Self-adaptive switching heavy-load liquid cargo liquid shake detection control system

Abstract

The invention provides a self-adaptive switching heavy-load liquid cargo liquid oscillation detection control system, which relates to the field of electric digital data processing, and comprises a container type identification unit, a detection mode switching unit, a liquid oscillation feature extraction unit, a wave height equivalent calculation unit and a PID feedback control unit. The container type identification unit applies calibration excitation to automatically judge the type of the container after each loading is completed; the detection mode switching unit completes linkage switching and locking of a liquid oscillation feature extraction mode and a PID parameter group before starting according to a judgment result; the liquid oscillation feature extraction unit applies phase compensation to the difference signal in an open container mode, and directly filters and outputs the difference signal at a relatively high cut-off frequency in a closed container mode; and the PID feedback control unit selects a corresponding parameter group to output speed correction in real time according to the type of the container. According to the invention, automatic identification and self-adaptive switching of two container scenes are realized by using a single sensor group, and the operation burden and safety risk of manual switching are eliminated.

Description

Technical Field

[0001] This invention relates to the field of electronic digital data processing, and more specifically to an adaptive switching detection and control system for heavy-duty liquid cargo sloshing. Background Technology

[0002] Heavy-duty circular rail shuttles are used in industrial logistics and warehousing scenarios to transport heavy-duty liquid goods, and liquid sloshing is a common problem during transportation. Liquid sloshing refers to the phenomenon where liquid inside a container sloshes under the acceleration of the vehicle. This can lead to minor issues like liquid spillage or cargo instability, or even container tipping, causing property damage and personal injury. Effectively detecting and controlling liquid sloshing wave height is a key technical issue for ensuring the safe transportation of heavy-duty liquid goods.

[0003] In real-world industrial scenarios, various types of containers are used for heavy-duty liquid goods, and it is common for open and closed containers to alternate within the same logistics system. In open containers, the liquid has a free surface, and liquid sloshing manifests as surface fluctuations, with wave height that can be directly measured. In closed containers, the liquid is completely enclosed, with no free surface, and liquid sloshing is manifested as the impact force of the liquid against the container walls; wave height cannot be directly measured. The fundamental differences in the liquid sloshing dynamics between the two types of containers present different technical requirements for their detection and control.

[0004] Existing liquid sloshing detection technologies are primarily designed for specific container types, lacking unified coverage for both open and closed containers. For open containers, liquid sloshing detection typically uses ultrasonic level sensors to directly measure the liquid surface wave height. This approach requires the sensor probe to be directly facing the liquid surface, placing high demands on installation conditions and rendering it completely unsuitable for closed containers. For closed containers, liquid sloshing detection usually indirectly reflects the liquid impact state using accelerometers or pressure sensors. However, the response characteristics of this approach to free surface fluctuations differ significantly between open and closed containers. Applying the same set of detection parameters to both container scenarios will drastically reduce detection accuracy.

[0005] When shuttle transport tasks switch between open and closed containers, existing systems typically rely on operators to manually switch detection modes and control parameters. This not only increases the operational burden but also poses a safety risk due to oversights in manual switching, leading to a mismatch between the detection mode and the actual container type. Currently, there is no liquid sloshing detection and control system specifically designed for heavy-duty shuttle scenarios that can automatically identify container types and adaptively switch detection modes and control parameters. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings by proposing an adaptive switching control system for detecting and controlling liquid sloshing in heavy-duty liquid cargo.

