Vibration actuators, systems, and methods for shear wave elastic imaging

Abstract

A vibration actuator (10) for mechanically generating shear waves includes n rotary vibrators (141, 142, 143), accelerometers (16), and a controller (18). The n rotary vibrators are capable of generating vibration vectors with desired directional behavior, which are selected from a plurality of vibration vectors (34, 36, 38) with different directional behaviors. Each rotary vibrator includes a separately controllable motor (20) with a drive shaft (22) and an eccentric disk (24). The accelerometers are arranged to detect vibration vectors generated by at least two of the n rotary vibrators. The controller selectively controls a first group of two rotary vibrators to rotate their respective eccentric disks in a first coordinated manner to generate a first vibration vector, and a second group of two rotary vibrators to rotate their respective eccentric disks in a second coordinated manner to generate a second vibration vector, which have different corresponding directional behaviors.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to vibration actuators and systems, and more specifically, to vibration actuators, systems, and methods for mechanically generating shear waves for shear wave elastography. Background Technology

[0002] Tissue viscoelasticity is associated with pathological processes such as cancer and inflammation. Furthermore, tissue viscoelasticity provides a significant contrast between healthy and diseased tissue. This is why palpation can be used, for example, to detect tumors in the human breast and thyroid gland.

[0003] One method for determining the viscoelasticity of tissues includes diagnosis via palpation. However, this method is limited to superficial layers and large structures with significant elastic contrasts. Furthermore, diagnosis via palpation is subjective, as its effectiveness depends heavily on the skill of the person performing the diagnosis.

[0004] Besides palpation, ultrasound can be used to measure the elastic properties of tissues. This is achieved by inducing mechanical disturbances that generate mechanical waves (i.e., shear waves) and measuring the speed at which these waves propagate through the tissue. The wave speed is directly related to the stiffness of the tissue; a faster speed indicates stiffer tissue. This method works at greater depths and is quantitative.

[0005] Shear wave elastography is a current feature of advanced ultrasound imaging systems. This type of ultrasound imaging system generates shear waves using specific acoustic driving pulses and tracks them using an ultrasound imaging beam. The driving pulses used to generate the shear waves have high power and extended durations, which undesirably imposes specific requirements on the design of the imaging probe and the driving electronics. Therefore, shear wave elastography can only be used on a limited selection of advanced / high-end platform ultrasound imaging probes, such as the Philips EPIQ. TM and Philips iU22 TM (Available from Koninklijke Philips NV).

[0006] Shear waves can also be generated using mechanical vibrators, thus avoiding the need for specific requirements regarding probe design and drive electronics. This allows for shear wave elastography on a large range of ultrasound imaging platforms and probes that currently lack this feature. However, known devices and methods have some problems and drawbacks.

[0007] In an example of a known vibrator for an ultrasound imaging tool, a pair of flywheels are driven by a motor along opposite rotational paths to introduce harmonic mechanical excitation into the object. In this respect, one flywheel rotates counterclockwise, while the second rotates clockwise. The flywheels rotate clockwise and counterclockwise at the same speed, canceling out any vibratory force in the X direction, thus resulting only in vibration in the Y direction. However, a drawback of this device is that it comprises a single motor and a gear drive, i.e., multiple gears, for rotating the two flywheels. One gear and its associated flywheel rotate clockwise, while the other gear and its associated flywheel rotate counterclockwise. The gears are connected such that the flywheels rotate at the same speed. Another drawback is that the direction of vibration cannot be adaptively controlled in a way that optimizes the direction of vibrational motion of the shear waves generated at the tissue location for ultrasound (US) shear wave imaging. For preferred shear wave measurements, the direction of tissue vibrational motion should be substantially aligned with the direction of the ultrasound imaging beam.

[0008] Therefore, an improved method and apparatus are desired to overcome the problems in this field. Summary of the Invention

[0009] According to one embodiment, a vibration actuator for mechanically generating shear waves includes a housing, a plurality of rotary vibrators, an accelerometer coupled to the housing, and a controller. The plurality of rotary vibrators are arranged in a geometric configuration and configured to generate vibration vectors having desired directional behavior, the vibration vectors being selected from a plurality of vibration vectors having different directional behaviors, where n is at least three. Each rotary vibrator includes an individually controllable motor having a drive shaft and an eccentric disk coupled to the drive shaft in a plane perpendicular to the axis of the drive shaft. The accelerometer is arranged to detect vibration vectors generated by at least two of the plurality of rotary vibrators and to generate an accelerometer output signal based on the detected vibration vectors. The controller is operatively coupled to each rotary vibrator for selectively controlling (i) a first group formed by two of the plurality of rotary vibrators to rotate the corresponding eccentric disk in a first coordinated manner, at least based on the accelerometer output signal, to generate a first vibration vector, and (ii) a second group formed by two of the plurality of rotary vibrators to rotate the corresponding eccentric disk in a second coordinated manner, at least based on the accelerometer output signal, to generate a second vibration vector. The directional behavior of the second vibration vector is different from that of the first vibration vector.

[0010] In another embodiment, the controller is further configured to selectively control (iii) two of the n plurality of rotary vibrators forming a third group to rotate their respective eccentric disks in a third coordination manner, at least based on accelerometer output signals, to generate a third vibration vector. The directional behavior of the third vibration vector differs from that of the second vibration vector and also differs from that of the first vibration vector. In yet another embodiment, the controller is further configured to (i) determine the directional behavior of the synthesized vibration vector based on (i)(a) the accelerometer output signals and (i)(b) two of the n plurality of rotary vibrators forming a first or second group selectively controlled to rotate their respective eccentric disks, (ii) compare the directional behavior of the synthesized vibration vector with the desired directional behavior of the vibration vector, and (iii) adjust the first or second coordination manner based on the comparison.

[0011] In another embodiment, the first or second coordination method includes rotating each of two corresponding eccentric disks in a corresponding first or second group of a plurality of rotary vibrators at the same rotational speed but in opposite rotational directions. In another embodiment, the first or second coordination method includes controlling the corresponding first or second group of rotary vibrators to (i) generate vector vibrations along the mid-plane direction between the corresponding eccentric disks when the corresponding eccentric disks are mirror-symmetrical, and (ii) generate vector vibrations deviating from the mid-plane direction when the corresponding eccentric disks are not mirror-symmetrical.

[0012] In one embodiment, the vibration actuator includes eccentric disks of respective motors in two corresponding first or second groups of a plurality of rotary vibrators arranged coplanarly within the corresponding first or second group. According to another embodiment, each corresponding motor comprises a dual-axis motor, and further, each corresponding eccentric disk comprises a first eccentric disk coupled to a first end of a corresponding drive shaft and a second eccentric disk coupled to a second end of a corresponding drive shaft. In yet another embodiment, each corresponding eccentric disk comprises a disk with an eccentric weight, and further, the corresponding eccentric weights of the corresponding eccentric disks of the corresponding first and second rotary vibrators are controlled by corresponding motors and controllers to rotate and generate vibrations at mutually symmetrical positions, wherein only the vibration component along the mid-plane between the corresponding first and second rotary vibrators is retained, while vibrations in all other directions cancel each other out.

[0013] According to another embodiment, the vibration actuator includes three rotary vibrators, and the geometric arrangement of the three rotary vibrators comprises a triangular arrangement. In one embodiment, the triangular arrangement comprises three rotary vibrators, the axes of their respective motor drive shafts being located at the vertices of the triangle, and further, the directional behavior of the first vibration vector and the directional behavior of the second vibration vector are selected from the group consisting of +120 degrees, 0 degrees, and -120 degrees. In another embodiment, the triangular arrangement is configured to enable 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 the range of ±10 to ±110 degrees. According to yet another embodiment, the geometric arrangement further includes a number of n rotary vibrators configured to generate multiple electronically selectable vibration vectors in n*(n-1) / 2 directions.

