Bulk material online suspension conveying flow self-adaptive regulation method

Abstract

The application discloses a kind of bulk material online suspension conveying flow self-adapting regulation method, it is related to bulk material conveying control technical field.The method includes: obtaining the real-time image sequence of bulk material loading area on suspension conveying chain and identifying bulk material accumulation profile;Determine instantaneous loading volume and bulk material distribution eccentricity;In combination with the real-time running speed of each section, predict the bulk material arrival timing of each conveying node in future time window;According to the arrival timing and the unloading capacity boundary of downstream unloading equipment, calculate the target conveying speed required for each section;Using bulk material distribution eccentricity generates barycentric offset compensation coefficient, correct target conveying speed to obtain corrected target conveying speed;According to the deviation between current actual speed and corrected target conveying speed, determine and adjust the excitation current of each drive wheel motor, so as to adjust output torque, so that the actual conveying speed of each section approaches to the correction value.The method can realize the prospective balanced regulation of conveying flow.

Description

Technical Field

[0001] This invention relates to the field of bulk material conveying control technology, specifically to an adaptive adjustment method for the flow rate of online suspended bulk material conveying. Background Technology

[0002] Overhead conveyor chains are widely used in bulk material transfer scenarios such as mining, metallurgy, and ports. Their core task is to continuously and smoothly transport bulk materials, after crushing or screening upstream, to downstream unloading equipment. Existing online bulk material conveying control methods mainly rely on deploying flow meters or belt scales at key nodes in the conveying path to estimate instantaneous flow rate by monitoring the mass or volume of passing material in real time. When the detected flow rate exceeds the processing threshold of downstream equipment, the control system usually adjusts the speed of the conveyor chain drive motor to suppress flow peaks. This method can maintain the system from overloading on a macroscopic level, but its adjustment accuracy and applicability have inherent defects when faced with differences in the material distribution within the loading hoist. First, existing flow detection methods can only sense the overall throughput and cannot know the accumulation pattern of bulk materials in each independent loading area. When bulk materials form agglomerates within the bucket due to fixed loading points or material characteristics, the center of gravity of the pile will deviate significantly from the geometric center of the bucket. This off-center loading condition causes the lifting device to sway and impact when the conveyor chain is running at high speed. Conventional speed control strategies based on overall flow completely ignore this, applying the same speed control command to the entire chain segment without specifically compensating for the eccentric torque of the internal load. This results in abnormal vibrations of the conveyor chain due to uneven stress in curves or speed change sections, exacerbating wear on the tracks and wheels, and even causing derailment accidents. Secondly, existing technologies exhibit significant lag in flow regulation. Since the flow meter is usually installed near the unloading point, the flow signal it provides already reflects the material data about to enter the downstream equipment. The control system receives the signal and initiates speed regulation, but by this time a large amount of material is already approaching the unloading end, and the buffer zone for speed adjustment is too small. To respond quickly, the system has to apply large acceleration and deceleration impacts, which not only damages the drive unit but also causes severe fluctuations in the overall tension of the conveyor chain. This passive control mode of "adjusting as it comes" makes it difficult to proactively intervene in flow fluctuations that have already formed in the upstream section before they reach the detection point. It is also unable to smooth out flow peaks and valleys over a longer time window, resulting in downstream equipment often operating under intermittent overload or underload conditions, which reduces the efficiency of the entire transfer system. Summary of the Invention

[0003] The purpose of this invention is to provide an adaptive flow rate adjustment method for online suspended conveying of bulk materials, in order to solve the problem that existing speed control ignores the torque effect of bulk material off-center load distribution, resulting in uneven force on the conveyor chain and operational instability; and further solve the problem that passive control caused by flow rate detection lag cannot proactively suppress flow rate fluctuations, resulting in unstable working cycles of downstream equipment and low overall efficiency of the conveying system.

[0004] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides an adaptive adjustment method for the flow rate of bulk material online overhead conveyor. This method acquires real-time image sequences of the bulk material loading areas on the overhead conveyor chain and identifies the bulk material accumulation contours of each loading area based on the real-time image sequences. Based on the bulk material accumulation contours, the instantaneous loading volume and bulk material distribution eccentricity of each loading area are determined, achieving accurate quantitative perception of the loading status.

[0005] Based on the real-time operating speed of each overhead conveyor chain segment and the instantaneous loading volume of each bulk material loading area, the arrival sequence of bulk materials at each conveying node within a future time window can be predicted, enabling advance forecasting of the spatiotemporal distribution of material flow. By combining the arrival sequence of bulk materials at each conveying node with the unloading capacity boundary of the downstream unloading equipment, the required target conveying speed for each overhead conveyor chain segment can be calculated, allowing for adjustment of the conveying rhythm from the source to avoid overloading or empty waiting at the unloading points.

[0006] Based on the eccentricity of the bulk material distribution, a center of gravity offset compensation coefficient is generated for each bulk material loading area. When the center of gravity of the bulk material accumulation deviates from the geometric center of the bottom surface, corresponding compensation is introduced to prevent swaying or speed fluctuations during the conveying process due to uneven loading. The target conveying speed of each suspended conveyor chain section is corrected by the center of gravity offset compensation coefficient to obtain the corrected target conveying speed, so that the speed adjustment takes into account the load distribution state and improves the smoothness of the conveying.

[0007] Based on the speed deviation between the current actual speed and the corrected target conveying speed of each suspended conveyor chain section, the excitation current adjustment amount of each drive wheel motor is determined, and the output torque of the corresponding drive wheel is adjusted according to the excitation current adjustment amount, so that the actual conveying speed of each suspended conveyor chain section approaches the corrected target conveying speed, thereby achieving closed-loop precise control of the suspended conveyor chain drive.

