Liquid level detection method and device, cleaning equipment and machine readable medium

Abstract

The invention provides a liquid level detection method and device, cleaning equipment and a machine readable medium, and belongs to the field of liquid level detection. The liquid level detection method comprises the following steps: starting timing in response to detecting a sensor output value meeting a high liquid level judgment condition, wherein the sensor output value is used for representing a liquid level state; if it is detected that the sensor output value larger than a first threshold value is suddenly changed in the timing process, and / or it is detected that the sensor output value is continuously changed for a preset number of times, timing is reset; and in response to the situation that the output value of the sensor continuously meets the high liquid level judgment condition within the preset duration, determining that the liquid level state is a high liquid level. According to the liquid level detection method and device, the cleaning equipment and the machine readable medium, through a timing confirmation and dynamic zero clearing judgment mechanism, the false alarm probability under the non-real high liquid level condition can be reduced, the liquid level is more accurate and stable, the user experience is improved, and meanwhile the adaptability to the complex dirty liquid environment can be enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of liquid level detection, and particularly relates to a liquid level detection method, device, cleaning equipment and machine readable medium. BACKGROUND

[0002] When a traditional scrubber is cleaning the ground, the sewage generated during the cleaning process is usually collected into a sewage tank. In order to avoid the sewage tank from overflowing due to reaching or exceeding the upper limit of the capacity during use, a high liquid level detection function of the sewage tank is usually configured to output a prompt when the sewage reaches a predetermined height. SUMMARY

[0003] The existing high liquid level detection scheme mainly includes an infrared photoelectric sensor and an electrode type liquid level sensor scheme. The infrared photoelectric sensor generally emits a light beam and receives a reflected / refracted signal, and uses the difference in optical characteristics such as refractive index and light transmittance between air and liquid to determine whether the liquid surface reaches the detection position. The electrode type liquid level sensor usually sets two electrodes and detects the electrical conductivity state between the electrodes. When the electrodes are connected by the conductive liquid to form a conduction, a trigger signal of the liquid level reaching is output.

[0004] However, the existing high liquid level detection scheme of the sewage tank of the scrubber has problems such as high false positive rate and unstable output, and it is difficult to meet the requirements of high liquid level detection accuracy in complex household stain scenarios.

[0005] The purpose of the present disclosure is to provide a liquid level detection method, device, cleaning equipment and machine readable medium, which can improve the accuracy and universality of liquid level detection.

[0006] To achieve the above purpose, the technical scheme provided by the present disclosure is as follows:

[0007] In a first aspect, the present disclosure provides a liquid level detection method, comprising:

[0008] In response to detecting a sensor output value satisfying a high liquid level determination condition, start timing. The sensor output value is used to represent the liquid level state. If a sensor output value greater than a first threshold value is detected during timing, and / or a predetermined number of consecutive changes of the sensor output value are detected, the timing is cleared. In response to the sensor output value continuously satisfying the high liquid level determination condition within a predetermined time, it is determined that the liquid level state is a high liquid level. By starting timing after detecting a sensor output value satisfying a high liquid level determination condition, and introducing a mutation and trend detection mechanism during timing, a high liquid level is only determined when the sensor output value continuously satisfies the high liquid level determination condition within a predetermined time, thereby suppressing false positives caused by transient interference such as splashing, foaming and adhesion, and improving the accuracy of high liquid level determination.

[0009] In one or more embodiments, when the sensor output value and the second threshold satisfy a preset determination relationship, the liquid level is determined to be high; otherwise, the liquid level is determined to be low. By unifying and abstracting the determination of high and low liquid levels into a preset determination relationship between the sensor output value and the second threshold, standardized discrimination of liquid level status is achieved.

[0010] In one or more embodiments, the sensor output value is a voltage value V_real, and the second threshold is a threshold voltage V_threshold; when V_real < V_threshold, the liquid level is determined to be high; when V_real ≥ V_threshold, the liquid level is determined to be low. By using the relationship between the voltage value and the threshold voltage as the criterion for high and low liquid levels, the liquid level status is distinguished by utilizing the electrical mechanism of voltage drop caused by electrode conduction.

[0011] In one or more embodiments, detecting a sudden change in sensor output value greater than a first threshold includes: periodically monitoring the difference between the sensor output value and a reference value during timing; when the difference exceeds the first threshold, determining that a sudden change in sensor output value has occurred, and updating the reference value to the current sensor output value. By periodically comparing the difference between the sensor output value and the reference value during timing to identify sudden changes, and updating the reference value after a sudden change, short-term, drastic fluctuations caused by splashing, foam bursting, or dirt passing by can be captured, enhancing anti-interference performance and reducing the probability of false triggering.

[0012] In one or more embodiments, the sensor output value is a voltage value V_real, the reference value is a reference voltage value V_compare, and the first threshold is ΔV. When |V_compare-V_real| > ΔV, it is determined that a sudden change has occurred in the sensor output value, and V_compare is updated to the current V_real. By specifying the change determination as a comparison between |V_compare-V_real| and ΔV, the voltage quantization criterion for change detection is further clarified, making change identification more feasible and adjustable in engineering.

[0013] In one or more embodiments, detecting the trend of change in the sensor output value over a predetermined time period to represent a decrease in liquid level includes: during timing, acquiring at least N sensor output value sampling points; when the number of consecutive changes in the direction representing a decrease in liquid level among the N sampling points is not less than M, determining that the trend represents a decrease in liquid level, where N≥3 and M≥2. By judging the continuous directional changes of at least N sampling points within a predetermined time period, and determining that the trend represents a decrease in liquid level when the number of consecutive changes is not less than M, the method suppresses slow-change false triggers caused by the dilution of the attached liquid film and the drop in liquid level, thereby improving the accuracy of judgment under complex sewage conditions.

[0014] In one or more embodiments, in response to detecting the relationship between the sensor output value and the second threshold, if the low liquid level determination condition is continuously met, the detection process is reset, and the system waits for the next timing to start. By actively resetting the detection process, it is possible to exit from the previous high liquid level determination process and return to the initial monitoring state, ensuring that the next high liquid level determination starts again with a new confirmation window.

