POSITION DETECTING SYSTEM AND POSITION DETECTING METHOD

• US 20110181273A1
• Filed: 09/15/2010
• Published: 07/28/2011
• Est. Priority Date: 03/16/2009
• Status: Active Grant

• Current Assignee: Olympus Corporation
• Original Assignee: Olympus Medical Systems Corporation (Olympus Corporation)
• Inventors: Kimura, Atsushi, Iida, Takahiro, Chiba, Atsushi, Uchiyawa, Akio
• Granted Patent: US 8,217,645 B2
• Time in Patent Office: Days
• US Class Current: 324/207.11
• CPC Class Codes: A61B 1/00158 using magnetic field
• CPC Class Codes: A61B 1/041 Capsule endoscopes for imaging
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: A61B 5/073 Intestinal transmitters
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

To provide a position detecting system including a detected object disposed in a detection space and an external device disposed outside the detection space. The detected object includes a resonant circuit that generates a resonant magnetic field according to a driving magnetic field formed in the detection space, and the external device includes at least two drive coils that form the driving magnetic field in the detection space, at least two drive-signal input units that respectively input a drive signal for forming the driving magnetic field to the drive coils, at least one sense coil that detects a magnetic field formed in the detection space, a signal adjustment unit that adjusts a phase and an amplitude of the drive signal input to each of the drive coils by the drive-signal input units, based on a magnetic field detected by the sense coil, and a position deriving unit that derives a position of the detected object based on the magnetic field detected by the sense coil.

Claims

1. A position detecting system comprising:

a detected object disposed in a detection space; and

an external device disposed outside the detection space, wherein

the detected object includes a resonant circuit that generates a resonant magnetic field according to a driving magnetic field formed in the detection space, and

the external device includes

at least two drive coils that form the driving magnetic field in the detection space;

at least two drive-signal input units that input a drive signal for forming the driving magnetic field to the drive coils, respectively;

at least one sense coil that detects a magnetic field formed in the detection space;

a signal adjustment unit that adjusts a phase and an amplitude of the drive signal input to each of the drive coils by the drive-signal input units, based on a magnetic field detected by the sense coil; and

a position deriving unit that derives a position of the detected object based on a magnetic field detected by the sense coil.

2. The position detecting system according to claim 1, wherein

the signal adjustment unit adjusts at least one of the phase and the amplitude of the drive signal, by using an evaluation function for evaluating at least one of the phase and the amplitude of the drive signal based on an intensity of a magnetic field detected by the sense coil, and

the evaluation function derives a solution by adding or multiplying a weight set according to a positional relation between each drive coil and each sense coil to or by an intensity of a magnetic field detected by the sense coils.

3. The position detecting system according to claim 1, wherein

the signal adjustment unit adjusts at least one of a phase and an amplitude of the drive signal, by using an evaluation function for evaluating at least one of the phase and the amplitude of the drive signal based on an intensity of a magnetic field detected by the sense coil, and

the evaluation function derives a solution by adding or multiplying a weight set according to at least one of a positional relation between each drive coil and each sense coil and a shape of each drive coil to or by the amplitude of the drive signal.

4. The position detecting system according to claim 2, wherein the signal adjustment unit changes the weight based on at least one of an amplitude or a phase of the drive signal and an intensity of a magnetic field detected by the sense coils.

5. The position detecting system according to claim 1, wherein the external device includes

an auxiliary coil that generates a auxiliary magnetic field that negates a driving magnetic field input to at least one of the sense coils;

and

an auxiliary-signal input unit that inputs an auxiliary signal for causing the auxiliary coil to generate the auxiliary magnetic field, and

the signal adjustment unit adjusts at least one of a phase and an amplitude of the drive signal input to at least one of the drive coils by the drive-signal input unit and/or a phase and an amplitude of the auxiliary signal input to the auxiliary coil by the auxiliary-signal input unit, based on a magnetic field detected by the sense coil.

6. The position detecting system according to claim 5, wherein

the signal adjustment unit adjusts at least one of a phase and an amplitude of at least one of the drive signal and the auxiliary signal, by using an evaluation function for evaluating the at least one of the phase and the amplitude of the at least one of the drive signal and the auxiliary signal based on an intensity of a magnetic field detected by the sense coils, and

the evaluation function derives a solution by adding or multiplying a weight set according to a positional relation between the respective drive coils and the auxiliary coil, and each sense coil to or by an intensity of a magnetic field detected by the sense coil.

7. The position detecting system according to claim 5, wherein

the signal adjustment unit adjusts the at least one of the phase and the amplitude of the at least one of the drive signal and the auxiliary signal, by using an evaluation function for evaluating the at least one of the phase and the amplitude of the at least one of the drive signal and the auxiliary signal based on an intensity of a magnetic field detected by the sense coil, and

the evaluation function derives a solution by adding or multiplying a weight set according to at least one of a positional relation between the respective drive coils and the auxiliary coil, and each sense coil, and a shape of each drive coil.