[0007] The present invention adopts the following technical solution: An adaptive switching heavy-duty liquid cargo sloshing detection and control system includes a container type identification unit, a detection mode switching unit, a sloshing feature extraction unit, a wave height equivalent calculation unit, and a PID feedback control unit. Each unit operates in a shuttle car PLC controller. The system uses a bottom four-corner weighing sensor group as the detection hardware. The bottom four-corner weighing sensor group consists of four weighing sensors installed at the four corners of the shuttle car's cargo platform, corresponding to the four support points of front left, front right, rear left, and rear right, respectively, and continuously outputs the real-time support force of each support point. After each loading is completed, the container type identification unit sends a calibration excitation command to the drive system, which drives the shuttle to perform a small-amplitude reciprocating motion with controlled amplitude along the direction of travel. Simultaneously, it collects the front and rear axle support force difference signal of the bottom four corner weighing sensor group and the excitation acceleration signal output by the drive system, extracts two feature parameters: phase lag and signal attenuation time constant, and outputs the container type identification result after comprehensive judgment. The detection mode switching unit receives the container type judgment result, completes the switching and locking of the detection mode before the shuttle starts running, and sends the container type flag to the liquid sloshing feature extraction unit and the PID feedback control unit. The liquid sloshing feature extraction unit selects the corresponding signal processing method according to the container type mark, processes the real-time support force signal of the bottom four corner weighing sensor group, and outputs the longitudinal and transverse liquid sloshing difference signal to the wave height equivalent calculation unit. The wave height equivalent calculation unit selects the corresponding conversion coefficient group according to the container type flag, and converts the longitudinal and transverse difference signals into an equivalent comprehensive wave height, which is then output to the PID feedback control unit. The PID feedback control unit runs the PID control algorithm with the liquid sloshing safety wave high threshold as the set value, selects the corresponding PID parameter group according to the container type flag, and outputs the speed correction to the shuttle motion control system.

[0008] Furthermore, the method for the container type identification unit to extract the phase hysteresis is as follows: The front and rear axle support force difference signal and the excitation acceleration signal are respectively subjected to bandpass filtering preprocessing. The filtering frequency band is centered on the calibrated excitation frequency, and the bandwidth is set to ±50% of the calibrated excitation frequency. Using the number of sampling points corresponding to the calibrated excitation duration as the calculation window, discrete cross-correlation calculation is performed on the two filtered signals, and the time delay corresponding to the peak value of the cross-correlation function sequence is taken as the estimated value of phase lag. If the phase lag exceeds a preset phase threshold, it is identified as an open container; if it is below the preset phase threshold, it is identified as a closed container.

[0009] Furthermore, the method for the container type identification unit to extract the signal attenuation time constant is as follows: Weighted least squares exponential decay fitting is performed on the attenuation segment of the front and rear axle support force difference signal after the calibration excitation ends. The weighting coefficient is set according to the signal-to-noise ratio of each sampling point, and sampling points with higher signal-to-noise ratio are given greater weight. When the fitting residual exceeds the preset residual threshold, the judgment result of the decay time constant is abandoned, and only the judgment result of the phase lag is used as the final basis and the fitting abnormality mark is recorded. If the decay time constant exceeds the preset decay threshold, it is judged as an open container; if it is below the preset decay threshold, it is judged as a closed container.

[0010] Furthermore, the container type identification unit outputs the final container type based on the judgment results of two characteristic parameters: phase lag and signal attenuation time constant. If the two judgment results are consistent, the result is directly adopted; if the two judgment results are inconsistent, the phase lag judgment result is used, and an abnormality flag is recorded at the same time.

[0011] Furthermore, the acceleration amplitude of the calibration excitation is determined based on the rated liquid level height and liquid density of the container, with the lower limit being the ability to generate a difference signal of not less than 5% of the full scale in the four corner weighing sensor groups at the bottom, and the upper limit being no more than 50% of the liquid sloshing safety wave height threshold, and the middle value is taken within the range of the upper and lower limits. The calibration excitation duration is set to 1.5 times the estimated period of free sloshing of the liquid.

[0012] Furthermore, the liquid sloshing feature extraction unit performs the following processing in the open container detection mode: Calculate the difference in support force between the front and rear axles and the difference in support force between the left and right sides to obtain the original longitudinal difference signal and the original lateral difference signal; The real-time phase compensation amount is obtained by interpolating from a table based on the current liquid level height, and phase compensation is applied to the two original difference signals. The compensated signal is low-pass filtered and then output to the wave height equivalent calculation unit.

