Tension adjustment system and method for an environmental perception based bucket wheel boom belt conveyor

Abstract

The application discloses a tension adjusting system and method of an environmental perception-based bucket wheel suspension belt conveyor, which comprises an environmental perception module for collecting environmental temperature and environmental humidity in real time under environmental conditions; a friction coefficient calculation unit for obtaining an estimated value of the friction coefficient between the belt and the driving drum liner according to the environmental temperature, the environmental humidity and a preset friction coefficient mapping model; an optimal tension force calculation unit for calculating an optimal target tension force value under the current environmental conditions based on the estimated value of the friction coefficient; a hydraulic execution module comprising a tension drum for changing the tensioning stroke of the belt, a hydraulic cylinder for driving the tension drum to move through a transmission mechanism and adjusting the actual tension force of the belt; a belt tension feedback module for detecting the actual tension force detection value of the belt in real time; and a control output unit for calculating the deviation of the optimal target tension force value and the actual tension force detection value and controlling the action of the hydraulic cylinder according to the deviation. The application has the feedforward pre-adjusting capability based on the change of environmental parameters.

Description

Technical Field

[0001] This invention relates to the field of bucket wheel excavator technology, and more specifically, to a tension adjustment system and method for a bucket wheel excavator cantilever belt conveyor based on environmental perception. Background Technology

[0002] Bucket wheel excavators are core equipment for bulk material handling operations, with their cantilever belt conveyors responsible for the continuous transport of materials at the cantilever end. The vertical tensioning device is a crucial component of the cantilever belt conveyor; its function is to provide appropriate pretension to the belt, ensuring sufficient frictional driving force between the drive drum and the belt, preventing the belt from slipping on the drive drum, and avoiding excessive tension that could lead to overstretching of the belt, overload of the drum bearings, and increased operating energy consumption.

[0003] Bucket wheel excavators typically operate in open-air environments, experiencing significant diurnal and seasonal temperature variations, as well as fluctuating humidity levels. These temperature and humidity changes alter the coefficient of friction between the conveyor belt and the drum liner: as temperature rises, the conveyor belt material softens, causing the coefficient of friction to vary within a certain range; as humidity increases, a water film may form on the conveyor belt surface and drum liner, shifting the coefficient of friction. Under fixed tension, this shift in the coefficient of friction means that the actual effective driving force fluctuates accordingly—a decrease in the coefficient of friction may lead to slippage, while an increase in the coefficient of friction results in unnecessarily excessive tension.

[0004] Currently, there are several main solutions for vertical tensioning technology of bucket wheel excavator cantilever belt conveyors.

[0005] (1) Gravity-based tensioning with a counterweight: A counterweight is suspended below the vertical tensioning roller, using gravity to provide a constant tension force. This method has a simple structure, but the counterweight usually weighs between 2 and 4 tons, which significantly increases the structural load on the cantilever. Once the counterweight is set, it cannot be dynamically adjusted according to changes in working conditions or environment, and it occupies a large space, which has an adverse effect on the pitching motion of the cantilever and the overall stability of the machine.

[0006] (2) Manual / Screw-type mechanical tensioning: As shown in Chinese invention patent application CN201811528665.4, a handwheel is used to drive the screw to extend and retract to adjust the position of the tensioning roller. This solution replaces the gravity counterweight with a mechanical structure, reducing the overall weight of the machine, but it requires manual operation and lacks real-time performance. When the ambient temperature or humidity changes significantly during operation, it cannot respond in time, and the conveyor belt may slip or wear excessively due to tension mismatch.

[0007] (3) Hydraulic automatic tensioning without environmental perception: For example, Chinese invention patent application number CN202110859769.9 discloses a vertical hydraulic tensioning device, which drives the roller to slide vertically through a hydraulic push rod and uses a mechanical contact tension force sensing unit to realize basic automatic start and stop.

[0008] The aforementioned hydraulic automatic tensioning scheme represents an advancement from passive tensioning to active automatic adjustment. However, its control logic relies on feedback from the tension force itself (such as mechanical contacts or pressure signals) and preset operating modes (stacking / retrieving), failing to incorporate external parameters affecting the frictional characteristics of the conveyor belt and rollers, such as ambient temperature and humidity. In other words, these schemes can detect when the tension force is too low and compensate accordingly, but they cannot predict when rising temperature or humidity will cause a decrease in the coefficient of friction. When environmental conditions change rapidly, this purely feedback-based adjustment exhibits a response lag.

[0009] (4) Multi-sensor monitoring of general-purpose belt conveyors: For example, Chinese invention patent application CN202511184463.2 discloses an intelligent tension adjustment and control system for belt conveyors, which arranges temperature and humidity sensors on general-purpose belt conveyors as part of the environmental information acquisition module. However, the main purpose of the temperature and humidity data in this scheme is for environmental background monitoring and target detection of materials on the conveyor belt (based on the YOLO algorithm), not for calculating the belt-drum friction coefficient, nor for participating in the calculation of the target value of tension force. In addition, this scheme is aimed at general-purpose belt conveyors and does not involve the vertical tensioning structure characteristics and variable angle pitching conditions of bucket wheel excavator cantilever belt conveyors.