8. The position detecting system according to claim 6, wherein the signal adjustment unit changes the weight based on at least one of an amplitude or a phase of the drive signal and an intensity of a magnetic field detected by the sense coils.

9. A position detecting method for detecting a position of a detected object that is inserted into a detection space where at least two drive coils that form a driving magnetic field are disposed to generate a resonant magnetic field for detecting a position of the detected object according to the driving magnetic field, the position detecting method comprising:

detecting a magnetic field formed in the detection space by at least one sense coil provided outside the detected object, by inputting a drive signal to the drive coils in a state with the detected object not being inserted into the detection space;

adjusting a phase and an amplitude of the drive signal based on the detected magnetic field;

forming a driving magnetic field in the detection space by inputting the drive signal, with a phase or an amplitude thereof being adjusted, to the drive coils in a state with the detected object being inserted into the detection space;

detecting a magnetic field in the detection space at a time of forming the driving magnetic field in the detection space by the at least one sense coil; and

deriving a position of the detected object based on the magnetic field detected at a time of forming the driving magnetic field in the detection space.

10. The position detecting method according to claim 9, wherein

the adjusting includes adjusting at least one of a phase and an amplitude of the drive signal by using an evaluation function for evaluating the at least one of the phase and the amplitude of the drive signal based on an intensity of a magnetic field detected by the sense coil, and

the evaluation function derives a solution by adding or multiplying a weight set according to a positional relation between each drive coil and each sense coil to or by an intensity of a magnetic field detected by the sense coil.

11. The position detecting method according to claim 9, wherein

the adjusting includes adjusting at least one of a phase and an amplitude of the drive signal by using an evaluation function for evaluating the at least one of the phase and the amplitude of the drive signal based on an intensity of a magnetic field detected by the sense coil, and

the evaluation function derives a solution by adding or multiplying a weight set according to at least one of a positional relation between each drive coil and each sense coil and a shape of each drive coil to or by the amplitude of the drive signal.

12. The position detecting method according to claim 9, wherein the adjusting includes fixing a phase or an amplitude of at least one drive signal of the drive signals input to each of the at least two drive coils, and adjusting at least one of a phase and an amplitude of the other drive signal with respect to a drive signal with the phase or the amplitude being fixed.

13. A position detecting system comprising:

a body-insertable apparatus disposed in a detection space in a state of being inserted into a subject; and

an external device disposed outside the detection space, wherein

the body-insertable apparatus includes a resonant circuit that generates a resonant magnetic field according to a driving magnetic field formed in the detection space, and

the external device includes

a sense coil that generates a detection signal according to a magnetic field formed in the detection space;

a drive coil that generates the driving magnetic field;

a driving-magnetic-field generating unit that inputs a drive signal for generating the driving magnetic field to the drive coil;

an auxiliary coil that generates a auxiliary magnetic field for reducing the driving magnetic field input to the sense coil;

an auxiliary-magnetic-field generating unit that inputs an auxiliary signal for generating the auxiliary magnetic field to the auxiliary coil;

a phase storage unit that stores a phase of the driving magnetic field formed in the detection space in a state with the body-insertable apparatus not being inserted into the detection space;

a combined-magnetic-field information storage unit that stores information of a combined magnetic field formed in the detection space, at a time of generating the driving magnetic field and the auxiliary magnetic field in a state with the body-insertable apparatus not being inserted into the detection space;

a signal processor that derives information of the magnetic field from the detection signal;

a position deriving unit that derives a position of the body-insertable apparatus by using information of the magnetic field derived by the signal processor, the phase stored in the phase storage unit, and information of the combined magnetic field stored in the combined-magnetic-field information storage unit; and

a control unit that causes the signal processor to derive information of the magnetic field based on the detection signal read from the sense coil, in a state that the auxiliary-magnetic-field generating unit inputs the auxiliary signal to the auxiliary coil, while the driving-magnetic-field generating unit inputs the drive signal to the drive coil, and causes the position deriving unit to derive a position of the body-insertable apparatus by using the acquired information of the magnetic field, the phase stored in the phase storage unit, and information of the combined magnetic field stored in the combined-magnetic-field information storage unit.

14. The position detecting system according to claim 13, wherein

information of the combined magnetic field is a complex vector including an intensity and a phase of the combined magnetic field,

information of the magnetic field is a complex vector including an intensity and a phase of the magnetic field, and

the position deriving unit subtracts the information of the combined magnetic field from the information of the magnetic field according to vector operation, to calculate a cosine component of the complex vector calculated by the subtraction with respect to the phase stored in the phase storage unit, and derives a position of the body-insertable apparatus by using the calculated cosine component.

15. The position detecting system according to claim 13, wherein the phase stored in the phase storage unit is a phase of the driving magnetic field detected by the sense coil at a time of generating the driving magnetic field, in a state with the body-insertable apparatus not being inserted into the detection space.