[0015] In one or more embodiments, after determining that the liquid level is high, a high liquid level indication signal is output, and alarm, shutdown, and / or power limiting operations are triggered based on the high liquid level indication signal. By outputting a high liquid level indication signal and triggering alarm, shutdown, and / or power limiting operations after determining that the liquid level is high, the liquid level determination result is linked with the overall protection strategy, which can promptly suppress potential overflow risks.

[0016] Secondly, this disclosure provides a liquid level detection device, which includes a timing module, a control module, and a determination module; the timing module is used to start timing in response to detecting a sensor output value that meets the high liquid level determination condition, the sensor output value being used to characterize the liquid level state; the control module is used to reset the timing of the timing module to zero when a sudden change in the sensor output value greater than a first threshold is detected during the timing process, and / or when a continuous change in the sensor output value is detected a predetermined number of times; the determination module is used to determine the liquid level state as high liquid level in response to the sensor output value continuously meeting the high liquid level determination condition within a predetermined time period.

[0017] Thirdly, this disclosure provides a cleaning device, which includes a liquid level sensor, a wastewater tank, and the aforementioned liquid level detection device. The liquid level sensor is used to detect the liquid level in the wastewater tank and output a corresponding sensor output value to the liquid level detection device.

[0018] Fourthly, this disclosure provides a machine-readable medium carrying executable instructions, which, when executed by a processor, are used to implement the liquid level detection method as described above.

[0019] The liquid level detection method, apparatus, cleaning equipment, and machine-readable medium disclosed herein upgrade the high liquid level determination from the traditional instantaneous triggering to continuous confirmation of the stability of the sensor output value through a timing confirmation and dynamic zeroing determination mechanism. Only when the sensor output value continuously meets the high liquid level determination conditions within a predetermined period of time is it finally determined to be a high liquid level. This can effectively filter out short-term conduction or signal abnormalities caused by splashing, foam bridging, attached liquid films, and violent fluctuations in the liquid surface, reduce the probability of false alarms and false shutdowns in non-true high liquid level situations, make the liquid level more accurate and stable, improve the user experience, and enhance the adaptability to complex sewage environments that may involve highly conductive, highly viscous, or dark-colored liquids. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a liquid level detection method in one embodiment of the present disclosure;

[0022] Figure 2 This is an execution logic diagram of a liquid level detection method in one embodiment of the present disclosure;

[0023] Figure 3 This is a schematic diagram of a liquid level detection device in one embodiment of the present disclosure;

[0024] Figure 4 This is a logic diagram of a liquid level detection device in one embodiment of the present disclosure. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0026] In real-world applications of floor scrubbers, the types of stains they need to handle are complex, especially in kitchens and restaurants where wastewater often contains highly conductive, highly chromatic, or highly adhesive components, such as soy sauce, vinegar, and concentrated broth. The physicochemical properties of this type of wastewater amplify the risk of misjudgment associated with traditional high-liquid-level detection methods.

[0027] For electrode-type liquid level sensors, highly conductive liquids can conduct electricity not only when the liquid level actually reaches the detection height, but also when liquid splashes, foam accumulates, or a liquid film adheres to the electrode surface, creating a momentary or localized conductive path. This causes the sensor output to show a trigger state similar to or close to a high liquid level. Such unstable and discontinuous conduction can lead to premature generation of a high liquid level signal, resulting in frequent alerts or equipment interruptions before the wastewater tank reaches its actual full level, affecting cleaning continuity and user experience. Furthermore, changes in wastewater composition or the state of deposits on the electrode surface can cause sudden changes or fluctuations in the sensor output within a short period, making detection strategies based on single-trigger or momentary criteria more prone to false alarms.

[0028] For infrared photoelectric sensors, highly chromatic wastewater has a strong absorption and scattering effect on light signals, which may weaken the effective signal at the receiving end and cause threshold drift. This can cause the detection output to show an abnormal response similar to that at high liquid levels when the liquid level is low. At the same time, highly adhesive wastewater components are prone to forming stains or residues on the optical window, which can alter the light transmission characteristics. This can make it difficult for the sensor output to return to its initial state stably or cause long-term deviations, leading to decreased reliability and increased maintenance frequency.

[0029] Through analysis and comparison of existing solutions, the inventors discovered that traditional liquid level detection often relies on the sensor output at a single moment as a criterion, or simply on whether the output crosses a certain fixed threshold to conclude that the liquid level is high. While such criteria work correctly in the ideal situation where the liquid level rises steadily and continuously covers the detection location, they are easily interfered with in real-world conditions by splashing, foam, residue, adhesion, and fluid disturbance within the wastewater tank.

[0030] Especially when the sewage has strong conductivity, high adhesion or obvious color, the sensor output may not only show a short-term phenomenon of meeting the high liquid level condition before the liquid level has reached the full water height, but may also fluctuate and drift as the sewage adheres, dilutes, and peels off, causing problems such as premature triggering, repeated triggering or difficulty in resetting the detection results.

[0031] Based on the above analysis, the technical implementation idea of ​​this disclosure redefines the conditions for the establishment of high liquid level from the level of signal judgment logic: the high liquid level is changed from an instantaneous satisfaction criterion to a continuous satisfaction criterion, and dynamic identification and elimination of interference features are introduced in the continuous judgment process.

[0032] When the actual liquid level rises to the detection height, it typically exhibits a relatively stable signal pattern. However, false triggers caused by splashing, foam bridging, or adhering liquid films often exhibit sudden, short-lived, or trend-like changes. Therefore, this disclosure establishes a time-dimensional verification mechanism and combines it with a joint judgment of the stability and trend of sensor output. This allows the system to enter the verification process when the output initially points to a high liquid level, while simultaneously judging abnormal signals that may be caused by disturbances. This avoids misjudging transient, occasional conduction or coverage as a high liquid level state.