[0010] In summary, the existing technology has shortcomings in the following aspects:

[0011] It lacks the ability to coordinate the perception of two key environmental parameters, temperature and humidity; it lacks a quantitative calculation model for the friction coefficient between the conveyor belt and the roller from the ambient temperature and humidity; and it lacks a fully closed-loop intelligent control system that integrates environmental perception, friction coefficient calculation, optimal tension calculation, and hydraulic cylinder execution. Summary of the Invention

[0012] The purpose of this invention is to provide a tension adjustment system and method that integrates ambient temperature and humidity sensing, friction coefficient calculation, optimal tension force calculation, and hydraulic cylinder tensioning execution into a complete adaptive control closed loop, so as to improve the above-mentioned problems.

[0013] To achieve the above objectives, the present invention provides a tension adjustment system for a bucket wheel excavator cantilever conveyor belt machine based on environmental perception, including an environmental perception module, a data processing and control module, a hydraulic execution module, and a conveyor belt tension feedback module.

[0014] The environmental sensing module is used to collect ambient temperature and humidity data in real time under the current environmental conditions.

[0015] The data processing and control module includes a friction coefficient calculation unit, an optimal tension force calculation unit, and a control output unit;

[0016] The friction coefficient estimation unit obtains the estimated friction coefficient between the conveyor belt and the drive roller liner based on the ambient temperature, ambient humidity, and the preset friction coefficient mapping model. The optimal tension calculation unit calculates the optimal target tension value under the current environmental conditions based on the estimated friction coefficient.

[0017] The hydraulic actuator module includes a tensioning roller for changing the tensioning stroke of the conveyor belt. The hydraulic cylinder drives the tensioning roller to move through the transmission mechanism to adjust the actual tension of the conveyor belt.

[0018] The tape tension feedback module is used to detect the actual tension of the tape in real time.

[0019] The control output unit calculates the deviation between the optimal target tension value and the actual detected tension value, and controls the hydraulic cylinder to operate based on the deviation.

[0020] This invention also provides a tension adjustment method for a bucket wheel excavator cantilever conveyor belt based on environmental perception, comprising:

[0021] S1. The data processing and control module loads the parameters of the preset friction coefficient mapping model, the operating parameters of the belt conveyor, and the PID control parameters.

[0022] S2. The environmental sensing module collects ambient temperature and humidity at a preset sampling period, and transmits them to the friction coefficient calculation unit after signal conditioning and digital filtering.

[0023] S3. The friction coefficient estimation unit calculates the estimated value of the friction coefficient based on the current ambient temperature and humidity by calling the friction coefficient mapping model.

[0024] S4. The optimal tension calculation unit calculates the target value of the optimal tension force based on the estimated value of the friction coefficient and the current operating parameters of the belt conveyor.

[0025] S5. The tape tension feedback module collects the actual tension force detection value of the current tape and calculates the deviation between the optimal target tension force value and the actual tension force detection value.

[0026] S6. The control output unit calculates the hydraulic control signal based on the deviation and through the PID algorithm, and outputs it to the hydraulic actuator module to drive the hydraulic cylinder to move.

[0027] S7. Return to step S2 and enter the next control cycle.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. By simultaneously collecting ambient temperature and humidity parameters and incorporating them into tension control decisions, the system can detect drift in belt-roller friction characteristics caused by changes in environmental conditions, thus pre-adjusting the tension before slippage or excessive wear actually occurs. It possesses feedforward pre-adjustment capabilities based on changes in environmental parameters.

[0030] 2. The friction coefficient calculation unit establishes a friction coefficient mapping model, realizing a quantitative mapping from ambient temperature and humidity to the estimated friction coefficient. This provides a calculation basis for setting the tension force based on the current environmental friction conditions, rather than relying on empirical values ​​or fixed preset values. Taking a bucket wheel excavator with a material handling capacity of 3000 t / h as an example, in its typical operating environment (temperature range -15°C to +45°C, relative humidity range 15% to 95%), the measured variation of the friction coefficient between the conveyor belt and the drum liner under different temperature and humidity combinations can reach ±18% to ±25% of the benchmark value (20°C, 50%RH). Under the above extreme friction coefficient conditions, a fixed tension force scheme either risks slippage or remains in an excessively high tension state for a long time. This invention, through real-time calculation of the friction coefficient estimate and dynamic adjustment of the target tension, ensures that the tension always tracks changes in the friction coefficient estimate. Theoretically, this can reduce the probability of slippage caused by friction coefficient drift to near zero. Simultaneously, it automatically reduces the target tension in environments with high friction coefficients to alleviate the load on the bearings inside the conveyor belt and tension drum. This solves the problem of friction coefficient drift between the conveyor belt and drive drum caused by changes in ambient temperature and humidity during open-air operation of bucket wheel excavator cantilever conveyor belts, a problem that existing fixed or tension-feedback-based adjustment methods cannot anticipate.

