An ultrasonic cleaning machine control method and system with a safety coordination mechanism

Abstract

The application provides an ultrasonic cleaning machine control method and system with a safety coordination mechanism, and belongs to the technical field of ultrasonic cleaning machines. The method comprises the following steps: driving a main transducer at a power lower than a cavitation threshold, judging whether there is liquid in the container according to the acquired electrical parameters of the main transducer, and preventing the cleaning from starting if there is no liquid; driving the main transducer to emit a pulse signal, judging whether the liquid level in the container reaches a preset height according to the electrical response signal of a secondary transducer installed at the preset safety liquid level, and preventing the cleaning from starting if the liquid level does not reach the preset height; driving the main transducer to emit a pulse sequence signal, acquiring the electrical response signal envelope of the secondary transducer to each pulse, judging whether there is a moving object in the liquid according to the variance of the envelope sequence, and preventing the cleaning from starting if there is a moving object. The three detection functions of water detection, liquid level detection and moving object detection are executed in series to form a multi-stage safety coordination mechanism, and the safety hidden danger in the starting stage of the cleaning machine is prevented.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic cleaning machine technology, specifically relating to an ultrasonic cleaning machine control method and system with a safety coordination mechanism. Background Technology

[0002] Ultrasonic cleaning technology utilizes the cavitation effect of ultrasound waves in liquids to clean the surfaces of items immersed in the liquid. As ultrasonic cleaning equipment gradually becomes more portable and suitable for home use, its application scenarios are becoming more diverse, and the user base is expanding from professionals to ordinary consumers, especially the elderly and other groups with relatively weaker operational skills. This has further amplified the safety hazards associated with the use of ultrasonic cleaning machines.

[0003] The most prominent safety hazards are those caused by starting the ultrasonic cleaner without water or by immersing the user in liquid. When starting an ultrasonic cleaner without water, the transducer heats up rapidly in a short period, which may damage the cleaner and, in severe cases, pose a risk of localized overheating. If the user starts the cleaning process without removing fingers or other body parts from the liquid, it may cause stinging, localized discomfort, or startle.

[0004] Therefore, a safety control scheme is needed for the start-up phase of an ultrasonic cleaner. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an ultrasonic cleaning machine control method and system with a safe collaborative mechanism.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An ultrasonic cleaner control method with a safety coordination mechanism includes: driving a main transducer with a power below a cavitation threshold; determining whether liquid exists in the cleaning container based on the acquired electrical parameters of the main transducer; if not, preventing cleaning from starting and issuing a warning signal; driving the main transducer to emit pulse signals; determining whether the liquid level in the container has reached a preset height based on the electrical response signal of an auxiliary transducer installed at a preset safe liquid level height; if not, preventing cleaning from starting and issuing a warning signal; driving the main transducer to emit a pulse sequence signal; acquiring the envelope of the electrical response signal of the auxiliary transducer for each pulse; determining whether there is a moving object in the liquid based on the variance of the envelope sequence; if there is, preventing cleaning from starting and issuing a warning signal; and disconnecting the signal transmission line of the auxiliary transducer and driving the main transducer to start cleaning.

[0007] Furthermore, the method for determining whether there is liquid in the cleaning machine container based on the obtained electrical parameters of the main transducer includes: obtaining a voltage sampling sequence of the voltage across a sampling resistor connected in series with the main transducer; converting the voltage sampling sequence into a current sampling sequence based on the resistance value of the sampling resistor; obtaining the root mean square value of the current sampling sequence; dividing the root mean square value by the driving voltage value of the main transducer to obtain the equivalent admittance amplitude; if the current equivalent admittance amplitude is less than the pre-calibrated waterless admittance threshold for the waterless state, then it is determined that there is liquid in the container; otherwise, it is determined that there is no liquid in the container.

[0008] Furthermore, the method for determining whether there is liquid in the cleaning machine container based on the obtained electrical parameters of the main transducer includes: obtaining a sequence of digital output values ​​corresponding to the voltage across the sampling resistor connected in series with the main transducer; obtaining the root mean square value of the digital output value sequence; if the root mean square value is less than the pre-calibrated waterless digital threshold, then it is determined that there is liquid in the container; otherwise, it is determined that there is no liquid in the container.