[0033] Furthermore, this disclosure uses the behavioral characteristics of sensor output as the criterion for judgment, rather than relying on a specific physical detection method. In other words, regardless of whether the sensor output value originates from electrical, optical, or other liquid level sensing methods, as long as it can characterize the liquid level state and present analyzable change characteristics, it can be included in this judgment framework. Through this overall strategy of continuous confirmation and dynamic judgment, this disclosure can adapt to complex sewage environments, avoiding premature triggering of high liquid levels under frequently interfering operating conditions, and providing reliable high liquid level conclusions when the liquid level has indeed reached the predetermined height and remained stable. Thus, without relying on additional complex hardware, it improves the anti-interference capability and accuracy of sewage tank liquid level detection.

[0034] Please refer to Figure 1 and Figure 2 The diagram shown is a flowchart of a liquid level detection method according to an embodiment of this disclosure. The liquid level detection method specifically includes the following steps:

[0035] S101: Timing is started in response to the detection of a sensor output value that meets the high liquid level determination condition, the sensor output value being used to characterize the liquid level state.

[0036] When the output value of the liquid level sensor just meets the high liquid level judgment condition, it does not directly give a high liquid level conclusion. Instead, it uses the sensor output value as the trigger condition to enter the high liquid level confirmation process, thereby starting the timer so that the liquid level status can be continuously and stably verified in the subsequent time window.

[0037] Specifically, during the liquid level detection process, the controller can periodically sample the liquid level sensor in real time to obtain the sensor output value that changes over time. The sensor output value can be any output form that can characterize the liquid level state, such as voltage value, current value, frequency value, duty cycle value, count value, or digital quantity after analog-to-digital conversion.

[0038] To facilitate subsequent judgment, the controller can pre-establish high liquid level judgment conditions. These conditions can manifest as the sensor output value and a threshold satisfying a preset judgment relationship. For example, the sensor output value may be less than the threshold, greater than the threshold, or fall within a threshold-defined range. The threshold can be a fixed threshold, a calibrated threshold, or a threshold dynamically updated based on the environment. When the real-time sampled sensor output value meets the high liquid level judgment conditions, the controller responds by initiating a timer, putting the timer into operation and recording the start time. This transforms liquid level detection from an instantaneous trigger judgment to a confirmation judgment based on a duration.

[0039] In one exemplary embodiment, when the sensor output value and the second threshold satisfy a preset determination relationship, the liquid level is determined to be high; otherwise, the liquid level is determined to be low.

[0040] The sensor output value is used to characterize the liquid level state. Its form is not limited to a certain physical quantity or electrical signal type. It can be the voltage or current value output by an electrode-type liquid level sensor, the frequency value or count value corresponding to the capacitance change output by a capacitive liquid level sensor, the voltage value or digital quantity corresponding to the light intensity value output by a photoelectric liquid level sensor, or a digital sampled value after analog-to-digital conversion.

[0041] The second threshold is used to establish the boundary between high and low liquid levels. This second threshold can be a fixed threshold, a calibration threshold, or an adaptive threshold. A fixed threshold is suitable for scenarios with good sensor consistency and minimal environmental changes, such as when cleaning equipment of the same model uses the same specification liquid level sensor and undergoes uniform calibration at the factory. In such cases, the second threshold can be set to a stable constant.

[0042] The calibration threshold can be determined by experimentally collecting the sensor output value distribution under different liquid level conditions and selecting a discrimination point within the distinguishable interval between high and low liquid levels. This ensures that the high liquid level triggers the detection while suppressing false detections at low liquid levels. The adaptive threshold, on the other hand, can be dynamically adjusted based on the sensor output baseline, temperature drift characteristics, or liquid medium change characteristics during equipment operation to improve robustness under complex operating conditions.

[0043] The preset judgment relationship is used to define the comparison method between the sensor output value and the second threshold. The preset judgment relationship can be a magnitude relationship, an interval inclusion relationship, or a double threshold relationship combined with hysteresis logic. By defining the preset judgment relationship, the high liquid level judgment condition can be matched with the output direction of a specific sensor. For example, if the output value of some sensors decreases after the liquid level rises and covers the detection position, the preset judgment relationship can be set to the sensor output value being less than the second threshold; while for sensors whose output value increases due to the rise in liquid level, the preset judgment relationship can be set to the sensor output value being greater than the second threshold.

[0044] Taking a capacitive liquid level sensor as an example, when liquid covers the sensing area, the capacitance increases, causing the sensor's output frequency to decrease or the output count value to change accordingly. The second threshold can then be set as either a frequency threshold or a count threshold. The preset judgment relationship is set to less than or greater than the output direction to distinguish between high and low liquid levels. Similarly, with a photoelectric liquid level sensor, when liquid reaches the detection position, it causes a change in reflected light intensity, resulting in a change in output voltage. The second threshold can be set as a threshold corresponding to the light intensity and voltage. The preset judgment relationship is also set based on the direction of output change with the liquid level.

[0045] Taking an electrode-type liquid level sensor as an example, the sensor output value can be the sensor output voltage value V_real, and the second threshold can be the threshold voltage V_threshold. When V_real < V_threshold, the liquid level is determined to be high; when V_real ≥ V_threshold, the liquid level is determined to be low.

[0046] When the sewage tank level does not reach the detection height, there is no stable conductive path between the electrodes, and V_real remains at a high level. When the liquid level rises and covers the electrode position, a conductive path is formed between the electrodes or the equivalent resistance decreases, V_real drops and falls into the high liquid level range. At this time, V_real < V_threshold, thus the liquid level is determined to be high.

[0047] In electrode-type liquid level sensors or equivalent conductive liquid detection structures, whether the liquid covers the detection position affects the conductivity or equivalent impedance between the electrodes. When the liquid level has not reached the detection height, the electrodes are mainly in an open circuit or high-resistance state, and the voltage division relationship keeps the voltage value V_real at the sensor output at a high level. When the liquid level rises and covers the detection electrodes, the conductive liquid forms a conductive path between the electrodes or significantly reduces the equivalent impedance, changing the voltage division relationship at the output. The voltage value V_real then decreases and falls into the voltage range corresponding to the high liquid level. Therefore, comparing V_real with the threshold voltage V_threshold and using "less than" as the high liquid level determination relationship can characterize the physical state of the electrodes being covered by conductive liquid at the signal level, thereby enabling rapid determination of the liquid level status.