[0008] As a technical solution of this invention, when determining the instantaneous loading volume and the eccentricity of the bulk material distribution, the stacking height distribution map and the bottom boundary of each bulk material loading area are extracted from the bulk material stacking profile. The instantaneous loading volume is obtained by integrating and accumulating the stacking height distribution map along the area enclosed by the bottom boundary of the stack. At the same time, the coordinates of the stacking mass center are calculated based on the stacking height distribution map, and the coordinates of the bottom geometric center are calculated based on the bottom boundary of the stack. The ratio of the offset distance between the stacking mass center coordinates and the bottom geometric center coordinates to the equivalent radius of the bottom boundary of the stack is used as the bulk material distribution eccentricity, thereby comprehensively reflecting the spatial distribution characteristics of the bulk material within the loading area.

[0009] Preferably, when predicting the arrival time sequence of bulk materials at each conveying node within a future time window, the overhead conveyor chain is first divided into multiple conveying sections and configured with corresponding real-time operating speeds. The remaining conveying time to each downstream conveying node is calculated based on the current conveying section and operating speed of each bulk material loading area. Then, the instantaneous loading volume of each bulk material loading area is sorted according to the remaining conveying time, generating the arrival time sequence of bulk materials at each conveying node within the future time window and the predicted arrival volume at each moment, so that the arrival time sequence prediction has spatiotemporal dual-dimensional information.

[0010] As a further aspect of this invention, when calculating the target conveying speed, the maximum acceptable volume of the downstream unloading equipment at each moment is used as the unloading capacity boundary. The predicted arrival volume of each conveying node at each moment is compared with the unloading capacity boundary to identify the overload moments and overload volumes where the predicted arrival volume exceeds the unloading capacity boundary. Then, based on the overload volume, the required speed reduction for the corresponding upstream conveying section of each conveying node is calculated. After adjusting the current operating speed, the target conveying speed required for each suspended conveyor chain section is obtained. This speed planning method directly addresses the unloading capacity constraint, effectively preventing material accumulation and blockage at the unloading port.

[0011] Preferably, when generating the center of gravity offset compensation coefficient, an eccentricity threshold is set. When the eccentricity of the bulk material distribution is less than or equal to the eccentricity threshold, the compensation coefficient is set as a first constant. When the eccentricity of the bulk material distribution is greater than the eccentricity threshold, the compensation coefficient is calculated based on the difference between the eccentricity and the threshold, as well as the instantaneous loading volume. The compensation coefficient increases with the increase of the difference and decreases with the increase of the instantaneous loading volume. This differentiated compensation strategy maintains stable adjustment when the off-center load is light, and applies stronger compensation intervention when the off-center load is severe and the loading volume is small.

[0012] In a preferred embodiment of the present invention, when correcting the target conveying speed, the set of bulk material loading areas carried by each suspended conveyor chain segment is determined, the center of gravity offset compensation coefficient corresponding to each bulk material loading area is extracted, and the weighted average of the center of gravity offset compensation coefficients of all bulk material loading areas is calculated as the overall compensation coefficient of the corresponding conveyor chain segment. The weights are determined based on the proportion of the instantaneous loading volume of each bulk material loading area to the total loading volume. The target conveying speed of the segment is then multiplied by this overall compensation coefficient to obtain the corrected target conveying speed. This weighted averaging process ensures that the correction comprehensively reflects the degree of off-center loading influence of all loading areas within the segment.

[0013] Furthermore, when determining the excitation current adjustment, the current excitation current value of each drive wheel motor is collected. The speed deviation value is calculated by comparing the corrected target conveying speed with the current actual speed. Based on the speed deviation value, the initial excitation current adjustment is obtained by consulting a preset deviation-current mapping table. Then, the current temperature value of each drive wheel motor is collected to calculate the temperature correction factor. The initial excitation current adjustment is multiplied by the temperature correction factor to obtain the final excitation current adjustment. Introducing the temperature correction factor can compensate for the differences in the excitation response of the motor under different thermal conditions, thereby improving the accuracy of current regulation.

[0014] Preferably, when calculating the speed deviation value, the corrected target conveying speed is used as the set speed, and the current actual speed is used as the feedback speed to obtain the initial speed deviation. Then, the current total load weight of each suspended conveyor chain section is obtained, and the inertia correction coefficient is obtained by looking up the preset load-inertia correction table. The initial speed deviation is multiplied by the inertia correction coefficient to obtain the speed deviation value. Through inertia correction, the speed deviation more realistically reflects the torque difference required for acceleration or deceleration under different load conditions.

[0015] Preferably, when calculating the temperature correction factor, temperature sensors are installed on the surface of each drive wheel motor housing to collect the current temperature value in real time. The current temperature value is compared with the preset rated operating temperature to calculate the temperature difference. When the temperature difference is less than or equal to zero, the temperature correction factor is set as the second constant. When the temperature difference is greater than zero, the temperature attenuation coefficient is calculated based on the product of the temperature difference and the preset temperature step coefficient. The difference between the temperature attenuation coefficient and the second constant is used as the temperature correction factor, so that the temperature correction factor decreases linearly as the temperature difference increases, thereby appropriately reducing the excitation regulation amount to protect the motor when the motor temperature rises.

[0016] As a complete control closed loop of this invention, the process of adjusting the output torque includes: converting the excitation current adjustment amount of each drive wheel motor into a corresponding excitation current adjustment command; adjusting the input current of the excitation winding according to the excitation current adjustment command; monitoring the actual output speed of each drive wheel motor in real time; performing closed-loop correction on the excitation current adjustment command based on the speed difference between the actual output speed and the target output speed; and adjusting the input current of the excitation winding again using the closed-loop corrected excitation current adjustment command until the speed difference is less than a preset threshold. This closed-loop control method ensures that the actual conveying speed can still accurately track the corrected target conveying speed under load disturbances and parameter changes.