[0013] Furthermore, the liquid sloshing feature extraction unit performs the following processing in the closed container detection mode: Calculate the difference in support force between the front and rear axles and the difference in support force between the left and right sides to obtain the original longitudinal difference signal and the original lateral difference signal; The two original difference signals are directly processed by low-pass filtering and then output to the wave height equivalent calculation unit. In closed container detection mode, the cutoff frequency of the low-pass filter is higher than that in open container detection mode.

[0014] Furthermore, upon receiving the container type flag, the PID feedback control unit executes the following switching procedure: First, clear the current accumulated value of the points to zero; Then switch the proportional term coefficient, integral term coefficient, and differential term coefficient to the parameter group corresponding to the container type; After the switching is completed, a parameter switching completion confirmation signal is sent to the detection mode switching unit; The detection mode switching unit can send a shuttle start permission signal to the drive system only after receiving a confirmation signal; The PID parameter group remains locked during shuttle operation and can only be unlocked after the shuttle stops and unloads its cargo at the end of the current transport mission.

[0015] Furthermore, the detection mode switching unit performs a switching process once after each loading is completed and the container type identification is finished. Even if the identification result is the same as the previous one, the zeroing operation of the integral term of the PID feedback control unit is still forcibly executed. After the shuttle arrives at the unloading position, completes unloading, and stops, the detection mode switching unit releases the detection mode lock and PID parameter group lock, and the system returns to the initial state of waiting for the next loading.

[0016] The beneficial effects achieved by this invention are: This invention achieves automatic container type identification by comprehensively judging two characteristic parameters: phase lag and signal decay time constant under calibrated excitation. Phase lag reflects the essential difference in force transmission paths between open and closed containers, while the decay time constant reflects the essential difference in liquid sloshing dynamics between the two types of containers. Both characteristic parameters originate from the physical mechanisms of the container's liquid sloshing dynamics and have clear physical meaning and distinguishability. Compared to identification schemes relying on a single feature, the comprehensive judgment using dual characteristic parameters maintains a stable identification accuracy even when liquid level, liquid density, or environmental vibrations change. Furthermore, when a single characteristic parameter fails due to fitting anomalies, the system can automatically degrade to single-feature judgment and record the anomaly, ensuring the robustness of the identification process.

[0017] This invention links the liquid sloshing feature extraction mode, the conversion coefficient group, and the PID parameter group during detection mode switching. After the switching is completed, the system is locked until the end of the current task. During the switching process, the integral term is forcibly cleared to eliminate the influence of the integral quantity left over from the previous task on the control accuracy of the new mode. Furthermore, the interlocking mechanism between the parameter switching completion confirmation signal and the start permission signal ensures that the shuttle car cannot start before the switching is completed. This mechanism eliminates the safety risk of the detection mode not matching the actual container type due to human error during switching.

[0018] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structural framework of the present invention; Figure 2 This is a schematic diagram of the container type identification process of the present invention; Figure 3 This is a schematic diagram illustrating the comparison of the signal characteristics of the difference between open and closed containers according to the present invention; Figure 4 This is a schematic diagram comparing the processing flow of two modes of the liquid sloshing feature extraction unit of the present invention; Figure 5 This is a schematic diagram of the system operation timing of the present invention. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions; this is stated beforehand. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention.

[0021] Example 1.

[0022] An adaptive switching heavy-duty liquid cargo sloshing detection and control system, combined with Figure 1 It includes a container type identification unit, a detection mode switching unit, a liquid sloshing feature extraction unit, a wave height equivalent calculation unit, and a PID feedback control unit, each of which runs in the shuttle car PLC controller.

[0023] The system uses a set of four bottom corner weighing sensors as the detection hardware. By applying different analysis and processing methods to the same set of sensor signals, it achieves integrated control of automatic container type identification, adaptive switching of detection mode, and high real-time quantization of liquid sloshing waves.