[0048] For example, in actual use, when cleaning the kitchen floor, highly conductive stains such as soy sauce, vinegar, or thick soup may be inhaled. This can cause splashing inside the wastewater tank, momentarily wetting the electrodes and causing V_real to drop below the threshold voltage V_threshold for a short time. In this situation, the aforementioned threshold comparison rule can promptly provide a signal indicating a potential high liquid level, allowing the controller to enter the high liquid level confirmation process. When the liquid level actually reaches the electrode height and forms a continuous coverage, V_real will remain more stably below the threshold voltage V_threshold, thus providing a consistent criterion for determining the final high liquid level. Conversely, when the wastewater tank is emptied or the liquid level drops below the electrode height, the conductivity between the electrodes disappears, V_real rises again and satisfies V_real≥V_threshold, determining the liquid level as low, thereby achieving liquid level reset and cyclic detection.

[0049] The threshold voltage V_threshold can be obtained through calibration or determined by combining test data under different operating conditions to establish a criterion with engineering margin. In practice, an analog-to-digital converter circuit can be configured at the output of the level sensor to sample the analog voltage into a digital quantity and read the corresponding voltage value V_real at a preset sampling period. The threshold voltage V_threshold can be directly stored in the controller as a voltage quantity and used for comparison.

[0050] The inventors collected sensor output voltages under the same test conditions when foam, clean water, sewage, cola, dark soy sauce, milk, and orange juice covered the detection electrode. The results showed that foam was approximately 2868mV, clean water was approximately 2190mV, sewage was approximately 2045mV, cola was approximately 1820mV, dark soy sauce was approximately 933mV, milk was approximately 2050mV, and orange juice was approximately 1765mV.

[0051] Based on the above distribution characteristics, the threshold voltage V_threshold can be set to 2450mV, so that even in the case of clean water with weak conductivity and more difficult to trigger, V_real < V_threshold can still be satisfied to enter the high liquid level judgment process. At the same time, in the case of equipment shaking or gas-liquid agitation causing a large amount of foam to accumulate, the output voltage corresponding to the foam is still higher than the threshold voltage V_threshold, so it is not easy to falsely trigger the high liquid level judgment.

[0052] S102: If, during the timing process, a sudden change in the sensor output value exceeding the first threshold is detected, and / or a continuous change in the sensor output value for a predetermined number of times is detected, the timing will be reset to zero.

[0053] In step S102, within the high liquid level confirmation process that has already started timing, dynamic judgment conditions for interference signals are introduced, enabling the liquid level detection to further determine whether the state that meets the high liquid level judgment conditions is stable and continuous, thereby eliminating false high liquid level signals caused by factors such as sewage splashing, foam, and wall-mounted liquid film.

[0054] In other words, by detecting the abrupt changes and trends in the sensor output values ​​during the timing process, signal patterns that are more consistent with transient interference or unstable coverage can be identified, and the high liquid level confirmation process can be terminated by resetting the timing, so that subsequent high liquid level determinations are based on stable coverage rather than short-term triggers.

[0055] By employing mutation detection and trend detection to trigger zeroing, complementary interference suppression effects can be achieved. Mutation detection targets short-term, severe disturbances, quickly eliminating transient anomalies caused by splashing, foam bursting, and debris passing by. The mutation detection mechanism can cover typical operating conditions such as violent turbulence of liquid inside the wastewater tank, droplet splashing hitting the electrode, instantaneous foam bridging, or debris passing by the electrode. These conditions often cause significant jumps in sensor output within a short period, while a stable liquid surface covering the detection location typically presents a more continuous and gradually changing output pattern.

[0056] Trend detection targets directional changes and can eliminate false high liquid levels caused by the dilution or detachment of the attached liquid film. Within the high liquid level confirmation window, if the sensor output value does not maintain a stable high liquid level characteristic but instead shows a trend change consistent with the liquid level decline, the current high liquid level status is considered unreliable, and the high liquid level confirmation should be rejected and the timer reset.

[0057] The high liquid level confirmation process is terminated by resetting the timer, ensuring that the final determination of the high liquid level is based on the fact that the sensor output value continuously meets the high liquid level determination conditions within a predetermined time and does not exhibit interference characteristics. This reduces the false alarm rate and unnecessary downtime or alarms. Furthermore, since this mechanism is mainly implemented by control logic, it can be upgraded on existing products without adding additional complex hardware structures.

[0058] In one exemplary embodiment, detecting a sudden change in sensor output value greater than a first threshold includes: periodically monitoring the difference between the sensor output value and a reference value during timing; when the difference is greater than the first threshold, determining that a sudden change in sensor output value has occurred, and updating the reference value to the current sensor output value.

[0059] During the timing process, the sensor output value is acquired periodically, and the difference between the current sensor output value and the reference value is compared. When the difference is greater than the first threshold, the change is identified as an abrupt change, thus providing a trigger condition for subsequent timing reset or rejection judgment. At the same time, by updating the reference value to the current sensor output value, abnormal jumps can be captured in a timely manner, while avoiding unnecessary misjudgments of normal gradual trends due to the long-term lack of reference updates.

[0060] Specifically, after the timing process begins, the controller can sample the liquid level sensor in real time according to a preset sampling period, obtaining a series of sensor output values ​​that change over time. To achieve abrupt change detection, the controller determines the sensor output value obtained from the current sampling in each period and reads or maintains a reference value. The reference value can be assigned from the sensor output value at the previous sampling moment before the timing starts, or it can be initialized from the current sampled value when the timing starts, or it can be obtained by averaging or median filtering multiple historical sampled values.

