An acoustic levitation device and method for adaptive adjustment of resonant distance
By using a signal feedback control module and a motor-driven slide in the acoustic levitation device, the resonant distance between the acoustic receiver and the acoustic transmitter is automatically adjusted, solving the problems of low adjustment efficiency and poor controllability in the prior art, and achieving automated and efficient levitation stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF ACOUSTICS CHINESE ACAD OF SCI
- Filing Date
- 2022-02-15
- Publication Date
- 2026-06-02
AI Technical Summary
In existing technologies, acoustic levitation devices require manual adjustment of the resonant distance or rely on the operator's experience, which is inefficient, has poor controllability, and makes it difficult to achieve adaptive adjustment.
A standing wave field is formed by an acoustic receiver and an acoustic transmitter. The resonant distance between the acoustic receiver and the acoustic transmitter is automatically adjusted by a signal feedback control module and a motor-driven slide table. Automatic adjustment is achieved by using sound pressure signal feedback.
It realizes the automation and adaptive adjustment of the resonance distance of the acoustic levitation device, improves the levitation stability and efficiency, and reduces human intervention.
Smart Images
Figure CN114653564B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of acoustic levitation applications, and particularly relates to an acoustic levitation device and method for adaptively adjusting the resonant distance. Background Technology
[0002] Standing wave levitation is an important levitation method. For an object to levitate in a specific area, a certain distance relationship must be maintained between the transmitting transducer and the reflecting end (approximately an integer multiple of half the wavelength of the sound wave in the surrounding medium; this is called the resonance condition). However, when the transducer frequency drifts or the sound velocity changes due to temperature variations or other reasons, the wavelength of the sound wave in the surrounding medium will change, and the original distance will no longer satisfy the resonance condition. The distance needs to be readjusted to meet the resonance condition. Traditional methods require estimating the resonance distance using approximate formulas and manually or using a control motor to adjust the distance between the levitation transducer and the reflecting end to meet the resonance condition (e.g., Chinese utility model patent CN214621971U). This method is inefficient, relies heavily on operator experience, and has poor controllability. Chinese patent application CN110031501A discloses an in-situ observation device and method for solidifying liquid metal under microgravity conditions. The device includes an ultrasonic levitation system and a sound field visualization system. The ultrasonic levitation system is used to suspend the liquid metal sample in the air, and the sound field visualization system is used to display the generated acoustic standing wave field and to observe the changes in the acoustic standing wave field during the cooling process of the liquid metal under microgravity conditions in real time. However, this patent uses a camera to observe the sound field distribution or the state of the suspended object, i.e., a "seeing" method to determine whether the distance meets the resonance condition. This method still requires manual observation and analysis of the images before adjusting the resonance distance, making it difficult to achieve adaptive adjustment of the resonance distance without human intervention. Summary of the Invention
[0003] The purpose of this invention is to provide an acoustic levitation device and method with adaptive adjustment of resonant distance. This device and method do not rely on operators; they use a receiving transducer to acquire the sound field information by "listening" and then provide feedback and automatic control to achieve adaptive adjustment of the acoustic levitation resonant distance. This invention can be applied to adjust the levitation resonant distance before placing a suspended object. More importantly, it can be applied to improve levitation stability when the transducer frequency drifts or the sound velocity changes due to temperature variations or other reasons in the medium between transducers, causing instability of the suspended object.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] An acoustic levitation device with adaptive resonant distance adjustment, the device comprising an acoustic receiver, an acoustic transmitter, a motor, a slide, and a signal feedback control module;
[0006] The sound receiver and the sound transmitter are set on the slide table. The motor drives the slide table and forms a standing wave field between the sound receiver and the sound transmitter. The sound receiver is connected to the signal feedback control module. The signal feedback control module communicates with the motor and controls the motor to drive the slide table to move, thereby adjusting the resonant distance between the sound receiver and the sound transmitter.