[0017] The technical effects and advantages provided by the present invention in the above technical solution are as follows: Real-time image sequences of the bulk material loading areas on the overhead conveyor chain are acquired, and the bulk material accumulation contours of each area are identified. The bulk material distribution eccentricity is then calculated based on these contours. Using this eccentricity, a center of gravity offset compensation coefficient is generated for each loading area, and the target conveying speed of the corresponding overhead conveyor chain segment is corrected accordingly. This processing method quantifies the degree of eccentric loading of bulk material within the bucket into a specific speed compensation value. When the bulk material accumulation in a loading area is severely eccentric, this compensation mechanism directionally reduces the operating speed of that segment to suppress the additional centrifugal torque and sway amplitude caused by the center of gravity offset. Compared to the conventional approach of uniformly adjusting speed regardless of internal eccentric loading, this eccentricity-based speed correction ensures more balanced force distribution in each segment during dynamic operation, reduces lateral sway of the spreader and lateral impact of the traveling wheels on the track, and maintains stable orientation of the conveyor chain at high speeds. Based on the real-time operating speed of each overhead conveyor chain segment and the instantaneous loading volume of each bulk material loading area, the arrival sequence of bulk materials at each conveying node within a future time window is predicted. The unloading capacity boundary of the downstream unloading equipment is also introduced. By analyzing the exceedance of the predicted arrival volume and the unloading capacity boundary, the target conveying speed of the overhead conveyor chain segment that can be intervened in advance is calculated. This mechanism moves the forefront of flow control from the unloading end to the entire overhead conveyor line. This means that the adjustment of conveying speed is no longer based on the delayed flow signal that has already arrived at the unloading point, but rather on the predicted cumulative arrival volume of multiple batches of bulk materials at various future times. This predictive speed pre-adjustment allows the conveyor chain to smoothly decelerate before the flow peak reaches the unloading equipment, actively stretching the originally concentrated material peak into a stable flow sequence during the conveying process. The unloading equipment does not need to face the impact of short-term strong overload, and the continuity of material flow in the entire transfer process is significantly improved, avoiding energy loss and mechanical stress caused by frequent emergency speed changes in the drive system. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1 This is a flowchart of a method for adaptive adjustment of flow rate in online suspended conveying of bulk materials. Figure 2 This is a flowchart for calculating the instantaneous volume and eccentricity of the bulk material loading area; Figure 3 This is a flowchart of the bulk material arrival volume prediction method; Figure 4 This is a flowchart of the calculation of the center of gravity offset compensation coefficient and speed correction for bulk material loading; Figure 5 This is a flowchart of the excitation current regulation and control process for the drive wheel of the suspended conveyor chain. Detailed Implementation

[0020] 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 embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See Figure 1 This invention provides an adaptive adjustment method for the flow rate of online overhead conveyor for bulk materials, comprising: acquiring a real-time image sequence of bulk material loading areas on the overhead conveyor chain; identifying the bulk material accumulation contour of each loading area based on the real-time image sequence; determining the instantaneous loading volume and bulk material distribution eccentricity of each loading area based on the bulk material accumulation contour; predicting the arrival time sequence of bulk materials at each conveying node within a future time window based on the real-time operating speed of each overhead conveyor chain segment and the instantaneous loading volume of each loading area; and calculating the flow rate of each overhead conveyor based on the arrival time sequence of bulk materials at each conveying node and the unloading capacity boundary of the downstream unloading equipment. The target conveying speed required for each section of the conveyor chain is determined; based on the eccentricity of the bulk material distribution, a center of gravity offset compensation coefficient is generated for each bulk material loading area; based on the center of gravity offset compensation coefficient, the target conveying speed of each suspended conveyor chain section is corrected to obtain the corrected target conveying speed; based on the speed deviation between the current actual speed of each suspended conveyor chain section and the corrected target conveying speed, the excitation current adjustment amount of the motor of each drive wheel is determined; according to the excitation current adjustment amount of the motor of each drive wheel, the output torque of the corresponding drive wheel is adjusted so that the actual conveying speed of each suspended conveyor chain section approaches the corrected target conveying speed.

[0022] Example 1: In specific implementation, please refer to Figure 2The method for extracting the stacking height distribution map and the bottom boundary of each bulk material loading area from the bulk material stacking profile is as follows: After acquiring a real-time image sequence of the bulk material loading area on the suspended conveyor chain, three-dimensional point cloud data of the surface of the bulk material loading area is generated using binocular stereo vision or structured light three-dimensional measurement technology. The three-dimensional point cloud data is projected onto a horizontal reference plane and rasterized according to a preset grid resolution. The maximum height value of the bulk material surface relative to the horizontal reference plane is recorded in each grid cell, thereby generating the stacking height distribution map. At the same time, boundary extraction is performed on the three-dimensional point cloud data, connecting the intersection points of the bulk material with the loading container wall or the conveyor chain bearing surface into a closed curve to obtain the bottom boundary of the stack. The bottom boundary of the stack can be represented as a closed polygon or a smooth curve in the horizontal plane.

[0023] To determine the instantaneous loading volume, the region enclosed by the bottom boundary of the stack is integrated and accumulated based on the stack height distribution map. The integration and accumulation process uses the following formula: in, This indicates the instantaneous loading volume of the bulk material loading area; This represents the region enclosed by the boundary of the stacked bottom surface on a horizontal reference plane; Indicates the area The coordinates of a point within the horizontal reference plane; Indicates coordinates The stacking height at a given location is read from the corresponding grid cell in the stacking height distribution map. In the discretization implementation, the integral accumulation process divides the region... Stacking height of all grid cells The instantaneous loading volume is obtained by multiplying the area of ​​the grid cell by the sum of the products.

