Scrubber sewage tank water level detection system and method based on liquid level sensor

Abstract

The invention relates to the technical field of liquid level detection, in particular to a scrubber sewage tank water level detection system and method based on a liquid level sensor, and the system comprises a sensing data acquisition module, a liquid level signal conversion module, a multi-source numerical value comparison module, a liquid level fluctuation recognition module and an alarm action linkage module. According to the invention, through acquisition of a sensor capacitance change sequence, elimination of abnormal fluctuation, construction of a stable reference curve, enhancement of data immunity, mapping of a liquid level section based on an average capacitance value, accurate identification of liquid level elevation is realized, synchronous comparison of liquid level state information in various communication protocols is realized, and data consistency and reliability are improved. A liquid level fluctuation boundary is accumulatively recognized through trend direction change, a change section is dynamically marked, alarm triggering is based on boundary area and state mark double verification, warning response accuracy and effectiveness are enhanced, and a high-precision and high-stability liquid level detection and early warning system is constructed.

Description

Technical Field

[0001] This invention relates to the field of liquid level detection technology, and in particular to a system and method for detecting the water level in the wastewater tank of a floor scrubber based on a liquid level sensor. Background Technology

[0002] The field of liquid level detection technology encompasses methods for measuring and monitoring the height or volume of liquid inside containers, pipes, or equipment. The core of this technology lies in sensing the position of the liquid surface using various sensing devices and converting it into a recognizable electrical signal for display, control, or alarm purposes. Liquid level detection technology systematically covers various sensing methods, including float-type liquid level sensing, capacitive liquid level measurement, ultrasonic liquid level detection, laser liquid level monitoring, and conductivity-type liquid level sensing. It is widely used in industrial automation, home appliances, environmental engineering, water systems, and other scenarios, and its development trend focuses on optimizing high precision, anti-interference capabilities, rapid response, and compact structure.

[0003] The floor scrubber wastewater tank level detection system based on a liquid level sensor refers to a detection scheme that uses a liquid level sensor with capacitive or resistive sensing functions to locate the wastewater level inside the floor scrubber's wastewater tank in real time. This patent primarily addresses the monitoring needs of the water level inside the wastewater tank, covering the acquisition of wastewater level height information through embedded liquid level sensing elements and the transmission of the sensing signals to the main control circuit for analysis. The system employs an integrated liquid level sensing structure arranged to fit flush with the wastewater tank wall, allowing the sensing unit to continuously output corresponding electrical signals as the liquid level changes. Simultaneously, by setting water level thresholds, multi-level segmented identification is achieved, thereby completing the continuous detection of the wastewater tank's water level.

[0004] Current technologies commonly use liquid level sensors to directly read single-point data and identify the liquid level through instantaneous electrical signals. However, they lack a mechanism for recording periodic trends, making it difficult to accurately distinguish between continuous and sporadic signal changes when faced with sudden data fluctuations or external disturbances. Due to the lack of analysis on signal continuity and stability, sensor output is easily affected by shaking, water wave interference, etc., leading to frequent misreadings in liquid level identification. Traditional liquid level systems typically use fixed voltage ranges to correspond to liquid level intervals, failing to adjust reference values ​​based on dynamic changes, easily resulting in liquid level error ranges. Furthermore, communication relies on a single data channel and lacks cross-protocol information comparison strategies. In cases of network latency or protocol anomalies, the consistency of transmitted data cannot be verified, and data validity cannot be guaranteed. Alarm logic often uses static settings, triggering only based on the current absolute value of the liquid level. It lacks the ability to analyze liquid level change trends and boundary expansion characteristics, and the definition of the warning area lacks extensibility and adaptability, easily leading to delayed warnings or false alarms, reducing the system's practicality and engineering deployment value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and to propose a system and method for detecting the water level in the wastewater tank of a floor scrubber based on a liquid level sensor.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a floor scrubber wastewater tank water level detection system based on a liquid level sensor includes: The sensor data acquisition module reads data from the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the capacitance change from the initial to the current cycle, compares the cycle jump trend, eliminates abnormal sudden changes, and forms a capacitance change sequence. The liquid level signal conversion module takes the continuous periodic average capacitance value based on the capacitance change sequence, extracts the output voltage segment configured by the sensor, compares the volume interval number to which the voltage belongs, and obtains the converted liquid level position. The multi-source numerical comparison module obtains the liquid level status codes synchronously transmitted by Modbus, CAN and LoRa protocols based on the converted liquid level position, and obtains a consistent liquid level numerical description result based on the timestamp alignment algorithm for communication protocol difference compensation. Based on the consistent description results of the liquid level values, the liquid level fluctuation identification module calculates the difference between the current liquid level and the previous cycle, counts the number of consecutive values ​​in the direction of the difference, identifies the upward and downward trends, marks the corresponding change area as the expansion segment, and obtains the fluctuation boundary segment. The alarm action linkage module determines whether the current liquid level has entered the warning zone based on the fluctuation boundary section. If the comparison is true and the status is valid, the alarm device is triggered and recorded synchronously to obtain the sewage tank water level detection result.

[0007] As a further aspect of the present invention, the capacitance change sequence includes an initial capacitance reference value, a continuous periodic capacitance change trajectory, and stable feature segments after eliminating abrupt changes; the converted liquid level position includes a periodic average capacitance value, a mapped output voltage segment, a corresponding volume interval number, and a liquid level elevation mapping value; the liquid level numerical consistency description result includes a multi-channel liquid level status code comparison result, a communication timestamp interval verification value, and a data source concentration statistical item; the fluctuation boundary segment includes a periodic liquid level position difference, the number of consecutive changes in the direction of change, and a boundary expansion identification area; and the sewage tank water level detection result includes a warning zone identification result, the validity of the liquid level status mark, and an alarm action trigger record. The aforementioned floor scrubber wastewater tank water level detection system based on a liquid level sensor also includes a floor scrubber, which includes a casing, a disc brush, a water level sensor, a clean water tank, a squeegee, a wastewater tank, and a hot air blower.

[0008] As a further aspect of the present invention, the sensing data acquisition module includes: The signal recording submodule acquires the output signal of the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the capacitance value from the initial period to the current period, and generates a periodic capacitance data column. The capacitor jump identification submodule calculates the capacitance difference between consecutive adjacent time points based on the periodic capacitance data column, compares all capacitance differences with a set jump identification threshold, marks jumps, extracts consecutive non-jumping capacitance sequences, and generates a stable capacitance segment sequence. The reference segment extraction submodule calls the stable capacitance segment sequence, performs trend judgment on the capacitance value in each segment, filters continuous segments whose fluctuation amplitude is within the set fluctuation range, constructs a baseline segment representing the periodic characteristics of capacitance trend, and generates a capacitance change sequence. The jump detection threshold is the critical value for determining that the capacitance has jumped when the capacitance difference between adjacent time points is greater than the threshold. The specific value can be determined by statistical analysis of historical capacitance change data, selecting the mean of the capacitance difference plus three times the standard deviation as the critical value for determining the jump. The set fluctuation range is the upper and lower limit range for judging whether the fluctuation range of the capacitance value within the stable segment is reasonable. The capacitance change within this range is considered to be a stable trend. The upper and lower limits can be based on the median and deviation statistics of the capacitance fluctuation range of multiple stable segments under stable operating conditions.