[0009] Furthermore, the method for determining whether the liquid level in the container has reached the preset height based on the electrical response signal of the auxiliary transducer includes: acquiring two sets of signals by collecting the electrical response signal of the auxiliary transducer according to a sampling window with two preset time intervals; acquiring the energy of the two sets of signals respectively using orthogonal demodulation; obtaining the ratio of the energy of the first set of signals to the energy of the second set of signals; if the energy ratio is less than the energy ratio threshold for when the liquid level just reaches the target, then the liquid level is determined to have reached the preset height; otherwise, the liquid level is determined not to have reached the preset height.

[0010] Furthermore, the method for determining whether the liquid level in the container has reached the preset height based on the electrical response signal of the auxiliary transducer includes: acquiring two sets of signals by collecting the electrical response signal of the auxiliary transducer according to a sampling window with two preset time intervals; acquiring the amplitude of the two sets of signals respectively using orthogonal demodulation; obtaining the absolute value of the amplitude difference between the two sets of signals; if the absolute value is greater than the amplitude difference threshold when the liquid level just reaches the target, it is determined that the liquid level has reached the preset height; otherwise, it is determined that the liquid level has not reached the preset height.

[0011] Furthermore, the method for determining whether there is a moving object in the liquid based on the variance of the envelope sequence includes: obtaining the overall variance of the envelope sequence; if the overall variance is greater than a pre-calibrated variance threshold when the liquid is basically still, then it is determined that there is a moving object in the liquid; otherwise, it is determined that there is no moving object in the liquid.

[0012] An ultrasonic cleaning machine control system with a safety coordination mechanism includes a microcontroller, a main transducer, a secondary transducer, a drive module, a current sampling module, and a signal conditioning module. The main transducer is fitted to the outer wall of the bottom of the cleaning machine container, and the secondary transducer is installed on the outer wall of the side of the cleaning machine container. The installation height of the secondary transducer corresponds to a preset safe liquid level height. The drive module is electrically connected between the microcontroller and the main transducer and is used to drive the main transducer to work according to the PWM signal of the microcontroller. The current sampling module is electrically connected between the microcontroller and the main transducer and includes a sampling resistor connected in series with the main transducer. The current sampling module is used to acquire the digital value corresponding to the voltage across the sampling resistor and send it to the microcontroller. The signal conditioning module is electrically connected between the microcontroller and the secondary transducer and is used to condition the electrical response signal of the secondary transducer and send it to the microcontroller.

[0013] Furthermore, the signal conditioning module includes a limiting unit, a bandpass filter unit, and an amplification unit connected in sequence; the limiting unit is electrically connected to the secondary transducer and is used to limit the voltage of the electrical response signal of the secondary transducer; the bandpass filter unit is used to filter out noise components other than the typical resonant frequency of the primary transducer; the amplification unit is used to amplify the signal amplitude and output it to the microcontroller.

[0014] Furthermore, it also includes a protection switch; the protection switch is connected in series between the auxiliary transducer and the signal conditioning module, and is controlled by the microcontroller.

[0015] Furthermore, it also includes a power module, which includes a charge / discharge management module and a voltage regulation module; the charge / discharge management module is used to control and protect the charging and discharging of the built-in lithium battery; the input terminal of the voltage regulation module is electrically connected to the output terminal of the charge / discharge management module, and is used to provide a driving voltage for the main transducer, and the driving voltage value is controlled by the microcontroller.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention drives the main transducer with a power below the cavitation threshold before cleaning starts. By detecting the electrical parameters of the main transducer, it determines whether there is liquid in the cleaning container. It can achieve waterless detection without the need for an additional liquid level sensor, avoiding the safety hazard of the main transducer overheating rapidly due to excessive current when starting under no-load conditions in a waterless state, which could even lead to permanent damage to the cleaning machine. This effectively extends the service life of the equipment.

[0017] This invention installs an auxiliary transducer at a preset safe liquid level height on the side of the cleaning container. It uses the difference in acoustic conduction characteristics at this location after the main transducer emits a pulse signal to determine whether the liquid level is up to standard. This allows the cleaning process to be stopped in time when the liquid level is insufficient, and the user is reminded to add water. This avoids problems such as reduced cleaning effect, excessive temperature rise, and excessive transducer load when the liquid level is too low.

[0018] This invention drives the main transducer to emit a pulse sequence signal, and determines the presence of moving objects in the liquid by analyzing the variance of the envelope sequence of each pulse response signal from the secondary transducer. Based on this mechanism, the system can detect, to a certain extent, whether human parts such as fingers are still immersed in the liquid before the cleaning process starts, promptly preventing the start-up and issuing a warning. This effectively avoids the stinging, local discomfort, and startling sensations caused by the direct action of ultrasonic energy on the human body, providing important safety protection for elderly users and other groups.