[0014] In one embodiment, each rotary vibrator further includes a position sensor arranged to detect the radial orientation or rotation angle of the corresponding eccentric disk and generate a corresponding position signal. In such an embodiment, control implemented by a controller further includes synchronously controlling (i) a first group of two of the n rotary vibrators to rotate the corresponding eccentric disk and generate a first vibration vector, and (ii) a second group of two of the n rotary vibrators to rotate the corresponding eccentric disk and generate a second vibration vector, based on the corresponding position signals. In another embodiment, the position sensor includes at least one selected from the group consisting of optical position sensors and inductive sensors, and the position sensor further includes one selected from the group consisting of: (i) a corresponding motor of the corresponding rotary vibrator integrated into the n rotary vibrators and (ii) an additional component connected to the corresponding motor.

[0015] According to another embodiment, an ultrasonic probe for shear wave elastography includes an ultrasonic transducer array for generating ultrasonic waves and a vibration actuator for generating mechanically induced shear waves according to embodiments disclosed herein. The ultrasonic probe further includes an ultrasonic probe controller operatively coupled to the ultrasonic transducer array and the linear vibration actuator to at least implement (i) a first operating mode for generating and receiving ultrasonic waves via the ultrasonic transducer array and (ii) a second operating mode for implementing a combination of (ii)(a) generating and receiving ultrasonic waves and (ii)(b) generating mechanically induced shear waves via the ultrasonic transducer array and the vibration actuator, respectively.

[0016] According to yet another embodiment, a system for shear wave elastography includes an ultrasound probe according to embodiments disclosed herein, and ultrasound system electronics operatively coupled to the ultrasound probe and arranged to acquire ultrasound images in a first mode and shear wave elastography images in a second mode. The system also includes a display coupled to the ultrasound system electronics for displaying the acquired ultrasound images and shear wave elastography images.

[0017] In one embodiment, a method for mechanically generating shear waves using vibration actuators includes providing a plurality of n rotary vibrators geometrically arranged and coupled to a housing and configured to generate vibration vectors having desired directional behavior, the vibration vectors being selected from a plurality of vibration vectors having different directional behaviors, where n is a number of at least three. Each rotary vibrator includes an individually controllable motor having a drive shaft and an eccentric disk coupled to the drive shaft in a plane perpendicular to the axis of the drive shaft. The method further includes detecting vibration vectors generated by at least two of the n rotary vibrators via an accelerometer coupled to the housing, and generating an accelerometer output signal based on the detected vibration vectors. Furthermore, the method includes selectively controlling (i) a first group formed by two of the n rotary vibrators to rotate their respective eccentric disks in a first coordinated manner, at least based on the accelerometer output signal, to generate a first vibration vector, and (ii) a second group formed by two of the n rotary vibrators to rotate their respective eccentric disks in a second coordinated manner, at least based on the accelerometer output signal, to generate a second vibration vector, via a controller operatively coupled to each rotary vibrator. The directional behavior of the second vibration vector is different from that of the first vibration vector.

[0018] In another embodiment, the method includes the steps of: selectively controlling, by a controller, a first or second group of rotary vibrators selectively controlled to rotate corresponding eccentric disks based on (i)(a) accelerometer output signals and (i)(b) two of a plurality of rotary vibrators selectively controlled to rotate corresponding eccentric disks, to determine the directional behavior of a synthetic vibration vector; (ii) comparing the directional behavior of the synthetic vibration vector with the desired directional behavior of the vibration vector; and (iii) adjusting a first or second coordination mode based on the comparison. According to another embodiment, the first or second coordination mode includes controlling the corresponding first or second group of rotary vibrators to (i) generate vector vibrations along a mid-plane direction between the corresponding eccentric disks when the corresponding eccentric disks are mirror-symmetric, and (ii) generate vector vibrations deviating from the mid-plane direction when the corresponding eccentric disks are not mirror-symmetric.

[0019] In another embodiment, the method further includes detecting the radial orientation or rotation angle of the corresponding eccentric disk via a position sensor of the corresponding rotary vibrator, and generating a corresponding position signal based on the detected orientation or rotation angle. In such an embodiment, the method includes the following steps: control implemented by a controller further includes synchronously controlling (i) a first group of two of a plurality of rotary vibrators to rotate the corresponding eccentric disk and generate a first vibration vector, and (ii) a second group of two of a plurality of rotary vibrators to rotate the corresponding eccentric disk and generate a second vibration vector, based on the corresponding position signal.

[0020] As will be understood from this disclosure, the embodiments of this disclosure offer various advantages over existing solutions. Ultrasonic shear wave elastography can be performed using shear waves mechanically generated by a vibrator. Ultrasonic tissue tracking is most efficient when the shear wave motion is primarily along the direction of the ultrasound imaging beam. For computationally efficient one-dimensional (1D) tracking along the imaging beam, shear wave motion in other directions degrades tracking performance; therefore, it is desirable to use actuators according to embodiments of this disclosure to align the shear wave motion along the direction of the redirected ultrasound imaging beam. Furthermore, rotary vibrators are highly efficient in generating large vibration intensities with a small footprint. However, rotary vibrators vibrate in a circular manner, which, if not coordinated, can cause tissue displacement in multiple directions different from the direction of the ultrasound tracking beam. Vibration actuators, systems, and methods according to embodiments of this disclosure advantageously enable the use of multiple coupled rotary vibrators operating in a coordinated manner to generate linear vibrations, thereby producing linear vibrations with a compact and energy-efficient footprint.

[0021] Further advantages and benefits will become apparent to those skilled in the art upon reading and understanding the following detailed description. Attached Figure Description

[0022] The embodiments of this disclosure may take the form of various components and arrangements formed by those components, as well as various steps and arrangements formed by those steps. Therefore, the accompanying drawings are for illustrative purposes only and should not be construed as limiting the embodiments. In the drawings, similar reference numerals refer to similar elements. Furthermore, it should be noted that these drawings need not be drawn to scale.

[0023] Figure 1 These are block diagrams and perspective views of a vibration actuator according to an embodiment of the present disclosure;

[0024] Figure 2 According to an embodiment of the present disclosure Figure 1 A top view of a vibration actuator;

[0025] Figure 3 According to another embodiment of this disclosure Figure 1A top view of the block diagram of a vibration actuator;

[0026] Figure 4 According to an embodiment of the present disclosure Figure 1 An illustrative perspective view illustrating the internal components of a rotating motor for a vibration actuator;

[0027] Figure 5 This is a top view of a vibration actuator according to another embodiment of the present disclosure;

[0028] Figure 6 This is a side view of a rotary vibrator of a vibration actuator according to another embodiment of the present disclosure;

[0029] Figure 7 This is a block diagram view of an ultrasonic probe and an ultrasonic system including a vibration actuator according to another embodiment of the present disclosure; and

[0030] Figure 8 This is a flowchart of a method for generating shear waves by a vibration actuator according to another embodiment of the present disclosure. Detailed Implementation

[0031] The embodiments of this disclosure, along with their various features and advantageous details, will be explained more fully with reference to the non-limiting examples described and / or illustrated in the accompanying drawings and detailed in the following description. It should be noted that the features shown in the drawings are not necessarily drawn to scale, and features of one embodiment may be used with other embodiments, as will be recognized by those skilled in the art, even if not explicitly stated herein. Descriptions of well-known components and processing techniques may be omitted to avoid unnecessarily obscuring the embodiments of this disclosure. The examples used herein are merely to facilitate understanding of how embodiments of the invention can be practiced and to further enable those skilled in the art to practice these embodiments. Therefore, the examples herein should not be construed as limiting the scope of the embodiments of this disclosure, which is defined only by the appended claims and applicable law.