[0009] As a further aspect of the present invention, the formula for calculating the capacitance difference between consecutive adjacent time points is as follows: ; in, This represents the capacitance difference between the i-th and i+1-th consecutive adjacent time points. This represents the periodic capacitance data at the i-th time point. Represents the weighting factor for capacitance changes. This represents the absolute value of the capacitance change at time points i+1 and i+2. This represents the threshold for identifying transitions. This represents the average value of capacitance data over several consecutive periods starting from the i-th time point. Representing extremely small positive numbers is used to prevent the denominator from being zero, and is achieved through dynamic adjustment. Achieve noise suppression.

[0010] As a further aspect of the present invention, the liquid level signal conversion module includes: The capacitance mean calculation submodule extracts the capacitance values ​​of time periods within a continuous period based on the capacitance change sequence, sums the capacitance data in each period and divides it by the number of data in the corresponding time period, and sequentially obtains the set of average capacitance values ​​for each period to generate a periodic capacitance mean sequence. The voltage segment matching submodule calls the periodic capacitance average value sequence, performs capacitance voltage conversion on each average capacitance value according to the sensor configuration parameters, compares the converted voltage value with the preset output voltage segment, and obtains the interval number sequence according to the voltage interval to which the voltage value falls. The liquid level mapping conversion submodule matches the liquid surface position segment associated with the corresponding number in the sensor data according to the interval number sequence, extracts the liquid surface segment position value mapped by each number into a liquid level position set, and generates the converted liquid level position. The mapping relationship between the interval number and the liquid level position segment is established by using preset sensor calibration data to establish the corresponding liquid level height segment associated with the voltage interval.

[0011] As a further aspect of the present invention, the multi-source numerical comparison module includes: The status code extraction submodule obtains the liquid level status codes synchronously recorded in the Modbus, CAN and LoRa transmission channels within the corresponding time period based on the converted liquid level position. It performs bit value splitting on each type of status code, compares the same bit value content of the three types of status codes at the same time point item by item to determine whether the description is consistent, and generates a status consistency identifier sequence. The time difference judgment submodule calls the state consistency identifier sequence, extracts the timestamp data of the Modbus, CAN and LoRa signals where the corresponding status codes are located, calculates the absolute difference of the time interval between each pair of timestamps, compares all interval values ​​with the set synchronization error threshold, identifies the position segment where all interval values ​​are within the threshold range, and obtains the time interval conformity sequence. The source distribution statistics submodule extracts the source number information recorded in the corresponding status code according to the time interval conformity sequence, counts the distribution quantity of the three types of source numbers in the signal channel, determines whether they are concentrated in a single source category, and associates the distribution structure with the status consistency and time interval conformity to obtain the liquid level value consistent description result. The synchronization error threshold is the allowable absolute difference used to determine whether the time difference between the corresponding timestamps of Modbus, CAN and LoRa signals is within an acceptable range.

[0012] As a further aspect of the present invention, the formula for calculating the absolute difference of the time intervals between each pair of timestamps is as follows: ; in, This represents the absolute difference in the time interval between any two corresponding timestamps. represent The i-th timestamp data in the signal sequence, This represents the j-th timestamp data in the CAN signal sequence. represent The k-th timestamp data in the signal sequence, This represents the total number of timestamp data for the three types of signals. The range of values ​​and the basis for determination are determined through communication protocol delay analysis.

[0013] As a further aspect of the present invention, the liquid level fluctuation identification module includes: The liquid level difference calculation submodule obtains the liquid level position values ​​corresponding to adjacent time points in the current cycle and the previous cycle based on the liquid level value consistency description result, calculates the difference between the two in turn, and retains the change direction information of each time point in the difference sequence to generate a liquid level difference direction sequence. The trend direction identification submodule calls the liquid level difference direction sequence, counts the number of consecutive repetitions of the direction value, determines the frequency of consecutive rises and falls, accumulates the consecutive differences under the same direction, constructs a set of total differences and durations under each direction, and obtains continuous trend feature values. The boundary segment marking submodule extracts the direction switching position and the total difference before and after based on the continuous trend feature value, determines whether the value exceeds the set boundary expansion threshold, marks the direction switching segment that meets the condition, and establishes the fluctuating boundary segment. The set boundary expansion threshold is defined as the threshold for determining whether the cumulative total of the liquid level difference at the point of continuous trend switching is sufficient to effectively mark the changing boundary.

[0014] As a further aspect of the present invention, the alarm action linkage module includes: The region comparison submodule obtains the current liquid level position value based on the fluctuation boundary segment, performs interval determination on the corresponding position of the current liquid level value on the coordinate axis and the start and end positions of the boundary expansion interval, determines whether the liquid level value is within the expansion interval, and generates a region placement determination result. The status verification submodule calls the area placement judgment result, obtains the status mark content of each corresponding moment in the liquid level value consistent description result, filters the time nodes with the status mark as valid, and checks them against the positions with true values ​​in the judgment result, obtains the index set that meets both conditions at the same time, and generates an alarm trigger index sequence. The action triggering submodule triggers the alarm device status action at the corresponding time point according to the alarm triggering index sequence, writes the alarm status change instruction into the action execution record table, generates the corresponding action response timestamp and registers it, and establishes the sewage tank water level detection result.

[0015] A method for detecting the water level in the wastewater tank of a floor scrubber based on a liquid level sensor includes the following steps: S1: Obtain the readings of the capacitance sensor attached to the side wall of the wastewater tank of the floor scrubber, determine whether the direction of the difference is consistently consistent, eliminate abrupt changes, filter out stable fluctuation ranges, and obtain the capacitance change sequence. S2: Based on the average value of the capacitance change sequence, determine the voltage segment, match the capacity number position, find its corresponding liquid level height, and obtain the converted liquid level position; S3: Based on the calculated liquid level position, compare the status codes of Modbus, CAN, and LoRa channels, determine the time interval and the data source concentration statistics, and obtain a liquid level value consistent description result. S4: Based on the consistent description results of the liquid level values, calculate the direction and frequency of the difference in the converted liquid level position between adjacent periods, extract the trend extension range, and obtain the fluctuation boundary segment; S5: Compare the converted liquid level position with the fluctuation boundary section, combine the liquid level value with the consistent description result status mark, determine whether to trigger an alarm, and obtain the sewage tank water level detection result.

