Low energy or minimum disturbance method for measuring frequency response functions of ultrasonic surgical devices in determining optimum operating point
A method for measuring frequency response is provided that includes supplying ultrasonic energy to an ultrasonic device configured to impart energy to tissue, providing a drive signal and a noise signal, combining the drive signal and the noise signal to create a combined signal, amplifying the combined signal and providing the amplified signal to the ultrasonic device, receiving an output signal from the ultrasonic device and the noise signal, calculating a transfer function estimate based on the output signal and the noise signal, adjusting the drive signal generator based on the calculated transfer function estimate, and determining a phase difference by time aligning the noise signal in the output signal with the noise signal provided.
1. A method for measuring frequency response, comprising:
supplying ultrasonic energy to an ultrasonic device configured to impart energy to tissue;
providing a drive signal;
providing a noise signal, wherein the noise signal is a pseudo random noise sequence;
combining the drive signal and the noise signal to create a combined signal; and
amplifying the combined signal and providing the amplified signal to the ultrasonic device.
2. The method according to claim 1 , further comprising:
receiving an output signal from the ultrasonic device and the noise signal;
calculating a transfer function estimate based on the output signal and the noise signal; and
adjusting the drive signal generator based on the calculated transfer function estimate.
3. The method according to claim 1 , further comprising determining a phase difference by time aligning the noise signal in the output signal with the noise signal provided.
4. The method according to claim 1 , wherein the noise signal is pink noise.
5. The method according to claim 1 , wherein the noise signal is a narrowband white noise.
6. The method according to claim 1 , wherein the combined signal is amplified by an amplifier having a gain.
7. The method according to claim 6 , wherein the gain is preset by a manufacturer.
8. The method according to claim 6 , wherein the gain is user selectable.
9. The method according to claim 2 , wherein the transfer function estimate is calculated by a Fast Fourier Transform of the output signal and the noise signal.
10. A method for supplying power to an ultrasonic device, comprising:
providing a drive signal;
amplifying the drive signal;
providing a noise signal;
providing an output of a resonance circuit to the ultrasonic device;
receiving an output signal of the ultrasonic device and the noise signal;
calculating a transfer function estimate based on the output signal of the ultrasonic device and the noise signal;
adjusting the drive signal based on the calculated transfer function estimate.
11. The method according to claim 10 , wherein the resonance circuit is an LC circuit.
12. The method according to claim 10 , wherein the drive signal is amplified by a Class D amplifier.