[0019] This invention executes three detection functions—waterless detection, liquid level detection, and moving object detection—in series. Passing the previous level of detection is a prerequisite for the execution of the next level of detection, forming a complete multi-level safety coordination mechanism. This enables the system to accurately intercept various abnormal states and trigger corresponding reminder signals, achieving full coverage protection against safety hazards during the start-up phase of the ultrasonic cleaner and significantly improving user safety. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings.

[0021] Figure 1 : Structural block diagram of Embodiment 1 of the present invention; Figure 2 Partial circuit schematic diagram of Embodiment 1 of the present invention; Figure 3 Flowchart of Embodiment 2 of the present invention; The components are: 1-Main control module, 11-Microcontroller, 2-Main transducer, 3-Auxiliary transducer, 4-Drive module, 5-Current sampling module, 6-Signal conditioning module, 61-Limiting unit, 62-Bandpass filter unit, 63-Amplification unit, 7-Protection switch, 8-Power supply module, 81-Charge and discharge management module, 82-Voltage regulation module. Detailed Implementation

[0022] To better understand the present invention, the content of the invention is further clearly illustrated below with reference to embodiments and accompanying drawings. However, the scope of protection of the present invention is not limited to the embodiments described below. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0023] Example 1: See Figures 1-2 The purpose of this embodiment is to provide an ultrasonic cleaning machine control system with a safe collaborative mechanism.

[0024] Ultrasonic cleaning machine containers are hollow containers with an opening at the top, used to hold the cleaning liquid (mostly water) and the items to be cleaned. The containers are preferably made of stainless steel (such as SUS304).

[0025] like Figure 1 As shown, the control system includes a main control module 1, a main transducer 2, an auxiliary transducer 3, a drive module 4, a current sampling module 5, a signal conditioning module 6, a protection switch 7, and a power supply module 8.

[0026] The main control module 1 includes a microcontroller 11, which operates at a frequency of not less than 170MHz, has a Flash memory capacity of not less than 32KB, and an SRAM memory capacity of not less than 8KB. The microcontroller 11 also has a PWM output port, a GPIO control port, and at least two ADC ports.

[0027] The main transducer 2 is an ultrasonic transmitting transducer, mounted flush against the outer wall of the bottom of the cleaning machine container. The auxiliary transducer 3 is an ultrasonic receiving transducer, mounted flush against the outer wall of the side of the cleaning machine container. Both the main transducer 2 and the auxiliary transducer 3 are piezoelectric ceramic transducers with a typical resonant frequency of 40kHz and a nominal impedance of 20–50Ω. The auxiliary transducer 3 operates in positive piezoelectric mode, converting the received acoustic signal into an electrical response signal for output. The installation height of the auxiliary transducer 3 corresponds to the preset safe liquid level (the level of the cleaning liquid in the cleaning machine container meets the minimum requirements for normal operation).

[0028] The driver module 4 is used to drive the main transducer 2 to operate according to the PWM signal of the microcontroller 11. Specifically, as shown... Figure 2As shown, the control input terminal (PWM_IN) of the drive module 4 is electrically connected to the PWM output port of the microcontroller 11, and the drive output terminal (interface CN1) is electrically connected to the main transducer 2. The drive module 4 is controlled by the microcontroller 11 and its power is adjustable. The drive module 4 includes a gate driver chip U9 (e.g., model UCC27517, maximum sink current 5A) and an N-channel field-effect transistor Q1 (e.g., model AON7544). The gate driver chip U9 generates a gate drive signal according to the PWM control signal of the microcontroller 11, and the field-effect transistor Q1 controls the conduction of the main transducer 2 and the drive power supply (VBUS) according to the gate drive signal. The microcontroller 11 adjusts the output power of the main transducer 2 by adjusting the duty cycle of the PWM signal and the VDR voltage. For example, in the normal cleaning mode, the duty cycle is 50% and the VDR voltage is the rated voltage (e.g., 20V); in the detection mode during the system startup phase, an extremely low duty cycle (e.g., 2%) is used, and the VDR voltage is adjusted to a low voltage (e.g., 5V).