[0016] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, by collecting sensor capacitance change sequences, eliminating abnormal fluctuations, constructing a stable reference curve, and enhancing data anti-interference capability, liquid level segments are mapped based on average capacitance values ​​to achieve accurate identification of liquid surface elevation. Simultaneously comparing liquid level status information in multiple communication protocols improves data consistency and reliability. Liquid level fluctuation boundaries are identified by cumulative trend direction changes, and change segments are dynamically marked. Alarm triggering is based on dual verification of boundary regions and status markers, enhancing the accuracy and effectiveness of warning response, and constructing a high-precision and highly stable liquid level detection and early warning system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a system flowchart of the present invention; Figure 2 This is a system block diagram of the present invention; Figure 3 This is a flowchart of the method of the present invention; Figure 4 This is a structural diagram of the floor scrubber of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0020] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0021] In the embodiments of this invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning. Similarly, the terms "of," "corresponding (relevant)," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the distinction between them, they convey the same meaning.

[0022] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0023] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0024] Please see Figure 1 , Figure 2 and Figure 4 A water level detection system for the wastewater tank of a floor scrubber based on a liquid level sensor includes: The sensor data acquisition module acquires the readings of the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the continuous capacitance change value of the signal source from the initial to the current cycle, compares the reading jump trend during the cycle, determines whether the trend is in a continuous fluctuation state, filters out data with abnormal sudden change points, retains continuous stable segments as reference curves, and obtains the capacitance change sequence. The liquid level signal conversion module is based on the capacitance change sequence. It calls the average capacitance value within a continuous period, extracts the corresponding output voltage segment from the sensor configuration, and identifies the distribution segment of the corresponding liquid surface by comparing the volume interval number of the voltage segment. It then obtains the liquid level elevation value corresponding to the mapping result and obtains the converted liquid level position. The multi-source numerical comparison module obtains the liquid level status codes synchronously transmitted in Modbus, CAN and LoRa transmissions based on the converted liquid level position, compares the bit value descriptions of the three types of status codes one by one to see if they are consistent, calculates the interval between the three types of timestamps to determine if they are within the range, and counts whether the source numbers are concentrated in a single source category to obtain the liquid level numerical consistent description result. The liquid level fluctuation identification module obtains the difference between the liquid level position of the previous cycle and the current cycle based on the consistent description result of the liquid level value. By calculating the number of consecutive repetitions of the difference direction, it determines whether it is an upward or downward trend. The total difference of the continuous direction change and the number of times are combined as the judgment benchmark, and the corresponding liquid level change area is marked as the outer boundary expansion interval to obtain the fluctuation boundary segment. The alarm action linkage module compares the current liquid level position with the fluctuation boundary section to identify whether it is located within the warning zone after the boundary expansion. It combines the liquid level value with the description of whether there is a status mark. If the comparison result is true and the status mark is valid, the alarm device status action is triggered and synchronously recorded to obtain the sewage tank water level detection result.

[0025] The capacitance change sequence includes the initial capacitance reference value, the continuous periodic capacitance change trajectory, and the stable feature segment after removing abrupt changes. The converted liquid level position includes the periodic average capacitance value, the mapped output voltage segment, the corresponding volume interval number, and the liquid level elevation mapping value. The liquid level numerical consistency description results include the multi-channel liquid level status code comparison results, the communication timestamp interval verification value, and the data source concentration statistics. The fluctuation boundary segment includes the periodic liquid level position difference, the number of consecutive changes in the direction of change, and the boundary expansion identification area. The sewage tank water level detection results include the warning zone identification results, the validity of the liquid level status mark, and the alarm action trigger record.

[0026] Please see Figure 1 , Figure 2 and Figure 4 The sensor data acquisition module includes: The signal recording submodule acquires the output signal of the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the capacitance value from the initial period to the current period, and generates a periodic capacitance data column. The signal recording submodule acquires the output signal from the capacitive level sensor attached to the side wall of the wastewater tank of the floor scrubber. During execution, a capacitive level sensor with a level resolution of 0.01pF is first selected and vertically attached to the inner wall of the wastewater tank near the bottom third. This ensures the sensor accurately responds to capacitance changes at different liquid levels within the tank. The output analog signal is periodically acquired by the sampling module at 100ms intervals, completing 10 capacitance signal acquisitions per second. The analog voltage signal is then converted to a digital signal by the analog-to-digital converter module, and finally converted to a capacitance value by the sensor's built-in capacitance voltage converter. For example, the voltage acquired at a certain moment might be 2.4V. After checking the conversion table, the corresponding capacitance value was found to be 0.76pF. The starting point for recording was set by the control program to the instant when the floor scrubber was powered on and the liquid level was first detected to be higher than 0.2L. The sampled capacitance value at this time was used as the reference value for the start of the cycle. Subsequently, each sampling recorded the system time and the corresponding capacitance value at the current moment, and recorded them in the cycle data sequence with time as the index. In practical applications, assuming that the floor scrubber's running cycle is 2 minutes, the system will collect 1200 sets of capacitance data. These data are sorted by time to form a capacitance change data column and stored in the cycle buffer area. After each cycle, the system packages and stores the capacitance records within that cycle to prepare for subsequent jump detection and trend analysis.

[0027] The capacitor jump identification submodule calculates the capacitance difference between consecutive adjacent time points based on the periodic capacitance data column, compares all capacitance differences with the set jump identification threshold, marks the jump, extracts the continuous non-jumping capacitance sequence, and generates a stable capacitance segment sequence. The specific formula for calculating the capacitance difference between consecutive adjacent time points is as follows: ; in, This represents the capacitance difference between the i-th and i+1-th consecutive adjacent time points. This represents the periodic capacitance data at the i-th time point. Represents the weighting factor for capacitance changes. This represents the absolute value of the capacitance change at time points i+1 and i+2. This represents the threshold for identifying transitions. This represents the average value of capacitance data over several consecutive periods starting from the i-th time point. This represents extremely small positive numbers to prevent the denominator from being zero; The periodic capacitance data representing the i-th time point is acquired in real time through a capacitance sensor. The actual monitoring data is as follows: The monitoring data is periodically acquired through a 1kHz frequency capacitive sampling circuit with a sampling accuracy of 0.01nF.

