Estimating state of ultrasonic end effector and control system therefor

Patent metadata

Field	Value
Publication number	US-11464559-B2
Application number	US-201816115214-A
Country	US
Kind code	B2
Filing date	Aug 28, 2018
Priority date	Dec 28, 2017
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

Various aspects of a generator, ultrasonic device, and method for estimating a state of an end effector of an ultrasonic device are disclosed. The ultrasonic device includes an electromechanical ultrasonic system defined by a predetermined resonant frequency, including an ultrasonic transducer coupled to an ultrasonic blade. A control circuit measures a complex impedance of an ultrasonic transducer, wherein the complex impedance is defined asZg⁡(t)=Vg⁡(t)Ig⁡(t).The control circuit receives a complex impedance measurement data point and compares the complex impedance measurement data point to a data point in a reference complex impedance characteristic pattern. The control circuit then classifies the complex impedance measurement data point based on a result of the comparison analysis and assigns a state or condition of the end effector based on the result of the comparison analysis.

First claim

The invention claimed is:

1. A method of estimating a state of an end effector of an ultrasonic device, the ultrasonic device including an electromechanical ultrasonic system defined by a predetermined resonant frequency, the electromechanical ultrasonic system including an ultrasonic transducer coupled to an ultrasonic blade, the method comprising:
measuring, by a control circuit, a complex impedance of an ultrasonic transducer, wherein the complex impedance is defined as

Z
g

(
t
)

=

V
g

(
t
)

I
g

(
t
)

;

receiving, by the control circuit, a reference complex impedance characteristic pattern comprising a plurality of data points from a database or memory coupled to the control circuit, wherein each of the plurality of data points is defined by an ultrasonic transducer impedance magnitude |Z|, an ultrasonic transducer impedance phase φ, and a frequency f at which the complex impedance of the ultrasonic transducer is measured;
generating, by the control circuit, the reference complex impedance characteristic pattern, wherein generating the reference complex impedance characteristic pattern comprises:
applying, by a drive circuit coupled to the control circuit, a nontherapeutic drive signal to the ultrasonic transducer starting at an initial frequency, ending at a final frequency, and at a plurality of frequencies therebetween;
measuring, by the control circuit, the complex impedance of the ultrasonic transducer at each frequency of the plurality of the frequencies;
storing, by the control circuit, a data point corresponding to each complex impedance measurement; and
curve fitting, by the control circuit, a plurality of data points comprising each data point corresponding to each complex impedance measurement to generate a three-dimensional curve representative of the reference complex impedance characteristic pattern, wherein the magnitude |Z| and the phase φ are plotted as a function of the frequency f,

receiving, by the control circuit, a complex impedance measurement data point;
comparing, by the control circuit, the complex impedance measurement data point to one of the plurality of data points of the reference complex impedance characteristic pattern;
classifying, by the control circuit, the complex impedance measurement data point based on a result of a comparison with the three-dimensional curve representative of the reference complex impedance characteristic pattern, wherein the three-dimensional curve representative of the reference complex impedance characteristic pattern includes a polynomial curve fit, a Fourier series, and/or a parametric equation; and
assigning, by the control circuit, a state of the end effector based on the result of the comparison.

2. The method of claim 1 , comprising:
receiving, by the control circuit, a new impedance measurement data point ; and
classifying, by the control circuit, the new impedance measurement data point using a Euclidean perpendicular distance from the new impedance measurement data point to a trajectory which has been fitted to the reference complex impedance characteristic pattern.

3. The method of claim 2 , comprising estimating, by the control circuit, a probability that the new impedance measurement data point is correctly classified.

4. The method of claim 3 , comprising adding, by the control circuit, the new impedance measurement data point to the reference complex impedance characteristic pattern based on the probability of the estimated correct classification of the new impedance measurement data point .

5. The method of claim 4 , comprising:
classifying, by the control circuit, data based on a set of training data S, wherein a plurality of elements of the set of training data S comprise a plurality of complex impedance measurement data ;
curve fitting, by the control circuit, the set of training data S using a parametric Fourier series for each of the plurality of elements of training data set S defined by:

p
⇀

=

a
⇀

0

+

∑

n
=
1

∞

(

a
⇀

n

⁢
cos
⁢

n
⁢
π
⁢
t

L

+

b
⇀

n

⁢
sin
⁢

n
⁢
π
⁢
t

L

)

wherein a period is defined by 2L;
wherein, for the new impedance measurement data point , the Euclidean perpendicular distance from to is found by:

D
=



p
⇀

-

z
⇀



⁢

when
:

⁢

∂
D

∂
t

=
0

Assignees

• Cilag Gmbh Int

Inventors

• Nott Cameron R
• Stulen Foster B
• Quigley Fergus P
• Brady John E
• Trees Gregory A
• Sawhney Amrita Singh
• Ortiz Rafael J Ruiz
• Scoggins Patrick J
• Denzinger Kristen G
• Faller Craig N
• Jayme Madeleine C
• Cuti Alexander R
• Schneider Matthew S
• Black Brian D
• Rockman Maxwell
• Bishop Gregory D
• Shelton Iv Frederick E
• Yates David C

Classifications

• A61B2017/00199

  with a console, e.g. a control panel with a display · CPC title

• A61B18/1206 Primary

  Generators therefor · CPC title

• A61B18/12

  by passing a current through the tissue to be heated, e.g. high-frequency current · CPC title

• A61B2017/00026

  Conductivity or impedance, e.g. of tissue · CPC title

• A61B2090/0811

  for the position of a particular part of an instrument with respect to the rest of the instrument, e.g. position of the anvil of a stapling instrument · CPC title