16. The position detecting system according to claim 14, wherein the phase stored in the phase storage unit is a phase of the driving magnetic field detected by a magnetic field sensor disposed in the detection space at a time of generating the driving magnetic field, in a state with the body-insertable apparatus not being inserted into the detection space.

17. A position detecting method for detecting a position of a body-insertable apparatus that is disposed in a detection space where a sense coil that detects a magnetic field, a drive coil that generates a driving magnetic field, and an auxiliary coil that generates a auxiliary magnetic field for reducing the driving magnetic field input to the sense coil are disposed, to generate a resonant magnetic field for detecting a position of the body-insertable apparatus according to the driving magnetic field, the position detecting method comprising:

detecting a phase of the driving magnetic field formed in the detection space in a state with the body-insertable apparatus not being disposed in the detection space;

acquiring information of a combined magnetic field formed in the detection space at a time of generating the driving magnetic field and the auxiliary magnetic field in a state with the body-insertable apparatus not being disposed in the detection space;

acquiring information of a magnetic field detected by the sense coil at a time of generating the driving magnetic field and the auxiliary magnetic field in a state with the body-insertable apparatus being disposed in the detection space; and

deriving a position of the body-insertable apparatus by using the acquired information of the magnetic field detected by the sense coil, the phase, and the acquired information of the combined magnetic field.

18. The position detecting method according to claim 17, wherein

information of the combined magnetic field is a complex vector including an intensity and a phase of the combined magnetic field,

information of the magnetic field is a complex vector including an intensity and a phase of the magnetic field, and

the position deriving unit subtracts the information of the combined magnetic field from the information of the magnetic field according to vector operation, to calculate a cosine component of the complex vector calculated by the subtraction with respect to the phase stored in the phase storage unit, and derives a position of the body-insertable apparatus by using the calculated cosine component.

19. The position detecting method according to claim 17, wherein the phase detecting includes detecting a phase of the driving magnetic field detected by the sense coil at a time of generating the driving magnetic field in a state with the body-insertable apparatus not being inserted in the detection space.

20. The position detecting method according to claim 17, wherein the phase detecting includes detecting a phase of the driving magnetic field detected by a magnetic field sensor disposed in the detection space at a time of generating the driving magnetic field in a state with the body-insertable apparatus not being inserted in the detection space.

21. A position detecting system comprising:

a detected object disposed in a detection space; and

an external device disposed outside the detection space, wherein

the detected object includes a resonating means for generating a resonant magnetic field according to a driving magnetic field formed in the detection space, and

the external device includes

at least two driving means for forming the driving magnetic field in the detection space;

at least two drive-signal inputting means for inputting a drive signal for forming the driving magnetic field, respectively, to the driving means;

at least one detecting means for detecting a magnetic field formed in the detection space;

a signal adjusting means for adjusting a phase and an amplitude of the drive signal input to each of the driving means by the drive-signal inputting means, based on a magnetic field detected by the detecting means; and

a position deriving means for deriving a position of the detected object based on a magnetic field detected by the detecting means.

22. A position detecting system comprising:

a body-insertable apparatus disposed in a detection space in a state of being inserted into a subject; and

an external device disposed outside the detection space, wherein

the body-insertable apparatus includes a resonating means for generating a resonant magnetic field according to a driving magnetic field formed in the detection space, and

the external device includes

a detecting means for generating a detection signal according to a magnetic field formed in the detection space;

a driving means for generating the driving magnetic field;

a driving-magnetic-field generating means for inputting a drive signal for generating the driving magnetic field to the driving means;

an auxiliary means for generating an auxiliary magnetic field for reducing the driving magnetic field input to the detecting means;

an auxiliary-magnetic-field generating means for inputting an auxiliary signal for generating the auxiliary magnetic field to the auxiliary means;

a phase storing means for storing a phase of the driving magnetic field formed in the detection space in a state with the body-insertable apparatus not being inserted into the detection space;

a combined-magnetic-field information storing means for storing information of a combined magnetic field formed in the detection space, at a time of generating the driving magnetic field and the auxiliary magnetic field in a state with the body-insertable apparatus not being inserted into the detection space;

a signal processing means for deriving information of the magnetic field from the detection signal;

a position deriving means for deriving a position of the body-insertable apparatus by using information of the magnetic field derived by the signal processing means, the phase stored in the phase storing means, and information of the combined magnetic field stored in the combined-magnetic-field information storing means; and

a controlling means for causing the signal processing means to derive information of the magnetic field based on the detection signal read by the detecting means, in a state that the auxiliary-magnetic-field generating means inputs the auxiliary signal to the auxiliary means, while the driving-magnetic-field generating means inputs the drive signal to the driving means, and causes the position deriving means to derive a position of the body-insertable apparatus by using the acquired information of the magnetic field, the phase stored in the phase storing means, and information of the combined magnetic field stored in the combined-magnetic-field information storing means.