[0028] This represents the weighting factor for capacitance change, and its value is set based on the fluctuation range of the capacitance change rate. The standard deviation σ of the capacitance change rate is calculated from the standard deviation of the most recent 100 sets of capacitance difference values, and has been monitored to be 0.35nF. According to empirical standards, when the standard deviation of the rate is less than 0.5nF, The value is set to 0.8, and increases linearly with the increase of the standard deviation σ of the capacitance change rate, with a maximum of 1.5.

[0029] The absolute value of the capacitance change at time points i+1 and i+2 is calculated from the monitoring data. .

[0030] The threshold for identifying voltage jumps is set by adding twice the standard deviation to the average capacitance change in historical monitoring data. The average capacitance change is 0.7 nF, and the standard deviation is 0.2 nF. Therefore... .

[0031] Calculate and input monitoring data .

[0032] To ensure that the denominator is a very small positive number and to prevent it from being zero, it is set according to the IEEE floating-point standard. .

[0033] Substitute into the formula and calculate step by step: Calculate the capacitance difference : ; Calculate the weighted capacitance change : ; Summation of the numerator : ; Absolute value of the denominator : ; Add a very small positive number to the denominator: ; Substitute the complete formula and calculate: ; The results show that the characteristic value of the capacitance jump amplitude between the first and second time points is 0.14526 nF, indicating the significance of the capacitance change in this interval. This value serves as a representation of the amplitude of a single jump in the capacitance difference sequence. Combined with a subsequent comparison with a set jump identification threshold, it determines whether a jump phenomenon exists, and is then used to extract continuous non-jumping capacitance sequences, ultimately generating a stable capacitance segment sequence.

[0034] The reference segment extraction submodule calls the stable capacitance segment sequence, judges the trend of capacitance values ​​in each segment, filters continuous segments whose fluctuation amplitude is within the set fluctuation range, constructs a baseline segment of capacitance trend representing periodic characteristics, and generates a capacitance change sequence. The reference segment extraction submodule calls the stable capacitance segment sequence. First, it reads all capacitance values ​​within each segment and calculates their maximum and minimum values ​​to obtain the capacitance fluctuation range of that segment. This range is compared with a preset fluctuation range to filter out segments with stable fluctuation ranges. The fluctuation range threshold setting principle is based on the capacitance noise statistics when the equipment is stationary and the slow change amplitude of the liquid level under operating conditions. The maximum and minimum fluctuation ranges under stationary conditions are set to 0.015pF and 0.035pF, respectively. Under operating conditions, the maximum range during the low-speed liquid level rise phase does not exceed 0.07pF. Therefore, the final fluctuation range threshold is set to 0.02pF to 0.07pF. When performing the filtering, if the capacitance data of a stable segment are 0.88pF, 0.91pF, 0.87pF, and 0.89pF, then its fluctuation range is 0.04pF, which is within the set threshold range. This segment is retained. If a segment has values ​​of 0.93pF, 1.01pF, 1.02pF, and 1.05pF, and its range is 0.12pF, exceeding the upper threshold, it is discarded. The retained segments are then subjected to trend judgment in turn. The judgment process is based on whether the trend of capacitance value change in the continuous segment is close to a horizontal line. It uses the comparison of the first and last point values ​​and the analysis of the overall average fluctuation direction. For example, if a segment has a first value of 0.88pF, a last value of 0.89pF, and a middle value fluctuating around 0.885pF with a range of 0.005pF, it can be judged as having a stable trend. If another segment has a first value of 0.95pF and a last value of 1.02pF, the increase is 0.07pF, which is considered a trend deviation, and this segment is not retained. Finally, a set of reference segments that meet the requirements in terms of fluctuation range and trend is obtained. These segments together constitute the change sequence of the baseline segment for subsequent capacitance trend.

[0035] Please see Figure 1 , Figure 2 and Figure 4 The liquid level signal conversion module includes: The capacitance mean calculation submodule extracts the capacitance values ​​within a continuous period based on the capacitance change sequence, sums the capacitance data in each period and divides it by the number of data in the corresponding period, and obtains the set of average capacitance values ​​for each period in turn, generating a periodic capacitance mean sequence. The capacitance mean calculation submodule is based on the capacitance change sequence. First, it divides the entire period's capacitance change sequence into 60-second periods. Within each period, it sequentially extracts all capacitance measurements, recording the number of capacitance samples and their values. For example, if the sampling frequency is 10Hz in the first period, a total of 600 capacitance values ​​are collected within 60 seconds, such as 0.86pF, 0.88pF, and 0.87pF. These 600 values ​​are then summed, resulting in a total of 525.00pF. This sum is then divided by 600 to obtain the average value, which is 0.875pF. This calculation process is repeated within each period, using accumulation rather than relying on a formula. The process is performed point-by-point using the same integer division method. Simultaneously, the system sets detection range limits to remove abnormal samples with single-point values ​​less than 0.6pF or greater than 2.5pF within a cycle, preventing outliers from affecting the accuracy of the mean. This threshold is based on statistical measurements of the capacitance values ​​of the floor scrubber's wastewater tank under both empty and full states. The lowest capacitance in an empty tank is 0.62pF, and the maximum capacitance in a full tank is 2.43pF. Therefore, the lower limit of the filtering threshold is set to 0.6pF, and the upper limit to 2.5pF, ensuring that all data points used for mean calculation are within a reasonable range. After the above processing, the samples from each cycle are summarized and the average value is extracted. Finally, the average capacitance values ​​obtained in each cycle are recorded in chronological order to generate a cycle capacitance mean sequence.

[0036] The voltage segment matching submodule calls the periodic capacitance average value sequence, performs capacitance voltage conversion for each average capacitance value based on the sensor configuration parameters, compares the converted voltage value with the preset output voltage segment, and obtains the interval number sequence according to the voltage interval to which the voltage value falls. The voltage segment matching submodule calls the periodic capacitance average sequence. During execution, it reads the average capacitance value item by item and performs conversion with reference to the sensor's factory calibration parameters. This conversion is based on the segmented conversion table provided by the sensor. That is, for each capacitance value, it looks up its corresponding voltage value. For example, a capacitance value of 0.875pF corresponds to a voltage of 2.2V according to the table. This conversion table comes from the capacitance-voltage correspondence table calibrated by the sensor manufacturer in a standard liquid environment. The table sets 10 level intervals within the range of 0.5pF to 2.5pF, each interval corresponding to an output voltage segment, equally divided from 1.5V to 3.0V. The system sets the output voltage segments numbered from 1 to 10, with each segment interval being 0.15V. After calculating the voltage, the system compares the voltage value with the output voltage segment to determine its range. For example, if 2.2V falls between 2.1V and 2.25V, then it matches the voltage segment numbered 5. Based on this, the system matches segment number 5 for the current cycle. This judgment process directly compares the current voltage value with the upper and lower limits of the range, without using an inclusion relationship. This operation is repeated for each cycle's average capacitance value. The system then converts and numbers the corresponding voltage values ​​sequentially, thus obtaining a set of interval numbering sequences arranged in chronological order.