[0029] The power module 8 includes a charge / discharge management module 81 and a voltage regulation module 82. The charge / discharge management module 81 controls and protects the charging and discharging of the built-in lithium battery of the cleaning machine, providing power for the operation of other components. The voltage regulation module 82 is a DC-DC step-up / step-down module. Its input terminal is electrically connected to the output terminal of the charge / discharge management module 81, its output terminal (VDR) is electrically connected to the main transducer 2, and its control terminal is electrically connected to the control port of the microcontroller 11. The microcontroller 11 can adjust the driving voltage of the main transducer 2 through the voltage regulation module 82.

[0030] The current sampling module 5 is used to collect the operating current of the main transducer 2. Specifically, such as... Figure 2 As shown, the current sampling module 5 includes a sampling resistor RS and a current detection chip U2 (e.g., INA282). The sampling resistor RS is connected in series between the source of the field-effect transistor Q1 and the reference ground. The current detection chip U2 amplifies the voltage across the sampling resistor RS and outputs it to the first ADC port of the microcontroller 11, enabling the microcontroller 11 to obtain the digital output value of the current sampling module 5 and to detect the drive current of the main transducer 2 based on the resistance value of the sampling resistor RS.

[0031] The signal input terminal of the signal conditioning module 6 is electrically connected to the auxiliary transducer 3, and the signal output terminal is electrically connected to the second ADC port of the microcontroller 11. The signal conditioning module 6 includes a limiting unit 61, a bandpass filter unit 62, and an amplification unit 63 connected in sequence. The limiting unit 61 is electrically connected to the auxiliary transducer 3 and is used to limit the voltage of the electrical response signal of the auxiliary transducer 3. The bandpass filter unit 62 is used to filter out noise components other than the typical resonant frequency of the main transducer 2. The amplification unit 63 is used to amplify the amplitude of the original signal and output it to the microcontroller 11.

[0032] In one implementation, such as Figure 2 As shown, interface CN2 is electrically connected to the auxiliary transducer 3. Limiting unit 61 consists of two diodes connected in anti-parallel, such as diode array D2 of type BAV99, which limits the electrical response signal output from auxiliary transducer 3 to within ±0.7V. Bandpass filter unit 62 is a resonant circuit composed of inductor L1 and capacitor C7 connected in parallel, with a resonant frequency... The bandpass filter unit 62 can also be implemented using an active bandpass filter, matching the typical resonant frequency of the main transducer 2. The amplification unit 63 uses a two-stage amplification circuit composed of amplifiers U4.1 and U4.2, where amplifier U4.1 provides a gain of 40dB and amplifier U4.2 provides a gain of approximately 20dB, amplifying the 1-5mV amplitude signal output from the auxiliary transducer 3 under normal conditions to 1-5V; amplifiers U4.1 and U4.2 can also be replaced by a dual operational amplifier such as model AD8052.

[0033] In another embodiment, the bandpass filter unit 62 is a digital filtering algorithm running on the microcontroller 11, and the amplification unit 63 is a signal amplification algorithm running on the microcontroller 11. In this embodiment, the output signal of the auxiliary transducer 3 is directly output to the second ADC port of the microcontroller 11 after passing through the limiting unit 61.

[0034] A protective switch 7 is connected in series between the auxiliary transducer 3 and the signal conditioning module 6. The microcontroller 11 uses the protective switch 7 to control the on / off state of the auxiliary transducer 3. Figure 2 As shown, the protection switch 7 is an N-channel field-effect transistor Q2, whose drain is electrically connected to the auxiliary transducer 3, its source is electrically connected to the input terminal of the signal conditioning module 6, and its gate is electrically connected to the control port of the microcontroller 11.

[0035] When the liquid level in the cleaning machine container is lower than the installation height of the auxiliary transducer 3, the inner wall of the container at that height is not covered by liquid. Due to the extremely low acoustic impedance of air and the severe acoustic impedance mismatch with the metal wall, acoustic energy cannot be directly conducted to the container wall at the auxiliary transducer 3 through the liquid. When the liquid level in the cleaning machine container reaches or exceeds the installation height of the auxiliary transducer 3, the acoustic impedance mismatch between the liquid and the metal wall is significantly reduced. Part of the ultrasonic signal energy can be transmitted through the liquid to the side wall material and reach the auxiliary transducer 3 through structural conduction, enabling the auxiliary transducer 3 to output a detectable electrical response signal. Therefore, one of the purposes of setting the auxiliary transducer 3 and the signal conditioning module 6 in this embodiment is to detect whether the liquid level in the cleaning machine container has reached the preset height.