[0024] To determine the eccentricity of bulk material distribution, the coordinates of the center of mass of each bulk material loading area are calculated based on the stacking height distribution map. (Center of mass coordinates) Calculated using a weighted average method with stacking height as the weight, i.e., for the region x-coordinates of all grid cells use Weighted summation divided by total volume get Similarly, we can obtain The coordinates of the mass center of the stockpile reflect the concentrated location of the bulk material mass on the horizontal plane.

[0025] Calculate the geometric center coordinates of the bottom surface of each bulk material loading area based on the bottom surface boundary of the stockpile. For the area enclosed by the bottom surface boundary of the stockpile... Coordinates of the geometric center of the base By calculating the region The centroid is obtained, that is, for the region Perform area integration, calculate the first moment, and then divide by the area. The total area. The coordinates of the bottom geometric center depend only on the geometry of the loading area and are independent of the height of the bulk material stack.

[0026] Calculate the coordinates of the center of mass of the stack. coordinates of the geometric center of the base offset distance between : Equivalent radius of the bottom boundary of the stack Obtained by: the area enclosed by the boundary of the bottom surface of the accumulation. area Calculate the equivalent radius based on the circular equivalent. In some embodiments, when the region When the shape is highly irregular, the equivalent radius can also be represented by a region. The minimum circumcircle radius or the region The radius of circles with equal areas.

[0027] Bulk material distribution eccentricity Calculated as offset distance Equivalent radius of the bottom boundary of the accumulation The ratio, i.e. The eccentricity of bulk material distribution is dimensionless, and its range is [value missing]. arrive Between these values, the larger the value, the more severe the deviation of the center of gravity of the bulk material pile from the geometric center of the bottom surface, and the worse the loading stability.

[0028] Example 2: In specific implementation, please refer to Figure 3 The overhead conveyor chain is divided into multiple conveying sections, and a corresponding real-time operating speed is configured for each section. This is achieved by placing several position sensors or RFID tags along the conveyor chain's path on the guide rails or support structure. The physical link between two adjacent position sensors or RFID tags is defined as a conveying section. Each conveying section is equipped with an independent drive wheel and motor. The real-time rotational speed of the drive wheel is collected by a motor encoder or speed sensor. Combined with the drive wheel's pitch circle diameter and the meshing relationship between the conveyor chain and the drive wheel, the real-time operating speed of each conveying section is calculated. The real-time operating speed is reported to the central controller by the motor driver of the corresponding conveying section.

[0029] The process of calculating the remaining conveying time for each bulk material loading area to reach its downstream conveying nodes, based on its current location within a conveying segment and its corresponding real-time operating speed, includes: determining the current position of each bulk material loading area within a conveying segment; obtaining the distance already traveled within that segment using position sensors located within the segment; for the current conveying segment, the remaining conveying distance is the total length of that segment minus the distance already traveled; starting from the next conveying segment before the current segment, summing the lengths of all conveying segments up to the downstream conveying nodes, and then adding this sum to the remaining conveying distance within the current segment to obtain the total remaining conveying distance for the bulk material loading area to reach its downstream conveying nodes; and finally, dividing the total remaining conveying distance by the real-time operating speed of the corresponding conveying segment, calculating the time segment by segment according to the order in which the bulk material loading area traverses different conveying segments, and then summing the results to obtain the remaining conveying time for the corresponding bulk material loading area to reach its downstream conveying nodes.

[0030] The instantaneous loading volume of each bulk material loading area is sorted according to the corresponding remaining conveying time to generate a bulk material arrival time sequence for each conveying node within a future time window. In specific implementation, the future time window is set to a preset time range, such as a fixed time interval from the current moment to the future. For a downstream conveying node, the identifiers, instantaneous loading volumes, and remaining conveying times of all bulk material loading areas are formed into triplet data, which are then arranged in ascending order of remaining conveying time to obtain a sequence of bulk material loading areas arriving at that conveying node in chronological order. For each bulk material loading area, its expected arrival time is the current moment plus the remaining conveying time. The expected arrival time and instantaneous loading volume are recorded accordingly to form a bulk material arrival time sequence.

[0031] Based on the bulk material arrival time series of each conveying node and the instantaneous loading volume of each bulk material loading area, the predicted arrival volume of each conveying node at each moment within a future time window is generated. The predicted arrival volume is generated as follows: the future time window is discretized into multiple time segments according to a preset time step. For each time segment, it is checked whether the expected arrival time in the bulk material arrival time series falls within that time segment. The instantaneous loading volumes of all bulk material loading areas falling within the same time segment are summed to obtain the predicted arrival volume corresponding to that time segment. The predicted arrival volume is calculated using the following formula: in, Indicates the transport node Time segments within a future time window The predicted arrival volume; For the identification index of the transport node, The range of values ​​is from Total number of transport nodes Integers; For identifying the time segment, The range of values ​​is from Total number of time segments Integers; For bulk material loading areas, collection The elements in the table represent the expected arrival times of the delivery nodes. Corresponding time segment Identification of all bulk material loading areas within the facility; Collection of bulk material loading areas A bulk material loading area identifier; Marking of bulk material loading areas The corresponding instantaneous loading volume is obtained through the integral accumulation process in Example 1.

[0032] Example 3: In practical implementation, the maximum acceptable volume of the downstream unloading equipment at each moment is used as the unloading capacity boundary. This is achieved by obtaining the rated processing capacity curve or real-time status data of the downstream unloading equipment, which can be a crusher, a transfer conveyor belt, or a unloading chute. The unloading capacity boundary is expressed as a function of the maximum acceptable volume with time as the independent variable. For each conveying node, based on the physical location of its corresponding downstream unloading equipment, the maximum acceptable volume function is mapped to each time segment of that conveying node, obtaining the unloading capacity boundary value of each conveying node in each time segment. It means that among them For the identification index of the transport node, This is the identifier index for the time segment.

