ACOUSTIC LEVITATION APPARATUS AND METHOD FOR ADAPTIVELY ADJUSTING RESONANCE DISTANCE

Abstract

An acoustic levitation apparatus and method for adaptively adjusting a resonance distance. The apparatus includes an acoustic receiver, an acoustic transmitter, a motor, a slide, and a signal feedback control module. The acoustic receiver and the acoustic transmitter are installed on the slide of which movement is controlled by the motor. The acoustic receiver is connected to the signal feedback control module. The signal feedback control module performs determination by detecting the magnitude of a signal outputted by the acoustic receiver and automatically controls the motor to adjust a spacing between the acoustic transmitter and the acoustic receiver to satisfy a resonance condition to form stable standing wave levitation. The acoustic transmitter is connected to an ultrasonic generator.

Claims

1. An acoustic levitation apparatus for adaptively adjusting a resonance distance, wherein the apparatus comprises an acoustic receiver, an acoustic transmitter, a motor, a slide, and a signal feedback control module; the acoustic receiver and the acoustic transmitter are disposed on the slide, the motor is drive-connected to the slide, a standing wave field is formed between the acoustic receiver and the acoustic transmitter, the acoustic receiver is connected to the signal feedback control module, and the signal feedback control module is communicatively connected to the motor and controls the motor to drive the slide to move to further adjust a resonance distance between the acoustic receiver and the acoustic transmitter; and the acoustic transmitter is connected to an ultrasonic generator.

2. The acoustic levitation apparatus for adaptively adjusting a resonance distance according to claim 1, wherein the signal feedback control module is a microcontroller.

3. The acoustic levitation apparatus for adaptively adjusting a resonance distance according to claim 1, wherein a matcher is disposed at the ultrasonic generator, and a matching parameter is adjusted to correspond to ultrasonic transducers with different frequencies.

4. The acoustic levitation apparatus for adaptively adjusting a resonance distance according to claim 1, wherein the radiating surface of the acoustic transmitter is a plane surface or a concave surface.

5. The acoustic levitation apparatus for adaptively adjusting a resonance distance according to claim 1, wherein the surface of the acoustic receiver is a plane surface or a concave surface.

6. An acoustic levitation method for adaptively adjusting a resonance distance, the method comprising the following steps: 1) forming a standing wave field by using an acoustic receiver as a reflector and making a spacing between the reflector and an acoustic transmitter satisfy a resonance condition; 2) measuring, by an acoustic receiver, acoustic pressure of a radiated acoustic wave of the acoustic transmitter, and converting an acoustic pressure signal into a voltage signal to be inputted into a signal feedback control module; 3) controlling, by the signal feedback control module, a motor to fine-tune a spacing between the acoustic transmitter and the acoustic receiver, detecting, by the signal feedback control module, a voltage value outputted by the acoustic receiver, and determining stability of levitation according to a change in the voltage value; and 4) when a levitated object becomes unstable under the influence of a frequency change or a temperature change, controlling the motor by using the signal feedback control module to drive the acoustic transmitter or the acoustic receiver to move, and adjusting a distance between the acoustic transmitter and the acoustic receiver, so that the resonance condition is satisfied when a voltage amplitude measured by the acoustic receiver reaches a maximum value, making the levitated object satisfy stable levitation in a levitation apparatus.

7. The acoustic levitation method for adaptively adjusting a resonance distance according to claim 6, wherein a resonance distance between the acoustic transmitter and the acoustic receiver is specifically adjusted in step 4) in one of two manners as follows: a manner 1: after the signal feedback control module receives the voltage signal, increasing the resonance distance, and after the resonance distance is increased, if an amplitude of the acoustic pressure signal measured by the acoustic receiver continues to increase, continuing to increase the resonance distance until the amplitude of the acoustic pressure signal measured by the acoustic receiver satisfies a maximum value, that is, the resonance distance is adjusted successfully; and after the resonance distance is increased, if the acoustic pressure signal measured by the acoustic receiver decreases, decreasing the resonance distance until the amplitude of the acoustic pressure signal measured by the acoustic receiver satisfies the maximum value, that is, the resonance distance is adjusted successfully; and a manner 2: after the signal feedback control module receives the voltage signal, decreasing the resonance distance, and after the resonance distance is decreased, if the acoustic pressure signal measured by the acoustic receiver continues to increase, continuing to decrease the resonance distance until the acoustic pressure signal measured by the acoustic receiver satisfies a maximum value, that is, the resonance distance is adjusted successfully; and after the resonance distance is decreased, if the acoustic pressure signal measured by the acoustic receiver decreases, increasing the resonance distance until the acoustic pressure signal measured by the acoustic receiver satisfies the maximum value, that is, the resonance distance is adjusted successfully.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0028] FIG. 1 is a schematic structural diagram of an acoustic levitation apparatus according to the present invention; and

[0029] FIG. 2 is a flowchart of feedback for adaptive adjustment of a resonance distance according to the present invention.

DETAILED DESCRIPTION

[0030] The present invention is further described below in detail with reference to the accompanying drawings and specific implementations.

Embodiment 1

[0031] As shown in FIG. 1, an acoustic levitation apparatus for adaptively adjusting a resonance distance is provided, the apparatus including an acoustic receiver, an acoustic transmitter, a motor, a slide, and a signal feedback control module.

[0032] The acoustic receiver and the acoustic transmitter are installed on the slide of which movement is controlled by the motor. The acoustic receiver is connected to the signal feedback control module. The signal feedback control module is communicatively connected to the motor and controls the movement of the motor to further adjust a resonance distance between the acoustic receiver and the acoustic transmitter.