[0036] If the cleaning process is started while human body parts such as fingers are still in the liquid, it will stimulate the body parts and cause them to be startled. Under normal circumstances, human body parts are not completely still, and the signal envelope value collected by the auxiliary transducer 3 can reflect the disturbance of the liquid by moving objects. Therefore, another purpose of setting up the auxiliary transducer 3 and the signal conditioning module 6 in this embodiment is to detect whether there are moving objects in the liquid in the cleaning machine container, so as to avoid the ultrasonic signal stimulating the human body to a certain extent.

[0037] The driving current of the main transducer 2 is directly related to its acoustic terminal load. Taking the BVD (Butterworth-VanDyke) equivalent model of the transducer as an example, at the series resonant frequency, the kinematic branch of the transducer is equivalent to a pure resistance, including a basically constant mechanical loss resistance and acoustic radiation resistance. When there is no liquid in the cleaning machine container, the main transducer 2 radiates ultrasonic waves into the air through the cleaning machine container. Due to the extremely low acoustic impedance of the air, the acoustic radiation resistance of the main transducer 2 is approximately zero, and its kinematic resistance at the series resonant frequency only includes the internal mechanical loss resistance, exhibiting low impedance and high current characteristics. When there is liquid in the cleaning machine container, the acoustic impedance of the liquid is significantly greater than that of the air, the acoustic radiation resistance of the transducer increases, and its total kinematic resistance at the series resonant frequency increases, exhibiting higher impedance and lower current characteristics. Therefore, the purpose of setting the current sampling module 5 in this embodiment is to determine whether there is liquid in the cleaning machine container by accurately detecting the magnitude of the driving current of the main transducer 2, or to directly determine whether there is liquid in the cleaning machine container based on the magnitude of the digital output value output by the current sampling module 5, so as to avoid the main transducer 2 being overheated and damaged due to excessive current when starting under no-load conditions in a waterless state.

[0038] When the main transducer 2 emits ultrasonic waves at full power for cleaning, the auxiliary transducer 3 receives a large-amplitude acoustic signal through the acoustic coupling path, thereby generating a high-amplitude electrical response signal. If the signal path remains open, the electrical response signal of the auxiliary transducer 3 will be continuously transmitted to the signal conditioning module 6, causing thermal stress accumulation in the limiting unit 61 and long-term saturation operation of the amplification unit 63, affecting the service life of the signal conditioning module 6. Therefore, the purpose of the protection switch 7 in this embodiment is to directly control the on / off state of the auxiliary transducer 3, ensuring that the signal transmission path of the auxiliary transducer 3 is physically cut off when the main transducer 2 is cleaning.

[0039] For details on implementing the above functions, please refer to the control method provided in Example 2.

[0040] Example 2: See Figure 3The purpose of this embodiment is to provide a control method for an ultrasonic cleaner with a safe collaborative mechanism, implemented using the control system of Embodiment 1. The control method is activated based on the start signal of the cleaner. For example, when the main control module 1 receives a "cleaning start" signal triggered by a button, voice, or remote control command, it first executes the control method of this embodiment and determines whether to start cleaning based on the execution result.

[0041] like Figure 3 As shown, the control method includes: S1. Drive the main transducer 2 with a power lower than the cavitation threshold, and determine whether there is liquid in the cleaning machine container based on the obtained electrical parameters of the main transducer 2; if there is no liquid, stop the start and issue a reminder signal.

[0042] The microcontroller 11 outputs a PWM signal with a first preset duty cycle (e.g., 2%) and controls the voltage regulation module 82 to output a first preset drive voltage (e.g., 5V), so that the drive module 4 continuously drives the main transducer 2 with a detection power lower than the cavitation threshold. The continuous drive time is not less than 100ms, of which the first 20ms is the amplitude establishment waiting time and the rest of the time is the parameter sampling time window.

[0043] In one embodiment, the microcontroller 11 acquires a voltage sampling sequence within a parameter sampling time window and converts the voltage sampling sequence into a current sampling sequence based on the resistance value of the sampling resistor RS. The root mean square (RMS) value of the current sampling sequence is obtained, and this RMS value is divided by a first preset drive voltage value to obtain the equivalent admittance amplitude of the main transducer 2. The current equivalent admittance amplitude is compared with a pre-calibrated anhydrous admittance threshold. If the current equivalent admittance amplitude is less than the anhydrous admittance threshold, it is determined that liquid exists in the container; otherwise, it is determined that no liquid exists.