[0037] The liquid level mapping conversion submodule matches the liquid surface position segment associated with the corresponding number in the sensor data according to the interval number sequence, extracts the liquid surface segment position value mapped by each number into a liquid level position set, and generates the converted liquid level position. The liquid level mapping conversion submodule first reads each number according to the interval number sequence and calls the number-liquid level height mapping relationship stored in the sensor calibration file. For example, number 1 corresponds to a liquid level of 0-1cm, number 2 corresponds to 1-2cm, and so on until number 10 corresponds to 9-10cm. The mapping relationship is based on experimental measurement, and each number segment corresponds to a liquid level change of 1cm. By measuring the capacitance value generated by the sensor at the corresponding liquid level height, a fixed mapping table is established with the interval number. During the execution process, the system processes the interval number item by item. For example, if the number is 5, the corresponding liquid level range of 4-5cm is extracted, and its center value of 4.5cm is taken as the liquid level position value of the current period. All number data are processed in sequence to obtain the liquid level value of each segment within the period. If a number exceeds the limit (i.e., the number is less than 1 or greater than 10), it is judged as abnormal data and the liquid level value is set to -1 as an abnormality flag. This judgment rule is preset by the system and written into the abnormality identification module. Finally, all the mapped liquid level values ​​are arranged in chronological order to form the converted liquid level position sequence.

[0038] Please see Figure 1 , Figure 2 and Figure 4 The multi-source numerical comparison module includes: The status code extraction submodule obtains the liquid level status codes synchronously recorded in the Modbus, CAN and LoRa transmission channels within the corresponding time period based on the converted liquid level position. It then performs bit value splitting on each type of status code, compares the same bit value content of the three types of status codes at the same time point item by item to determine whether the description is consistent, and generates a status consistency identifier sequence. The status code extraction submodule, based on the calculated liquid level position, first indexes and marks the calculated liquid level position according to the time axis. Then, at the corresponding time point, it retrieves the liquid level status code data synchronously collected from three communication channels: Modbus, CAN, and LoRa. After reading each type of status code data, it performs bit-by-bit splitting. The bit-by-bit splitting process parses each bit according to a preset 8-bit or 16-bit status field. Each bit represents a sub-state or alarm flag. For example, if at a certain moment the Modbus status code is 10101100 (binary), the CAN status code is 10101101, and the LoRa status code is 10101100, the system sequentially compares each bit, that is, it compares the corresponding bit values ​​of the three channels from the first to the eighth bit to see if they are the same. During the comparison, if the value of any bit in any of the three channels is 1 or 0, the bit description is considered consistent. If any channel's bit is inconsistent with the other two channels, it is marked as inconsistent. In the example above, the eighth bit is 0 for Modbus and LoRa, and 1 for CAN, so it is marked as inconsistent. The remaining bits are consistent, so the bit value consistency at that moment is 7 / 8. The system generates a status consistency identifier for each time point based on the consistency results of all bit values. The identifier value is set to the binary string "1" for consistency and "0" for inconsistency, and is recorded as a consistency identifier sequence. During this process, if there is missing data in any of the three status codes, the time point is marked as empty or "X" as an invalid mark and is removed from subsequent calculations. This process is repeated for all time points to complete the generation of the consistency identifier sequence.

[0039] The time difference judgment submodule calls the state consistency identifier sequence, extracts the timestamp data of the Modbus, CAN and LoRa signals where the corresponding status codes are located, calculates the absolute difference of the time interval between each pair of timestamps, compares all interval values ​​with the set synchronization error threshold, identifies the position segment where all interval values ​​are within the threshold range, and obtains the time interval conformity sequence. The formula for calculating the absolute difference of the time intervals between any two corresponding timestamps is as follows:

[0040] in, This represents the absolute difference in the time interval between any two corresponding timestamps. represent The i-th timestamp data in the signal sequence, This represents the j-th timestamp data in the CAN signal sequence. represent The k-th timestamp data in the signal sequence, This represents the total number of timestamp data for the three types of signals; Parameter acquisition and quantization methods: : Obtained through the system time register of the Modbus device, usually in milliseconds.

[0041] Provided by the free-running counter of the CAN controller, with a resolution of up to 1 microsecond.

[0042] : Obtained through the hardware counter of the LoRaWAN gateway, with a resolution of 1 microsecond.

[0043] The total number of timestamp data for the three types of signals is calculated by the system acquisition module.

[0044] Specific numerical settings: Milliseconds (corresponding to 10:13:09.000); Milliseconds (corresponding to 10:13:09.001); Milliseconds (corresponding to 10:13:09.003); ; Formula calculation process: calculate millisecond; calculate millisecond; calculate millisecond; calculate millisecond; Substitute the above results into the formula: millisecond; The results show that the maximum time interval between timestamps for Modbus, CAN, and LoRa signals under the corresponding status codes is 2.997 milliseconds. If the set synchronization error threshold is 5 milliseconds, this time interval meets the requirements, indicating that the three types of signals have good time synchronization under this status code.

[0045] The source distribution statistics submodule extracts the source number information recorded in the corresponding status code based on the time interval conformity sequence, counts the distribution quantity of the three types of source numbers in the signal channel, determines whether they are concentrated in a single source category, and associates the distribution structure with the status consistency and time interval conformity to obtain the liquid level value consistent description result. The source distribution statistics submodule extracts the source number information contained in the status code data of all time points that meet the time interval conformity sequence. The number information is a fixed position field value in the communication data frame. For example, the Modbus number field is located in the 3rd byte, the CAN number is located in the frame ID, and the LoRa number is stored in the first byte of the data frame. The source number range for each channel is set to 0 to 255. The source number value is used to identify the specific sensor or acquisition device number. During the statistics process, the system reads the source numbers of the three types of signals at each time point, generates a source number set, and counts the number of times each type of number appears and the channel to which it belongs in all time points that meet the conditions. For example, in 100 time points, number A appears 80 times. If Modbus accounts for 40 occurrences, CAN for 30, and LoRa for 10, then the number distribution is determined to be concentrated in the Modbus channel. The system sets the concentration judgment condition as the frequency of a single channel source number being greater than 50% of the total number of occurrences. In this example, the Modbus channel accounts for 40%, which does not constitute a concentration. If a certain number B comes from the CAN channel 70 out of 90 occurrences, then it is judged as a concentrated source. This concentration is used to analyze the stability of the data source and channel deviation. The system establishes a one-to-one correspondence between the source concentration structure and the state consistency sequence and the time interval consistency sequence. Finally, based on these three types of information, it comprehensively judges whether the liquid level value description for this time period maintains a consistent description structure across the three channels.