[0033] The process of comparing the predicted arrival volume of each conveying node with the unloading capacity boundary at each time point, and identifying the overload time and overload volume when the predicted arrival volume exceeds the unloading capacity boundary, includes: for each conveying node Each time segment Obtain the predicted arrival volume calculated through Example 2. The predicted volume will be reached. Boundary values ​​of unloading capacity for the corresponding conveying node and the corresponding time segment Perform numerical comparisons. When When established, this time segment Marked as transport node The overload moment and the overload volume are calculated. .when Upon establishment, the transport node In time segment If there is no overload, the overload volume is recorded as zero.

[0034] Based on the overload volume of each conveying node at the time of overload, calculate the required speed reduction for each upstream conveying section corresponding to each conveying node. In specific implementation, the upstream conveying section of a conveying node is defined as all conveying sections on the overhead conveyor chain that will transport bulk materials to that conveying node. The set of upstream conveying sections is represented as follows: The elements in the set are the transport section identifiers. The speed reduction is calculated using the following formula: in, Indicates the upstream transport section The required rate of decrease, in meters per second; Indicates the transport node During overload The overload volume, which is obtained through the aforementioned comparison steps; Indicates the upstream transport section The current real-time operating speed is collected and reported by the speed sensor configured in this transport section; Indicates the transport node The corresponding set of upstream transport sections; Represents a set One of the transport sections The total instantaneous loading volume of the bulk materials carried on the conveying section is the sum of the instantaneous loading volume of the bulk materials carried on the conveying section. The instantaneous loading volume of all bulk material loading areas is accumulated and added, and the instantaneous loading volume of each bulk material loading area is obtained by the method of Example 1; To prevent the default constant from having a denominator of zero, Values This ensures computational stability when the denominator approaches zero.

[0035] speed reduction With overload volume Positive correlation with the transport section Current speed Positively correlated with the total carrying volume of all upstream conveying sections, and negatively correlated with the total carrying volume of all upstream conveying sections. When the overload volume increases, a larger deceleration is required to delay the arrival of bulk materials; when the current speed of the conveying section is high, the same deceleration has a more significant effect on flow regulation, so the proportion increases; when the total carrying volume of the upstream conveying sections is large, the system inertia is large, and the change in arriving volume caused by a unit speed change is large, so the deceleration required for the same overload volume is smaller.

[0036] Based on the speed reduction rate of each upstream conveyor section, the current real-time operating speed is adjusted to decrease, thus obtaining the target conveying speed required for each suspended conveyor chain section. In specific implementation, the upstream conveyor sections... Calculate the target conveying speed After obtaining the target conveying speed, compare the target conveying speed with the preset minimum allowable speed for the section. If a comparison is made, Then the target conveying speed will be adjusted to ;like If the calculated value remains unchanged, the adjusted target conveying speed is used as the target conveying speed required for each section of the overhead conveyor chain and is conveyed to the subsequent speed control stage.

[0037] Example 4: In specific implementation, please refer to Figure 4 An eccentricity threshold is set, and the eccentricity of the bulk material distribution in each loading area is compared with the eccentricity threshold. The eccentricity threshold is set based on the maximum allowable safe deviation of the bulk material during transportation, and the value range of the eccentricity threshold is [value missing]. to Between these parameters, when the conveyor chain speed is high or the friction coefficient between bulk material particles is low, the eccentricity threshold is set to a smaller value; when the conveyor chain speed is low or the loading container has an anti-slip sidewall structure, the eccentricity threshold is set to a larger value. From the bulk material distribution eccentricity calculated in Example 1, each bulk material loading area is extracted one by one. Eccentricity of bulk material distribution The eccentricity of the bulk material distribution With eccentricity threshold Perform numerical comparisons.

[0038] When the eccentricity of the bulk material distribution Less than or equal to the eccentricity threshold At that time, the corresponding bulk material loading area will be... Center of gravity offset compensation coefficient Let it be the first constant. The value of the first constant is... This means that when the deviation of the center of gravity of the bulk material accumulation is within a safe range, no additional compensation correction is required for the conveying speed. The suspended conveyor chain can meet the stable conveying requirements by running at the target conveying speed calculated in Example 3.

[0039] When the eccentricity of the bulk material distribution Greater than the eccentricity threshold At this time, there is a significant shift in the center of gravity of the bulk material pile. During operation, centrifugal force or vibration may cause the bulk material to slip or the loading container to overturn. In this situation, the eccentricity of the bulk material distribution should be considered. With eccentricity threshold The difference, and the bulk loading area Instantaneous loading volume The corresponding bulk loading area is calculated. Center of gravity offset compensation coefficient Center of gravity offset compensation coefficient The calculation uses the following formula: in, Indicates bulk loading area The center of gravity offset compensation coefficient, The range of values ​​is to between, The smaller the value, the greater the deceleration compensation required for the target conveying speed. Indicates bulk loading area The eccentricity of the bulk material distribution is calculated from the ratio of the offset distance to the equivalent radius of the bottom boundary of the pile in Example 1. This indicates the eccentricity threshold, which is preset based on the characteristics of the bulk material and the operating parameters of the conveyor chain. The specific setting method is as described above. Indicates bulk loading area The instantaneous loading volume is obtained by integrating and accumulating the stacking height distribution map in Example 1. The eccentricity influence coefficient. The range of values ​​is to When the ratio of the average particle size of the bulk material to the depth of the loading container is large, the eccentricity influence coefficient... Take the larger value; when the ratio of the average particle size of the bulk material to the depth of the loading container is small, the eccentricity influence coefficient is... Take the smaller value. It is the volume smoothing constant. Values cubic meters, used to prevent instantaneous loading volume When the value is extremely small, the denominator is too small, leading to numerical instability. (Center for centroid offset compensation coefficient) With difference The rate of decrease decreases as the eccentricity of the bulk material distribution exceeds the eccentricity threshold; the greater the rate of deceleration compensation, the greater the rate of decrease. (The center of gravity offset compensation coefficient is also mentioned.) With instantaneous loading volume As the load increases, the impact of the center of gravity shift on overall stability is partially offset by the volume effect, and the compensation range decreases accordingly.

