Method for controlling smart energy devices
A method for controlling an operation of an ultrasonic blade of an ultrasonic electromechanical system is disclosed. The method includes providing an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an ultrasonic blade via an ultrasonic waveguide; applying, by an energy source, a power level to the ultrasonic transducer; determining, by a control circuit coupled to a memory, a mechanical property of the ultrasonic electromechanical system; comparing, by the control circuit, the mechanical property with a reference mechanical property stored in the memory; and adjusting, by the control circuit, the power level applied to the ultrasonic transducer based on the comparison of the mechanical property with the reference mechanical property.
1. A method for determining a characteristic of an ultrasonic blade of an ultrasonic electromechanical system, the method comprising:
providing an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an ultrasonic blade via an ultrasonic waveguide;
applying, by an energy source, a power level to the ultrasonic transducer;
determining, by a control circuit coupled to a memory, the characteristic of the ultrasonic blade, wherein determining, by a control circuit coupled to a memory, the characteristic of the ultrasonic blade comprises determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade; and
generating, by the control circuit, a temperature estimator and state space model of the temperature of the ultrasonic blade as a function of a resonant frequency of the ultrasonic electromechanical system based on a set of non-linear state space equations;
wherein generating, by the control circuit, a state space model of the temperature of the ultrasonic blade based on a set of non-linear state space equations comprises generating, by the control circuit, a state space model defined by:
[
F
.
n
T
.
]
=
f
(
t
,
T
(
t
)
,
F
n
(
t
)
,
E
(
t
)
)
y
.
=
h
(
t
,
T
(
t
)
,
F
n
(
t
)
,
E
(
t
)
)
,
wherein the state space model represents a rate of change of a natural frequency {dot over (F)} n of the ultrasonic electromechanical system and a rate of change of the temperature {dot over (T)} with respect to the natural frequency F n (t), the temperature T(t), energy E(t) applied to the ultrasonic blade, and time t, and wherein {dot over (y)} represents observability of the natural frequency F n (t) of the ultrasonic electromechanical system, the temperature T(t) of the ultrasonic blade, the energy E(t) applied to the ultrasonic blade, and time t.
2. The method of claim 1 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises:
determining, by the control circuit, a resonant frequency of the ultrasonic blade; and
comparing, by the control circuit, the resonant frequency of the ultrasonic blade to a reference resonant frequency stored in the memory of the control circuit.
3. The method of claim 1 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises measuring, by the control circuit, a phase angle φ between a voltage signal Vg(t) and a current signal Ig(t) applied to the ultrasonic transducer by the energy source.
4. The method of claim 1 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises measuring, by the control circuit, an impedance Zg(t) equal to a ratio of a voltage signal Vg(t) to a current signal Ig(t) applied to the ultrasonic transducer by the energy source.
5. A method for determining a characteristic of an ultrasonic blade of an ultrasonic electromechanical system, the method comprising:
providing an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an ultrasonic blade via an ultrasonic waveguide;
applying, by an energy source, a power level to the ultrasonic transducer;
determining, by a control circuit coupled to a memory, the characteristic of the ultrasonic blade, wherein determining, by a control circuit coupled to a memory, the characteristic of the ultrasonic blade comprises determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade;
generating, by the control circuit, a temperature estimator and state space model of the temperature of the ultrasonic blade as a function of a resonant frequency of the ultrasonic electromechanical system based on a set of non-linear state space equations; and
applying, by the control circuit, a Kalman filter to improve the temperature estimator and state space model;
wherein applying, by the control circuit, a Kalman filter to improve the temperature estimator and state space model comprises applying, by the control circuit, a Kalman filter having a state variance of a state estimator of the Kalman filter defined by:
(σ k − ) 2 =σ k-1 2 +σ P k 2 and
a gain K of the Kalman filter is defined by:
K
=
(
σ
k
-
)
2
(
σ
k
-
)
2
+
σ
m
2
,
wherein σ k − is defined as the state variance, σ k-1 is defined as prior variance, σ P k is defined as predicted variance, and σ m is defined as observed variance.