[0007] The acoustic emission end is connected to an ultrasonic generator.
[0008] Preferably, the end face of the acoustic emitting end is a plane or a concave spherical surface. An ultrasonic transducer can be used.
[0009] Preferably, the end face of the sound receiver is a plane or a concave spherical surface, serving as both a reflective surface and a means of measuring sound pressure. A receiving transducer or a reflective surface covered with a piezoelectric ceramic sheet can be selected.
[0010] In this invention, the acoustic transmitter and receiver can be designed as concave spherical surfaces to generate a focused sound field, thereby increasing the acoustic levitation capability and stability.
[0011] In this invention, the acoustic levitation device can be single-axis or multi-axis. If the acoustic levitation device is multi-axis, the ultrasonic generator can output multiple high-power signals of the same frequency to drive multiple transducers to work effectively.
[0012] Preferably, the ultrasonic generator is equipped with a matching box, which can be used with ultrasonic transducers of different frequencies by adjusting the matching parameters.
[0013] In this invention, the ultrasonic frequency is 20kHz or higher. A higher frequency is used when suspending small objects, and a lower frequency is used when suspending large objects.
[0014] In this invention, referring to the adaptive adjustment feedback flowchart, a single-chip microcomputer is used to control a motor and other lifting devices to adjust the distance of the resonant cavity.
[0015] The present invention also provides an acoustic levitation method for adaptively adjusting the resonant distance, the method comprising the following steps:
[0016] 1) Using the sound receiver as the reflecting end, the distance between the receiver and the sound emitting end satisfies the resonance condition to form a standing wave field;
[0017] 2) The sound receiver measures the sound pressure of the radiated sound waves at the sound transmitter and converts the sound pressure signal into a voltage signal, which is then input to the signal feedback control module.
[0018] 3) The signal feedback control module controls the motor to fine-tune the distance between the sound transmitting end and the sound receiving end. The signal feedback control module detects the voltage value output by the sound receiving end and judges the stability of the suspension based on the change in voltage value.
[0019] 4) When the suspended object becomes unstable due to frequency or temperature changes, the signal feedback control module is used to control the motor to drive the sound transmitting end or the sound receiving end to move, and adjust the distance between the sound transmitting end or the sound receiving end until the voltage amplitude measured by the sound receiver is at its maximum value, thus reaching the resonance condition and making the suspended object stably suspended in the suspension device.
[0020] In step 3), the principle of judging the levitation stability based on voltage changes is as follows:
[0021] When the levitation system is stable, increasing or decreasing the distance between the sound transmitter and the sound receiver will decrease the voltage output of the sound receiver; when the levitation system is unstable, increasing or decreasing the distance between the sound transmitter and the sound receiver will result in one of two situations where the voltage output of the sound receiver increases.
[0022] In step 4), adjusting the resonant distance between the moving acoustic transmitter and receiver can be done in two ways:
[0023] Method 1: After receiving the voltage signal, the signal feedback control module increases the resonant distance. If the sound pressure signal measured by the sound receiver continues to increase after the resonant distance is increased, the resonant distance is further increased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful. If the sound pressure signal measured by the sound receiver decreases after the resonant distance is increased, the resonant distance is decreased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful.
[0024] Method 2: After receiving the voltage signal, the signal feedback control module reduces the resonant distance. If the sound pressure signal measured by the sound receiver continues to increase after reducing the resonant distance, the resonant distance is further reduced until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful. If the sound pressure signal measured by the sound receiver decreases after reducing the resonant distance, the resonant distance is increased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful.
[0025] In this invention, the maximum value produced by different suspended objects or suspension conditions is also different, and it is a value that achieves stable acoustic suspension during the dynamic adjustment of the acoustic suspension resonance distance.
