodes of claim 1, wherein the computing formula of the first contribution function is that:

contr1(s_i, α

_i)=Σ

(o_j.level′

−

o_j.level), ∀

o_j.

4. The method for selecting sensor nodes of claim 3, wherein o_j.level′

means that a new coverage level for the object o_j when adding a new sensor node s_i for providing the sensing coverage to the object o_j.

5. The method for selecting sensor nodes of claim 2, wherein θ

′

means a minimum rotating angle for counterclockwise rotating the sensing direction α

_i, such that at least one object o_j may enter the sensing coverage radius of the sensor node s_i after the sensing direction α

_i is counterclockwise rotated the minimum rotating angle.

6. The method for selecting sensor nodes of claim 2, wherein θ

′

means a minimum rotating angle for counterclockwise rotating the sensing direction α

_i, such that at least one object o_j may quit the sensing coverage radius of the sensor node s_i after the sensing direction α

_i is counterclockwise rotated the minimum rotating angle.

7. The method for selecting sensor nodes of claim 2, wherein θ

′

means a minimum rotating angle for counterclockwise rotating the sensing direction α

_i, such that at least one object o_j may enter the sensing coverage radius of the sensor node s_i and at least one object o_j may quit the sensing coverage radius of the sensor node s_i after the sensing direction α

_i is counterclockwise rotated the minimum rotating angle.

8. The method for selecting sensor nodes of claim 2, wherein the sensing coverage radius of each the sensor node s_i is 2θ

.

9. A method for selecting sensor nodes, comprising steps of:

(A) determining a sensor node group S={s₁, s₂, . . . , s_i} and an object group O={o₁, o₂, . . . , o_j};

(B) determining a sub sensor node group C′

of the sensor node group S capable of providing the sensing coverage to the object group O, and calculating a coverage level o_j.level of a plurality of objects o_j in the object group O, respectively;

(C) calculating a second contribution function of a plurality of sensor nodes s_i having an undecided state in the sensor node group S;

(D) sorting all values in each the second contribution function;

(E) comparing the first values in the second contribution functions of all the sensor nodes s_i;

(F) selecting the sensor node s_i having the maximum first value in the second contribution function thereof;

(G) directing the sensor node s_i toward a sensing direction α

_i;

(H) changing the state of the sensor node s_i to a fixed state;

(I) removing the sensor node s_i in the fixed state from the sensor node group S;

(J) determining whether all of the sensor nodes s_i are in the fixed state, if yes, proceeding to step (K), otherwise, repeatedly proceeding to the step (B);

(K) determining whether the number of the value coverage level of all objects in the object group is equal to a default value k, if yes, proceeding to step (L), otherwise, repeatedly proceeding to the step (B); and

(L) determining whether there are no sensor nodes s_i in an undecided state can make the contributions to the coverage level o_j.level of the plurality of objects o_j, if yes, ending the step, otherwise, repeatedly proceeding to the step (B).

10. The method for selecting sensor nodes of claim 9, wherein the step (B) further comprises the steps of:

(B1) defining the object group O={o₁, o₂, . . . , o_j};

(B2) setting the sensing direction α

_i=dir({right arrow over (s_io₁)})+θ

in the include angle formed by X-axis and a vector {right arrow over (s_io_j)} of the sensor node s_i and the object o_j;

(B3) rotating the sensing direction α

_i counterclockwise and making the α

_i=α

_i+θ

′

;

(B4) defining the sub sensor node group C′

={s₁, s₂, . . . , s_x};

(B5) choosing one sensing node s_x from the sub sensor node group C′

;

(B6) rotating a vector dir({right arrow over (o_js_x)}) of the sensing node s_x and the object o_j;

(B7) determining whether a sensing node s_x+1 is met capable of making the included angle formed by the sensing node s_x, the object o_j and the sensing node s_x+1 larger than 90°

, if yes, proceeding to step (B8), otherwise, proceeding to step (BA);

(B8) including the sensing node s_x+1 into the sub sensor node group C′

;

(B9) letting s_x+1=s_x, and repeatedly proceeding to the step (B6);

(BA) determining whether there are no sensor nodes s_x+1 can be include into the sub sensor node group if yes, proceeding to step (BB), otherwise, repeatedly proceeding to the step (B6); and

(BB) determining whether the sensing direction α

_i=α

_i+θ

, if yes, proceeding to the step (C), otherwise, repeatedly proceeding to the step (B3).

11. The method for selecting sensor nodes of claim 10, wherein the computing formula of the second contribution function is that:

contr2(s_i, α

_i)=[r_k′

−

r_k, r<sub>k−

1</sub>′

−

r<sub>k−

1</sub>, . . . r₁′

−

r₁].

12. The method for selecting sensor nodes of claim 11, wherein the r_k means that a value of the objects'"'"' coverage level o_j.level, in which the value of the coverage level o_j.level is equal to the number of the sensor nodes s_x in the fixed state;

in addition, the r_k′

means that a value of the objects'"'"' coverage level o_j.level after the sensor node s_x+1 is included into the sub sensor node group C′

, in which the value of the coverage level o_j.level is equal to the number of the sensor nodes s_x in the fixed state.

13. The method for selecting sensor nodes of claim 10, wherein θ

′

means a minimum rotating angle for counterclockwise rotating the sensing direction α

_i, such that at least one object o_j may enter the sensing coverage radius of the sensor node s_i.

14. The method for selecting sensor nodes of claim 10, wherein the sensing coverage radius of each the sensor node s_i is 2θ

.