[0044] Alternatively, in another implementation, the microcontroller 11 acquires the sequence of digital output values ​​from the current sampling module 5 within the parameter sampling time window, and obtains the root mean square (RMS) value of the digital output value sequence. This RMS value is compared with a pre-calibrated anhydrous digital threshold. If the current RMS value is less than the anhydrous digital threshold, it is determined that liquid exists in the container; otherwise, it is determined that no liquid exists.

[0045] If it is determined that there is no liquid in the container, the microcontroller 11 sends a reminder signal (such as a voice reminder, sound reminder, LED light reminder, etc.) to remind the user to add water and terminates the execution of subsequent steps without starting the cleaning process; if it is determined that there is liquid in the container, it continues to execute the subsequent steps.

[0046] The waterless admittance threshold and waterless digital threshold are calibrated at the factory stage. Based on the first preset duty cycle and the first preset drive voltage, in the waterless state, the calibration is performed by obtaining the root mean square values ​​of the current sampling sequence and the digital output value sequence, and the calibration results are stored in the main control module 1.

[0047] During this step of the test, the microcontroller 11 disconnects the protection switch 7.

[0048] S2. Drive the main transducer 2 to emit a pulse signal. Based on the electrical response signal of the auxiliary transducer 3 installed at the preset safe liquid level, determine whether the liquid level in the container has reached the preset height. If it has not reached the preset height, stop the start-up and issue a reminder signal.

[0049] When the liquid level in the container reaches the preset height, the pulse signal emitted by the main transducer 2 will be transmitted to the auxiliary transducer 3 through the metal wall and the water, respectively. Due to the difference in sound velocity, the auxiliary transducer 3 will receive two sets of signals with significantly different energies. The first set of signals is the signal transmitted through the metal wall, and the second set of signals is the superposition of the signals transmitted through the metal wall path and the water path. When the liquid level has not reached the preset height, the change in signal energy received by the auxiliary transducer 3 is not obvious.

[0050] The microcontroller 11 controls the drive module 4 to drive the main transducer 2 to continuously emit 3 to 5 acoustic pulses (also with a detection power below the cavitation threshold). Each acoustic pulse contains 20 to 80 carrier cycles of typical resonant frequencies (e.g., 40 kHz), the pulse width should exceed the arrival time of the water path signal by 2 to 5 ms, and the interval between pulses should exceed the arrival time of the water path signal by 2 to 5 ms.

[0051] The microcontroller 11 collects the signals received by the auxiliary transducer 3 from the signal conditioning module 6 according to the preset first sampling window and second sampling window. The sampling rate of the microcontroller 11 is not less than 2MHz. The first sampling window is set before the water path signal arrives and the second sampling window is set after the water path signal arrives.

[0052] In one implementation, orthogonal demodulation is used to acquire the energy of the two sets of signals (acquiring the first signal energy corresponding to the first sampling window and the second signal energy corresponding to the second sampling window). The ratio of the first signal energy to the second signal energy is compared with a pre-calibrated energy ratio threshold when the liquid level is exactly reached. If the current ratio is less than the energy ratio threshold, it is determined that the liquid level has reached the preset height.

[0053] In another implementation, the amplitudes of the two sets of signals are acquired using orthogonal demodulation (acquiring the amplitude of the first signal corresponding to the first sampling window and the amplitude of the second signal corresponding to the second sampling window). The absolute value of the difference between the amplitudes of the first and second signals is calculated, and the absolute value is compared with a pre-calibrated amplitude difference threshold when the liquid level reaches the target. If the current absolute value is greater than the amplitude difference threshold, it is determined that the liquid level has reached the preset height.

[0054] If the liquid level in the container is determined to be below the preset height, the microcontroller 11 will issue a reminder signal (such as a voice reminder, sound reminder, LED light reminder, etc.) to remind the user to continue adding water and terminate the execution of subsequent steps without starting the cleaning process; if the liquid level in the container is determined to be above the preset height, the subsequent steps will continue to be executed.

[0055] The energy ratio threshold and amplitude difference threshold are calibrated at the factory stage. When the liquid level meets the standard, the main transducer 2 is driven to emit acoustic pulses with the same parameters as above. The signals are collected according to the first sampling window and the second sampling window respectively. The energy ratio and the absolute value of the amplitude difference are used for calibration, and the calibration results are stored in the main control module 1.

[0056] During this step of the test, the microcontroller 11 conducts the protection switch 7.

[0057] S3. Drive the main transducer 2 to transmit a pulse sequence signal, obtain the electrical response signal envelope of the auxiliary transducer 3 for each pulse, and determine whether there is a moving object in the liquid based on the variance of the envelope sequence; if there is, stop the start and issue a warning signal.

