Vibration actuator for shear wave elastography, system and method

Patent metadata

Field	Value
Publication number	US-2024055936-A1
Application number	US-202118266667-A
Country	US
Kind code	A1
Filing date	Dec 14, 2021
Priority date	Dec 15, 2020
Publication date	Feb 15, 2024
Grant date	—

Abstract

A vibration actuator ( 10 ) for mechanically generating a shear wave comprises a plurality of n rotational vibrators ( 141, 142, 143 ), an accelerometer ( 16 ), and a controller ( 18 ). The plurality of n rotational vibrators enables generation of a vibration vector with desired directional behavior selected from a plurality of vibration vectors ( 34, 36, 38 ) of different directional behaviors. Each rotational vibrator comprises an independently controllable motor ( 20 ) having a drive shaft ( 22 ) and an eccentric disk ( 24 ). The accelerometer is arranged to detect a vibration vector generated by at least two of the plurality of n rotational vibrators. The controller selectively controls a first set of two rotational vibrators to rotate respective eccentric disks in a first coordinated manner to produce a first vibration vector, and a second set of two rotational vibrators to rotate respective eccentric disks in a second coordinated manner to produce a second vibration vector, with different respective directional behaviors.

First claim

1 . A vibration actuator for mechanically generating a shear wave, comprising:
a housing; a plurality of n rotational vibrators coupled to the housing in a geometric arrangement configured to enable generation of a vibration vector with desired directional behavior selected from a plurality of vibration vectors of different directional behaviors, wherein n is a number of at least three, wherein each rotational vibrator comprises an independently controllable motor having a drive shaft and an eccentric disk coupled to the drive shaft in a plane perpendicular to an axis of the drive shaft; an accelerometer coupled to the housing, wherein the accelerometer is arranged to detect a vibration vector generated by at least two of the plurality of n rotational vibrators and generate an accelerometer output signal based on the detected vibration vector; and a controller operatively coupled to each rotational vibrator for selectively controlling (i) a first set of two of the plurality of n rotational vibrators to rotate respective eccentric disks in a first coordinated manner based at least on the accelerometer output signal to produce a first vibration vector, and (ii) a second set of two of the plurality of n rotational vibrators to rotate respective eccentric disks in a second coordinated manner based at least on the accelerometer output signal to produce a second vibration vector, wherein a directional behavior of the second vibration vector is different from a directional behavior of the first vibration vector.

2 . The vibration actuator according to claim 1 , wherein the controller is further for selectively controlling (iii) a third set of two of the plurality of n rotational vibrators to rotate respective eccentric disks in a third coordinated manner based at least on the accelerometer output signal to produce a third vibration vector, wherein a directional behavior of the third vibration vector is different from the directional behavior of the second vibration vector and different from the directional behavior of the first vibration vector.

3 . The vibration actuator according to claim 1 , wherein the controller is further configured for (i) determining a directional behavior of a resultant vibration vector based on (i)(a) the accelerometer output signal and (i)(b) the selectively controlled first set or second set of two of the plurality of n rotational vibrators to rotate respective eccentric disks, (ii) performing a comparison of a directional behavior of the resultant vibration vector to the desired directional behavior of the vibration vector, and (iii) adjusting the first or the second coordinated manner based on the comparison.

4 . The vibration actuator according to claim 1 , wherein the first coordinated manner or the second coordinated manner includes rotating each respective eccentric disk of the respective first set or second set of two of the plurality of n rotational vibrators at a same rotary speed, but in opposite rotational directions.

5 . The vibration actuator according to claim 1 , wherein the first or second coordinated manner includes controlling the respective first or second set of rotational vibrators (i) with mirror symmetry of the respective eccentric disks to produce a vector vibration along a mid-plane direction between respective eccentric disks, and (ii) without mirror symmetry of the respective eccentric disks to produce a vector vibration deviation from the mid-plane direction.

6 . The vibration actuator according to claim 1 , wherein each eccentric disk of a respective motor of the respective first set or second set of two of the plurality of n rotational vibrators is arranged co-planar to one another within the respective first set or second set.

7 . The vibration actuator according to claim 1 , wherein each respective motor comprises a bi-axial motor, and further wherein each respective eccentric disk comprises a first eccentric disk coupled to a first end of a respective drive shaft and a second eccentric disk coupled to a second end of the respective drive shaft.

8 . The vibration actuator according to claim 1 , wherein each respective eccentric disk comprises a disk having an off-center weight, further wherein the respective off-center weight of respective eccentric disks of a respective first and second rotational vibrator are controlled, via the respective motor and the controller, to rotate in positions that are symmetrical to one another and to generate vibrations, wherein only vibrational components along a mid-plane between the respective first and second rotational vibrator remains, while vibrations in all other directions cancel each other.

9 . The vibration actuator according to claim 1 , wherein n comprises three, and wherein the geometric arrangement of three rotational vibrators comprises a triangular arrangement.

10 . The vibration actuator according to claim 9 , wherein the triangular arrangement comprises the three rotational vibrators having axes of their respective motor drive shafts located at apexes of a triangle, and further wherein the directional behavior of the first vibration vector ( 34 ) and the directional behavior of the second vibration vector ( 36 ) are selected from the group consisting of +120 degrees, 0 degrees and −120 degrees.

11 . The vibration actuator according to claim 9 , wherein the triangular arrangement is configured to enable achievement of multiple electronically selectable vibration orientations selected from the group consisting of (i) +15 degrees, 0 degrees and −15 degrees, (ii) +20 degrees, 0 degrees and −20 degrees, (iii) +30 degrees, 0 degrees and −30 degrees, and (iv) orientations in a range from +−10 to +−110 degrees.

12 . The vibration actuator according to claim 1 , wherein the geometric arrangement further includes the number of n rotational vibrators configured to enable generation of multiple electronically selectable vibration vectors in n*(n−1)/2 directions.

13 . The vibration actuator according to claim 1 , wherein each rotational vibrator further comprises a position sensor arranged to detect a radial orientation or rotational angle of the respective eccentric disk and generate a respective position signal, and
wherein controlling via the controller further comprises synchronously controlling, based on respective position signals, (i) the first set of two of the plurality of n rotational vibrators to rotate respective eccentric disks and produce the first vibration vector and (ii) the second set of two of the plurality of n rotational vibrators to rotate respective eccentric disks and produce the second vibration vector.

14 . The vibration actuator according to claim 13 , wherein the position sensor comprises at least one selected from the group consisting of an optical position sensor and an inductive sensor, and wherein the position sensor further comprises one selected from the group consisting of (i) being integrated into a respective motor of a respective rotational vibrator of the plurality of n rotational vibrators and (ii) bring an additional component coupled to the respective motor.

15 . An ultrasound probe for shear wave elastography, comprising:
an ultrasound transducer array for generating ultrasound waves; and a vibration actuator according to claim 1 for generating mechanically induced shear waves; and an ultrasound probe controller operatively coupled to the ultrasound transducer array and the vibration actuator for implementing at least (i) a first mode of operation for generating and receiving ultrasound waves via the ultrasound transducer array and (ii) a second mode of operation for a combination o

Assignees

• Koninklijke Philips Nv

Inventors

• Nguyen Man M
• Erkamp Ramon Quido

Classifications

• G01N29/043

  in the interior, e.g. by shear waves · CPC title

• H02K7/063 Primary

  integrally combined with motor parts, e.g. motors with eccentric rotors · CPC title

• A61B8/485

  involving measuring strain or elastic properties · CPC title

• H02K11/22

  Optical devices · CPC title

• A61B8/4488

  the transducer being a phased array · CPC title