[0032] It should be understood that the embodiments of this disclosure are not limited to the specific methods, protocols, apparatuses, devices, materials, applications, etc., described herein, as these are subject to variation. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the claimed embodiments. It must be noted that, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly specifies otherwise.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this disclosure pertain. Preferred methods, apparatus, and materials are described, but any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of these embodiments.

[0034] Now for reference Figure 1 This diagram illustrates a block diagram / perspective view of a vibration actuator 10 for mechanically generating shear waves according to an embodiment of the present disclosure. The vibration actuator 10 includes a housing 12, a plurality of rotary vibrators (generally indicated by reference numeral 14), an accelerometer 16, and a controller 18. In a preferred embodiment, the symbol n includes a quantity of at least three. In one embodiment, the plurality of rotary vibrators 14 (e.g., ...) Figure 1 The figure (shown) includes three rotary vibrators. These three rotary vibrators are indicated by reference numerals 141, 142, and 143, representing the first, second, and third rotary vibrators, respectively. Each rotary vibrator is substantially identical to the others, and therefore, for the sake of simplicity, this paper will only discuss the details of one rotary vibrator.

[0035] The first rotary vibrator 141 includes a separately controllable DC motor 20 coupled to a housing 12 and having a rotary drive shaft 22 extending from the motor body. An eccentric disk 24 is fixedly coupled to the drive shaft 22 for rotation about the longitudinal axis of the drive shaft, the eccentric disk being located in a plane perpendicular to the longitudinal axis of the drive shaft 22. In one embodiment, the eccentric disk 24 includes a disk 26 having an eccentric weight 28. In another embodiment, the eccentric disk is a mass of any shape that has the functional capability of serving as an eccentric weight or an eccentric rotating object. As described above, rotary vibrators are substantially the same to each other. Therefore, the discussion of the separately controllable DC motor, rotary drive shaft, and eccentric disk of the first rotary vibrator 141 also applies to those of the second rotary vibrator 142 and the third rotary vibrator 143, respectively. Furthermore, as will be discussed further below, a plurality of rotary vibrators 14 are geometrically arranged and connected to the housing 12 and configured to generate vibration vectors with desired directional behavior, the vibration vectors being selected from a plurality of different electronically selectable vibration vectors having different directional behaviors.

[0036] Still refer to Figure 1 Accelerometer 16 is coupled to housing 12. Accelerometer 16 includes any suitable accelerometer arranged to (i) detect vibration vectors generated by at least two of the n rotating vibrators 14, for example, synthesized vibration vectors, and (ii) generate an accelerometer output signal based on the detected vibration vectors, which will be discussed further below.

[0037] In one embodiment, controller 18 includes one or more of a microprocessor, microcontroller, field-programmable gate array (FPGA), integrated circuit, discrete analog or digital circuit components, hardware, software, firmware, or any combination thereof, for performing the various functions discussed herein, and further, according to the requirements of the implementation and / or application of a given vibration actuator. Controller 18 may also include one or more of various modules, units, or subsystems, including, for example, a motor controller.

[0038] Now for reference Figure 1 and Figure 2 In one embodiment, the symbol n includes three, and the geometric arrangement of the three rotary vibrators 141, 142, and 143 (as indicated by reference numeral 32) comprises a triangular arrangement. With respect to the triangular arrangement, the axes of the respective DC motor drive shafts 22 of the three rotary vibrators 141, 142, and 143 are located at the vertices of the triangle. In the case of an equilateral triangle, the directional behavior of the first shear wave vibration vector and the directional behavior of the second shear wave vibration vector are selected from the group consisting of +120 degrees, 0 degrees, and -120 degrees, as will become apparent from the following disclosure. In other embodiments, the triangular arrangement is configured such that the respective motor drive shafts are located at the vertices of a given triangle to enable 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 the range of ±10 to ±110 degrees.

[0039] Still referencing Figure 1 and Figure 2 The controller 18 is connected via a power / signal line (generally indicated by reference numeral 30 in the attached figure). Figure 1 The controller 18 is operatively connected to each DC motor and accelerometer 16 of a corresponding rotary vibrator among the n rotary vibrators 14. The controller 18 is adapted to selectively control (i) two of the n rotary vibrators (e.g., 141 and 142, ...). Figure 2 The first set of eccentric disks 24, formed at least based on accelerometer output signals, rotates in a first coordinated manner to generate a first shear wave vibration vector (in...). Figure 2 (Referring to figure 34 in the figure). Controller 18 is further adapted to selectively control (ii) two of the plurality of rotary vibrators (e.g., 142 and 143, ...). Figure 2 The second set, formed at least based on the accelerometer output signal, rotates the corresponding eccentric disk in a second coordinated manner to generate a second shear wave vibration vector (in Figure 2(Referring to the figure in Figure 36). It should be noted that the directional behavior of the second shear wave vibration vector 36 is different from that of the first shear wave vibration vector 34.

[0040] Furthermore, the controller 18 is further adapted to selectively control (iii) two of the plurality of rotary vibrators 14 (e.g., 143 and 141, Figure 2 The third group, formed at least based on the accelerometer output signal, rotates the corresponding eccentric disk in a third coordinated manner to generate a third shear wave vibration vector (in...). Figure 2 (Represented by reference numeral 38 in the attached figure). It should also be noted that the directional behavior of the third shear wave vibration vector 38 differs from that of the second shear wave vibration vector 36, and also differs from that of the first shear wave vibration vector 34. Therefore, for Figure 1 and Figure 2 In one embodiment, a geometric arrangement 32 formed by a plurality of three rotary vibrators 141, 142 and 143 connected to the housing 12 in a triangular form is capable of generating a vibration vector with a desired directional behavior, which is selected from a plurality of different electronically selectable vibration vectors with different directional behaviors (e.g., indicated by reference numerals 34, 36 and 38).

[0041] Still referencing Figure 1 and Figure 2 In one embodiment, the first or second coordination method includes rotating each of two corresponding eccentric disks of two of a plurality of rotary vibrators 14 formed in a corresponding first or second group at the same rotational speed but in opposite rotational directions. (See also...) Figure 2 The first arrow (indicated by reference numeral 40) indicates that the corresponding drive shaft 22 and eccentric disk 24 of the first rotary vibrator 141 rotate in a counterclockwise direction. The second arrow (indicated by reference numeral 42) indicates that the corresponding drive shaft and eccentric disk of the second rotary vibrator 142 rotate in a clockwise direction. Furthermore, in one embodiment, each eccentric disk 24 of the corresponding DC motor 20 of two corresponding first groups (e.g., 141 and 142) or second groups (e.g., 142 and 143) formed from the plurality of rotary vibrators 14 is arranged to be coplanar with each other within the corresponding first or second group.