[0024] The bottom four-corner weighing sensor group consists of four weighing sensors installed at the four corners of the shuttle truck's cargo platform, corresponding to the four support points: front left, front right, rear left, and rear right. It continuously outputs the real-time support force of each support point. The sampling frequency is synchronized with the sampling cycle of the PLC controller. The sum of the support forces of the four weighing sensors reflects the total weight of the container and liquid. The difference in the front and rear axle support forces along the direction of travel reflects the longitudinal dynamic distribution of the liquid in the container, and the difference in the left and right support forces perpendicular to the direction of travel reflects the lateral dynamic distribution of the liquid.

[0025] Combination Figure 2The container type identification unit is responsible for automatically determining the type of container being loaded before each time the shuttle completes loading and starts operation. After the shuttle is stationary and loaded, the container type identification unit sends a calibration excitation command to the drive system, which drives the shuttle to perform a small-amplitude reciprocating motion with controlled amplitude along the direction of travel. This applies a longitudinal inertial excitation of known amplitude to the liquid inside the container. The acceleration amplitude and duration of the calibration excitation are pre-calibrated to ensure that a measurable sloshing response is generated to the liquid without causing liquid spillage or cargo instability.

[0026] The acceleration amplitude of the calibration excitation is determined based on the rated liquid level and liquid density of the container. The lower limit is set at generating a difference signal of no less than 5% of the full scale in the four corner weighing sensor groups at the bottom, and the upper limit is set at no more than 50% of the safe wave height threshold of the liquid sloshing. The midpoint between the upper and lower limits is taken as the calibration excitation acceleration amplitude to ensure that the excitation intensity is sufficient to excite a measurable liquid sloshing response while retaining sufficient safety margin. The calibration excitation duration is set to 1.5 times the estimated period of free sloshing of the liquid. The estimated period of free sloshing of the liquid is initially estimated based on the internal cavity dimensions of the container along the direction of travel and the rated liquid level using an empirical formula, so that the liquid can undergo at least one complete decaying oscillation cycle after the excitation ends, providing sufficient signal length for the subsequent extraction of the decay time constant. When the container specifications or liquid density change, the calibration excitation parameters are recalculated based on the new container parameters.

[0027] During the calibration excitation application period, the container type identification unit synchronously collects the front and rear axle support force difference signals of the bottom four corner weighing sensor group, and compares and analyzes them with the excitation acceleration signal synchronously output by the drive system to extract the following two feature parameters for container type determination.

[0028] The first characteristic parameter is the phase lag. When the liquid in the open container is excited, it generates free surface ripples. The liquid momentum is transferred to the container wall and then to the bottom support structure through the surface ripples. This transfer path is relatively long, resulting in a significant phase lag between the front and rear axis support force difference signal and the excitation acceleration signal. In the closed container, the liquid is completely sealed and directly impacts the container wall when excited. The force transfer path is short, and the phase lag between the front and rear axis support force difference signal and the excitation acceleration signal is significantly smaller than that of the open container. The container type identification unit performs the following calculation process on the front and rear axle support force difference signal and the excitation acceleration signal to extract the phase hysteresis: First, bandpass filtering preprocessing is performed on the two signals respectively. The filtering frequency band is centered on the calibrated excitation frequency, and the bandwidth is set to ±50% of the calibrated excitation frequency. Low-frequency drift and high-frequency vibration noise are filtered out, and signal components related to the excitation frequency are retained.

[0029] Using the number of sampling points corresponding to the calibrated excitation duration as the calculation window, discrete cross-correlation calculation is performed on the two filtered signals within this window to obtain a cross-correlation function sequence.

[0030] The time delay corresponding to the peak value of the cross-correlation function sequence is taken as the estimated value of the phase lag.

[0031] If the phase lag exceeds a preset phase threshold, it is identified as an open container; if it is below the preset phase threshold, it is identified as a closed container.

[0032] The phase threshold was determined through an offline calibration experiment. In the calibration experiment, calibration excitation was applied to typical open containers and typical closed containers under different liquid levels and different liquid densities. The phase lag was collected and calculated under each working condition. The midpoint value of the distribution range of the two sets of phase lag values ​​for open containers and closed containers was taken as the phase threshold.