[0058] When the liquid in the cleaning machine container contains only stationary objects (such as items to be cleaned that have sunk to the bottom), the relatively stable ultrasonic wave emission creates a standing wave field mode that remains essentially constant. The response envelope value of the secondary transducer 3 remains relatively stable across multiple pulse samplings, with variance close to the baseline noise level. However, when moving objects are present in the liquid (such as a user's finger moving in the water), the moving objects disturb the standing wave field mode, causing fluctuations in the path and intensity of the acoustic signal reaching the secondary transducer 3. This results in significant dispersion in the envelope values ​​obtained from each pulse sampling, and a marked increase in variance.

[0059] The microcontroller 11 controls the drive module 4 to drive the main transducer 2 to continuously emit a sequence of acoustic pulses (also at a power below the cavitation threshold). The pulse sequence includes 40 to 60 pulses, each pulse contains 20 to 80 carrier cycles (e.g., 40 kHz), and the interval between adjacent pulses is 10 ms.

[0060] For each pulse in the pulse sequence, after a preset delay following pulse transmission, the microcontroller 11 acquires the conditioned signal output by the signal conditioning module 6 and extracts the response envelope peak value of the corresponding auxiliary transducer 3. This yields a sequence of envelope values ​​arranged in time sequence. Subsequently, the overall variance of all pulse envelope values ​​is calculated based on the acquired envelope peak values. This overall variance is compared with a pre-calibrated variance threshold when the liquid is essentially still. If the current overall variance is greater than the variance threshold, it is determined that there is a moving object in the liquid.

[0061] If a moving object is detected in the liquid, the microcontroller 11 sends an alert signal (such as a voice alert, sound alert, LED light alert, etc.) to remind the user and terminates the execution of subsequent steps without initiating the cleaning process; if no moving object is detected in the liquid, the subsequent steps continue to be executed.

[0062] The variance threshold is calibrated at the factory stage. When the liquid is basically still, the main transducer 2 is driven to emit a sequence of acoustic pulses with the same parameters as above. Based on the response envelope peak value of the auxiliary transducer 3, the overall variance of all obtained pulse envelope values ​​is used for calibration, and the calibration result is stored in the main control module 1.

[0063] During this step of the test, the microcontroller 11 conducts the protection switch 7.

[0064] S4. Cut off the signal transmission line of the auxiliary transducer 3 and drive the main transducer 2 to start cleaning.

[0065] After all S1-S3 tests pass, the microcontroller 11 cuts off the signal transmission line of the auxiliary transducer 3 through the protection switch 7, and then drives the main transducer 2 to start cleaning with preset parameters (preset power and working time).

[0066] 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. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A control method for an ultrasonic cleaner with a safety coordination mechanism, characterized in that, include: The main transducer is driven with power below the cavitation threshold. The presence of liquid in the cleaning machine container is determined based on the obtained electrical parameters of the main transducer. If no liquid is present, the cleaning process is stopped and a warning signal is issued. The main transducer is driven to emit a pulse signal. The electrical response signal of the auxiliary transducer installed at the preset safe liquid level height is used to determine whether the liquid level in the container has reached the preset height. If it has not reached the preset height, the cleaning is prevented from starting and a reminder signal is issued. The main transducer is driven to emit a pulse sequence signal, and the electrical response signal envelope of the auxiliary transducer to each pulse is obtained. The variance of the envelope sequence is used to determine whether there is a moving object in the liquid. If there is, the cleaning is prevented from starting and an alarm signal is issued. Disconnect the signal transmission line of the auxiliary transducer and drive the main transducer to start cleaning.

2. The ultrasonic cleaning machine control method with a safety coordination mechanism according to claim 1, characterized in that, Methods for determining whether there is liquid inside the cleaning machine container based on the obtained electrical parameters of the main transducer include: Obtain the voltage sampling sequence of the voltage across the sampling resistor connected in series with the main transducer; The voltage sampling sequence is converted into a current sampling sequence based on the resistance value of the sampling resistor; Obtain the root mean square value of the current sampling sequence; The equivalent admittance amplitude is obtained by dividing the root mean square value by the drive voltage value of the main transducer; If the current equivalent admittance amplitude is less than the pre-calibrated anhydrous admittance threshold for anhydrous state, then it is determined that there is liquid in the container; otherwise, it is determined that there is no liquid in the container.