[0042] In another embodiment, the first or second coordination method further includes controlling the respective first or second set of rotary vibrators to (i) generate vector vibration along the mid-plane direction between the respective eccentric disks when the respective eccentric disks are mirror-symmetrical, and (ii) generate vector vibration deviating from the mid-plane direction (not shown, but will include deviations from the mid-plane direction 34, i.e., directions other than the mid-plane direction 34) when the respective eccentric disks are not mirror-symmetrical. Figure 2The illustration of the first rotary vibrator 141 and the second rotary vibrator 142 is merely an example of the mirror symmetry of the corresponding eccentric disks of the first rotary vibrator 141 and the second rotary vibrator 142, which generates vector vibration in the mid-plane direction between the corresponding eccentric disks, as indicated by reference numeral 34. For example, the eccentric disk 24 of the first rotary vibrator 141 can be controlled to rotate counterclockwise 40, while the eccentric disk of the second rotary vibrator 142 can be controlled to rotate clockwise 42. To achieve mirror symmetry, the weight 28 of the eccentric disk 24 of the first rotary vibrator 141 rotates about the corresponding drive shaft 22, wherein the position of the weight is a mirror image of the position of the weight on the eccentric disk of the second rotary vibrator 142 as the latter rotates about its corresponding drive shaft. This mirror image is about a mirror plane, which is set perpendicular to the plane of the corresponding eccentric disks of the first and second rotary vibrators and positioned halfway between them. Furthermore, to help better understand non-mirror symmetry, we still refer to Figure 2 Consider an example of non-mirror symmetry of the corresponding eccentric disks of the first rotary vibrator 141 and the third rotary vibrator 143. Assuming that the eccentric disk of the third rotary vibrator rotates in a clockwise direction, the eccentric disks of the first and third rotary vibrators will not have mirror symmetry with respect to each other at any given moment during rotation, thus producing vector vibrations that deviate from the mid-plane direction 38 or have a direction other than the mid-plane direction 38.

[0043] In other words, in the embodiment with mirror symmetry, the eccentric weights of the corresponding eccentric disks of the corresponding first and second rotary vibrators are controlled by the corresponding DC motors and controller 18 to rotate and generate vibrations at mutually symmetrical positions, wherein only the vibration component along the mid-plane between the corresponding first and second rotary vibrators is retained, while vibrations in all other directions cancel each other out. On the other hand, when the corresponding eccentric disks are not mirror symmetric, controlling the first rotary vibrator 141 and the second rotary vibrator 142 respectively will produce vector vibrations (not shown) deviating from the mid-plane direction, i.e., deviating from the mid-plane direction indicated by reference numeral 34. The third coordination method is similar to the first or second coordination method and may include controlling the corresponding rotary vibrators with or without mirror symmetry, as discussed above.

[0044] exist Figure 2In one embodiment, the geometric arrangement 32 formed by the three rotary vibrators comprises a triangular arrangement in the form of an equilateral triangle. In the case of mirror symmetry, the directional behavior of the first shear wave vibration vector 34 is 0 degrees. The directional behavior of the second shear wave vibration vector 36 is -120 degrees. Finally, the directional behavior of the third shear wave vibration vector 38 is +120 degrees. Regarding the geometric arrangement 32 including the triangular arrangement, wherein the triangular arrangement takes the form of a given triangle other than an equilateral triangle, the triangular arrangement can be configured to achieve multiple electronically selectable vibration orientations. In one example, the positions of the three rotary vibrators can be configured in a triangular arrangement such that the three electronically selectable vibration directions are closer to each other, for example, differing by 20 degrees instead of 120 degrees, meaning that the vibration force can vary in 20-degree increments: +20, 0, and -20 degrees. Multiple electronically selectable vibration directions can also be selected from the following groups: (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 the range of ±10 to ±110 degrees. Depending on the specific requirements of the vibration actuator, other electronically selectable vibration orientations are also envisioned, such as +20 degrees, 0 degrees, and -25 degrees, etc.

[0045] In another embodiment, the geometric arrangement further includes a rotary vibrator configured to generate n electronically selectable vibration vectors in n*(n-1) / 2 directions. Accordingly, a vibration actuator with four rotary vibrators is capable of generating multiple electronically selectable vibration vectors in six directions (i.e., 4*(4-1) / 2 = 6 directions). The following will combine... Figure 5 The embodiments further discuss examples of such vibration actuators. The number of rotary vibrators, n, is not limited to 3 or 4, but can be any number of rotary vibrators configured in a geometric arrangement to generate multiple electronically selectable vibration vectors for a given vibration actuator implementation and / or application. In one embodiment, the vibration actuator includes a linear vibration actuator having at least three rotary vibrators for mechanically generating electronically selectable vibration vectors or shear waves in at least two different directions. In another embodiment, the vibration actuator may include at least three rotary vibrators for generating electronically selectable vibration vectors in non-purely linear vibration modes.

[0046] Reference again Figure 1 and Figure 2The controller 18 is further configured to (i) determine the directional behavior of the synthesized vibration vector based on (i)(a) the accelerometer output signal and (i)(b) two of the plurality of rotary vibrators 14 selectively controlled to rotate corresponding eccentric disks in a first group (e.g., 141 and 142) or a second group (e.g., 142 and 143), (ii) compare the directional behavior of the synthesized vibration vector with the desired directional behavior of the vibration vector, and (iii) adjust a first coordination mode or a second coordination mode based on the comparison. In this way, the controller provides feedback control over the directional behavior of the synthesized vibration vector to maintain the desired directional behavior of the synthesized vibration vector. In other words, synchronization can be achieved by using the speed regulation electronics of the controller 18 to drive the rotary vibrators in a control loop employing sensors (e.g., accelerometers and position sensors) to monitor various aspects of vibration activity.

[0047] In one example of this disclosure, three rotary vibrators are rigidly attached to each other, for example, via housing 12, such that the unbalanced weights 28 of the respective eccentric disks 24 are configured to rotate in the same plane. Each rotary vibrator is physically connected relative to each other but can rotate independently. Accelerometer 16 serves as a sensor in an electronic control loop, wherein controller 18 or control electronics coordinates the independent movement of each respective eccentric disk among the individual vibrators to achieve the desired vibration behavior and / or pattern.

[0048] Regarding the achievement of linear vibration, Figure 1 and Figure 2 Of the three rotary vibrators, only two are activated in opposite directions of rotation, while the third rotary vibrator does not rotate. For example... Figure 2 As indicated by arrows 40 and 42, a first rotary vibrator 141 and a second rotary vibrator 142 are used to obtain upper / lower linear vibration and shear wave force (represented by reference numeral 34). Similarly, by using a second pair of rotary vibrators 141 and 143, or a third pair of rotary vibrators 142 and 143, the orientation of the linear vibration or shear wave force can be changed by +120 degrees and -120 degrees, respectively. Therefore, the vibration actuator 10 can electronically switch between three different orientations of the linear vibration force. This electronic switching of the vibration force orientation can help optimize the angle between the mechanical shear wave and the ultrasound tracking beam, for example, for different tissue areas of interest. It should be noted that the wavefront of the shear wave generated by the mechanical vibration depends on the vibration direction of the vibration actuator 10.

[0049] In one embodiment, the correct coordinated motion of linear vibration is achieved by observing accelerometer signals. When the two rotary vibrators of the vibration actuator rotate perfectly symmetrically, there is only linear vibrational force along one axis in the plane containing the three eccentric disks; this state is maintained by a control loop via a controller. Once the position of one rotary vibrator begins to drift away from the other, and the two rotary vibrators lose their mirror symmetry, an additional vertical vibration component begins to appear in the plane with the three eccentric disks. The control loop is used to adjust the speed of one rotary vibrator relative to the other, either constantly or with a given adjusted duty cycle, to minimize the vertical vibration component.