[0031] 3. The dual-closed-loop control architecture combines the speed of feedforward with the accuracy of feedback. The outer loop environmental sensing → friction coefficient estimation → optimal target tension value calculation constitute the feedforward path. The response speed depends on the preset sampling period of the environmental sensing module and the control calculation period of the entire method (usually 0.5 to 2 seconds), which is much faster than the time lag of changes in environmental temperature and humidity. The inner loop belt tension feedback module provides feedback to form a closed-loop correction, eliminating the deviation between the friction coefficient estimation and the actual value. The two work together to avoid the cumulative error of pure feedforward open-loop control and the response lag of pure feedback control.

[0032] 4. The application of the system can reduce the frequency of manual inspections and manual tension adjustments of the cantilever conveyor belt of the bucket wheel excavator. Taking a bulk material stockpile equipped with 4 bucket wheel excavators as an example, the number of manual tension re-inspections due to changes in environmental conditions can be reduced by 1 to 2 per shift, reducing the exposure time of operators in the cantilever high-altitude area.

[0033] 5. The system's modular design allows it to be adapted for hydraulic tensioning retrofits of existing bucket wheel excavator cantilever belt conveyors. The environmental sensing module and data processing and control module can be added as independent units to the existing hydraulic tensioning actuator, communicating with the original PLC via CAN bus or RS-485 interface, without requiring replacement of the mechanical structure. This effectively reduces the retrofitting costs and downtime of existing equipment. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a diagram showing the overall architecture of the tension adjustment system disclosed in this invention;

[0036] Figure 2 This is a flowchart of the tension adjustment method disclosed in this invention;

[0037] Figure 3 This is a schematic diagram of the tension adjustment system disclosed in this invention;

[0038] Figure 4 This is a schematic diagram of the path structure of the tape bypassing the tension roller disclosed in this invention.

[0039] In the diagram: 1. Tensioning mounting bracket; 2. Hydraulic cylinder; 3. Tensioning roller; 4. Slide rail; 5. Accumulator; 6. Tension sensor. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0041] It should be noted that similar reference numerals or letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this invention, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] like Figure 1-3 The tension adjustment system of the bucket wheel excavator cantilever conveyor belt based on environmental perception shown includes an environmental perception module, a data processing and control module, a hydraulic execution module, and a conveyor belt tension feedback module.

[0043] The environmental sensing module is used to collect ambient temperature and humidity under the current environmental conditions;

[0044] The data processing and control module includes a friction coefficient calculation unit, an optimal tension force calculation unit, and a control output unit;

[0045] The friction coefficient estimation unit obtains the estimated friction coefficient between the conveyor belt and the drive roller liner based on the ambient temperature, ambient humidity, and the preset friction coefficient mapping model. The optimal tension calculation unit calculates the optimal target tension value under the current environmental conditions based on the estimated friction coefficient.

[0046] The hydraulic actuator module includes a tensioning roller 3 for changing the tensioning stroke of the conveyor belt, and a hydraulic cylinder 2 drives the tensioning roller to move through a transmission mechanism to adjust the actual tension of the conveyor belt.

[0047] The tape tension feedback module is used to detect the actual tension of the tape in real time.

[0048] The control output unit calculates the deviation between the optimal target tension value and the actual detected tension value, and controls the hydraulic cylinder to operate based on the deviation.

[0049] This invention provides a system capable of sensing changes in environmental conditions in real time and adaptively adjusting the belt tension accordingly, forming a closed-loop control chain of "sensing-decision-execution-feedback". An environmental sensing module is installed at an outdoor exposed location on the bucket wheel excavator's boom or body to collect real-time environmental temperature and humidity data, transmitting this data to a data processing and control module. The data processing and control module receives the environmental temperature and humidity data, calculates the optimal target tension value under the current environmental conditions, and outputs the corresponding hydraulic control command. By using both temperature and humidity as input variables for tension control, it differs from existing bucket wheel excavator tensioning devices that adjust solely based on preset operating modes or tension feedback. The data processing and control module includes a friction coefficient calculation unit, converting the real-time collected environmental temperature and humidity into an estimated value of the friction coefficient between the belt and the drive drum liner, providing a quantitative basis for calculating the optimal target tension.

[0050] The hydraulic actuator module includes a hydraulic station, a hydraulic cylinder, and a tensioning roller. It receives hydraulic control commands from the data processing and control module, drives the tensioning roller to move along the slide rail through the hydraulic cylinder, changes the tensioning stroke of the conveyor belt, and thus adjusts the actual tension of the conveyor belt.

[0051] The environmental sensing module includes a temperature sensor for collecting ambient temperature and a humidity sensor for collecting ambient humidity. The output signals of the temperature sensor and the humidity sensor are amplified and filtered by the signal conditioning circuit and then transmitted to the data processing and control module.