[0061] Subsequently, the difference between the current sensor output value and the reference value is calculated and compared with a first threshold. When the difference exceeds the first threshold, a sudden change in the sensor output value is determined, and the reference value is updated to the current sensor output value, so that the difference judgment in the next cycle is based on the new reference. This update mechanism allows the reference value to be dynamically adjusted with the overall change of the sensor output value, avoiding the situation where the difference remains too large due to a fixed reference value. Thus, it can maintain reasonable sensitivity to sudden changes even when the signal is changing slowly or has a certain degree of drift.

[0062] The monitoring cycle for mutation detection can be set according to the rate of liquid level change, the intensity of fluid disturbance inside the sewage tank, and the computing power of the controller. For example, a monitoring cycle of 50~150ms can cover most typical time scales of splashing and foam bursting without significantly increasing the computational burden, so that mutation detection can respond to transient disturbances in a timely manner and avoid excessive amplification of high-frequency noise.

[0063] Taking the voltage output of an electrode-type liquid level sensor as an example, the sensor output value can be represented as the voltage value V_real, the reference value can be represented as the reference voltage value V_compare, and the first threshold can be represented as the voltage difference threshold ΔV. During the timing process, the controller samples the current voltage value V_real in each monitoring cycle and calculates |V_compare-V_real|. When |V_compare-V_real| > ΔV, it can be determined that a sudden change in the voltage value has occurred, and thus a sudden change in the sensor output value can be identified.

[0064] Since electrode-type liquid level sensors typically exhibit a relatively stable voltage output when the liquid surface stably covers the detection position, while unstable contact or transient conduction often causes the voltage output to fluctuate significantly in a short period of time, using the absolute difference |V_compare-V_real| as a quantitative indicator of the magnitude of the sudden change can capture abnormal changes caused by interference with low computational complexity.

[0065] In one implementation, the output of the level sensor can be periodically sampled using an analog-to-digital converter circuit to obtain the voltage value V_real corresponding to each sampling period, and a reference voltage value V_compare can be maintained in memory. At the start of timing, V_compare is set to the sensor output voltage value V_real from the moment preceding the start of timing. This ensures that the reference voltage value V_compare remains continuous with the signal state at the start of timing, thus avoiding false triggering due to sudden changes in the reference value.

[0066] Subsequently, within each sampling period of the timing window, the difference between the current voltage value V_real and the reference voltage value V_compare is calculated, and the absolute value is taken. When |V_compare-V_real| exceeds the first threshold ΔV, it is determined that the voltage value V_real has abruptly changed relative to the reference voltage value V_compare. The first threshold ΔV can be set according to the sensor noise level, sampling resolution, and the intensity of disturbances inside the sewage tank. For example, under the premise that the voltage change amplitude caused by circuit noise and normal liquid level fluctuations is usually small, setting ΔV to 30~60mV can reduce the probability of misjudging normal small fluctuations while ensuring sensitivity to severe disturbances such as splashing.

[0067] After a sudden change in the sensor output value is detected, the timer is reset to zero, and the reference voltage value V_compare is updated to the current voltage value V_real. This allows the sudden change judgment in the next sampling period to use the new state as a reference point, so that the reference voltage value V_compare can be adaptively adjusted as the signal changes, avoiding continuous misjudgments or oversensitivity caused by reference lag.

[0068] In one exemplary embodiment, detecting the trend of change of sensor output value within a predetermined time to represent a drop in liquid level includes: during the timing process, acquiring at least N sensor output value sampling points; when the number of consecutive changes of the N sampling points in the direction representing a drop in liquid level is not less than M, determining that the trend of change represents a drop in liquid level, where N≥3 and M≥2.

[0069] Within the high liquid level confirmation timing window, the directionality of signal changes is determined. By identifying the continuous change trend of the sensor output value that is consistent with the liquid level drop within a short period of time, false high liquid level signals caused by unstable factors such as adhesion, dilution, detachment, or recovery from liquid surface fluctuations are eliminated. This avoids misjudging a high liquid level when the liquid level has not actually stabilized at the detection height.

[0070] When the actual liquid level stably covers the detection position, the sensor output value usually shows relative stability or fluctuates slightly around a certain level. Conversely, when the sensor output value changes continuously in the direction representing the drop in liquid level within the confirmation window, it usually indicates that the conduction path is weakening, the coverage is decreasing, or the liquid level is falling back. This is inconsistent with the stable coverage state formed by actual full water. Therefore, the high liquid level confirmation process can be terminated by resetting the timer.

[0071] In one implementation, a short-term historical data queue can be maintained during the timing process to record sensor output value sampling points within a predetermined time period. The timing duration (e.g., 500ms) can be set according to the typical timescale of liquid disturbance in the wastewater tank and the length of the high liquid level confirmation window, so that it can cover the gradual process of the attached liquid film being washed away and diluted, but is not too long to cause a slow trend judgment response.

[0072] The controller continuously acquires at least N sensor output value sampling points within the timing period (e.g., sampling once every 100ms), where N is not less than 3 to ensure the most basic continuity of trend judgment; at the same time, the controller can predefine the direction representing the drop in liquid level. For example, when the drop in liquid level causes the sensor output value to increase, the increase in output value can be defined as the direction representing the drop in liquid level; when the drop in liquid level causes the sensor output value to decrease, the decrease in output value can be defined as the direction representing the drop in liquid level.

[0073] Based on the definition of the direction of liquid level descent, the controller performs a sequential comparison of sampling points within the timing period. When the number of consecutive changes of the sampling point in the direction representing liquid level descent is not less than M, the controller determines that the trend of the sensor output value within the timing period represents liquid level descent and triggers the timing to be reset. The number of consecutive changes M is used to suppress misjudgments caused by random fluctuations. M not less than 2 ensures that there are at least two consecutive directional changes, thereby distinguishing random noise or single disturbances from a process of change with continuous directionality.

[0074] Taking the sensor output value as a voltage value V_real as an example, when liquid covers the electrode, causing the voltage value V_real to decrease, and when the coverage weakens or the conduction path disappears, causing the voltage value V_real to rise again, the continuous rise of the voltage value V_real can be defined as characterizing the drop in liquid level.