[0033] The second characteristic parameter is the signal attenuation time constant. After the calibration excitation is completed, the container type identification unit performs weighted least squares exponential attenuation fitting on the subsequent attenuation segment of the difference signal between the front and rear axle support forces. The attenuation time constant obtained by fitting is used as the second characteristic parameter. The fitting model is the product of the amplitude and the attenuation time constant plus a constant term. The fitting input is the sampling sequence of the difference signal continuously collected after the calibration excitation is completed. The fitting output is the estimated value of the attenuation time constant. The weighting coefficient is set according to the signal-to-noise ratio of each sampling point. Sampling points with higher signal-to-noise ratios are given greater weights. The attenuation threshold is determined in the same way as the phase threshold, taking the midpoint value of the attenuation time constant distribution range of the two groups of open and closed containers.

[0034] Combination Figure 3 The container type identification unit outputs the final container type based on the combined judgment results of two characteristic parameters: phase lag and signal attenuation time constant. If the two judgment results are consistent, the result is directly adopted; if the two judgment results are inconsistent, the phase lag judgment result shall prevail, and an anomaly flag shall be recorded for operation and maintenance personnel to check.

[0035] The detection mode switching unit receives the container type judgment result output by the container type identification unit, completes the switching and locking of the detection mode before the shuttle starts running, and sends the container type flag to the liquid sloshing feature extraction unit and the PID feedback control unit to trigger the switching of the corresponding parameter group. During operation, the detection mode remains fixed and does not switch until the shuttle completes the current transportation task and stops to unload, at which point the next identification and switching process can be triggered.

[0036] Combination Figure 4 The liquid sloshing feature extraction unit receives the real-time support force signal from the four bottom corner weighing sensor groups, selects the corresponding signal processing method to extract the liquid sloshing feature according to the container type flag sent by the detection mode switching unit, and outputs it to the wave height equivalent calculation unit.

[0037] In open container detection mode, the liquid sloshing feature extraction unit performs the following processing flow on the raw support force signal of the bottom four corner weighing sensor group: First, the difference between the front and rear axle support forces and the difference between the left and right side support forces are calculated to obtain the original longitudinal difference signal and the original lateral difference signal. Since the force of the liquid fluctuation on the container wall is transmitted to the bottom support through the container structure, there is phase lag and amplitude attenuation. The original difference signal cannot directly reflect the real-time state of the liquid surface fluctuation. Phase compensation processing needs to be applied to the two original difference signals respectively.

[0038] Phase compensation is achieved by performing a fixed-duration advance shift on the original difference signal. The advance shift duration is the phase compensation amount. The phase compensation amount is determined in the offline calibration experiment based on the container geometry and the rated liquid level. During calibration, a calibration excitation is applied to an open container with a known liquid level, and the phase lag of the original difference signal relative to the excitation acceleration signal is measured. This phase lag amount is stored in the parameter table as the phase compensation amount at the corresponding liquid level. During runtime, the real-time phase compensation amount is obtained by interpolation based on the current liquid level.

[0039] The longitudinal and lateral difference signals after phase compensation are then processed by low-pass filtering to remove high-frequency noise introduced by vehicle vibration, and output to the wave height equivalent calculation unit.

[0040] In the closed container detection mode, the liquid sloshing feature extraction unit also first calculates the difference between the front and rear axial support forces and the difference between the left and right side support forces to obtain the original longitudinal difference signal and the original lateral difference signal. The impact force of the liquid in the closed container on the container wall is directly transmitted to the bottom support with minimal phase lag, so no phase compensation processing is required. The two original difference signals are directly output to the wave height equivalent calculation unit after low-pass filtering. In the closed container detection mode, the cutoff frequency of the low-pass filter is appropriately increased compared to the open container detection mode to retain the components with higher response frequencies in the liquid impact signal of the closed container and avoid the liquid sloshing impact peak being filtered out due to the cutoff frequency being too low.