[0050] Now for reference Figure 3 Another embodiment according to this disclosure is shown. Figure 1 A top view of the block diagram of a vibration actuator. Figure 3 Implementation examples and Figure 1 The embodiments are similar, and the discussion also applies to them. Figure 3 The embodiments described herein differ in the following ways. Each rotary vibrator 141, 142, and 143 further includes position sensors 151, 152, and 153, respectively, which are arranged to detect the radial orientation or rotation angle of the corresponding eccentric disk 24 of the rotary vibrator 141, 142, and 143. Furthermore, each position sensor 151, 152, and 153 is further arranged to generate a corresponding position signal indicating the radial orientation or rotation angle of the corresponding eccentric disk 24 of the rotary vibrator 141, 142, and 143. A controller 18 is further operatively coupled to the position sensors 151, 152, and 153 via a power / signal line (generally indicated by reference numeral 30). In operation, the control implemented by the controller 18 further includes synchronously controlling (i) two of the n rotary vibrators 14 forming a first group (e.g., 141 and 142) to rotate the corresponding eccentric disk 24 and generate a first vibration vector (e.g., 34) and (ii) two of the n rotary vibrators 14 forming a second group (e.g., 142 and 143) to rotate the corresponding eccentric disk 24 and generate a second vibration vector (e.g., 36).

[0051] In one embodiment, each position sensor 151, 152, and 153 includes at least one selected from the group consisting of optical position sensors and inductive sensors. For embodiments with optical position sensors, position sensors 151, 152, and 153 include additional components coupled to the DC motor 20 of the respective rotary vibrators 141, 142, and 143 among the plurality of rotary vibrators 14. Furthermore, the optical position sensors cooperate with corresponding position indicators / references 161, 162, and 163 of the eccentric disks 24 of the respective rotary vibrators 141, 142, and 143. The corresponding position indicators / references 161, 162, and 163 cause the corresponding optical position sensors to generate corresponding position signals indicating the radial orientation or rotation angle of the eccentric disks 24 of the respective rotary vibrators 141, 142, and 143. Through the corresponding position signals, the radial orientation or rotation angle information enables the controller 18 to synchronize and / or mirror-symmetrically mirror a given pair of eccentric disks relative to each other.

[0052] In the embodiment with an inductive sensor, the position sensor is integrated into the DC motor 20 of the respective rotary vibrators 141, 142, and 143 of the plurality of rotary vibrators 14, and will be referred to herein. Figure 3 and Figure 4 Further discussion. Figure 4 It shows Figure 1 A perspective view of the internal components of the DC motor 20 of the rotary vibrator (141, 142, or 143) of the vibration actuator 10. These components include, for example, a rotor 50 including a drive shaft 22, a plurality of metal laminations 52 coupled to the drive shaft, a plurality of rotor windings 54 wound around the inner portions of the metal laminations 52 in a manner known in the art, and a commutator 56 consisting of a plurality of commutator plates 58 or segments. Each commutator plate or segment is separated from adjacent commutator segments by gaps (e.g., indicated by reference numeral 60).

[0053] In one embodiment, all gaps 60 have a given equal size, except for at least one gap that has a different size. The at least one gap with a different size provides a given inductive electrical characteristic that can be detected by an inductive sensor during motor operation. This given electrical characteristic provides a corresponding position signal as a function of the at least one gap with a different size. Given that the eccentric disk 24 is fixedly coupled to the motor shaft of the DC motor, this position signal indicates the radial orientation or rotation angle of the eccentric disk 24 of the respective rotary vibrators 141, 142, and 143. Through the corresponding position signal, the radial orientation or rotation angle information enables the controller 18 to achieve synchronization and / or mirror symmetry of a given pair of eccentric disks relative to each other.

[0054] In other words, a slight asymmetry can be introduced in the commutator plates 58 compared to a standard 4-plate commutator, for example, by increasing a gap between the plates. This will result in a current disturbance pattern that can be detected by the appropriate drive electronics of the controller 18. Alternatively, the number of windings in one of the rotor windings 54 can be increased or decreased, or a detectable electronic component can be connected in parallel with one of the rotor windings 54.

[0055] In one embodiment, motion coordination can also be accomplished via an electronic control loop through controller 18, where feedback is also based on signals from position sensors. Figure 3 As shown, each rotary vibrator has a corresponding position sensor. For example, each position sensor can provide an indication via a position sensor signal when the weight 28 of the corresponding eccentric disk 24 is at a zero-degree (0°) rotation angle.

[0056] Now for reference Figure 5 The image shows a top view of a vibration actuator 10 according to another embodiment of the present disclosure. Figure 5 Implementation examples and Figure 1 The embodiments are similar, and the discussion also applies to them. Figure 5 The embodiment is described, but with the following differences. The geometric arrangement 32 includes four rotary vibrators 141, 142, 143, and 144, which are connected to the housing 12 in a quadrilateral configuration. That is, the axes of the corresponding DC motor drive shafts 22 of the four rotary vibrators 141, 142, 143, and 144 are located at the vertices of the quadrilateral. The quadrilateral geometric arrangement 32 is capable of generating vibration vectors with desired directional behavior, selected from a plurality of different electronically selectable vibration vectors with different directional behaviors, for example, indicated by reference numerals 34, 36, 38, 62, 64, and 66. As discussed above, the geometric arrangement 32 includes n rotary vibrators configured to generate a plurality of electronically selectable vibration vectors in n*(n-1) / 2 directions. Accordingly, as... Figure 5 The embodiment of the vibration actuator 10 shown, which has four rotary vibrators 141, 142, 143 and 144, is capable of generating multiple electronically selectable vibration vectors in six directions (i.e., 4*(4-1) / 2 = 6 directions).

[0057] Now for reference Figure 6 The image shows a side view of a rotary vibrator (e.g., rotary vibrator 141) according to another embodiment of the present disclosure. Figure 6 Implementation examples and Figure 1 The embodiments are similar, and the discussion also applies to them. Figure 6The embodiment differs from the previous one in the following ways. In this embodiment, each corresponding DC motor 20 includes a dual-axis motor, and further, each corresponding eccentric disk 24 includes a first eccentric disk 241 fixedly connected to a first end of the corresponding drive shaft 22 and a second eccentric disk 262 fixedly connected to a second end (opposite to the first end) of the corresponding drive shaft 22. Figure 6 As shown, the first eccentric disk 241 and the second eccentric disk 242 are connected to the drive shaft 22 in a mirror-symmetrical manner. Utilizing the configuration formed by the dual-axis motor and the first eccentric disk 241 and the second eccentric disk 242, Figure 1 The weight of each eccentric disk 24 in each rotary vibrator can be divided into two halves and evenly distributed between the first eccentric disk 241 and the second eccentric disk 242, respectively. Therefore, compared with setting the eccentric disk only at one end of the DC motor drive shaft, it is advantageous to reduce the unwanted strain on the DC motor drive shaft.

[0058] Now turn Figure 7 This illustration shows a block diagram view of an ultrasound probe 68 and an ultrasound system 70 including a vibration actuator 10, according to another embodiment of the present disclosure. The ultrasound probe 68 is configured for shear wave elastography and includes an ultrasound transducer array 72 and an ultrasound probe controller 74. The ultrasound probe 68 further includes one or more vibration actuators 10 according to various embodiments of the present disclosure, as disclosed herein. The ultrasound probe 68 further includes a housing suitable for a given ultrasound probe implementation, wherein the ultrasound transducer array 72, the ultrasound probe controller 74, and the vibration actuator 10 are arranged relative to the ultrasound probe housing according to a specific implementation. For example, the orientation and / or position of the vibration actuator 10 relative to the ultrasound transducer array 72 and relative to the ultrasound probe housing is determined at least in part based on (i) generating and receiving ultrasound waves and (ii) generating mechanically induced shear waves (as applicable) to achieve a cost-effective elastography implementation for determining the elasticity of tissues using a given ultrasound platform and / or probe.

