Methods, systems, and computer-readable media for calibrating an electromagnetic navigation system

• US 10,638,952 B2
• Filed: 10/28/2016
• Issued: 05/05/2020
• Est. Priority Date: 10/28/2016
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Morgan, Sean M., Koyrakh, Lev A.
• Primary Examiner(s): Alkafawi, Eman A
• Application Number:
  US15/337,099
• Publication Number:
  US 20180116548A1
• Time in Patent Office: 1,285 Days
• Field of Search: 702 95
• CPC Class Codes: A61B 5/062 using magnetic field
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38

Abstract

Systems, methods, and computer-readable media for calibrating an electromagnetic navigation system are provided. A signal having a first magnitude value and a first phase value is received by way of a receiving antenna. A non-calibrated in-phase component and a non-calibrated quadrature component are computed based on the first magnitude value and the first phase value. A calibrated phase value is computed based on the non-calibrated in-phase component and the non-calibrated quadrature component, and a calibrated in-phase component is computed based on the calibrated phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component. A calibrated quadrature component is computed based on the calibrated phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component, and a calibrated magnitude value is computed based on the calibrated in-phase component. The calibrated phase value and the calibrated magnitude value are stored in a table for use during an electromagnetic navigation procedure.

Claims

1. A method for calibrating an electromagnetic navigation system configured to identify a location of a medical device in an electromagnetic field and including a transmitting antenna and a receiving antenna, the method comprising:

transmitting, via the transmitting antenna, an electromagnetic signal;

receiving, via the receiving antenna positioned at a location, the electromagnetic signal transmitted directly from the transmitting antenna;

measuring a non-calibrated in-phase component and a non-calibrated quadrature component based on a first magnitude value and a first phase value of the received electromagnetic signal, wherein the non-calibrated in-phase component is a signal component of the received electromagnetic signal and the non-calibrated quadrature component is a noise component of the received electromagnetic signal;

computing a second phase value based on the non-calibrated in-phase component and the non-calibrated quadrature component;

computing a calibrated in-phase component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

computing a calibrated quadrature component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

computing a second magnitude value based on the calibrated in-phase component; and

storing the second phase value and the second magnitude value with the location of the receiving antenna in a table in a memory of the electromagnetic navigation system for identifying a location of a medical device used during an electromagnetic navigation procedure,

wherein the transmitting and receiving of the electromagnetic signal are synchronized to one another.

2. The method of claim 1, further comprising:

performing a lookup in at least one of a sine table or a cosine table based on the first magnitude value and the first phase value, wherein the computing of at least one of the non-calibrated in-phase component or the non-calibrated quadrature component is further based on a result of the performing of the lookup.

3. The method of claim 1, wherein the second phase value is computed according to the equation:

4. The method of claim 1, wherein the calibrated in-phase component is computed according to the equation:

I_calibrated=I_{non-calibrated}×

cos(θ

_cal)+Q_{non-calibrated}×

sin(θ

_cal),

where I_calibrated represents the calibrated in-phase component, I_{non-calibrated} represents the non-calibrated in-phase component, θ

_cal represents the second phase value, and Q_{non-calibrated} represents the non-calibrated quadrature component.

5. The method of claim 1, wherein the calibrated quadrature component is computed according to the equation:

Q_calibrated=−

I_{non-calibrated}×

sin(θ

_cal)+Q_{non-calibrated}×

cos(θ

_cal),

where Q_calibrated represents the calibrated quadrature component, I_{non-calibrated} represents the non-calibrated in-phase component, θ

_cal represents the second phase value, and Q_{non-calibrated} represents the non-calibrated quadrature component.

6. The method of claim 1, wherein the second magnitude value is computed according to the equation:

7. The method of claim 1, further comprising:

determining whether the second magnitude value is less than zero; and

in response to a determination that the second magnitude value is less than zero;

computing a third phase value, and

recomputing the second magnitude value, the calibrated in-phase component, and the calibrated quadrature component based on the third phase value.

8. The method of claim 1, further comprising:

determining whether the second magnitude value is less than zero and whether the second phase value is less than or equal to zero; and

in response to a determination that the second magnitude value is less than zero and the second phase value is less than or equal to zero;

computing a third phase value according to the equation;

θ

_cal′

=θ

_cal+π

,

where θ

_cal′

represents the third phase value and θ

_cal represents the second phase value; and

recomputing the second magnitude value, the calibrated in-phase component, and the calibrated quadrature component based on the third phase value.

9. The method of claim 1, further comprising:

determining whether the second magnitude value is less than zero and whether the second phase value is greater than zero; and

in response to a determination that the second magnitude value is less than zero and the second phase value is greater than zero;

computing a third phase value according to the equation;

θ

_cal′

=θ

_cal−

π

,

where θ

_cal′

represents the third phase value and θ

_cal represents the second phase value; and

recomputing the second magnitude value, the calibrated in-phase component, and the calibrated quadrature component based on the third phase value.