[0041] The wave height equivalent calculation unit receives the longitudinal and transverse difference signals output by the liquid sloshing feature extraction unit. Based on the container type, it selects the corresponding conversion coefficients and converts the difference signals into equivalent longitudinal wave height components and equivalent transverse wave height components. The equivalent comprehensive wave height is then synthesized and output to the PID feedback control unit. Open containers and closed containers correspond to different conversion coefficient sets. The conversion coefficients are determined through calibration experiments. During calibration, regression fitting is performed on the support force difference signals under different liquid level heights and different excitation amplitudes and the measured wave heights of liquid sloshing to obtain the conversion coefficient sets for open containers and closed containers, respectively.

[0042] The PID feedback control unit receives the equivalent comprehensive wave height output by the wave height equivalent calculation unit, runs the PID control algorithm with the liquid sloshing safe wave height threshold as the set value, and outputs the speed correction to the shuttle motion control system. The PID feedback control unit configures independent PID parameter groups for open containers and closed containers respectively. The liquid sloshing attenuation of open containers is relatively slow and the liquid surface fluctuation inertia is large. The integral term coefficient in the corresponding PID parameter group is large to eliminate continuous deviation, and the derivative term coefficient is moderate. The liquid impact response of closed containers is rapid and the force transmission path is short. The proportional term coefficient and derivative term coefficient in the corresponding PID parameter group are relatively large to achieve fast response, and the integral term coefficient is relatively small. After the container type identification unit completes identification and outputs the container type judgment result, the detection mode switching unit immediately sends a container type flag to the PID feedback control unit. Upon receiving the container type flag, the PID feedback control unit executes the following switching procedure: First, clear the current accumulated points to zero, eliminating the points left over from the previous transport mission; Then switch the proportional term coefficient, integral term coefficient, and differential term coefficient to the parameter group corresponding to the container type; After the switch is completed, a parameter switch completion confirmation signal is sent to the detection mode switching unit.

[0043] Only after the detection mode switching unit receives the parameter switching completion confirmation signal can it send the shuttle start permission signal to the drive system. The shuttle must not start running before the PID parameter group switching is completed.

[0044] The above switching process is executed once after each loading and container type identification is completed. Even if the identification result is the same as the previous one, the integral term clearing operation is still forcibly executed to ensure that PID control is started in the initial state for each transportation task. During the operation of the shuttle, the PID parameter group remains locked and does not respond to any parameter switching requests until the transportation task is completed, the vehicle stops, and the equipment is unloaded.

[0045] Example 2: Combination Figure 5 This embodiment uses a complete transportation task as an example to illustrate the working sequence of each unit of the system.

[0046] After the shuttle completes loading at the loading position, the drive system remains stationary. Upon detecting the loading completion signal, the container type identification unit initiates the identification process. The container type identification unit sends a calibration excitation command to the drive system, driving the shuttle to perform a small-amplitude reciprocating motion with controlled amplitude along the direction of travel. During the calibration excitation, the four corner weighing sensor groups continuously collect the support force at each support point and calculate the difference signal between the front and rear axle support forces in real time. The container type identification unit simultaneously receives this difference signal and the excitation acceleration signal output by the drive system. After performing bandpass filtering preprocessing on the two signals, it performs discrete cross-correlation calculation within the calculation window corresponding to the calibration excitation duration to extract the phase lag and complete the first feature parameter judgment. After the calibration excitation ends, the container type identification unit continues to collect the subsequent attenuation segment of the difference signal, performs weighted least squares exponential attenuation fitting to extract the attenuation time constant, and completes the second feature parameter judgment. After both feature parameter judgment results are obtained, the container type identification unit outputs the final container type judgment result and transmits it to the detection mode switching unit.

[0047] After receiving the container type judgment result, the detection mode switching unit immediately sends a container type flag to the liquid sloshing feature extraction unit to complete the detection mode switching and locking. At the same time, it sends a container type flag to the PID feedback control unit to trigger the PID parameter group switching process. After receiving the container type flag, the PID feedback control unit sequentially executes the integral term clearing and parameter group switching. After the switching is completed, it sends a parameter switching completion confirmation signal to the detection mode switching unit. After receiving the confirmation signal, the detection mode switching unit sends a shuttle start permission signal to the drive system, and the shuttle enters normal operation.