3. The ultrasonic cleaning machine control method with a safety coordination mechanism according to claim 1, characterized in that, Methods for determining the presence of liquid in the cleaning machine container based on the obtained electrical parameters of the main transducer include: Obtain the sequence of digital output values ​​corresponding to the voltage across the sampling resistor connected in series with the main transducer; Obtain the root mean square value of the sequence of digital output values; If the root mean square value is less than the pre-defined waterless digital threshold, then it is determined that there is liquid in the container; otherwise, it is determined that there is no liquid in the container.

4. The ultrasonic cleaning machine control method with a safety coordination mechanism according to claim 1, characterized in that, Methods for determining whether the liquid level in the container has reached a preset height based on the electrical response signal of the auxiliary transducer include: Two sets of signals are obtained by collecting the electrical response signal of the auxiliary transducer according to the sampling window of two preset time intervals; The energy of the two sets of signals is obtained separately using orthogonal demodulation. Obtain the ratio of the energy of the previous signal group to the energy of the next signal group; If the energy ratio is less than the pre-calibrated energy ratio threshold when the liquid level just reaches the target, the liquid level is determined to have reached the preset height; otherwise, the liquid level is determined not to have reached the preset height.

5. The ultrasonic cleaning machine control method with a safety coordination mechanism according to claim 1, characterized in that, Methods for determining whether the liquid level in the container has reached a preset height based on the electrical response signal of the auxiliary transducer include: Two sets of signals are obtained by collecting the electrical response signal of the auxiliary transducer according to the sampling window of two preset time intervals; The amplitudes of the two sets of signals are obtained separately using orthogonal demodulation. Obtain the absolute value of the amplitude difference between the two sets of signals; If the absolute value is greater than the amplitude difference threshold when the liquid level just reaches the target, the liquid level is determined to have reached the preset height; otherwise, the liquid level is determined not to have reached the preset height.

6. The ultrasonic cleaning machine control method with a safety coordination mechanism according to claim 1, characterized in that, Methods for determining the presence of moving objects within a liquid based on the variance of the envelope sequence include: Obtain the overall variance of the envelope sequence; If the overall variance is greater than the pre-defined variance threshold when the liquid is essentially still, then it is determined that there is a moving object in the liquid; otherwise, it is determined that there is no moving object in the liquid.

7. A control system for an ultrasonic cleaner with a safety coordination mechanism, characterized in that, It includes a microcontroller, a main transducer, a secondary transducer, a drive module, a current sampling module, and a signal conditioning module; The main transducer is fitted to the outer wall of the bottom of the cleaning machine container, and the auxiliary transducer is installed on the outer wall of the side of the cleaning machine container. The installation height of the auxiliary transducer corresponds to the preset safe liquid level height. The drive module is electrically connected between the microcontroller and the main transducer, and is used to drive the main transducer to work according to the PWM signal of the microcontroller; The current sampling module is electrically connected between the microcontroller and the main transducer, and includes a sampling resistor connected in series with the main transducer. The current sampling module is used to obtain the digital value corresponding to the voltage across the sampling resistor and send it to the microcontroller. The signal conditioning module is electrically connected between the microcontroller and the auxiliary transducer, and is used to condition the electrical response signal of the auxiliary transducer and send it to the microcontroller.

8. The ultrasonic cleaning machine control system with a safety coordination mechanism according to claim 7, characterized in that, The signal conditioning module includes a limiting unit, a bandpass filter unit, and an amplification unit connected in sequence. The limiting unit is electrically connected to the auxiliary transducer and is used to limit the voltage of the electrical response signal of the auxiliary transducer; the bandpass filter unit is used to filter out noise components other than the typical resonant frequency of the main transducer; the amplification unit is used to amplify the signal amplitude and output it to the microcontroller.

9. The ultrasonic cleaning machine control system with a safety coordination mechanism according to claim 7, characterized in that, It also includes a protection switch; the protection switch is connected in series between the auxiliary transducer and the signal conditioning module, and is controlled by the microcontroller.

10. The ultrasonic cleaning machine control system with a safety coordination mechanism according to claim 7, characterized in that, It also includes a power module, which comprises a charge / discharge management module and a voltage regulation module; The charge and discharge management module is used to control and protect the charging and discharging of the built-in lithium battery. The input terminal of the voltage regulation module is electrically connected to the output terminal of the charge / discharge management module, and is used to provide a driving voltage for the main transducer. The driving voltage value is controlled by the microcontroller.

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