[0040] After obtaining the center-of-gravity offset compensation coefficient for each bulk material loading area, the target conveying speed of each overhead conveyor chain segment is corrected. The set of bulk material loading areas carried by each overhead conveyor chain segment is determined by reading the identifiers of all bulk material loading areas currently within the range of that conveying segment using position sensors or RFID tags installed on the overhead conveyor chain segment, thus forming the set of bulk material loading areas. ,in This is for identifying sections of the overhead conveyor chain. (Collection from bulk loading area) In the middle, extract each bulk material loading area Corresponding center of gravity offset compensation coefficient .

[0041] Calculate the set of bulk loading areas The weighted average of the center of gravity offset compensation coefficients for all bulk loading areas. (Each bulk loading area...) weight According to the bulk loading area Instantaneous loading volume Bulk loading area collection The proportion of the total loading volume is determined. Total loading volume For set The sum of the instantaneous loading volumes of all bulk material loading areas. Weight When the total loading volume When the weight is zero, the weight of all bulk loading areas Take the same value. Weighted average. Calculated using the following formula: The weighted average As the corresponding suspended conveyor chain section The overall compensation coefficient.

[0042] The corresponding suspended conveyor chain section Target conveying speed Multiply by the overall compensation coefficient The corrected target conveying speed is obtained. Corrected target delivery speed With respect to the preset minimum permissible speed of the section If the corrected target conveyor speed is lower than the minimum permissible speed of the section, the corrected target conveyor speed will be adjusted to the minimum permissible speed of the section. (Minimum permissible speed of the section) The value is determined based on the physical characteristics and control precision of the drive wheel and motor, and the range is [range missing]. meters per second to Meters per second. The corrected target conveying speed is used as the setpoint for speed control and then transmitted to the subsequent excitation current regulation stage.

[0043] Example 5: In specific implementation, please refer to Figure 5 The method for collecting the current excitation current value of each drive wheel motor is as follows: a Hall current sensor is connected in series in the excitation circuit of each drive wheel motor. The Hall current sensor converts the excitation current signal into a voltage signal, which is then digitally acquired by an analog-to-digital converter at a preset sampling frequency to obtain the current excitation current value. The current excitation current value serves as the reference for superimposing subsequent excitation current adjustments.

[0044] The process of calculating the speed deviation value based on the corrected target conveying speed and the current actual speed includes: using the corrected target conveying speed as the set speed and the current actual speed as the feedback speed. Corrected target conveying speed The current actual speed was calculated from Example 4. From the transport section The speed sensor installed on the device collects and uploads data in real time. The difference between the set speed and the feedback speed is calculated to obtain the initial speed deviation. , Initial speed deviation represents the absolute difference between the current conveying speed and the desired conveying speed.

[0045] Obtain the current total load weight for each section of the overhead conveyor chain, and based on the current total load weight, query the preset load-inertia correction table to obtain the inertia correction coefficient. Current total load weight Through the transport section The instantaneous loading volume of all bulk material loading areas is obtained by multiplying each volume by the bulk material density and then summing the results. The bulk material density is pre-determined based on the type of material being transported and stored in the controller. The preset load-inertia correction table is a two-dimensional lookup table, with the horizontal axis representing the total load weight range and the vertical axis representing the inertia correction coefficient. The load-inertia correction table is constructed based on the ratio of the change in excitation current required to determine a unit velocity deviation under different total load weights, to that under no-load conditions. Inertia correction coefficient. The range of values ​​is to When the total load weight increases, the system inertia increases, and the speed response caused by the same change in excitation current becomes slower, thus affecting the inertia correction factor. The initial velocity deviation is increased accordingly to compensate for inertial hysteresis. Multiply by the inertia correction factor The speed deviation value is obtained. .

[0046] Speed ​​deviation value The calculation uses the following formula: in, Indicates the section of the overhead conveyor chain The speed deviation value, in meters per second; Indicates the section of the overhead conveyor chain The inertia correction factor is obtained by looking up the load-inertia correction table from the current total load weight. The range of values ​​is to ; Indicates the section of the overhead conveyor chain The corrected target conveying speed was calculated from Example 4; Indicates the section of the overhead conveyor chain The current actual speed is collected by the speed sensor.

[0047] Based on speed deviation value The initial excitation current adjustment is obtained by querying the preset deviation-current mapping table. The deviation-current mapping table is a pre-calibrated two-dimensional lookup table, with the horizontal axis representing the speed deviation range and the vertical axis representing the corresponding initial excitation current adjustment. The calibration method for the deviation-current mapping table is as follows: Under no-load standard operating conditions, apply step changes in excitation current of different amplitudes to the drive wheel motor, record the steady-state speed changes, and establish the correspondence between the speed changes and the excitation current changes. The sign of the initial excitation current adjustment is determined according to the direction of the speed deviation value. When the speed deviation value is positive, the initial excitation current adjustment is positive, indicating that the excitation current needs to be increased to increase the output torque and thus increase the actual speed; when the speed deviation value is negative, the initial excitation current adjustment is negative, indicating that the excitation current needs to be decreased to reduce the output torque and thus decrease the actual speed.