[0052] The data processing and control module also includes a data preprocessing unit, which performs digital filtering and outlier removal on the output signals from the received temperature and humidity sensors.

[0053] The environmental sensing module includes at least one temperature sensor and at least one humidity sensor. When multiple temperature or humidity sensors are used, the average value of the measurements from all sensors is taken as the ambient temperature and humidity data. The temperature sensor collects the air temperature at the bucket wheel excavator's operating site, and the humidity sensor collects the relative humidity of the ambient air. The output signals from the temperature and humidity sensors are amplified and filtered by a signal conditioning circuit before being transmitted to the data processing and control module.

[0054] In one embodiment, the temperature and humidity sensors are integrated into a single temperature and humidity composite sensor, housed within a radiation-proof ventilated enclosure to minimize the impact of solar radiation and rainfall on measurement accuracy. The sensor's sampling period is adjustable from 1 to 60 seconds to accommodate response requirements under varying climatic conditions.

[0055] For the data processing and control module, one of the following can be selected: programmable logic controller (PLC), industrial computer, or embedded microcontroller, which contains the following functional units:

[0056] (a) Data preprocessing unit: performs digital filtering and outlier removal on the raw signals from the temperature and humidity sensors, and stores the processed temperature and humidity values ​​in the data buffer. In one embodiment, a sliding window midpoint filter is used, with a window length of 5 to 15 sampling points.

[0057] (b) Friction coefficient estimation unit: Receives the temperature and humidity values ​​output by the data preprocessing unit, and calculates the estimated friction coefficient between the conveyor belt and the drive roller liner under the current environmental conditions through a preset friction coefficient mapping model.

[0058] (c) Optimal tension calculation unit: Receives the friction coefficient estimate output by the friction coefficient calculation unit, calculates the minimum tension required to keep the belt from slipping based on the mechanical model of the belt conveyor, and calculates the optimal tension target value in combination with the preset safety factor.

[0059] (d) Control output unit: The optimal tension target value F_target is compared with the current actual tension detection value F_actual measured by the belt tension feedback module. The deviation ΔF = F_target-F_actual is calculated, and the control signal of the hydraulic station proportional valve or servo valve is generated through PID or fuzzy PID control algorithm to drive the hydraulic actuator to adjust the tension.

[0060] In one embodiment, for the friction coefficient estimation unit: after receiving the ambient temperature and ambient humidity, it calculates the estimated value of the friction coefficient under the current environmental conditions through a preset friction coefficient mapping model;

[0061] The friction coefficient mapping model is constructed based on pre-calibrated data from laboratory bench tests;

[0062] The pre-calibration method for laboratory bench testing is as follows: In a controlled temperature and humidity environment, the coefficient of friction of actual adhesive tape samples and roller padding materials is measured, and the results are recorded at different temperatures. and different relative humidity Friction coefficient measurement under combined conditions This forms a three-dimensional data table {( , , Then, a continuous mapping function is constructed using binary interpolation or least squares surface fitting algorithms. , For ambient temperature, For ambient humidity, This is an estimated value for the friction coefficient.

[0063] For example, the friction coefficient can be measured under different temperature combinations (-20°C to +50°C) and relative humidity combinations (e.g., 10% to 95%) to form a corresponding three-dimensional data table. A continuous mapping function can be constructed using binary interpolation or least squares surface fitting methods.

[0064] More specifically, the friction coefficient mapping model also introduces the tape usage time or wear degree as a correction factor to compensate for the impact of tape aging on surface friction characteristics.

[0065] Correction factor The friction coefficient estimate was corrected by recording the cumulative operating hours of the tape or by ultrasonic measurements based on the tape thickness. .

[0066] The duration of tape use or degree of wear is introduced as a correction factor to compensate for the effect of tape aging on surface frictional properties. The estimated coefficient of friction is corrected to... .

[0067] In another embodiment, friction coefficient tests are conducted on actual tape samples and roller liner materials in a controlled temperature and humidity environment. The friction coefficient measurements are recorded under different combinations of ambient temperature, ambient humidity, and cumulative running time to obtain training samples. The friction coefficient estimation unit then uses a machine learning model based on extreme learning machine or support vector regression, with ambient temperature, ambient humidity, and cumulative running time as input features and friction coefficient measurements as output labels, to perform offline training to obtain a friction coefficient mapping model. After training, the parameters of the friction coefficient mapping model are stored in the memory of the data processing and control module.

[0068] Among them, the optimal tension calculation unit receives the friction coefficient estimate and calculates the minimum tension F_min required to keep the belt from slipping according to the Euler friction transmission formula, and then calculates the optimal tension target value F_target in combination with the preset safety factor K_s.

[0069] Euler's friction drive formula is:

[0070] F_min = F_eff / (e^( ·α)- 1);

[0071] Where F_eff is the effective circumferential force that the drive roller needs to transmit, and α is the wrap angle (in radians) of the belt on the drive roller. The friction coefficient F_eff is estimated by the real-time material intake of the bucket wheel excavator, the belt running speed, and the drive motor power.