[0033] The acoustic transmitter is connected to a UGD-type ultrasonic generator. A matcher is disposed at the ultrasonic generator.

[0034] An end surface of the acoustic transmitter is a flat surface. A sandwich piezoelectric ceramic transducer may be used. In a connection order, components are sequentially back matching, a piezoelectric ceramic sheet, an electrode sheet, front matching, and a booster.

[0035] An Intel-80C51 microcontroller is used for the signal feedback control module, receives a signal outputted by the acoustic receiver, performs a logical operation, and outputs an instruction to control the motor to adjust a distance.

[0036] The motor is a servo motor with the model of Panasonic servo motor A6, and is mainly used for controlling the slide to adjust linear displacements of two ends of the levitation apparatus.

[0037] The slide is MOTTA-MSR, and is mainly used for adjusting the linear displacements of the two ends of the levitation apparatus.

[0038] The surface of the acoustic receiver is a plane surface. The acoustic receiver is used as a reflector and is also used for measuring an acoustic pressure. A sandwich piezoelectric ceramic transducer may be chosen. In a connection order, components are sequentially back matching, a piezoelectric ceramic sheet, an electrode sheet, front matching, and a booster.

[0039] In the present invention, the acoustic transmitter and the acoustic receiver may be designed as concave surfaces to generate a focusing acoustic field, thereby increasing the capability and stability of acoustic levitation.

[0040] In the present invention, the acoustic levitation apparatus is of a single-axis type. The ultrasonic generator is provided with a matcher, and a matching parameter may be adjusted for use with ultrasonic transducers with different frequencies.

[0041] The present invention further provides an acoustic levitation method for adaptively adjusting a resonance distance, which may be used to adjust a resonance distance before a levitated object is placed, and more importantly is used to adjust a resonance distance when the frequency of a transducer drifts or the speed of sound changes in a medium between the transducers due to a temperature change or for another reason and a levitated object becomes unstable, thereby improving the stability of levitation. The method includes the following steps:

[0042] 1) forming a standing wave field by using an acoustic receiver as a reflector and making a spacing between the reflector and an acoustic transmitter satisfy a resonance condition;

[0043] 2) measuring, by an acoustic receiver, acoustic pressure of a radiated acoustic wave of the acoustic transmitter, and inputting a measured acoustic pressure signal into a signal feedback control module;

[0044] 3) controlling, by using a microcontroller, a motor to fine-tune a spacing between the acoustic transmitter and the acoustic receiver, detecting, by the signal feedback control module, a voltage value outputted by the acoustic receiver, and determining stability of levitation according to a change in the voltage value, where the principle is specifically that when a levitation system becomes stable, the voltage value outputted by the acoustic receiver is decreased by increasing or decreasing the spacing between the acoustic transmitter and the acoustic receiver, and when the levitation system is unstable, the voltage value outputted by the acoustic receiver is increased by either of increasing and decreasing the spacing between the acoustic transmitter and the acoustic receiver.

[0045] 4) controlling the motor according to a determination result of stability of levitation to drive the acoustic transmitter or the acoustic receiver to move, and adjusting a resonance distance between the acoustic transmitter and the acoustic receiver, so that the resonance condition is satisfied when a voltage amplitude measured by the acoustic receiver reaches a maximum value, making the levitated object satisfy stable levitation in a levitation apparatus.

[0046] As shown in FIG. 2, a resonance distance between the acoustic transmitter and the acoustic receiver is specifically adjusted in step 4) in one of two manners as follows:

[0047] a manner 1: after the signal feedback control module receives the acoustic pressure signal, increasing the resonance distance, and after the resonance distance is increased, if an amplitude of the acoustic pressure signal measured by the acoustic receiver continues to increase, continuing to increase the resonance distance until the amplitude of the acoustic pressure signal measured by the acoustic receiver satisfies a maximum value, that is, the resonance distance is adjusted successfully; and after the resonance distance is increased, if the acoustic pressure signal measured by the acoustic receiver decreases, decreasing the resonance distance until the amplitude of the acoustic pressure signal measured by the acoustic receiver satisfies the maximum value, that is, the resonance distance is adjusted successfully; and

[0048] a manner 2: after the signal feedback control module receives the acoustic pressure signal, decreasing the resonance distance, and after the resonance distance is decreased, if the acoustic pressure signal measured by the acoustic receiver continues to increase, continuing to decrease the resonance distance until the acoustic pressure signal measured by the acoustic receiver satisfies a maximum value, that is, the resonance distance is adjusted successfully; and after the resonance distance is decreased, if the acoustic pressure signal measured by the acoustic receiver decreases, increasing the resonance distance until the acoustic pressure signal measured by the acoustic receiver satisfies the maximum value, that is, the resonance distance is adjusted successfully.

[0049] In this embodiment, the adaptation may use conventional adaptive algorithms in the field, for example, a zero-forcing algorithm, a steepest descent algorithm, an LMS algorithm, an RLS algorithm, and various blind equalization algorithms, which are embedded in the signal feedback control module can be used.

[0050] Conventional technical knowledge in the field may be used for content that is not described in detail in the present invention.

[0051] Finally, it should be noted that the foregoing embodiments are merely intended for describing the technical solutions of the present invention rather than limiting the present invention. Although the present invention is described in detail with reference to the embodiments, persons of ordinary skill in the art should understand that they may still make modifications or equivalent replacements to the technical features of the present invention without departing from the spirit and scope of the technical solutions of the technical solutions of the present invention. These modifications or equivalent replacements shall all fall within the scope of the claims the present invention.