[0075] Within the timing period, for example, if the timing period is set to 500ms, the controller acquires multiple voltage values ​​V_real at a fixed sampling period (100ms) and compares adjacent sampling points. When the relationship V_real(k)>V_real(k−1) is satisfied for no less than 3 consecutive times, it is determined that the voltage value V_real shows a continuous upward trend, thereby determining that the trend indicates a drop in liquid level and resetting the timing to zero.

[0076] This trend detection mechanism effectively covers typical false triggering processes under conditions of highly conductive and highly adhesive liquids. For example, when cleaning stains containing dark soy sauce, the surface of the level sensor electrode may be rapidly wetted by the highly conductive liquid, causing the voltage value V_real to briefly meet the high liquid level judgment condition and start timing. However, as clean water continuously enters the wastewater tank and dilutes and washes away the liquid film near the electrode, the equivalent conduction between the electrodes gradually weakens, and the voltage value V_real shows a gradual upward trend. Even within the confirmation window, it may occasionally fall below the threshold voltage V_threshold, but the overall trend reflects that the coverage is fading. At this time, the trend detection mechanism can promptly identify this upward process and avoid misjudging the adhesion conduction as a stable high liquid level by resetting the timing.

[0077] For example, if the liquid level inside the sewage tank drops briefly after hitting the electrode due to changes in the equipment's posture, the voltage value V_real may rise rapidly after contact. The aforementioned trend detection mechanism can also identify this rise as a liquid level drop, thereby improving the adaptability to posture disturbances.

[0078] S103: In response to the sensor output value continuously meeting the high liquid level determination condition within a predetermined time period, the liquid level state is determined to be high.

[0079] In terms of implementation, step S103 can employ either a counting-based or a timing-based continuous determination logic. In the timing-based logic, the controller maintains a timer and records the timing start point. When the timer accumulates to a predetermined duration, the status of the sensor output value within the timing window is confirmed. In the counting-based logic, the controller acquires the sensor output value at a fixed sampling period, maintains a count of sampling points that continuously meet the high liquid level determination condition, and determines the liquid level status as high when the count reaches a counting threshold corresponding to a predetermined duration.

[0080] The condition of continuously meeting the high liquid level judgment condition within the predetermined time period can be understood as meeting the high liquid level judgment condition throughout the entire predetermined time period, or as the cumulative time of meeting the high liquid level judgment condition within the predetermined time period reaching a preset proportion, thereby compatibility with the extremely short-term jitter caused by sensor quantization noise.

[0081] Furthermore, steps S102 and S103 can be executed in parallel in the determination process. That is, within the same timing window, the controller can continuously determine whether the sensor output value meets the high liquid level determination condition to advance the confirmation process of step S103, and at the same time execute sudden change detection and change trend detection to advance the interference rejection process of step S102.

[0082] When step S102 triggers the timer reset, the continuity confirmation corresponding to step S103 is immediately interrupted and monitoring resumes. When step S102 does not trigger the timer reset and step S103 meets the continuity condition for the predetermined duration, the liquid level status is finally determined to be high. Through this parallel determination method, the system can improve its anti-interference capability while maintaining response speed and avoid missed or false judgments caused by the order of determination.

[0083] Taking an electrode-type liquid level sensor as an example, the sensor output value is a voltage value V_real. The high liquid level determination condition can be set to V_real being less than the threshold voltage V_threshold. When the liquid level actually rises and covers the detection electrode, the conductivity between the electrodes increases, and the voltage value V_real will be stably maintained below the threshold voltage V_threshold. As the timer accumulates to a predetermined duration (e.g., 500ms), it is confirmed that the voltage value V_real continuously meets the high liquid level determination condition within the predetermined duration, thereby determining the liquid level state as high and outputting a high liquid level indication signal.

[0084] Conversely, when the cleaning equipment sucks in wastewater containing soy sauce or thick soup, splashing or foam accumulation may occur in the wastewater tank, causing the voltage value V_real to briefly fall below the threshold voltage V_threshold at a certain moment. However, due to the sliding of splashing droplets, foam rupture, or dilution and rinsing of the attached liquid film, the voltage value V_real often cannot maintain a position below the threshold voltage V_threshold for a predetermined period of time, and will not meet the persistence threshold, thus avoiding the misjudgment of instantaneous conduction as a true high liquid level.

[0085] In one exemplary embodiment, after determining that the liquid level is high, a high liquid level indication signal can be output, and alarm, shutdown and / or power limiting operations can be triggered based on the high liquid level indication signal.

[0086] The high liquid level indication signal can be understood as a control command generated by the controller after determining that the liquid level is high. This control command can be a software status bit inside the controller, or a level signal, bus message, or event notification output to the external circuit, used to drive subsequent alarm, shutdown, or power limiting actions.

[0087] Taking the wastewater tank of cleaning equipment as an example, the high liquid level indicator signal can be output by the controller to the human-machine interface module, causing the module to display a "wastewater tank is full" message on the screen, illuminate the corresponding indicator light, or output an alarm sound via a buzzer or speaker, thus prompting the user to empty the wastewater tank in time. The alarm can take the form of audible and visual alarms, or screen text, icons, or vibration prompts, depending on the equipment's form and interaction design. Through the alarm, users can intuitively understand the current liquid level status and take timely action to avoid wastewater overflow due to continued cleaning.

[0088] In addition to alarms, the high liquid level indicator signal can also trigger a shutdown operation, causing the cleaning equipment to stop suction or stop the delivery of the gas-liquid mixture to the wastewater tank, limiting the continued entry of wastewater into the tank. The shutdown operation can manifest as shutting down the suction motor, turning off the liquid recovery pump, or disabling the suction-related drive mechanisms, depending on the equipment architecture. Shutdown can be complete or partial; for example, stopping suction but allowing the roller brush to continue rotating at a low speed so the user can complete the final step of removing the cleaning head from the ground.

[0089] Power limiting operation provides a protection strategy between continued operation and complete shutdown. When a high liquid level is detected, it does not immediately cut off all functions. Instead, it limits the output capacity of the suction motor or related actuators to a preset upper limit, reduces the rate of continued wastewater recycling or reduces the conveying intensity of the gas-liquid mixture, allowing the equipment to enter standby mode in a gentler manner.