[0072] The optimal target tension value is F_target = F_min × K_s, where the safety factor K_s ranges from 1.15 to 1.50, preferably from 1.20 to 1.35.

[0073] The minimum tension required to prevent slippage is calculated in real time and a safety factor is added to obtain the optimal target tension, realizing end-to-end quantitative derivation from environmental parameters to the tension setpoint.

[0074] The belt tension feedback module includes a tension sensor 6 installed at the bearing housing at both ends of the tensioning roller or at the telescopic end of the piston rod of the hydraulic cylinder. It is used to detect the actual tension force of the belt in real time and feed the actual tension force to the data processing and control module to form an inner ring tension closed loop.

[0075] The cantilever conveyor belt machine has only one drive roller, which is not shown in the figure. The hydraulic actuator module is prior art, as described in application number CN202110859769.9, "A Vertical Hydraulic Tensioning Device".

[0076] Preferably, the hydraulic actuator module also includes a tensioning mounting bracket 1 fixed to the bucket wheel excavator cantilever frame, a hydraulic control valve group, and a transmission mechanism including roller supports located at both ends of the tensioning roller and two slide rails 4; there are two hydraulic cylinders, each hydraulic cylinder driving one roller support;

[0077] The hydraulic control valve group receives control signals from the control output unit through electro-hydraulic proportional directional valves or electro-hydraulic servo valves to adjust the flow and direction of hydraulic oil entering or exiting the hydraulic cylinder;

[0078] The cylinder body of the hydraulic cylinder is fixed on the tensioning mounting bracket, which is equipped with a pair of opposing slide rails. Each roller bracket is slidably connected to the slide rail.

[0079] The two ends of the tensioning roller are rotatably connected to two roller supports through bearing seats with bearings. The piston rod of the hydraulic cylinder drives one roller support to move, thereby moving the tensioning roller.

[0080] In one implementation, the hydraulic actuator module also includes a hydraulic pump station and an accumulator 5.

[0081] The hydraulic pump station provides high-pressure hydraulic oil to the system, with a working pressure range of 10 to 25 MPa.

[0082] The hydraulic cylinder is a double-acting hydraulic cylinder, and its cylinder body is fixed on the tensioning mounting bracket of the bucket wheel excavator cantilever frame. The extension and retraction of the hydraulic cylinder piston rod drives the tensioning roller to move along the slide rail. When the piston rod extends, the tensioning stroke increases (tension force increases), and when the piston rod retracts, the tensioning stroke decreases (tension force decreases).

[0083] An accumulator is connected in parallel to the rodless or rod-side oil circuit of the hydraulic cylinder to absorb transient tension fluctuations in the conveyor belt caused by sudden loads or cantilever pitching movements. Simultaneously, when the data processing and control module detects a rapid change in the estimated friction coefficient (i.e., the rate of change of the friction coefficient exceeds a preset threshold), the control output unit of the data processing and control module actively triggers the accumulator to pre-charge or pre-discharge, achieving rapid compensation for transient tension. This differs from the purely passive buffering function of accumulators in existing technologies. In addition to passively absorbing pressure shocks, the accumulator, in conjunction with the data processing and control module, provides transient tension compensation faster than the response of a hydraulic pump. In contrast, the response time of a hydraulic pump station, from receiving a control command to establishing the target pressure, is typically 5 to 15 seconds, which cannot cover the risk of transient slippage when the friction coefficient changes abruptly.

[0084] In one implementation, the slide rail is horizontal in length, the hydraulic cylinder is horizontal, and the tensioning roller is a redirecting roller structure, installed below the return section of the cantilever conveyor belt. Figure 4 As shown, the tape wraps around the tensioning roller and other redirecting rollers in a horizontal S-shape. The tape tension is adjusted by changing the total length of the tape path through the left and right displacement of the tensioning roller.

[0085] A tension adjustment method for a bucket wheel excavator cantilever belt conveyor based on environmental perception includes:

[0086] S1. The data processing and control module loads the parameters of the preset friction coefficient mapping model, the operating parameters of the belt conveyor, and the PID control parameters.

[0087] S2. The environmental sensing module collects ambient temperature and humidity at a preset sampling period, and transmits them to the friction coefficient calculation unit after signal conditioning and digital filtering.

[0088] S3. The friction coefficient estimation unit calculates the estimated value of the friction coefficient based on the current ambient temperature and humidity by calling the friction coefficient mapping model.

[0089] S4. The optimal tension calculation unit calculates the target value of the optimal tension force based on the estimated value of the friction coefficient and the current operating parameters of the belt conveyor.

[0090] S5. The tape tension feedback module collects the actual tension force detection value of the current tape and calculates the deviation between the optimal target tension force value and the actual tension force detection value.

[0091] S6. The control output unit calculates the hydraulic control signal based on the deviation and the PID algorithm, and outputs it to the hydraulic actuator module to drive the hydraulic cylinder to move.