[0026] In this invention, the suspended object is placed in a standing wave field formed by an acoustic transmitter and an acoustic receiver. The acoustic receiver is a receiving transducer that receives ultrasonic waves emitted by the acoustic transmitter and converts the acoustic signal into an electrical signal. The signal feedback control module determines whether the distance between the two transducers meets the standing wave condition by detecting whether the voltage value output by the acoustic receiver reaches its maximum value. The signal feedback control module uses a microcontroller to control a motor to drive the acoustic transmitter or acoustic receiver to move a small distance. The voltage amplitude output by the acoustic receiver is detected again. If the voltage amplitude increases, the movement continues; if the voltage amplitude decreases, the movement reverses. This continues until the voltage amplitude reaches its maximum value, reaching the resonance condition and achieving adaptive adjustment of the resonance distance.
[0027] This invention utilizes the measurement of the sound pressure level of the radiated sound waves from the levitation transducer at the opposite reflecting end to adjust the spacing of the levitation resonant cavities. The underlying physical principle is that when standing wave acoustic levitation reaches resonance, the sound pressure amplitude at the reflecting end face is always at its maximum. This method enables automated and adaptive adjustment of the resonant distance of the acoustic levitation device. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the acoustic levitation device of the present invention;
[0029] Figure 2 This is a flowchart illustrating the adaptive adjustment feedback of the resonant distance in this invention. Detailed Implementation
[0030] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0031] Example 1
[0032] like Figure 1 As shown, an acoustic levitation device with adaptive resonant distance adjustment is disclosed. The device includes an acoustic receiver, an acoustic transmitter, a motor, a slide, and a signal feedback control module.
[0033] The sound receiver and the sound transmitter are mounted on a slide controlled by a motor. The sound receiver is connected to a signal feedback control module, which communicates with the motor and controls the movement of the motor to adjust the resonant distance between the sound receiver and the sound transmitter.
[0034] The acoustic emission end is connected to a UGD type ultrasonic generator, and the ultrasonic generator is equipped with a matching box.
[0035] The end face of the acoustic emission end is flat. A sandwich-type piezoelectric ceramic transducer can be used, and the components, in the order of connection, are: rear matching, piezoelectric ceramic sheet, electrode sheet, front matching, and amplitude transformer.
[0036] The signal feedback control module uses an Intel-80C51 microcontroller to receive the output signal from the sound receiver, perform logic operations, and output commands to control the motor to adjust the distance.
[0037] The motor is a servo motor, model Panasonic servo motor A6, and its main function is to control the linear displacement of both ends of the slide adjustment suspension device.
[0038] The slide is a MOTTA-MSR, and its main function is to adjust the linear displacement at both ends of the suspension device.
[0039] The end face of the acoustic receiver is flat, serving as both a reflective surface and a measure of sound pressure. A sandwich-type piezoelectric ceramic transducer can be selected, with the components arranged in the following order: rear matching, piezoelectric ceramic plate, electrode plate, front matching, and amplitude transformer.
[0040] In this invention, the acoustic transmitter and receiver can be designed as concave spherical surfaces to generate a focused sound field, thereby increasing the acoustic levitation capability and stability.
[0041] In this invention, the acoustic levitation device is a single-axis type. The ultrasonic generator is equipped with a matching box, and by adjusting the matching parameters, it can be used with ultrasonic transducers of different frequencies.
[0042] This invention also provides an adaptive resonant distance adjustment method for acoustic levitation, which can be applied to adjust the resonant distance before placing a suspended object. More importantly, it can be applied to improve levitation stability when the transducer frequency drifts or the sound velocity changes due to temperature variations in the medium between transducers, causing instability in the suspended object. The method includes the following steps:
[0043] 1) Using the sound receiver as the reflecting end, the distance between the receiver and the sound emitting end satisfies the resonance condition to form a standing wave field;
[0044] 2) The sound receiver measures the sound pressure of the radiated sound waves at the sound transmitter and inputs the measured sound pressure signal into the signal feedback control module.