[0059] In one embodiment, the vibration actuator 10 is coupled to the housing of the ultrasound probe 68 via a vibration isolation attachment member 11. This attachment member 11 is configured to provide desired vibration isolation characteristics between the vibration actuator 10 and the housing of the ultrasound probe 68 for a given ultrasound probe implementation. The attachment member 11 may include any suitable form of vibration damping mechanism to prevent vibration of the ultrasound imaging probe aperture itself and the undesirable introduction of shear waves into the tissue. Furthermore, the vibration actuator 10 also includes a vibration coupler 13 coupled to the housing of the vibration actuator 10. The vibration coupler 13 is configured to provide desired vibration device orientation and coupling between the vibration actuator 10 and a similar substance of the subject's tissue or object to which shear wave elastography is applied. For example, it is desirable to introduce vibration into the tissue through a relatively small contact area (i.e., through the vibration coupler 13 on the tissue surface) such that, from the tissue's perspective, the vibration is caused by something more like a point source. In other words, the entire transducer housing does not vibrate. Therefore, the vibration coupler 13 includes small protrusions that will contact the surface of the tissue.

[0060] like Figure 7 As shown, the dashed arrows within the tissue indicate the vibration direction of the shear wave that can be generated within the tissue to accommodate an ultrasound imaging beam that is directed downwards or diverted to the left or right. It should also be noted that the vibration direction of the actuator 10 can be adjusted or changed via controller 18 and / or controller 74. Adjustment of the vibration direction can be in response to refraction effects from the tissue, which result in a change in the direction of the generated vibrational motion. Therefore, the vibration direction can be advantageously aligned relative to the tracking beam direction of the region of interest. Although Figure 7 An example of vibration orientation relative to skin or tissue and a probe housing are shown, but other embodiments integrating the vibration module with the ultrasound probe are also feasible.

[0061] Furthermore, the vibration actuator 10 has a vibration vector reference (not shown), which is designated as a reference for determining the remaining vibration vectors generated by the rotating vibrators for a given vibration actuator. In other words, the vibration vector reference may include a specific reference point or line located on one side or a portion of the housing 12 between two given rotating vibrators, further corresponding to one side or a portion of the housing that will face the subject's skin when the vibration actuator 10 is used. The actuation pulse generated by the vibration actuator 10 for determining the elasticity of a given tissue is preferably emitted from the side of the vibration actuator 10 facing the subject's skin for a given elastography implementation. It is contemplated that in some implementations, more than one side of the housing of the vibration actuator may be useful. Furthermore, referring again... Figure 2 The vibration vector reference may include Figure 2The reference points and / or lines (i.e., lines perpendicular to the drawing) on ​​the top wall of the middle housing 12 are located at the midpoint between the first rotary vibrator 141 and the second rotary vibrator 142, respectively. The positions of other specific vibration vector references are also possible, depending on the specific implementation of the vibration actuator and the ultrasonic probe. Furthermore, the spatial relationships between the corresponding rotary vibrators are known through the given structure of the specific vibration actuator.

[0062] An ultrasonic probe controller 74 is operatively connected to an ultrasonic transducer array 72 for generating and receiving ultrasonic waves, as known in the art. The ultrasonic probe controller 74 is further operatively coupled to a vibration actuator 10 for generating mechanically induced shear waves, comprising shear waves with desired directional behavior, as discussed herein. The generation of the mechanically induced shear waves is further coordinated with the generation and reception of ultrasonic waves via the ultrasonic transducer array 72, thereby utilizing appropriate elastography techniques known in the art.

[0063] In one embodiment, the ultrasound probe controller 74 is operatively coupled to the ultrasound transducer array 72 and the vibration actuator 10 to at least achieve (i) a first operating mode for generating and receiving ultrasound waves via the ultrasound transducer array 72 and (ii) a second operating mode for combining (ii)(a) generating and receiving ultrasound waves and (ii)(b) generating mechanically induced shear waves via the ultrasound transducer array 72 and the vibration actuator 10, respectively. The ultrasound probe 68 is well-suited for low-cost ultrasound systems configured for elastography, such as in hepatologists diagnosing liver disease, emergency medical diagnosis, or military medical diagnosis in the field. Furthermore, the ultrasound probe 68 with the vibration actuator 10 advantageously enables the generation of linear vibrations using multiple coupled rotating vibrators operating in a coordinated manner, resulting in linear vibrations within a compact and energy-efficient form factor. This contrasts with high-cost prior art systems that generate shear waves via specific acoustically driven pulses, placing specific requirements on the imaging probe design and drive electronics.

[0064] Still referencing Figure 7According to another embodiment, an ultrasound system 70 for shear wave elastography is shown. The ultrasound system 70 includes an ultrasound probe 68 as described above herein. The ultrasound system 70 also includes ultrasound system electronics 76 and a display 78. The ultrasound probe and display are operatively coupled to the ultrasound system electronics. Specifically, the ultrasound system electronics 76 is operatively coupled to the ultrasound probe 68 and arranged to acquire ultrasound images in a first mode and shear wave elastography images in a second mode. The ultrasound system electronics 76 may include any suitable ultrasound system controller and associated electronics for performing shear wave elastography. Shear wave elastography and determination of tissue elasticity via shear waves can be performed using suitable elastography techniques known in the art.

[0065] For example, ultrasound system electronics 76 may include one or more of a microprocessor, microcontroller, field-programmable gate array (FPGA), integrated circuit, discrete analog or digital circuit elements, hardware, software, firmware, or any combination thereof, for performing the various functions discussed herein and further for the implementation and / or application of a given shear wave elastography ultrasound system. Ultrasound system electronics 76 may also include one or more of various modules, units or subsystems, power supplies, memory, input / output devices, user interfaces, haptic output devices, touchscreens, optical displays, microphones, keypads, keyboards, pointing devices, image capture devices, cameras, audio output devices, and any combinations thereof, selected as appropriate according to the requirements of the implementation and / or application of the given shear wave elastography ultrasound system. In one embodiment, a display 78 is operatively coupled to ultrasound system electronics 76 for displaying acquired ultrasound images and shear wave elastography images according to the requirements of the implementation of the given shear wave elastography ultrasound system.

[0066] Further reference Figure 7 In other embodiments, the vibration actuator 10 and / or vibration actuation systems and methods of this disclosure are performed on an ultrasound imaging apparatus 70 configured to control one or more transducer arrays 72 to emit ultrasound waves and receive echoes for generating ultrasound images based on the echoes. The ultrasound imaging apparatus may include a processor, beamformer, and electronic circuitry (e.g., represented collectively by ultrasound system electronics 76) required for signal processing and image generation. The ultrasound transducer arrays may be configured to generate 1D, 2D, and / or 3D images. The transducer arrays may be incorporated into probes, patches, or other configurations. The ultrasound imaging system can be used to image in a variety of different modes (e.g., B-mode, M-mode, PW Doppler, spectral Doppler, etc.). For example, the imaging apparatus may be an ultrasound imaging system implemented on a handheld device (such as a tablet, smartphone, etc.), such as the VISIQ provided by PHILIPS.TM Or LUMIFY TM Ultrasound systems. In some examples, the imaging device can be an ultrasound imaging system implemented in a more conventional form factor, such as a larger but still typically portable base, which can provide a variety of imaging capabilities (e.g., B-mode, M-mode, color flow Doppler, PW Doppler, spectral Doppler, and other ultrasound imaging modes). For example, the imaging device can be an ultrasound imaging system such as the SPARQ provided by PHILIPS. TM or EPIQ TM Ultrasound system. Other ultrasound systems may also be used.