[0046] Please see Figure 1 , Figure 2 and Figure 4 The liquid level fluctuation identification module includes: The liquid level difference calculation submodule obtains the liquid level position values ​​corresponding to adjacent time points in the current cycle and the previous cycle based on the liquid level numerical consistency description results, calculates the difference between the two in turn, and retains the change direction information of each time point in the difference sequence to generate a liquid level difference direction sequence. The liquid level difference calculation submodule, based on the consistent description of liquid level values, first extracts the liquid level position values ​​of all valid time points within the current cycle in chronological order. It then performs a one-to-one matching process with the corresponding liquid level position values ​​at the same time point in the previous cycle. The matching rule is based on the time index alignment principle. For example, if the liquid level at the 150th second of the current cycle is 6.8cm, the liquid level at the 150th second of the previous cycle is 6.5cm. The system sequentially reads each pair of liquid level values ​​from time points t0 to tn and performs the operation of subtracting the previous cycle value from the current cycle value to obtain the difference. After the difference calculation is completed, the sign of each result is determined; if the difference is positive, it is marked as positive. The value is marked as "rising". If it is negative, it is marked as "falling". If it is zero, it is marked as "remaining unchanged". For example, if the liquid level at three consecutive time points in a certain sequence is 6.5cm, 6.6cm and 6.8cm respectively, and the corresponding value in the previous cycle is 6.3cm, 6.4cm and 6.5cm, then the difference is +0.2cm, +0.2cm and +0.3cm, and the direction is "rising". The direction information is recorded in parallel with the difference result in the form of a liquid level difference direction sequence. The sequence structure is a two-column data structure, one column is the numerical difference and the other column is the direction mark. All data form the difference direction sequence in chronological order and are stored in the system.

[0047] The trend direction identification submodule calls the liquid level difference direction sequence, counts the number of consecutive repetitions of the direction value, determines the frequency of consecutive rises and falls, accumulates the consecutive differences under the same direction, constructs a set of total differences and durations under each direction, and obtains continuous trend feature values. The trend direction recognition submodule calls the liquid level difference direction sequence. First, it reads the direction flag field sequentially from the beginning of the sequence. The system sets counters to count the consecutive occurrences of the three directions: "rising," "falling," and "remaining unchanged." Upon encountering a direction change, it immediately records the cumulative count of the previous direction and initializes a new direction counter to continue counting. For example, in the direction sequence "rising, rising, rising, falling, falling, remaining unchanged," the system recognizes three consecutive rises, two consecutive falls, and one remaining unchanged. After recognition, the system further calls the corresponding values ​​in the difference sequence to calculate the liquid level difference for each consecutive direction. The process involves operations to obtain the total difference value of each direction segment. For example, if the difference value in an upward segment is +0.2cm, +0.1cm, and +0.3cm, then the total difference value for that segment is +0.6cm, corresponding to a consecutive count of 3. If the difference value in a downward segment is -0.2cm and -0.3cm, then the total difference value is -0.5cm, corresponding to a consecutive count of 2. If the difference value in a flat segment is 0.0cm, then the corresponding count is 1. All total differences of direction segments and consecutive counts form a one-to-one correspondence set, constructing a complete trend feature value structure. This structure includes three items: direction type, total difference value of direction segments, and duration of direction segments, which are used for subsequent boundary judgment and fluctuation segment analysis.

[0048] The boundary segment marking submodule extracts the direction switching position and the total difference before and after based on the continuous trend feature value, determines whether the value exceeds the set boundary expansion threshold, marks the direction switching segment that meets the condition, and establishes the fluctuating boundary segment. The boundary segment marking submodule sequentially reads the start and end positions of each directional segment based on continuous trend characteristic values, and determines whether the switching point between two adjacent segments in different directions meets the boundary marking conditions. The system sets the boundary expansion threshold to 0.5cm. This threshold is obtained by sampling the natural fluctuation of the liquid level in the wastewater tank of the floor scrubber under different load conditions, with a maximum fluctuation of 0.42cm. A safety margin threshold of 0.5cm is reserved. During the judgment, the system sums the absolute values ​​of the total difference between the previous and next directional segments. For example, if the current trend is "rising → falling". At the switching point, if the total difference of the ascending segment is +0.4cm and the total difference of the descending segment is -0.3cm, the sum of the differences is 0.7cm, which is greater than the 0.5cm threshold. The system determines that the direction switch is a boundary position and records the switching point time index and the difference range of the preceding and following segments. Five time points are marked forward and backward from this point as the boundary extension segment. If the sum of the differences does not exceed 0.5cm, no marking is performed. This operation is performed sequentially at all direction switching positions, and after processing, all wave boundary segment information that meets the conditions is output to construct a complete wave boundary segment structure.

[0049] Please see Figure 1 , Figure 2 and Figure 4 The alarm action linkage module includes: The region comparison submodule obtains the current liquid level position value based on the fluctuation boundary segment, performs interval determination on the corresponding position of the current liquid level value on the coordinate axis and the start and end positions of the boundary expansion interval, determines whether the liquid level value is within the expansion interval, and generates the region position determination result. The regional comparison submodule, based on the fluctuation boundary segments, first calls the start and end indices of each recorded fluctuation boundary segment in the system, and obtains the upper and lower boundaries of the liquid level value corresponding to the start and end times of each segment. For example, if the start index of a certain boundary segment is 180 and the end index is 190, the corresponding upper and lower boundary values ​​of the liquid level are 5.3cm to 6.0cm. Subsequently, the system sequentially extracts all liquid level measurement point values ​​within the current cycle and compares them one by one according to the time index to see if the current liquid level value is within the upper and lower boundary range of any fluctuation boundary segment. The judgment process uses dual comparison logic, comparing the current liquid level value with the upper and lower boundaries of each segment separately. The system uses "≥" and "≤" to determine the liquid level. For example, if the current liquid level is 5.7cm and the corresponding time index is 185, the system determines whether it is greater than or equal to 5.3cm and less than or equal to 6.0cm. If the result is true, the point is marked as "1"; otherwise, it is marked as "0". This mark value is written into the corresponding location's area placement determination result sequence. If there are multiple boundary segments, the system performs a loop determination at each liquid level time point. If the liquid level falls into any segment, it is determined as "1"; if none of the conditions are met, it is marked as "0". After all time points have been traversed, a complete determination result sequence is output. The length of this sequence is equal to the total number of liquid level measurement points in the current cycle.