[0045] 3) The microcontroller controls the motor to fine-tune the distance between the sound transmitter and receiver. The signal feedback control module detects the voltage value output by the sound receiver and judges the stability of the suspension based on the change in voltage value. The specific principle is that when the suspension system is stable, increasing or decreasing the distance between the sound transmitter and receiver will make the voltage value output by the sound receiver decrease; when the suspension system is unstable, increasing or decreasing the distance between the sound transmitter and receiver will result in one of the following situations: the voltage value output by the sound receiver will increase.
[0046] 4) Based on the judgment result of suspension stability, control the motor to drive the sound transmitting end or the sound receiving end to move, and adjust the resonant distance between the sound transmitting end or the sound receiving end until the voltage amplitude measured by the sound receiver is at its maximum value, so that the suspended object can achieve stable suspension in the suspension device.
[0047] like Figure 2 As shown, in step 4), adjusting the resonant distance between the sound transmitting end and the sound receiving end can be done in two ways:
[0048] Method 1: After receiving the sound pressure signal, the signal feedback control module increases the resonant distance. If the sound pressure signal measured by the sound receiver continues to increase after increasing the resonant distance, the resonant distance is further increased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful. If the sound pressure signal measured by the sound receiver decreases after increasing the resonant distance, the resonant distance is decreased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful.
[0049] Method 2: After receiving the sound pressure signal, the signal feedback control module reduces the resonant distance. If the sound pressure signal measured by the sound receiver continues to increase after reducing the resonant distance, the resonant distance is further reduced until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful. If the sound pressure signal measured by the sound receiver decreases after reducing the resonant distance, the resonant distance is increased until the sound pressure signal measured by the sound receiver reaches its maximum value, indicating that the resonant distance adjustment is successful.
[0050] In this embodiment, the adaptive algorithm can be a conventional adaptive algorithm in the field, such as the zero-forcing algorithm, the steepest descent algorithm, the LMS algorithm, the RLS algorithm, and various blind equalization algorithms, which can be embedded in the signal feedback control module.
[0051] All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. An acoustic levitation device with adaptive adjustment of resonant distance, characterized in that, The acoustic levitation device includes an acoustic receiver, an acoustic transmitter, a motor, a sliding table, and a signal feedback control module. The sound receiver and the sound transmitter are set on the slide table. The motor drives the slide table and forms a standing wave field between the sound receiver and the sound transmitter. The sound receiver is connected to the signal feedback control module. The signal feedback control module communicates with the motor and controls the motor to drive the slide table to move, thereby adjusting the resonant distance between the sound receiver and the sound transmitter. The acoustic emitting end is connected to an ultrasonic generator; The end face of the acoustic emitting end is a plane or a concave spherical surface; the end face of the acoustic receiving end is a plane or a concave spherical surface. The acoustic levitation device uses an acoustic receiver as a reflector, and the distance between the receiver and the emitter satisfies the resonance condition to form a standing wave field. The sound receiver measures the sound pressure of the sound waves radiated by the sound transmitter and converts the sound pressure signal into a voltage signal, which is then input to the signal feedback control module. The signal feedback control module controls the motor to fine-tune the distance between the sound transmitting end and the sound receiving end. The signal feedback control module detects the voltage value output by the sound receiving end and judges the stability of the suspension based on the change in voltage value. When a suspended object becomes unstable due to frequency or temperature changes, the signal feedback control module controls the motor to drive the sound transmitter or receiver to move, adjusting the distance between the sound transmitter or receiver until the voltage amplitude measured by the receiver reaches its maximum value, thus achieving resonance and allowing the suspended object to achieve stable suspension in the suspension device.
2. The acoustic levitation device with adaptive resonant distance adjustment according to claim 1, characterized in that, The signal feedback control module is a microcontroller.
3. The acoustic levitation device with adaptive resonant distance adjustment according to claim 1, characterized in that, The ultrasonic generator is equipped with a matching box, and the matching parameters are adjusted to correspond to ultrasonic transducers of different frequencies.