[0067] Now refer to Figure 8 Now, a method 100 for mechanically generating shear waves by means of a vibration actuator, according to another embodiment of the present disclosure, will be discussed. The method begins at step 102, providing a plurality of n rotary vibrators geometrically arranged and coupled to a housing and configured to generate vibration vectors having desired directional behavior, selected from a plurality of vibration vectors having different directional behaviors. The symbol n is a quantity of at least three. Furthermore, each rotary vibrator includes an individually controllable motor having a rotary drive shaft and an eccentric disk fixedly coupled to the rotary drive shaft in a plane perpendicular to the axis of the rotary drive shaft.

[0068] At step 104, method 100 includes detecting vibration vectors generated by at least two of a plurality of rotary vibrators via an accelerometer coupled to the housing, and generating an accelerometer output signal based on the detected vibration vectors. The method then proceeds to step 106, which includes selectively controlling (i) a first group formed by two of the plurality of rotary vibrators to rotate their respective eccentric disks in a first coordinated manner, at least based on the accelerometer output signal, to generate a first shear wave vibration vector, and (ii) a second group formed by two of the plurality of rotary vibrators to rotate their respective eccentric disks in a second coordinated manner, at least based on the accelerometer output signal, to generate a second shear wave vibration vector. The directional behavior of the second shear wave vibration vector differs from that of the first shear wave vibration vector.

[0069] In one embodiment, step 106 involves selectively controlling, via a controller, a further step including (i) determining the directional behavior of a synthetic vibration vector based on (i)(a) an accelerometer output signal and (i)(b) two of a plurality of rotary vibrators selectively controlled to rotate corresponding eccentric disks, in order to rotate the respective eccentric disks; (ii) comparing the directional behavior of the synthetic vibration vector with the desired directional behavior of the vibration vector; and (iii) adjusting a first coordination mode or a second coordination mode based on the comparison. In another embodiment, the first or second coordination mode includes controlling the respective first or second group of rotary vibrators to (i) generate vector vibrations along the mid-plane direction between the respective eccentric disks when the respective eccentric disks are mirror-symmetrical, and (ii) generate vector vibrations deviating from the mid-plane direction when the respective eccentric disks are not mirror-symmetrical.

[0070] According to another embodiment, method 100 further includes detecting the radial orientation or rotation angle of the corresponding eccentric disk via a position sensor of the corresponding rotary vibrator, and generating a corresponding position signal based on the detected orientation or rotation angle. Furthermore, the step of implementing control via a controller further includes synchronously controlling (i) a first group formed by two of the n rotary vibrators to rotate the corresponding eccentric disk and generate a first vibration vector, and (ii) a second group formed by two of the n rotary vibrators to rotate the corresponding eccentric disk and generate a second vibration vector, based on the corresponding position signal.

[0071] Although only a few exemplary embodiments have been described in detail above, those skilled in the art will readily understand that many modifications can be made to the exemplary embodiments without substantially departing from the novel teachings and advantages of the embodiments of this disclosure. For example, embodiments of this disclosure can be advantageously used as an additional feature of non-advanced ultrasound systems, namely, generating mechanically induced shear waves. In this way, embodiments of this disclosure enable cost-effective elastography on a wider range of ultrasound platforms / probes. Embodiments of vibration actuators can also be used in applications involving one or more of elastography, ultrasound imaging, tissue elasticity properties, hepatology, and mechanical vibration shear waves. As previously stated, it is advantageous to align the vibrational motion with the direction of the ultrasound tracking beam in determining tissue elasticity. To achieve this alignment, it is advantageous to be able to change the direction of the shear wave motion during the determination of tissue elasticity. For example, one may decide to perform multiple sequential measurements of tissue elasticity in a specific region, but with a range of beam steering angles (e.g., multiple bursts of tracking beams). Each beam steering angle requires a different direction of shear wave motion to optimize alignment. In another example, as a shear wave travels from a vibration actuator to a region of interest, its direction of travel can change as it propagates through the tissue due to refraction effects caused by the spatially varying tissue stiffness along its path. Therefore, the direction of vibration cannot be optimized in advance as it depends on the tissue composition. Instead, one can measure the direction of the shear wave within the region of interest and adaptively modify the vibration mode to optimize the alignment of the vibrational motion. Therefore, all these modifications are intended to be included within the scope of embodiments of this disclosure as defined in the following claims. In the claims, the phrase "mode plus function" is intended to cover the structures described herein that perform the functions, as well as not only structural equivalents but also equivalent structures.

[0072] Furthermore, any reference numerals enclosed in parentheses in one or more claims should not be construed as limiting the claims. The words "comprising," etc., do not exclude the presence of elements or steps other than those listed in any claim or the entire specification. A singular reference to an element does not exclude a plural reference to that element, and vice versa. One or more embodiments may be implemented by hardware comprising several different elements and / or by a suitably programmed computer. In an apparatus claim enumerating several units, several of these units may be implemented by the same piece of hardware. The fact that certain measures are recited merely in mutually different dependent claims does not indicate that a combination of these measures cannot be used to obtain an advantage.

Claims

1. A vibration actuator (10) for mechanically generating shear waves, comprising: Shell (12); n or more rotary vibrators (14), the n or more rotary vibrators being connected to the housing (12) in a geometric arrangement (32) and configured to generate vibration vectors having desired directional behavior, the vibration vectors being selected from a plurality of vibration vectors (34, 36, 38) having different directional behaviors, where n is a number of at least three, wherein each rotary vibrator (141, 142, 143) includes a motor (20) that can be controlled individually, the motor having a drive shaft (22) and an eccentric disk (24) connected to the drive shaft in a plane perpendicular to the axis of the drive shaft; An accelerometer (16) is connected to the housing (12), wherein the accelerometer (16) is arranged to detect vibration vectors generated by at least two of the n plurality of rotating vibrators and to generate an accelerometer output signal based on the detected vibration vectors; as well as A controller (18), operatively coupled to each rotary vibrator (141, 142, 143), is used to selectively control (i) a first group formed by two (141, 142) of the plurality of rotary vibrators to rotate their respective eccentric disks in a first coordinated manner at least based on the accelerometer output signal to generate a first vibration vector (34), and (ii) a second group formed by two (142, 143) of the plurality of rotary vibrators to rotate their respective eccentric disks in a second coordinated manner at least based on the accelerometer output signal to generate a second vibration vector (36), wherein the directional behavior of the second vibration vector (36) is different from that of the first vibration vector (34).

2. The vibration actuator (10) according to claim 1, wherein, The controller is further configured to selectively control (iii) a third group formed by two (141, 143) of the plurality of rotary vibrators to rotate the corresponding eccentric disks in a third coordinated manner at least based on the accelerometer output signal to generate a third vibration vector (38), wherein the directional behavior of the third vibration vector (38) is different from that of the second vibration vector (36) and different from that of the first vibration vector (34).

3. The vibration actuator (10) according to claim 1, wherein, The controller (18) is further configured to (i) determine the directional behavior of the synthesized vibration vector based on (i)(a) the accelerometer output signal and (i)(b) the first or second group of two of the plurality of rotary vibrators selectively controlled to rotate the corresponding eccentric disks, (ii) compare the directional behavior of the synthesized vibration vector with the desired directional behavior of the vibration vector, and (iii) adjust the first or second coordination mode based on the comparison.