[0090] In one exemplary embodiment, in response to detecting the relationship between the sensor output value and the second threshold, if the low liquid level determination condition is continuously met, the detection process is reset and the system waits for the next timing start.

[0091] When the sensor output value is detected to meet the low liquid level determination condition with the second threshold, the system does not necessarily reset immediately. Instead, it further determines whether the low liquid level determination condition is continuously met within a predetermined duration or within several consecutive sampling periods, thus forming the basis for continuous satisfaction. If continuous satisfaction is confirmed, the reset detection process is executed. The reset action may include clearing the timer, updating the reference value to the current sensor output value, clearing the historical sampling queue, clearing the transient flag of the high liquid level indicator, and switching the state machine to a monitoring state waiting for the next timer to start.

[0092] Taking an electrode-type liquid level sensor as an example, the sensor output value is the voltage value V_real, the second threshold is the threshold voltage V_threshold, and the low liquid level determination condition is V_real ≥ V_threshold. When the sewage is emptied by the user or the liquid level drops significantly, the conduction between the electrodes disappears, and the voltage value V_real recovers to a stable level much higher than the threshold voltage V_threshold. If the relationship between V_real and the threshold voltage V_threshold continuously satisfies the low liquid level determination condition, that is, V_real is continuously greater than or equal to the threshold voltage V_threshold, the reset detection process can be executed accordingly, clearing the timer and historical sampling queue and returning to the waiting state.

[0093] Please refer to Figure 3 As shown, based on the same inventive concept as the aforementioned liquid level detection method, this disclosure provides a liquid level detection device 300, which includes a timing module 301, a control module 302, and a determination module 303.

[0094] The timing module 301 is used to start timing in response to detecting a sensor output value that meets the high liquid level determination condition, wherein the sensor output value is used to characterize the liquid level state; the control module 302 is used to reset the timing of the timing module 301 when a sudden change in the sensor output value greater than a first threshold is detected during the timing process, and / or when a continuous change in the sensor output value for a predetermined number of times is detected; the determination module 303 is used to determine the liquid level state as high liquid level in response to the sensor output value continuously meeting the high liquid level determination condition within a predetermined time period.

[0095] The timing module 301 can be implemented using a hardware timer, a software timer, or a counter based on the sampling period. It can record the timing start point and accumulate the timing value, while providing a unified time reference for the control module 302 and the determination module 303.

[0096] The control module 302 may include a sampling unit, a difference calculation unit, and a trend judgment unit. The sampling unit is used to acquire sensor output value sampling points during the timing process. The difference calculation unit is used to compare the difference between the current sampling point and the reference value to identify sudden changes. The trend judgment unit is used to perform directional judgment on the sampling sequence of a predetermined number of times to identify continuous changing trends. The control module 302 can reset the timing by resetting the timing module 301 or setting the accumulated timing value to zero.

[0097] The determination logic of module 303 can be implemented by triggering a timed threshold or by counting sampling points that continuously meet the conditions. During the high liquid level confirmation process, module 303 can continuously determine whether the sensor output value continues to meet the high liquid level determination conditions and output the high liquid level determination result.

[0098] Please refer to Figure 4 As shown, taking an electrode-type liquid level sensor as an example, the liquid level detection process uses the sensor output value V_real as the characterization quantity of the liquid level state, and introduces a threshold V_threshold (second threshold), a reference value V_compare, a counter CNT, and a timing variable time to achieve stability determination.

[0099] When the liquid level detection device is powered on or enters monitoring mode, it first initializes V_compare to the currently sampled V_real and sets CNT to 0. Then, it continuously samples the liquid level sensor to update V_real. When V_real does not satisfy V_real < V_threshold, it is considered that the liquid level does not cover the detection position or has not reached the trigger range. The process remains in the monitoring loop, and V_compare is refreshed with the current V_real and CNT is kept at 0 when necessary to ensure that subsequent judgments are based on the latest operating conditions.

[0100] When V_real is detected to satisfy V_real < V_threshold, a potential high liquid level trigger signal is considered to have occurred, and the process enters the high liquid level confirmation phase, setting time to 0. Time is used as the cumulative duration for high liquid level confirmation. During the confirmation phase, the benchmark update logic is first executed based on the periodic condition of time. When time satisfies time%100=0 (i.e., time is an integer multiple of 100ms), V_compare is updated to the current V_real, making V_compare a comparison benchmark that is updated over time.

[0101] When time does not satisfy time%100=0, V_compare remains unchanged and the subsequent judgment continues. Then, the relationship between V_compare and V_real is compared. When V_compare<V_real, it is considered that V_real is changing in an upward direction relative to the benchmark, and CNT performs accumulation to record the strength of the continuous upward trend; when V_compare≥V_real, it is considered that the upward trend is not valid, and CNT is cleared to avoid the cumulative interference of historical trends on the current judgment.

[0102] After completing the trend count, |V_real - V_compare| is further calculated and compared with 50mV (first threshold). When |V_real - V_compare| does not meet the requirement of being less than 50mV, it is considered that V_real has undergone a large-scale change relative to the benchmark. This change is more likely to be caused by interference factors such as splashing, foam bridging, dirt passing by, or unstable momentary contact of the electrode. Therefore, the confirmation process is directly reset, the time is cleared to zero, and the process re-enters the confirmation starting point.

[0103] When |V_real-V_compare| is less than 50mV, it is considered that the change of V_real relative to the benchmark is within an acceptable stable fluctuation range, and trend judgment continues. When CNT is greater than 2, it is considered that V_real has risen multiple times in a row, reflecting that the conduction state is gradually weakening or the liquid level is in the process of falling back and recovering, that is, the high liquid level state is unstable. Therefore, the confirmation process is reset and time is cleared to zero.

[0104] When CNT does not satisfy CNT>2, the cumulative duration confirmation judgment is entered. The final confirmation is completed by comparing time with 600ms. When time satisfies time>600ms, it is considered that V_real is continuously in the trigger interval corresponding to V_real<V_threshold within the confirmation window and is not rejected by the mutation criterion and trend criterion. Therefore, the water full (high liquid level) judgment result is output.