[0092] S7. Return to step S2 and enter the next control cycle.

[0093] S1 Initialization: After the system is powered on, the data processing and control module loads the preset friction coefficient mapping model parameters, belt conveyor operating parameters (including at least the wrap angle α, effective circumferential force F_eff, and optional safety factor K_s, correction factor) and PID control parameters.

[0094] S2 Environmental Parameter Acquisition: The environmental sensing module acquires the ambient temperature T and ambient humidity H at a preset sampling period, and transmits them to the data processing and control module after signal conditioning and digital filtering.

[0095] S3 Friction Coefficient Estimation: The friction coefficient estimation unit calculates the estimated value of the friction coefficient by calling the friction coefficient mapping model based on the current ambient temperature T and ambient humidity H.

[0096] S4 Optimal Tension Calculation: The optimal tension calculation unit calculates the target value of the optimal tension based on the estimated friction coefficient and the current operating parameters of the belt conveyor.

[0097] S5 Tension Feedback Comparison: Reads the current friction coefficient estimate from the tape tension feedback module and calculates its deviation from the optimal tension target value.

[0098] S6 Control Output: The control output unit calculates the hydraulic control signal based on the deviation and outputs it to the hydraulic control valve group to drive the hydraulic cylinder to move.

[0099] S7 loop: Return to step S2 and enter the next control cycle.

[0100] In one embodiment, the control cycle for steps S2 to S7 is 0.1 to 5 seconds, preferably 0.5 to 2 seconds. Changes in ambient temperature and humidity are typically gradual processes occurring on the order of minutes or even hours. This control cycle is much faster than the timescale of environmental changes, ensuring the system can promptly track changes in the friction coefficient while preventing the hydraulic system from having its lifespan shortened due to overly frequent minor adjustments.

[0101] Furthermore, the effective circumferential force F_eff in step S4 is obtained as follows: the set value or measured value of the current material taking amount is obtained from the PLC or upper control system of the bucket wheel excavator, and the effective circumferential force that the drive drum needs to transmit is calculated in combination with the belt running speed signal and the output torque of the drive motor. When the material taking amount signal cannot be obtained, F_eff_max corresponding to the maximum designed material taking amount is used as a conservative value for calculation.

[0102] Example 1 (Basic Example)

[0103] This embodiment describes a basic application scenario of the present invention.

[0104] A steel plant's raw material yard is equipped with a cantilever bucket wheel stacker-reclaimer with a reclaiming capacity of 3000 t / h. Its cantilever belt conveyor has a width of 1600 mm, using ST-1250 steel cord conveyor belts. The drive drum has a diameter of 1250 mm, with ceramic-coated roller padding. The belt wrap angle on the drive drum is α = 210° (approximately 3.665 rad). The tensioning drum is installed below the cantilever's return section and is driven by a double-acting hydraulic cylinder with a diameter of 160 mm, a rod diameter of 110 mm, and a stroke of 800 mm. The hydraulic station has a rated working pressure of 16 MPa and is equipped with an electro-hydraulic proportional directional valve. The environmental sensing module uses an integrated temperature and humidity sensor (model example: SHT35), installed inside a radiation-proof ventilation hood above the bucket wheel cantilever, with a sampling period set to 2 seconds. The data processing and control module uses a Siemens S7-1200 series PLC with the following built-in calculation functions:

[0105] The friction coefficient mapping model was constructed based on laboratory bench calibration data. Calibration conditions: For ST-1250 tape samples and ceramic-coated gasket samples, temperature gradients of -15℃, -5℃, 5℃, 15℃, 25℃, 35℃, and 45℃ (7 gradients) and relative humidity gradients of 15%, 30%, 50%, 70%, and 90% were set in a temperature and humidity test chamber. Friction coefficient measurements were performed under each (T, H) combination condition, with each condition repeated 5 times and the average value taken, resulting in 35 sets of calibration data. The mapping function was obtained by fitting a bivariate quadratic polynomial surface.

[0106] The fitting coefficients to The value is determined using the least squares method and then written into the PLC memory. The safety factor K_s is set to 1.25.

[0107] The system operation process is illustrated using a summer afternoon thunderstorm as an example. The pre-rain environmental conditions are: ambient temperature T = 38℃, relative humidity H = 45%, and the friction coefficient calculation unit output... 0.38. At this point, the effective circumferential force F_eff is approximately 62 kN (calculated based on the current material handling rate of approximately 2400 t / h). According to Euler's formula, F_min≈62 / (e^(0.38×3.665)-1)≈62 / 3.03≈20.5 kN, F_target=20.5×1.25≈25.6 kN. The system controls the hydraulic cylinder to maintain the actual tension force at this target value, and the tension sensor measures F_actual≈25.4 kN.