10. The method of claim 1, further comprising:

during the electromagnetic navigation procedure,

receiving a second signal having a third magnitude value and a third phase value;

computing a second non-calibrated in-phase component and a second non-calibrated quadrature component based on the third magnitude value and the third phase value; and

computing a corrected in-phase component and a corrected quadrature component based on the second phase value, the second magnitude value, the second non-calibrated in-phase component, and the second non-calibrated quadrature component.

11. The method of claim 9, wherein the corrected in-phase component is computed according to the equation:

I_c=M_cal×

((I_non-cal2)×

cos(θ

_cal)+(Q_non-cal2)×

sin(θ

cal)),

and wherein the corrrected quadrature component is computed according to the equation;

Q_c=M_cal×

(−

(I_non-cal2)×

sin(θ

_cal)+(Q_non-cal2)×

cos(θ

_cal)),

Where I_c represents the corrected in-phase component, M_cal represents the second magnitude value, I_non-cal2 represents the second non-calibrated in-phase component, θ

_cal represents the second phase value, Q_non-cal2 represents the second non-calibrated quadarture component, and Q_c represents the corrected quadrature component.

13. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to compute the second phase value according to the equation:

14. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to compute the calibrated in-phase component according to the equation:

I_calibrated=I_{non-calibrated}×

cos(θ

_cal)+Q_{non-calibrated}×

sin(θ

_cal),

where I_calibrated represents the calibrated in-phase component, I_{non-calibrated} represents the non-calibrated in-phase component, θ

_cal represents the second phase value, and Q_{non-calibrated} represents the non-calibrated quadrature component.

15. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to compute the calibrated quadrature component according to the equation:

Q_calibrated=−

I_{non-calibrated}×

sin(θ

_cal)+Q_{non-calibrated}×

cos(θ

_cal),

where Q_calibrated represents the calibrated quadrature component, I_{non-calibrated} represents the non-calibrated in-phase, θ

_cal represents the second phase value, and Q_{non-calibrated} represents the non-calibrated quadrature component.

16. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to compute the second magnitude value according to the equation:

17. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to:

determine whether the second magnitude value is less than zero; and

in response to a determination that the second magnitude value is less than zero;

compute a third phase value, and

recompute the second magnitude value, the calibrated in-phase component, and the calibrated quadrature component based on the third phase value.

18. The system of claim 11, wherein the memory further stores instructions that, when executed by the processor, cause the processor to:

during the electromagnetic navigation procedure,

receive a second signal having a third magnitude value and a third phase value;

compute a second non-calibrated in-phase component and a second non-calibrated quadrature component based on the third magnitude value and the third phase value; and

compute a corrected in-phase component and a corrected quadrature component based on the second phase value, the second magnitude value, the second non-calibrated in-phase component, and the second non-calibrated quadrature component.

12. A system for calibrating an electromagnetic navigation system configured to identify a location of a medical device in an electromagnetic field, the system comprising:

a transmitting antenna configured to transmit an electromagnetic signal;

a receiving antenna positioned at a location and configured to receive the electromagnetic signal transmitted directly from the transmitting antenna;

a processor; and

a memory including instructions that, when executed by the processor, cause the processor to;

measure a non-calibrated in-phase component and a non-calibrated quadrature component based on a first magnitude value and a first phase value of the received electromagnetic signal, wherein the non-calibrated in-phase component is a signal component of the received electromagnetic signal and the non-calibrated quadrature component is a noise component of the received electromagnetic signal;

compute a second phase value based on the non-calibrated in-phase component and the non-calibrated quadrature component;

compute a calibrated in-phase component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

compute a calibrated quadrature component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

compute a second magnitude value based on the calibrated in-phase component; and

store, in the memory, the second phase value and the second magnitude value with the location of the receiving antenna in a table for identifying a location of a medical device used during an electromagnetic navigation procedure,

wherein the transmitting and receiving of the electromagnetic signal are synchronized to one another.

19. A non-transitory computer-readable medium having stored thereon sequences of instructions that, when executed by an electromagnetic navigation system configured to identify a location of a medical device in an electromagnetic field and including a transmitting antenna and a receiving antenna, cause the electromagnetic navigation system to:

transmit, via the transmitting antenna, an electromagnetic signal;

receive, via the receiving antenna positioned at a location, the electromagnetic signal transmitted directly from the transmitting antenna;

measure a non-calibrated in-phase component and a non-calibrated quadrature component based on a first magnitude value and a first phase value of the received electromagnetic signal, wherein the non-calibrated in-phase component is a signal component of the received electromagnetic signal and the non-calibrated quadrature component is a noise component of the received electromagnetic signal;

compute a second phase value based on the non-calibrated in-phase component and the non-calibrated quadrature component;

compute a calibrated in-phase component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

compute a calibrated quadrature component based on the second phase value, the non-calibrated in-phase component, and the non-calibrated quadrature component;

compute a calibrated magnitude value based on the calibrated in-phase component; and

store the second phase value and the calibrated magnitude value with the location of the receiving antenna in a table for identifying a location of a medical device used during an electromagnetic navigation procedure,

wherein the transmitting and receiving of the electromagnetic signal are synchronized to one another.