Method and systems for locating a source of particle, molecule, or fragment of molecule using their reception rate

• US 7,885,768 B2
• Filed: 07/07/2006
• Issued: 02/08/2011
• Est. Priority Date: 07/07/2006
• Status: Expired due to Fees

• Current Assignee: Centre National De La Recherche Scientifique, Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Villermaux, Emmanuel, Shraiman, Boris, Vergassola, Massimo
• Primary Examiner(s): Zeman; Mary K
• Application Number:
  US11/481,944
• Publication Number:
  US 20080010023A1
• Time in Patent Office: 1,677 Days
• Field of Search: None
• US Class Current: 702/19
• CPC Class Codes: G01N 33/0062 concerning the measuring method, e.g. intermittent, or the display, e.g. digital
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

A method and systems for locating a source of particles, molecules, or fragments of molecules using particle, molecule, or fragment of molecule reception rate is disclosed. According to the invention, the particle, molecule, or fragment of molecules diffusion parameters in the search space are determined and a lattice is designed on the search space. After having determined whether or not at least one particle, molecule, or fragment of molecule is detected by a sensor, a probability is computed for each node of said search space lattice. The probability associated to each node of the search space lattice corresponds to the probability that the particle, molecule, or fragment of molecule source is located on the node. Then, the move of the sensor is evaluated according to the entropy of the computed probabilities.

Claims

1. A method implemented by a computer programmed to move a mobile sensor to locate a source of particles, molecules, or fragments of molecules in a search space, the mobile sensor being adapted to detect the presence of such particle, molecule, or fragment of particle, the method comprising:

determining the particle, molecule, or fragment of molecule diffusion parameters in said search space;

designing a lattice on said search space;

determining if at least one particle, molecule, or fragment of molecule is detected by said sensor;

computing, by a processor of the computer, a probability for each node of said search space lattice to be the source of said particles, molecules, or fragments of molecules according to the determined particle, molecule, or fragment of molecule diffusion parameters and to the detected particles, molecules, or fragments of molecules;

evaluating a movement of said sensor according to said computed probabilities to locate a source of particles, molecules, or fragments of molecules in a search space; and

moving said sensor according to the evaluated movement.

2. The method of claim 1 further comprising repeating, until one of said computed probabilities is approximately equal to a predetermined threshold, the steps of

determining if at least one particle, molecule, or fragment of molecule is detected by said sensor;

computing a probability for each node of said search space lattice to be the source of said particle, molecule, or fragment of molecule according to the determined particle, molecule, or fragment of molecule diffusion parameters and to the detected particles, molecules or fragments of molecules;

evaluating a movement of said sensor according to said computed probabilities; and

,

moving said sensor.

3. The method of either claim 1 or claim 2 wherein the rate R(r|r₀) at which particles, molecules, or fragments of molecules are received at point r from the source of said particles, molecules, or fragments of molecules located in r₀ is expressed as follow,

4. The method of claim 1, wherein said probability P₁(r₀) associated to each node of said search space lattice to be the source of said particles, molecules, or fragments of molecules is computed according to the next relation,

5. The method of claim 1, wherein said step of evaluating a movement of said sensor according to said computed probabilities is based upon the entropy of said computed probabilities.

6. The method of claim 5 wherein the movement of said sensor is determined so as to maximize the variation of entropy of said computed probabilities.

7. The method of claim 6 wherein the variation entropy Δ

S(r→

r_j) of said computed probabilities is determined according to the following relation,

Δ

S(r →

r_j)=−

SP_t(r_j)+(1−

P_t(r_j))[ρ

₀(r_j)Δ

S₀+ρ

₁(r_j)Δ

S₁+ . . . +ρ

_n(r_n)Δ

S_n]

wherein,

P_i(r_j) is the probability at time t that node r_j corresponds to the source of said particles, molecules, or fragments of molecules;

p_i(r_j) denotes the probability that i particle, molecule, or fragment of molecule detections are made at node r_j during 25 a time step Δ

t; and

,

Δ

S_i denotes the change of entropy between the fields P_t+1(r₀) and P_t(r_o).

8. The method of claim 1, wherein at least two different types of particles, molecules, or fragments of molecules are emitted by said source of particles, molecules, or fragments of molecules to be localized, said mobile sensor being adapted to detect each of said at least two different types of particles, molecules, or fragments of molecules, a probability being computed for each of said at least two different types of particles, molecules, or fragments of molecules, for each node of said search space lattice to be the source of said particles, molecules, or fragments of molecules.

9. The method of claim 1, wherein said molecules or fragments of molecules are biological molecules, biological fragments of molecules, proteins, fragments of proteins, or pathogens.

10. The method of claim 1, wherein said particles, molecules, or fragments of molecules 20 characterizes an odorous substance.

11. The method of claim 1, wherein said search space is located within a gaseous environment or within a liquid environment.

12. An apparatus comprising a computer including a computer program to move a mobile sensor to locate a source of particles, molecules, or fragments of molecules in a search space, the mobile sensor being adapted to detect the presence of such particle, molecule, or fragment of particle, the computer program causing the computer to determine the particle, molecule, or fragment of molecule diffusion parameters in said search space;

design a lattice on said search space;

determine if at least one particle, molecule, or fragment of molecule is detected by said sensor;

compute, by a processor of the computer, a probability for each node of said search space lattice to be the source of said particles, molecules, or fragments of molecules according to the determined particle, molecule, or fragment of molecule diffusion parameters and to the detected particles, molecules, or fragments of molecules;

evaluate a movement of said sensor according to said computed probabilities; and

move the sensor according to the evaluated movement.

13. The apparatus of claim 12, comprising a robot embedding said sensor, said robot being mobile in said search space, wherein-said first robot and said computer exchange data.

14. A non-transitory computer-readable medium storing a computer program that when executed by a computer, causes the computer to move a mobile sensor to locate a source of particles, molecules, or fragments of molecules in a search space, the mobile sensor being adapted to detect the presence of such particle, molecule, or fragment of particle, the computer program comprising instructions to

determine the particle, molecule, or fragment of molecule diffusion parameters in said search space;

design a lattice on said search space;

determine if at least one particle, molecule, or fragment of molecule is detected by said sensor;

compute, by a processor of the computer, a probability for each node of said search space lattice to be the source of said particles, molecules, or fragments of molecules according to the determined particle, molecule, or fragment of molecule diffusion parameters and to the detected particles, molecules, or fragments of molecules;

evaluate a movement of said sensor according to said computed probabilities; and

move the sensor according to said evaluated movement.