Methods for estimating and controlling state of ultrasonic end effector

Patent metadata

Field	Value
Publication number	US-11464532-B2
Application number	US-201816144383-A
Country	US
Kind code	B2
Filing date	Sep 27, 2018
Priority date	Mar 8, 2018
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

Various aspects of a generator, ultrasonic device, and method for estimating and controlling 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. The control circuit estimates the state of the end effector of the ultrasonic device and controls the state of the end effector of the ultrasonic device based on the estimated state.

First claim

The invention claimed is:

1. A method for estimating and controlling a state or condition 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 complex impedance measurement data point;
comparing, by the control circuit, the complex impedance measurement data point to a data point in a reference complex impedance characteristic pattern;
classifying, by the control circuit, the complex impedance measurement data point based on a result of the comparison;
assigning, by the control circuit, the state or condition of the end effector based on the result of the comparison;
estimating, by the control circuit, an estimated state or condition of the end effector of the ultrasonic device;
controlling, by the control circuit, the state or condition of the end effector of the ultrasonic device based on the estimated state or condition of the end effector;
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.

2. The method of claim 1 , comprising:
receiving, by the control circuit, the reference complex impedance characteristic pattern from a database or memory coupled to the control circuit; and
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, an impedance of the ultrasonic transducer at each frequency;
storing, by the control circuit, a data point corresponding to each impedance measurement; and
curve fitting, by the control circuit, a plurality of data points to generate a three-dimensional curve representative of the reference complex impedance characteristic pattern, wherein the magnitude |Z| and phase φ of the reference complex impedance characteristic pattern are plotted as a function of frequency f.

3. The method of claim 2 , where the curve fitting includes a polynomial curve fit, a Fourier series, and/or a parametric equation.

4. The method of claim 1 , comprising estimating, by the control circuit, a probability that the new impedance measurement data point is correctly classified.

5. The method of claim 4 , 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.

6. The method of claim 1 , comprising:
classifying by the control circuit, data based on a set of training data S, wherein the set of training data S comprises a plurality of complex impedance measurement data {right arrow over (p)};
curve fitting, by the control circuit, the set of training data S using a parametric Fourier series for each element {right arrow over (p)} of the set of training data 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 a new impedance measurement data point {right arrow over (z)}, a perpendicular distance from {right arrow over (p)} to {right arrow over (z)} is found by:

D
=



p
⇀

-

z
⇀



when:

∂
D

∂
t

=
0

then:

D
=

D
⊥

Assignees

• Ethicon Llc
• Cilag Gmbh Int

Inventors

• Nott Cameron R
• Stulen Foster B
• Quigley Fergus P
• Brady John E
• Trees Gregory A
• Sawhney Amrita S
• Scoggins Patrick J
• Denzinger Kristen G
• Faller Craig N
• Jayme Madeleine C
• Cuti Alexander R
• Schneider Matthew S
• Boudreaux Chad P
• Black Brian D
• Rockman Maxwell T
• Bishop Gregory D
• Roberson Eric M
• Leuck Stephen M
• Wilson James M

Classifications

• A61B17/320092 Primary

  with additional movable means for clamping or cutting tissue, e.g. with a pivoting jaw · CPC title

• A61B17/22012

  in direct contact with, or very close to, the obstruction or concrement (for removing obstructions in blood vessels by laser A61B18/245) · CPC title

• A61B2090/066

  for measuring torque · CPC title

• A61B2217/005

  with suction drainage system · CPC title

• A61B2018/00648

  using more than one sensed parameter · CPC title