[0108] Approximately 3 minutes after the rainfall, the environmental conditions changed to T=26℃ and H=92%, and the friction coefficient calculation unit recalculated and output the results. ≈0.28 (due to the decrease in friction coefficient caused by wetting of the roller liner surface). F_min was recalculated as ≈62 / (e^(0.28×3.665)-1)≈62 / 1.80≈34.4 kN, F_target=34.4×1.25≈43.0 kN. The system detected that the target tension jumped from 25.6 kN to 43.0 kN, exceeding the preset friction coefficient change rate threshold, and the control strategy judged it as a rapid change event in the friction coefficient. The controller immediately triggered the accumulator pre-charge valve to open, and simultaneously started the hydraulic pump and proportional valve to increase the hydraulic cylinder thrust to the corresponding target pressure. The entire process, from the sensor detecting the sudden change in humidity to the hydraulic cylinder starting to respond, took approximately 1.8 seconds, and the tension stabilized within approximately 8 seconds to within ±5% of the target value. No belt slippage alarm occurred during the rainfall.

[0109] After the onset of dry autumn weather, on a certain day at noon, the environmental conditions were T=12℃ and H=22%. The friction coefficient calculation unit output... ≈0.43. At this point, the effective circumferential force F_eff≈75 kN (close to full load material handling), F_min≈75 / (e^(0.43×3.665)−1)≈75 / 3.84≈19.5 kN, and F_target≈24.4 kN. Based on this, the controller reduces the hydraulic cylinder output, and the actual belt tension drops from approximately 43 kN under the previous high humidity conditions to approximately 24 kN, thereby reducing the operating load on the belt and roller bearings.

[0110] Example 2 (an optimized example including tension feedback closed loop and running time correction)

[0111] This embodiment adds the following optimized features based on Embodiment 1.

[0112] (a) Tension sensor closed-loop feedback

[0113] A resistance strain gauge tension sensor (range 0 to 100 kN, accuracy ±0.5% FS) is installed below the bearing housing at both ends of the tensioning roller. This sensor measures the vertical resultant force component of the conveyor belt acting on the roller bearing housing in real time, and calculates the actual tension force of the conveyor belt and the actual tension force detection value F_actual. The tension sensor signal is input to the PLC analog input module via a 4 to 20 mA analog output.

[0114] The PLC implements an incremental PID control algorithm. The PID parameters are tuned as follows: proportional coefficient Kp = 0.8, integral time Ti = 15s, and derivative time Td = 3s. The input to the PID controller is the deviation ΔF = F_target - F_actual, and the output is the correction amount of the proportional valve's current signal. When |ΔF| ≤ F_target × 3%, the PID output retains the previous effective value (setting a dead zone) to prevent the hydraulic system from frequently operating due to small deviations.

[0115] Experimental data show that after introducing tension closed-loop feedback, the steady-state fluctuation range of the actual tension force under stable environmental conditions is reduced from ±8% under open-loop feedforward control to ±2.5% (based on tension data recorded during 72 hours of continuous operation of the bucket wheel excavator, with a sample size of n≈129,600 sampling points).

[0116] (b) Tape run time correction

[0117] The tape has accumulated approximately 8500 hours of operation. The data processing and control module maintains a timer for the accumulated operating hours, with a preset correction factor kage = 1 + 0.03 × (operating hours / 10000). When the operating hours reach 8500, kage ≈ 1.026. The friction coefficient calculation output is corrected accordingly. ×kage, meaning the corrected estimated coefficient of friction is approximately 2.6% higher than the calibrated value. This correction is conservative—slightly overestimating the coefficient of friction leads to a slight underestimation of the required tension, but the tension feedback closed loop can detect and correct this deviation. Meanwhile, the gradual increase in the correction factor year by year is consistent with the general rule that the surface roughness of the tape increases and the coefficient of friction slightly increases after wear.

[0118] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0119] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception, characterized in that, It includes an environmental sensing module, a data processing and control module, a hydraulic actuation module, and a belt tension feedback module; The environmental sensing module is used to collect ambient temperature and humidity under the current environmental conditions; The data processing and control module includes a friction coefficient calculation unit, an optimal tension force calculation unit, and a control output unit; The friction coefficient estimation unit obtains the estimated friction coefficient between the conveyor belt and the drive roller liner based on the ambient temperature, ambient humidity, and the preset friction coefficient mapping model. The optimal tension calculation unit calculates the optimal target tension value under the current environmental conditions based on the estimated friction coefficient. The hydraulic actuator module includes a tensioning roller for changing the tensioning stroke of the conveyor belt. The hydraulic cylinder drives the tensioning roller to move through the transmission mechanism to adjust the actual tension of the conveyor belt. The tape tension feedback module is used to detect the actual tension of the tape in real time. The control output unit calculates the deviation between the optimal target tension value and the actual detected tension value, and controls the hydraulic cylinder to operate based on the deviation.

2. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, The environmental sensing module includes a temperature sensor for collecting ambient temperature and a humidity sensor for collecting ambient humidity. The output signals of the temperature sensor and the humidity sensor are amplified and filtered by a signal conditioning circuit before being transmitted to the data processing and control module. The data processing and control module also includes a data preprocessing unit, which performs digital filtering and outlier removal on the output signals from the received temperature and humidity sensors.

3. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, After receiving the ambient temperature and humidity, the friction coefficient estimation unit calculates the estimated value of the friction coefficient under the current environmental conditions through a preset friction coefficient mapping model. The friction coefficient mapping model is constructed based on pre-calibrated data from laboratory bench tests; The pre-calibration method for laboratory bench testing is as follows: In a controlled temperature and humidity environment, the coefficient of friction of actual adhesive tape samples and roller padding materials is measured, and the results are recorded at different temperatures. and different relative humidity Friction coefficient measurement under combined conditions This forms a three-dimensional data table {( , , Then, a continuous mapping function is constructed using binary interpolation or least squares surface fitting algorithms. , For ambient temperature, For ambient humidity, This is an estimated value for the coefficient of friction.

4. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 3, characterized in that, The friction coefficient mapping model also introduces the tape usage time or wear degree as a correction factor to compensate for the effect of tape aging on surface friction characteristics; Correction factor The friction coefficient estimate was corrected by recording the cumulative operating hours of the tape or by ultrasonic measurements based on the tape thickness. .

5. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, In a controlled temperature and humidity environment, friction coefficient tests were conducted on actual tape samples and roller pad materials, and the measured values ​​of friction coefficients were recorded under different combinations of ambient temperature, ambient humidity, and cumulative running time. The friction coefficient estimation unit uses a machine learning model based on extreme learning machine or support vector regression. It takes ambient temperature, ambient humidity and cumulative running time as input features and friction coefficient measurement values ​​as output labels to conduct offline training to obtain a friction coefficient mapping model. After training, the parameters of the friction coefficient mapping model are stored in the memory of the data processing and control module.

6. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, The optimal tension calculation unit receives the friction coefficient estimate and calculates the minimum tension F_min required to keep the belt from slipping according to the Euler friction transmission formula. Then, it calculates the optimal tension target value F_target by combining the preset safety factor K_s. Euler's friction drive formula is: F_min = F_eff / (e^( ·α)- 1); Where F_eff is the effective circumferential force that the drive roller needs to transmit, and α is the wrap angle of the belt on the drive roller. F_eff is the estimated value of the friction coefficient, e is the natural constant, and F_eff is obtained by estimating the real-time material intake, belt running speed and drive motor power of the bucket wheel excavator. The optimal target tension value is F_target = F_min × K_s, where the safety factor K_s ranges from 1.15 to 1.

50.

7. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, The control output unit compares the optimal tension target value F_target with the actual tension detection value F_actual measured by the belt tension feedback module to obtain the deviation ΔF = F_target-F_actual. The deviation is then generated by the PID or fuzzy PID control algorithm to produce the control signal of the proportional valve or servo valve of the hydraulic station, which drives the hydraulic actuator to adjust the tension.

8. The tension adjustment system for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 1, characterized in that, The hydraulic actuator module also includes a tensioning mounting bracket fixed to the bucket wheel excavator boom frame, a hydraulic control valve group, and a transmission mechanism including drum brackets located at both ends of the tensioning drum and two slide rails; The hydraulic control valve group receives control signals from the control output unit through electro-hydraulic proportional directional valves or electro-hydraulic servo valves to adjust the flow and direction of hydraulic oil entering or exiting the hydraulic cylinder; The cylinder body of the hydraulic cylinder is fixed on the tensioning mounting bracket, which is equipped with a slide rail. The roller bracket is slidably connected to the slide rail. The two ends of the tensioning roller are connected to two roller supports. The piston rod of a hydraulic cylinder drives one roller support to move, thereby moving the tensioning roller.

9. A tension adjustment method for a bucket wheel excavator cantilever conveyor belt based on environmental perception, characterized in that, include: S1. The data processing and control module loads the parameters of the preset friction coefficient mapping model, the operating parameters of the belt conveyor, and the PID control parameters. S2. The environmental sensing module collects ambient temperature and humidity at a preset sampling period, and transmits them to the friction coefficient calculation unit after signal conditioning and digital filtering. S3. The friction coefficient estimation unit calculates the estimated value of the friction coefficient based on the current ambient temperature and humidity by calling the friction coefficient mapping model. S4. The optimal tension calculation unit calculates the target value of the optimal tension force based on the estimated value of the friction coefficient and the current operating parameters of the belt conveyor. S5. The tape tension feedback module collects the actual tension force detection value of the current tape and calculates the deviation between the optimal target tension force value and the actual tension force detection value. S6. The control output unit calculates the hydraulic control signal based on the deviation and the PID algorithm, and outputs it to the hydraulic actuator module to drive the hydraulic cylinder to move. S7. Return to step S2 and enter the next control cycle.

10. The tension adjustment method for a bucket wheel excavator cantilever conveyor belt based on environmental perception according to claim 9, characterized in that, One control cycle from S2 to S7 is 0.1 to 5 seconds.

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