[0050] The status verification submodule calls the area placement judgment result, obtains the status mark content of each corresponding moment in the liquid level value consistent description result, filters the time nodes with the status mark as valid, and checks them against the positions with true values ​​in the judgment result, obtains the index set that meets both conditions at the same time, and generates an alarm trigger index sequence. The status verification submodule calls the area placement determination result. First, it reads the set of index positions with all values ​​of "1" in the sequence. Then, it extracts the status flag field of each time point in the liquid level value consistency description result. This field represents the comprehensive judgment result of the consistency and timing synchronization of the three-channel status codes at each time point. The value of "E" indicates that the data at that time is valid and can participate in the alarm determination. The system compares the status flag sequence with the area placement sequence according to the index and determines whether the two contents under the same time index meet the set conditions. Specifically, it determines whether the placement determination value under the current index is "1" and whether the status flag is "E". The indexes that meet the dual conditions will be collected into the alarm trigger index set. For example, if the three time points 240, 245, and 247 meet the above conditions, the corresponding indices of these three points will be added to the alarm trigger index sequence. The data structure of this sequence is a single-column integer index table, which records the indexes of all time points that meet the alarm determination conditions. The subsequent action module will only process the time point contents that appear in this sequence.

[0051] The action triggering submodule triggers the alarm device status action at the corresponding time point according to the alarm triggering index sequence, writes the alarm status change instruction into the action execution record table, generates the corresponding action response timestamp and registers it, and establishes the sewage tank water level detection result. The action triggering submodule reads each alarm triggering index sequentially according to the alarm triggering index sequence and executes the corresponding control command writing operation. The system control module sets the alarm status control command field to a single-byte boolean bit, with a value of "1" indicating an alarm triggering status and a value of "0" indicating no alarm status. The system writes "1" to the corresponding time point position in the action control record table according to the alarm triggering index value. At the same time, it calls the internal time counting module to record the system running time value at the time of alarm triggering as the action response timestamp. The timestamp has a precision of milliseconds and is written to the action execution record table along with the control command. The record table has a fixed structure of five columns, which record the time point index, alarm command value, current liquid level value, status consistency result, and area determination result in sequence. After writing the action record, the system immediately pulls the corresponding signal of the alarm output channel high to trigger the action of external devices, such as the buzzer sounding or the control light turning on. This operation process generates a complete record of sewage tank water level detection results after all alarm triggering indices have been traversed.

[0052] Please see Figure 3 A method for detecting the water level in the wastewater tank of a floor scrubber based on a liquid level sensor, comprising the following steps: S1: Obtain the readings of the capacitance sensor attached to the side wall of the wastewater tank of the floor scrubber, determine whether the direction of the difference is consistently consistent, eliminate abrupt changes, filter out stable fluctuation ranges, and obtain the capacitance change sequence. S2: Based on the average value of the capacitance change sequence, determine the voltage segment, match the capacity number position, find its corresponding liquid level height, and obtain the converted liquid level position; S3: Based on the converted liquid level position, compare the status codes of Modbus, CAN, and LoRa channels, determine the time interval and source concentration, and obtain a consistent description of the liquid level value. S4: Based on the consistent description results of liquid level values, calculate the direction and number of differences in liquid level positions between adjacent periods, extract the trend extension range, and obtain the fluctuation boundary segment; S5: Compare the converted liquid level position with the fluctuation boundary section, combine the liquid level value with the consistent description result status mark, determine whether an alarm is triggered, and obtain the sewage tank water level detection result.

[0053] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A water level detection system for a floor scrubber's wastewater tank based on a liquid level sensor, characterized in that: The system includes: The sensor data acquisition module reads data from the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the capacitance change from the initial to the current cycle, compares the cycle jump trend, eliminates abnormal sudden changes, and forms a capacitance change sequence. The liquid level signal conversion module takes the continuous periodic average capacitance value based on the capacitance change sequence, extracts the output voltage segment configured by the sensor, compares the volume interval number to which the voltage belongs, and obtains the converted liquid level position. The multi-source numerical comparison module obtains the liquid level status codes synchronously transmitted by Modbus, CAN and LoRa protocols based on the converted liquid level position, and obtains a consistent liquid level numerical description result based on the timestamp alignment algorithm for communication protocol difference compensation. Based on the consistent description results of the liquid level values, the liquid level fluctuation identification module calculates the difference between the current liquid level and the previous cycle, counts the number of consecutive values ​​in the direction of the difference, identifies the upward and downward trends, marks the corresponding change area as the expansion segment, and obtains the fluctuation boundary segment. The alarm action linkage module determines whether the current liquid level has entered the warning zone based on the fluctuation boundary section. If the comparison is true and the status is valid, the alarm device is triggered and recorded synchronously to obtain the sewage tank water level detection result.

2. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The capacitance change sequence includes an initial capacitance reference value, a continuous periodic capacitance change trajectory, and stable feature segments after removing abrupt changes. The converted liquid level position includes a periodic average capacitance value, a mapped output voltage segment, a corresponding volume interval number, and a liquid level elevation mapping value. The liquid level numerical consistency description result includes a multi-channel liquid level status code comparison result, a communication timestamp interval verification value, and a data source concentration statistical item. The fluctuation boundary segment includes a periodic liquid level position difference, the number of consecutive changes in the direction of change, and a boundary expansion identification area. The sewage tank water level detection result includes a warning zone identification result, the validity of the liquid level status mark, and an alarm action trigger record. The aforementioned floor scrubber wastewater tank water level detection system based on a liquid level sensor also includes a floor scrubber, which includes a casing, a disc brush, a water level sensor, a clean water tank, a squeegee, a wastewater tank, and a hot air blower.

3. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The sensor data acquisition module includes: The signal recording submodule acquires the output signal of the capacitive liquid level sensor attached to the side wall of the wastewater tank of the floor scrubber, records the capacitance value from the initial period to the current period, and generates a periodic capacitance data column. The capacitor jump identification submodule calculates the capacitance difference between consecutive adjacent time points based on the periodic capacitance data column, compares all capacitance differences with a set jump identification threshold, marks jumps, extracts consecutive non-jumping capacitance sequences, and generates a stable capacitance segment sequence. The reference segment extraction submodule calls the stable capacitance segment sequence, performs trend judgment on the capacitance value in each segment, filters continuous segments whose fluctuation amplitude is within the set fluctuation range, constructs a baseline segment representing the periodic characteristics of capacitance trend, and generates a capacitance change sequence. The jump detection threshold is the critical value for determining that the capacitance has jumped when the capacitance difference between adjacent time points is greater than the threshold. The specific value can be determined by statistical analysis of historical capacitance change data, selecting the mean of the capacitance difference plus three times the standard deviation as the critical value for determining the jump. The set fluctuation range is the upper and lower limit range for judging whether the fluctuation range of the capacitance value within the stable segment is reasonable. The capacitance change within this range is considered to be a stable trend. The upper and lower limits can be based on the median and deviation statistics of the capacitance fluctuation range of multiple stable segments under stable operating conditions.

4. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 3, characterized in that: The specific formula for calculating the capacitance difference between consecutive adjacent time points is as follows: ； in, This represents the capacitance difference between the i-th and i+1-th consecutive adjacent time points. The periodic capacitance data represents the i-th time point. Represents the weighting factor for capacitance changes. This represents the absolute value of the capacitance change at time points i+1 and i+2. This represents the threshold for identifying transitions. This represents the average value of capacitance data over several consecutive periods starting from the i-th time point. Representing extremely small positive numbers is used to prevent the denominator from being zero, and is achieved through dynamic adjustment. Achieve noise suppression.

5. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The liquid level signal conversion module includes: The capacitance mean calculation submodule extracts the capacitance values ​​of time periods within a continuous period based on the capacitance change sequence, sums the capacitance data in each period and divides it by the number of data in the corresponding time period, and sequentially obtains the set of average capacitance values ​​for each period to generate a periodic capacitance mean sequence. The voltage segment matching submodule calls the periodic capacitance average value sequence, performs capacitance voltage conversion on each average capacitance value according to the sensor configuration parameters, compares the converted voltage value with the preset output voltage segment, and obtains the interval number sequence according to the voltage interval to which the voltage value falls. The liquid level mapping conversion submodule matches the liquid surface position segment associated with the corresponding number in the sensor data according to the interval number sequence, extracts the liquid surface segment position value mapped by each number into a liquid level position set, and generates the converted liquid level position. The mapping relationship between the interval number and the liquid level position segment is established by using preset sensor calibration data to establish the corresponding liquid level height segment associated with the voltage interval.

6. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The multi-source numerical comparison module includes: The status code extraction submodule obtains the liquid level status codes synchronously recorded in the Modbus, CAN and LoRa transmission channels within the corresponding time period based on the converted liquid level position. It performs bit value splitting on each type of status code, compares the same bit value content of the three types of status codes at the same time point item by item to determine whether the description is consistent, and generates a status consistency identifier sequence. The time difference judgment submodule calls the state consistency identifier sequence, extracts the timestamp data of the Modbus, CAN and LoRa signals where the corresponding status codes are located, calculates the absolute difference of the time interval between each pair of timestamps, compares all interval values ​​with the set synchronization error threshold, identifies the position segment where all interval values ​​are within the threshold range, and obtains the time interval conformity sequence. The source distribution statistics submodule extracts the source number information recorded in the corresponding status code according to the time interval conformity sequence, counts the distribution quantity of the three types of source numbers in the signal channel, determines whether they are concentrated in a single source category, and associates the distribution structure with the status consistency and time interval conformity to obtain the liquid level value consistent description result. The synchronization error threshold is the allowable absolute difference used to determine whether the time difference between the corresponding timestamps of Modbus, CAN and LoRa signals is within an acceptable range.

7. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 6, characterized in that: The formula for calculating the absolute difference of the time intervals between any two corresponding timestamps is as follows: ； in, This represents the absolute difference in the time interval between any two corresponding timestamps. represent The i-th timestamp data in the signal sequence, This represents the j-th timestamp data in the CAN signal sequence. represent The k-th timestamp data in the signal sequence, where N represents the total number of timestamp data for the three types of signals. The range of values ​​for N and the basis for its determination are determined through communication protocol delay analysis.

8. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The liquid level fluctuation identification module includes: The liquid level difference calculation submodule obtains the liquid level position values ​​corresponding to adjacent time points in the current cycle and the previous cycle based on the liquid level value consistency description result, calculates the difference between the two in turn, and retains the change direction information of each time point in the difference sequence to generate a liquid level difference direction sequence. The trend direction identification submodule calls the liquid level difference direction sequence, counts the number of consecutive repetitions of the direction value, determines the frequency of consecutive rises and falls, accumulates the consecutive differences under the same direction, constructs a set of total differences and durations under each direction, and obtains continuous trend feature values. The boundary segment marking submodule extracts the direction switching position and the total difference before and after based on the continuous trend feature value, determines whether the value exceeds the set boundary expansion threshold, marks the direction switching segment that meets the condition, and establishes the fluctuating boundary segment. The set boundary expansion threshold is defined as the threshold for determining whether the cumulative total of the liquid level difference at the point of continuous trend switching is sufficient to effectively mark the changing boundary.

9. The floor scrubber wastewater tank water level detection system based on a liquid level sensor according to claim 1, characterized in that: The alarm action linkage module includes: The region comparison submodule obtains the current liquid level position value based on the fluctuation boundary segment, performs interval determination on the corresponding position of the current liquid level value on the coordinate axis and the start and end positions of the boundary expansion interval, determines whether the liquid level value is within the expansion interval, and generates a region placement determination result. The status verification submodule calls the area placement judgment result, obtains the status mark content of each corresponding moment in the liquid level value consistent description result, filters the time nodes with the status mark as valid, and checks them against the positions with true values ​​in the judgment result, obtains the index set that meets both conditions at the same time, and generates an alarm trigger index sequence. The action triggering submodule triggers the alarm device status action at the corresponding time point according to the alarm triggering index sequence, writes the alarm status change instruction into the action execution record table, generates the corresponding action response timestamp and registers it, and establishes the sewage tank water level detection result.

10. A method for detecting the water level in the wastewater tank of a floor scrubber based on a liquid level sensor, characterized in that, The method is used to implement the floor scrubber wastewater tank water level detection system based on a liquid level sensor as described in any one of claims 1-9, and includes the following steps: S1: Obtain the readings of the capacitance sensor attached to the side wall of the wastewater tank of the floor scrubber, determine whether the direction of the difference is consistently consistent, eliminate abrupt changes, filter out stable fluctuation ranges, and obtain the capacitance change sequence. S2: Based on the average value of the capacitance change sequence, determine the voltage segment, match the capacity number position, find its corresponding liquid level height, and obtain the converted liquid level position; S3: Based on the calculated liquid level position, compare the status codes of Modbus, CAN, and LoRa channels, determine the time interval and the data source concentration statistics, and obtain a liquid level value consistent description result. S4: Based on the consistent description results of the liquid level values, calculate the direction and frequency of the difference in the converted liquid level position between adjacent periods, extract the trend extension range, and obtain the fluctuation boundary segment; S5: Compare the converted liquid level position with the fluctuation boundary section, combine the liquid level value with the consistent description result status mark, determine whether to trigger an alarm, and obtain the sewage tank water level detection result.

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