[0105] If the time condition does not meet the requirement of time > 600ms, the high liquid level confirmation phase can continue to cyclically sample and repeatedly execute the baseline value update, trend detection, abrupt change detection, and cumulative duration judgment until the water full condition is met or the reset condition is triggered. Through the above execution logic, the high liquid level confirmation is based on the constraints of time persistence and signal stability, thereby effectively suppressing false alarms caused by transient conduction and unstable coverage under high conductivity and high adhesion liquid conditions.

[0106] This disclosure also provides a cleaning device, which includes a liquid level sensor, a wastewater tank, and the aforementioned liquid level detection device. The liquid level sensor is used to detect the liquid level in the wastewater tank and output a corresponding sensor output value to the liquid level detection device.

[0107] The wastewater tank is used to collect wastewater generated during the cleaning process. Structurally, the wastewater tank can be a detachable container or an integrated receiving cavity with the machine body. The inside of the wastewater tank forms a receiving space for holding wastewater. When the cleaning equipment is running, the receiving space receives the gas-liquid mixture flow from the suction channel.

[0108] The liquid level sensor is installed on or inside the sewage tank to detect the liquid level in the sewage tank and output a sensor output value that can characterize the liquid level status. The sensor output value can be an analog or digital quantity and can be transmitted to the liquid level detection device through wire connection, plug-in connection or bus communication.

[0109] The liquid level detection device receives the sensor output value from the liquid level sensor and executes high liquid level determination logic based on the sensor output value to determine the liquid level status and output a high liquid level indication signal. This signal is then linked with the cleaning equipment's alarm, shutdown, or power limiting control strategies. The liquid level detection device can be integrated into the main controller of the cleaning equipment or installed as a separate module on the circuit board and communicate with the main controller. After receiving the sensor output value, the liquid level detection device can execute the logic of the aforementioned liquid level detection method.

[0110] This disclosure also provides a machine-readable medium carrying executable instructions that, when executed by a processor, can be used to implement various operations and functions of the liquid level detection method described in the various embodiments of this specification.

[0111] The machine-readable medium in this disclosure can be a machine-readable signal medium or a machine-readable storage medium, or any combination thereof. A machine-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a machine-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a machine-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0112] In this disclosure, the machine-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying machine-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The machine-readable signal medium may also be any machine-readable medium other than a machine-readable storage medium, capable of transmitting, propagating, or transmitting a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the machine-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wireline, optical fiber, RF, etc., or any suitable combination thereof.

[0113] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, systems, or program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a program product embodied on one or more storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing program code.

[0114] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0115] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A liquid level detection method, characterized in that, include: A timing is started in response to the detection of a sensor output value that meets the high liquid level determination condition, the sensor output value being used to characterize the liquid level state; If, during the timing process, a sudden change in the sensor output value exceeding the first threshold is detected, and / or a continuous change in the sensor output value for a predetermined number of times is detected, the timing will be reset to zero. If the sensor output value continuously meets the high liquid level determination condition within a predetermined time period, the liquid level status is determined to be high.

2. The liquid level detection method according to claim 1, characterized in that, When the sensor output value and the second threshold satisfy a preset determination relationship, the liquid level is determined to be high; otherwise, the liquid level is determined to be low.

3. The liquid level detection method according to claim 2, characterized in that, The sensor output value is a voltage value V_real, and the second threshold is a threshold voltage V_threshold; When V_real < V_threshold, the liquid level is determined to be high. When V_real≥V_threshold, the liquid level is determined to be low.

4. The liquid level detection method according to claim 1, characterized in that, The detection of a sudden change in sensor output value greater than a first threshold includes: During the timing process, the difference between the sensor output value and the reference value is periodically monitored. When the difference is greater than a first threshold, it is determined that the sensor output value has changed abruptly, and the reference value is updated to the current sensor output value.

5. The liquid level detection method according to claim 4, characterized in that, The sensor output value is a voltage value V_real, the reference value is a reference voltage value V_compare, and the first threshold value is ΔV; When |V_compare-V_real|>ΔV, it is determined that the sensor output value has changed abruptly, and V_compare is updated to the current V_real.

6. The liquid level detection method according to claim 1, characterized in that, The detection of the trend of change in the sensor output value over a predetermined time period characterizes the drop in liquid level, including: During the timing process, at least N sensor output value sampling points are acquired. When the number of consecutive changes of the N sampling points in the direction representing the drop in liquid level is not less than M, the trend of change representing the drop in liquid level is determined, where N≥3 and M≥2.

7. The liquid level detection method according to claim 2, characterized in that, Also includes: In response to the detection of the relationship between the sensor output value and the second threshold, if the low liquid level determination condition is continuously met, the detection process is reset and the system waits for the next timing start.

8. The liquid level detection method according to claim 1, characterized in that, Also includes: After determining that the liquid level is high, a high liquid level indication signal is output, and alarm, shutdown and / or power limiting operations are triggered based on the high liquid level indication signal.

9. A liquid level detection device, characterized in that, include: A timing module is used to start timing in response to the detection of a sensor output value that meets the high liquid level determination condition, wherein the sensor output value is used to characterize the liquid level state; The control module is used to reset the timing module when it detects a sudden change in the sensor output value greater than a first threshold during the timing process, and / or detects a continuous change in the sensor output value a predetermined number of times. The determination module is used to determine the liquid level as high when the sensor output value continuously meets the high liquid level determination condition within a predetermined time period.

10. A cleaning device, characterized in that, The device includes a liquid level sensor, a wastewater tank, and the liquid level detection device as described in claim 9. The liquid level sensor is used to detect the liquid level in the wastewater tank and output a corresponding sensor output value to the liquid level detection device.

11. A machine-readable medium, characterized in that, The machine-readable medium carries execution instructions, which, when executed by a processor, are used to implement the liquid level detection method as described in any one of claims 1 to 8.

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