4. The vibration actuator (10) according to claim 1, wherein, The first coordination method or the second coordination method includes rotating two of the n plurality of rotary vibrators at the same rotational speed but in opposite rotational directions, forming each of the corresponding eccentric disks in the corresponding first group or second group.

5. The vibration actuator (10) according to claim 1, wherein, The first coordination method or the second coordination method includes controlling the corresponding first group of rotary vibrators or the second group of rotary vibrators to (i) generate vector vibration along the mid-plane direction of the corresponding eccentric disk (24) when the corresponding eccentric disk (24) is mirror-symmetrical, and (ii) generate vector vibration deviating from the mid-plane direction when the corresponding eccentric disk (24) is not mirror-symmetrical.

6. The vibration actuator (10) according to claim 1, wherein, Each eccentric disk (24) of the corresponding motors of two of the n rotary vibrators in the corresponding first group or second group is arranged to be coplanar with each other in the corresponding first group or second group.

7. The vibration actuator (10) according to claim 1, wherein, Each corresponding motor (20) includes a dual-shaft motor, and further, each corresponding eccentric disk (24) includes a first eccentric disk (241) connected to a first end of the corresponding drive shaft (22) and a second eccentric disk (242) connected to a second end of the corresponding drive shaft (22).

8. The vibration actuator (10) according to claim 1, wherein, Each corresponding eccentric disk (24) includes a disk (26) with an eccentric weight (28). Further, the corresponding eccentric weights of the corresponding eccentric disks of the corresponding first and second rotary vibrators are controlled by the corresponding motors (20) and controllers (18) to rotate in positions symmetrical to each other and generate vibrations, wherein only the vibration component along the mid-plane between the corresponding first and second rotary vibrators is retained, while vibrations in all other directions cancel each other out.

9. The vibration actuator (10) according to claim 1, wherein, n includes three, and the geometric arrangement (32) of the three rotary vibrators includes a triangular arrangement.

10. The vibration actuator (10) according to claim 9, wherein, The triangular arrangement structure includes the three rotary vibrators (141, 142, 143), the axes of their respective motor drive shafts (22) being located at the vertices of the triangle, and further, the directional behavior of the first vibration vector (34) and the directional behavior of the second vibration vector (36) are selected from a group consisting of +120 degrees, 0 degrees and -120 degrees.

11. The vibration actuator (10) according to claim 9, wherein, The triangular arrangement is configured to enable multiple electronically selectable vibrational orientations selected from a 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 the range of ±10 to ±110 degrees.

12. The vibration actuator (10) according to claim 1, wherein, The geometric arrangement structure (32) further includes a rotary vibrator configured to generate a plurality of electronically selectable vibration vectors in n*(n-1) / 2 directions.

13. The vibration actuator (10) according to claim 1, wherein, Each rotary vibrator (141, 142, 143) further includes a position sensor (151, 152, 153) arranged to detect the radial orientation or rotation angle of the corresponding eccentric disk (24) and generate a corresponding position signal. The control implemented by the controller (18) further includes synchronous control based on the corresponding position signals: (i) the first group of two (141, 142) of the n-fold rotary vibrators rotates the corresponding eccentric disk (24) and generates the first vibration vector (34); and (ii) the second group of two (142, 143) of the n-fold rotary vibrators rotates the corresponding eccentric disk (24) and generates the second vibration vector (36).

14. The vibration actuator (10) according to claim 13, wherein, The position sensors (151, 152, 153) include at least one selected from the group consisting of optical position sensors and inductive sensors, and the position sensors (151, 152, 153) further include one selected from the group consisting of: (i) being integrated into the respective motor (20) of the respective rotary vibrator (141, 142, 143) among the n plurality of rotary vibrators, and (ii) bringing additional components connected to the respective motor (20).

15. An ultrasonic probe (68) for shear wave elastography, comprising: An ultrasonic transducer array (72) for generating ultrasonic waves; and The vibration actuator (10) according to claim 1 is used to generate a mechanically induced shear wave; and An ultrasonic probe controller (74) is operatively coupled to the ultrasonic transducer array (72) and the vibration actuator (10) to at least realize (i) a first operating mode for generating and receiving ultrasonic waves via the ultrasonic transducer array (72), and (ii) a second operating mode for realizing a combination of (ii)(a) generating and receiving ultrasonic waves via the ultrasonic transducer array (72) and the vibration actuator (10) and (ii)(b) generating mechanically induced shear waves.

16. A system (70) for shear wave elastic imaging, comprising: The ultrasonic probe (68) according to claim 15; An ultrasound system electronics (76) is operatively connected to the ultrasound probe (68) and is arranged to acquire ultrasound images in a first mode and shear wave elastography images in a second mode. and A display (78), which is connected to the ultrasound system electronics (76), is used to display the acquired ultrasound images and the shear wave elastography images.

17. A method (100) for mechanically generating a shear wave by means of a vibration actuator, comprising: Provided (102) n plurality of rotary vibrators, the plurality of rotary vibrators being geometrically arranged and coupled to a housing and configured to generate vibration vectors having desired directional behavior, the vibration vectors being selected from a plurality of vibration vectors having different directional behaviors, wherein n is a quantity of at least 3, wherein each rotary vibrator includes a motor that can be individually controlled, the motor having a drive shaft and an eccentric disk coupled to the drive shaft in a plane perpendicular to the axis of the drive shaft; An accelerometer connected to the housing is used to detect (104) vibration vectors generated by at least two of the n plurality of rotating vibrators, and an accelerometer output signal is generated based on the detected vibration vectors; and By means of a controller operatively connected to each rotary vibrator, (106) (i) a first group formed by two of the n rotary vibrators rotates their respective eccentric disks in a first coordinated manner at least based on the accelerometer output signal to generate a first vibration vector, and (ii) a second group formed by two of the n rotary vibrators rotates their respective eccentric disks in a second coordinated manner at least based on the accelerometer output signal to generate a second vibration vector, wherein the directional behavior of the second vibration vector is different from that of the first vibration vector.

18. The method (100) according to claim 17, wherein, The selective control by the controller (106) further includes (i) determining the directional behavior of the synthesized vibration vector based on (i)(a) the accelerometer output signal and (i)(b) the first or second group of two of the plurality of rotary vibrators selectively controlled to rotate the corresponding eccentric disks, (ii) comparing the directional behavior of the synthesized vibration vector with the desired directional behavior of the vibration vector, and (iii) adjusting the first or second coordination mode based on the comparison.

19. The method (100) according to claim 17, wherein, The first coordination method or the second coordination method includes controlling the corresponding first group of rotary vibrators or the second group of rotary vibrators to (i) generate vector vibration along the mid-plane direction between the corresponding eccentric disks when the corresponding eccentric disks are mirror-symmetrical, and (ii) generate vector vibration deviating from the mid-plane direction when the corresponding eccentric disks are not mirror-symmetrical.

20. The method (100) according to claim 17, wherein, The method further includes: The radial orientation or rotation angle of the corresponding eccentric disk is detected by the position sensor of the corresponding rotary vibrator, and a corresponding position signal is generated based on the detected orientation or rotation angle. The control implemented by the controller further includes synchronously controlling (i) two of the n-plus rotary vibrators forming the first group to rotate the corresponding eccentric disks and generate the first vibration vector based on the corresponding position signals, and (ii) two of the n-plus rotary vibrators forming the second group to rotate the corresponding eccentric disks and generate the second vibration vector.

Images