[0048] After the shuttle vehicle starts operating, the four corner weighing sensor groups at the bottom continuously collect the support force at each support point. The liquid sloshing feature extraction unit selects the corresponding signal processing flow based on the locked container type flag. If it is an open container mode, the liquid sloshing feature extraction unit calculates the difference between the front and rear axles and the left and right side support forces, and obtains the real-time phase compensation amount by interpolation based on the current liquid level. After applying phase compensation to the two difference signals, the signals are low-pass filtered and output to the wave height equivalent calculation unit. If it is a closed container mode, the liquid sloshing feature extraction unit calculates the difference between the front and rear axles and the left and right side support forces, and directly passes the signals through a low-pass filter with a higher cutoff frequency. After processing, the signal is output to the wave height equivalent calculation unit. The wave height equivalent calculation unit selects the corresponding conversion coefficient group according to the container type mark, converts the longitudinal and lateral difference signals into equivalent longitudinal wave height components and equivalent lateral wave height components, and synthesizes the equivalent comprehensive wave height and continuously outputs it to the PID feedback control unit. The PID feedback control unit uses the liquid sloshing safe wave height threshold as the set value and continuously runs the PID control algorithm according to the currently locked PID parameter group. It outputs the speed correction amount to the shuttle motion control system in real time to dynamically correct the shuttle's travel speed and suppress the liquid sloshing wave height within the safe threshold.

[0049] After the shuttle arrives at the unloading position, completes unloading, and stops, the detection mode switching unit detects the task end signal, releases the detection mode lock and PID parameter group lock, and the system returns to the initial state of waiting for the next loading. After the next loading is completed, the container type identification process is triggered again, and the adaptive switching process for the next transportation task is entered.

[0050] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of protection of the present invention. Therefore, all equivalent technical changes made based on the content of the present invention specification and drawings are included within the scope of protection of the present invention. Furthermore, the elements therein can be updated as technology develops.

Claims

1. An adaptive switching control system for detecting and controlling liquid sloshing in heavy-duty liquid cargo, characterized in that, The system includes a container type identification unit, a detection mode switching unit, a liquid sloshing feature extraction unit, a wave height equivalent calculation unit, and a PID feedback control unit. Each unit operates in the shuttle car PLC controller. The system uses a bottom four-corner weighing sensor group as the detection hardware. The bottom four-corner weighing sensor group consists of four weighing sensors installed at the four corners of the shuttle car's cargo platform, corresponding to the four support points: front left, front right, rear left, and rear right, respectively, and continuously outputs the real-time support force of each support point. After each loading is completed, the container type identification unit sends a calibration excitation command to the drive system, which drives the shuttle to perform a small-amplitude reciprocating motion with controlled amplitude along the direction of travel. Simultaneously, it collects the front and rear axle support force difference signal of the bottom four corner weighing sensor group and the excitation acceleration signal output by the drive system, extracts two feature parameters: phase lag and signal attenuation time constant, and outputs the container type identification result after comprehensive judgment. The detection mode switching unit receives the container type judgment result, completes the switching and locking of the detection mode before the shuttle starts running, and sends the container type flag to the liquid sloshing feature extraction unit and the PID feedback control unit. The liquid sloshing feature extraction unit selects the corresponding signal processing method according to the container type mark, processes the real-time support force signal of the bottom four corner weighing sensor group, and outputs the longitudinal and transverse liquid sloshing difference signal to the wave height equivalent calculation unit. The wave height equivalent calculation unit selects the corresponding conversion coefficient group according to the container type flag, and converts the longitudinal and transverse difference signals into an equivalent comprehensive wave height, which is then output to the PID feedback control unit. The PID feedback control unit runs the PID control algorithm with the liquid sloshing safety wave high threshold as the set value, selects the corresponding PID parameter group according to the container type flag, and outputs the speed correction to the shuttle motion control system.

2. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 1, characterized in that, The method for extracting phase hysteresis by the container type identification unit is as follows: The front and rear axle support force difference signal and the excitation acceleration signal are respectively subjected to bandpass filtering preprocessing. The filtering frequency band is centered on the calibrated excitation frequency, and the bandwidth is set to ±50% of the calibrated excitation frequency. Using the number of sampling points corresponding to the calibrated excitation duration as the calculation window, discrete cross-correlation calculation is performed on the two filtered signals, and the time delay corresponding to the peak value of the cross-correlation function sequence is taken as the estimated value of phase lag. If the phase lag exceeds a preset phase threshold, it is identified as an open container; if it is below the preset phase threshold, it is identified as a closed container.

3. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 2, characterized in that, The method for extracting the signal attenuation time constant by the container type identification unit is as follows: Weighted least squares exponential decay fitting is performed on the attenuation segment of the front and rear axle support force difference signal after the calibration excitation ends. The weighting coefficient is set according to the signal-to-noise ratio of each sampling point, and sampling points with higher signal-to-noise ratio are given greater weight. When the fitting residual exceeds the preset residual threshold, the judgment result of the decay time constant is abandoned, and only the judgment result of the phase lag is used as the final basis and the fitting abnormality mark is recorded. If the decay time constant exceeds the preset decay threshold, it is judged as an open container; if it is below the preset decay threshold, it is judged as a closed container.

4. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 3, characterized in that, The container type identification unit outputs the final container type based on the judgment result of two characteristic parameters: phase lag and signal attenuation time constant. If the two judgment results are consistent, the result is directly adopted; if the two judgment results are inconsistent, the phase lag judgment result is used, and an abnormality flag is recorded at the same time.

5. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 4, characterized in that, The acceleration amplitude of the calibration excitation is determined based on the rated liquid level height and liquid density of the container. The lower limit is that it can generate a difference signal of not less than 5% of the full scale in the four corner weighing sensor groups at the bottom, and the upper limit is that it does not exceed 50% of the liquid sloshing safety wave height threshold. The middle value is taken within the range of the upper and lower limits. The calibration excitation duration is set to 1.5 times the estimated period of free sloshing of the liquid.

6. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 5, characterized in that, The liquid sloshing feature extraction unit performs the following processing in the open container detection mode: Calculate the difference in support force between the front and rear axles and the difference in support force between the left and right sides to obtain the original longitudinal difference signal and the original lateral difference signal; The real-time phase compensation amount is obtained by interpolating from a table based on the current liquid level height, and phase compensation is applied to the two original difference signals. The compensated signal is low-pass filtered and then output to the wave height equivalent calculation unit.

7. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 6, characterized in that, The liquid sloshing feature extraction unit performs the following processing in the closed container detection mode: Calculate the difference in support force between the front and rear axles and the difference in support force between the left and right sides to obtain the original longitudinal difference signal and the original lateral difference signal; The two original difference signals are directly processed by low-pass filtering and then output to the wave height equivalent calculation unit. In closed container detection mode, the cutoff frequency of the low-pass filter is higher than that in open container detection mode.

8. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 7, characterized in that, Upon receiving the container type flag, the PID feedback control unit executes the following switching procedure: First, clear the current accumulated value of the points to zero; Then switch the proportional term coefficient, integral term coefficient, and differential term coefficient to the parameter group corresponding to the container type; After the switching is completed, a parameter switching completion confirmation signal is sent to the detection mode switching unit; The detection mode switching unit can send a shuttle start permission signal to the drive system only after receiving a confirmation signal; The PID parameter group remains locked during shuttle operation and can only be unlocked after the shuttle stops and unloads its cargo at the end of the current transport mission.

9. The adaptive switching heavy-duty liquid cargo sloshing detection and control system as described in claim 8, characterized in that, The detection mode switching unit performs a switching process once after each loading is completed and the container type identification is finished. Even if the identification result is the same as the previous one, the zeroing operation of the integral term of the PID feedback control unit is still forcibly executed. After the shuttle arrives at the unloading position, completes unloading, and stops, the detection mode switching unit releases the detection mode lock and PID parameter group lock, and the system returns to the initial state of waiting for the next loading.

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