6. The method of claim 5 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises:
determining, by the control circuit, a resonant frequency of the ultrasonic blade; and
comparing, by the control circuit, the resonant frequency of the ultrasonic blade to a reference resonant frequency stored in the memory of the control circuit.
7. The method of claim 5 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises measuring, by the control circuit, a phase angle φ between a voltage signal Vg(t) and a current signal Ig(t) applied to the ultrasonic transducer by the energy source.
8. The method of claim 5 , wherein determining, by the control circuit coupled to the memory, a temperature of the ultrasonic blade comprises measuring, by the control circuit, an impedance Zg(t) equal to a ratio of a voltage signal Vg(t) to a current signal Ig(t) applied to the ultrasonic transducer by the energy source.
9. A method, comprising:
providing an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an ultrasonic blade via an ultrasonic waveguide;
applying energy to the ultrasonic blade;
determining a temperature of the ultrasonic blade; and
generating a state space model defined by:
[
F
˙
n
T
˙
]
=
f
(
t
,
T
(
t
)
,
F
n
(
t
)
,
E
(
t
)
)
y
˙
=
h
(
t
,
T
(
t
)
,
F
n
(
t
)
,
E
(
t
)
)
,
wherein the state space model represents a rate of change of a natural frequency {dot over (F)} n of the ultrasonic electromechanical system and a rate of change of the temperature {dot over (T)} with respect to the natural frequency F n (t), the temperature T(t), the energy E(t) applied to the ultrasonic blade, and time t, and wherein {dot over (y)} represents observability of the natural frequency F n (t) of the ultrasonic electromechanical system, the temperature T(t) of the ultrasonic blade, the energy E(t) applied to the ultrasonic blade, and time t.
10. The method of claim 9 , wherein determining a temperature of the ultrasonic blade comprises:
determining a resonant frequency of the ultrasonic blade; and
comparing the resonant frequency of the ultrasonic blade to a reference resonant frequency.
11. The method of claim 9 , wherein determining a temperature of the ultrasonic blade comprises measuring a phase angle φ between a voltage signal Vg(t) and a current signal Ig(t) applied to the ultrasonic transducer.
12. The method of claim 9 , wherein determining a temperature of the ultrasonic blade comprises measuring an impedance Zg(t) equal to a ratio of a voltage signal Vg(t) to a current signal Ig(t) applied to the ultrasonic transducer.
13. A method, comprising:
providing an ultrasonic electromechanical system comprising an ultrasonic transducer coupled to an ultrasonic blade via an ultrasonic waveguide;
determining a temperature of the ultrasonic blade;
generating a temperature estimator and state space model of the temperature of the ultrasonic blade; and
applying a Kalman filter having a state variance of a state estimator of the Kalman filter defined by:
(σ k − ) 2 =σ k-1 2 +σ P k 2 and
a gain K of the Kalman filter is defined by:
K
=
(
σ
k
-
)
2
(
σ
k
-
)
2
+
σ
m
2
,
wherein σ k − is defined as the state variance, σ k-1 is defined as prior variance, σ P k is defined as predicted variance, and σ m is defined as observed variance.
14. The method of claim 13 , wherein determining a temperature of the ultrasonic blade comprises:
determining a resonant frequency of the ultrasonic blade; and
comparing the resonant frequency of the ultrasonic blade to a reference resonant frequency.
15. The method of claim 13 , wherein determining a temperature of the ultrasonic blade comprises measuring a phase angle φ between a voltage signal Vg(t) and a current signal Ig(t) applied to the ultrasonic transducer.
16. The method of claim 13 , wherein determining a temperature of the ultrasonic blade comprises measuring an impedance Zg(t) equal to a ratio of a voltage signal Vg(t) to a current signal Ig(t) applied to the ultrasonic transducer.