[0048] The system collects the current temperature values ​​of the motors of each drive wheel and calculates a temperature correction factor based on these values. The temperature acquisition is achieved by installing PT100 platinum resistance temperature sensors on the surface of the motor housings of each drive wheel. The sensors are tightly fitted to the motor housings using thermally conductive silicone grease. The signals from the temperature sensors are converted into digital signals by a temperature transmitter and then transmitted to the controller to obtain the current temperature value. Set the current temperature value. With the preset rated operating temperature Compare and calculate the temperature difference. Preset rated operating temperature Determined based on the insulation class and design operating conditions of the drive wheel motor. Values Celsius.

[0049] When temperature difference When the temperature is less than or equal to zero, the current temperature value does not exceed the rated operating temperature, the motor is operating within the normal temperature range, and the copper loss heating of the excitation winding does not cause a significant change in the winding resistance. Therefore, the temperature correction factor is adjusted accordingly. Set as the second constant. The value of the second constant is... This indicates that the initial excitation current adjustment is not subject to temperature decay.

[0050] When temperature difference When the value is greater than zero, the motor is in an overheated state. The resistance of the excitation winding increases with rising temperature, and the actual excitation current will decrease under the same excitation voltage. To avoid insulation damage due to continuous loading caused by overheating, the excitation current regulation is derated. This is based on the temperature difference. With the preset temperature step factor The product of these factors is used to calculate the temperature decay coefficient. Preset temperature step factor Determined based on the heat resistance characteristics of the motor insulation material. Values Each degree Celsius means every time the temperature exceeds the rated operating temperature. Celsius, excitation current regulation attenuation Temperature decay coefficient With the second constant The difference is used as a temperature correction factor. ,Right now Temperature correction factor With temperature difference As the temperature difference increases, the temperature correction factor decreases, and the magnitude of the attenuation of the excitation current regulation increases.

[0051] Adjust the initial excitation current Multiply by temperature correction factor The excitation current adjustment of the motors for each drive wheel is obtained. .

[0052] The process of adjusting the output torque of the corresponding drive wheel according to the excitation current adjustment of the motor of each drive wheel includes: adjusting the excitation current adjustment of the motor of each drive wheel... Compared with the current excitation current value By superimposing the values, the target excitation current value is obtained. The target excitation current value is converted into a corresponding excitation current adjustment command. This command, a digital signal, is sent to the motor driver via a fieldbus. The motor driver includes an adjustable constant current source circuit that adjusts the input current of the excitation windings of each drive wheel's motor according to the excitation current adjustment command, thereby changing the magnetic flux density and thus altering the electromagnetic torque output of the drive wheels.

[0053] The actual output speed of each drive wheel motor is monitored in real time. The actual output speed is acquired by an incremental encoder. The A-phase and B-phase pulse signals of the encoder are processed by a quadrature decoder to obtain the actual output speed of the motor. Based on the actual output speed With the target output speed The speed difference is used to perform closed-loop correction of the excitation current adjustment command. Target output speed Based on the corrected target transport speed It is obtained by conversion with the pitch circle diameter of the drive wheel. Closed-loop correction uses a proportional-integral (PI) controller, whose input is the speed difference. The output is the correction amount for the excitation current regulation command. Based on the closed-loop corrected excitation current regulation command, the input current of the excitation winding is adjusted again until the speed difference is less than the preset threshold. The preset threshold is set to... When the speed difference is less than the preset threshold, the actual conveying speed is considered to be close to the corrected target conveying speed, and the closed-loop adjustment process ends.

[0054] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for adaptive flow rate adjustment of bulk material online overhead conveying, characterized in that, include: Acquire real-time image sequences of the bulk material loading areas on the overhead conveyor chain, and identify the bulk material accumulation contours of each bulk material loading area based on the real-time image sequences; Based on the bulk material accumulation profile, determine the instantaneous loading volume and bulk material distribution eccentricity of each bulk material loading area; Based on the real-time operating speed of each overhead conveyor chain section and the instantaneous loading volume of each bulk material loading area, the arrival time sequence of bulk materials at each conveying node within the future time window is predicted. Based on the arrival time of bulk materials at each conveying node and the unloading capacity boundary of the downstream unloading equipment, calculate the target conveying speed required for each section of the overhead conveyor chain; Based on the eccentricity of the bulk material distribution, a center of gravity offset compensation coefficient is generated for each bulk material loading area. Based on the center of gravity offset compensation coefficient, the target conveying speed of each suspended conveyor chain section is corrected to obtain the corrected target conveying speed. Based on the speed deviation between the current actual speed of each suspended conveyor chain section and the corrected target conveying speed, the excitation current adjustment of the motor of each drive wheel is determined. Adjust the output torque of the corresponding drive wheel according to the excitation current adjustment of the motor of each drive wheel, so that the actual conveying speed of each suspended conveyor chain section approaches the corrected target conveying speed.

2. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 1, characterized in that, Based on the bulk material accumulation profile, determine the instantaneous loading volume and bulk material distribution eccentricity of each bulk material loading area, including: Extract the stacking height distribution map and the stacking bottom boundary of each bulk material loading area from the bulk material stacking outline; Based on the stacking height distribution map, the area enclosed by the bottom boundary of the stack is integrated and accumulated to obtain the instantaneous loading volume of each bulk material loading area; Based on the stacking height distribution map, calculate the coordinates of the stacking mass center of each bulk material loading area; Calculate the geometric center coordinates of the bottom surface of each bulk material loading area based on the bottom surface boundary of the stack. Calculate the offset distance between the coordinates of the mass center of the stack and the coordinates of the geometric center of the bottom surface, and use the ratio of the offset distance to the equivalent radius of the bottom boundary of the stack as the eccentricity of the bulk material distribution.

3. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 2, characterized in that, Based on the real-time operating speed of each overhead conveyor chain segment and the instantaneous loading volume of each bulk material loading area, the arrival time sequence of bulk materials at each conveying node within the future time window is predicted, including: The overhead conveyor chain is divided into multiple conveying sections, and a corresponding real-time operating speed is configured for each conveying section; Based on the current conveying section and corresponding real-time operating speed of each bulk material loading area, calculate the remaining conveying time for each bulk material loading area to reach each downstream conveying node. The instantaneous loading volume of each bulk material loading area is sorted according to the corresponding remaining conveying time to generate the bulk material arrival time sequence of each conveying node within the future time window; Based on the bulk material arrival time sequence of each conveying node and the instantaneous loading volume of each bulk material loading area, the predicted arrival volume of each conveying node at each moment within the future time window is generated.

4. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 3, characterized in that, Based on the arrival time sequence of bulk materials at each conveying node and the unloading capacity boundary of the downstream unloading equipment, calculate the target conveying speed required for each section of the overhead conveyor chain, including: The maximum acceptable volume of the downstream unloading equipment at each moment is taken as the unloading capacity boundary. By comparing the predicted arrival volume of each conveying node at each time with the unloading capacity boundary, the overload time and overload volume when the predicted arrival volume exceeds the unloading capacity boundary are identified. Based on the overload volume of each conveying node at the overload time, calculate the required speed reduction for each upstream conveying section corresponding to each conveying node; Based on the speed reduction rate of each upstream conveying section, the current real-time operating speed is adjusted to reduce speed, thereby obtaining the target conveying speed required for each suspended conveyor chain section.

5. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 4, characterized in that, Based on the bulk material distribution eccentricity, a center of gravity offset compensation coefficient is generated for each bulk material loading area, including: Set an eccentricity threshold and compare the eccentricity of the bulk material distribution in each bulk material loading area with the eccentricity threshold; When the eccentricity of the bulk material distribution is less than or equal to the eccentricity threshold, the center of gravity offset compensation coefficient of the corresponding bulk material loading area is set to the first constant. When the eccentricity of the bulk material distribution is greater than the eccentricity threshold, the center of gravity offset compensation coefficient of the corresponding bulk material loading area is calculated based on the difference between the eccentricity of the bulk material distribution and the eccentricity threshold, and the instantaneous loading volume of the bulk material loading area. The center of gravity offset compensation coefficient increases with the increase of the difference and decreases with the increase of the instantaneous loading volume.

6. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 5, characterized in that, Based on the aforementioned center of gravity offset compensation coefficient, the target conveying speed of each suspended conveyor chain section is corrected to obtain the corrected target conveying speed, including: Determine the set of bulk material loading areas carried by each section of the overhead conveyor chain; Extract the center of gravity offset compensation coefficient corresponding to each bulk material loading area from the set of bulk material loading areas; Calculate the weighted average of the center of gravity offset compensation coefficients of all bulk material loading areas in the bulk material loading area set, wherein the weight of each bulk material loading area is determined according to the proportion of its instantaneous loading volume to the total loading volume of the bulk material loading area set; The weighted average value is used as the overall compensation coefficient for the corresponding suspended conveyor chain section; The corrected target conveying speed is obtained by multiplying the target conveying speed of the corresponding suspended conveyor chain section by the overall compensation coefficient.

7. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 6, characterized in that, Based on the speed deviation between the current actual speed of each suspended conveyor chain segment and the corrected target conveying speed, the excitation current adjustment of the motor of each drive wheel is determined, including: Collect the current excitation current value of the motor of each drive wheel; Calculate the speed deviation value based on the corrected target conveying speed and the current actual speed; Based on the speed deviation value, the initial excitation current adjustment amount is obtained by querying the preset deviation-current mapping table. Collect the current temperature value of the motor of each drive wheel, and calculate the temperature correction factor based on the current temperature value; Multiply the initial excitation current adjustment by the temperature correction factor to obtain the excitation current adjustment of the motors for each drive wheel.

8. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 7, characterized in that, According to the excitation current adjustment of the motor of each drive wheel, the output torque of the corresponding drive wheel is adjusted to make the actual conveying speed of each suspended conveyor chain section approach the corrected target conveying speed, including: The excitation current adjustment of each drive wheel motor is converted into a corresponding excitation current adjustment command. According to the excitation current adjustment command, adjust the input current of the excitation winding of the motor of each drive wheel; The actual output speed of the motors of each drive wheel is monitored in real time, and the excitation current adjustment command is corrected in a closed loop based on the speed difference between the actual output speed and the target output speed. Based on the closed-loop corrected excitation current adjustment command, the input current of the excitation winding is adjusted again until the speed difference is less than the preset threshold.

9. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 8, characterized in that, Based on the corrected target conveying speed and the current actual speed, calculate the speed deviation value, including: The corrected target conveying speed is used as the set speed, and the current actual speed is used as the feedback speed; Calculate the difference between the set speed and the feedback speed to obtain the initial speed deviation; Obtain the current total load weight of each suspended conveyor chain section, and based on the current total load weight, query the preset load-inertia correction table to obtain the inertia correction coefficient; The initial velocity deviation is multiplied by the inertia correction factor to obtain the velocity deviation value.

10. The method for adaptive flow adjustment of bulk material online overhead conveying according to claim 9, characterized in that, Collect the current temperature value of the motor of each drive wheel, and calculate the temperature correction factor based on the current temperature value, including: Temperature sensors are installed on the housing surface of the motors of each drive wheel, and the current temperature value is collected in real time through the temperature sensors; The current temperature value is compared with the preset rated operating temperature, and the temperature difference is calculated. When the temperature difference is less than or equal to zero, the temperature correction factor is set to a second constant; When the temperature difference is greater than zero, the temperature decay coefficient is calculated based on the product of the temperature difference and the preset temperature step coefficient, and the difference between the temperature decay coefficient and the second constant is used as the temperature correction factor. The temperature correction factor decreases linearly as the temperature difference increases.

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