Variable frequency speed regulation control method of conveyor based on material flow prediction

Abstract

The application discloses a conveyor variable frequency speed regulation control method based on material flow prediction and relates to the technical field of conveyor operation control, which comprises the following steps: establishing a transfer space-time coordinate at a transfer position of an upstream conveyor and a downstream conveyor, collecting a material flow occupation value of the upstream conveyor, a variable frequency instruction change process and an actual belt speed change process, identifying a predicted material peak interval, forming a material peak occupation unit according to a sampling time sequence, correcting an arrival time sequence and an occupation state of the material peak occupation unit, and forming a material peak arrival occupation state; determining a downstream bearing calculation period according to the material peak arrival occupation state, and correcting a downstream bearing area according to a deviation prediction state of the downstream conveyor. The application establishes the material peak arrival judgment on the basis of the common correction of the actual belt speed change and the material flow change before the transfer position, and can reduce the advance or lag deviation generated when the arrival time is calculated according to the target frequency or the fixed belt speed.

Description

Technical Field

[0001] This invention relates to the field of conveyor operation control technology, specifically a conveyor frequency conversion speed control method based on material flow prediction. Background Technology

[0002] Belt conveyors are commonly used in continuous material conveying scenarios such as mines, ports, building materials, metallurgy, and power. To adapt to different conveying loads and operating rhythms, conveyors are usually equipped with frequency converters, which change the belt speed by adjusting the output frequency. In multi-stage conveying systems, upstream and downstream conveyors are connected through transfer positions. The unloading rhythm of the upstream conveyor, the arrival time of the material, and the receiving position of the downstream conveyor all affect the material dropping state during the transfer process. Therefore, the frequency conversion speed regulation of multi-stage conveyors involves not only the belt speed control of a single conveyor, but also the timing coordination between the upstream material release process and the downstream receiving process. In existing conveyor speed control, the material arrival time can usually be estimated based on the material flow rate detected upstream, the conveying distance, the current belt speed, or the target belt speed, and the operating frequency of the upstream or downstream conveyor can be adjusted accordingly. Alternatively, the speed can be limited, reduced, or shut down based on the operating status, rated load capacity, or deviation detection results of the downstream conveyor. The above methods can meet the flow regulation and equipment protection requirements under general conveying conditions. However, when the material flow increases in a short period of time, the material peak formed at the upstream detection position will not simply arrive at the transfer position at the belt speed corresponding to the target frequency. Changes in the inverter output frequency, the actual belt speed establishment process, and changes in the actual material flow before the transfer position may all cause the actual arrival time of the material peak to be earlier or later than the predicted arrival time. Furthermore, when the downstream conveyor deviates from its designated receiving position, its effective carrying area will shift along the bandwidth direction. At this time, even if the downstream conveyor is still in an operational state, the lateral occupancy range of the material peak may no longer correspond to the actual downstream carrying boundary, especially the edge of the material peak may exceed the effective carrying range on the left or right. If the speed control generates frequency commands based solely on the upstream predicted flow rate or the downstream rated carrying capacity, there may be situations where the upstream release rhythm has changed, and the actual downstream receiving range is insufficient to cover the material drop range. Summary of the Invention

[0003] The purpose of this invention is to provide a variable frequency speed control method for conveyors based on material flow prediction, so as to solve the problems mentioned in the background art.

[0004] This invention can be achieved through the following technical solution: a conveyor frequency conversion speed control method based on material flow prediction, comprising: Step 1: Establish the transfer time and space coordinates at the transfer position of the upstream conveyor and the downstream conveyor, collect the material flow occupancy value, frequency conversion command change process and actual belt speed change process of the upstream conveyor, identify the predicted material peak interval, form the predicted material peak interval into material peak occupancy units according to the sampling time sequence, and correct the arrival time sequence and occupancy status of the material peak occupancy units to form the material peak arrival occupancy status. Step 2: Determine the downstream load-bearing time period based on the material peak arrival and occupancy status, correct the downstream load-bearing area based on the predicted deviation status of the downstream conveyor, and compare the material peak arrival and occupancy status with the corrected downstream load-bearing area to form the initial off-center load coverage status. Step 3: Taking the uncovered material peak occupancy unit in the initial coverage state of off-center load as the adjustment object, generate candidate differential frequency converter control quantities, and calculate the material drop overlap change corresponding to the candidate differential frequency converter control quantities to form the material drop overlap adjustment quantity. Step 4: Determine the receiving gap based on the material drop overlap adjustment amount. Under the constraints of the downstream conveyor's allowable speed limit and the receiving stable speed limit defined by the deviation prediction state, form the downstream advance receiving amount. Then, deduct the downstream advance receiving amount, the upstream peak reduction amount, and the delayed coverage occupancy amount corresponding to the upstream delayed release amount in sequence from the receiving gap. For the part that is still not covered after deduction, form a prohibited frequency increase state to obtain the gap sharing control amount. Step 5: Generate a dual-end differential frequency converter control command based on the material drop overlap adjustment amount and the gap sharing control amount, and control the upstream and downstream conveyors according to the dual-end differential frequency converter control command.

[0005] A further technical improvement of the present invention is that: step one, establishing the spatiotemporal coordinates of the transport, includes: Read the unloading center of the upstream conveyor at the transfer position and the bearing center of the downstream conveyor at the receiving position, project the unloading center onto the bearing surface of the downstream conveyor to form the transfer and dropping center, and determine the coordinate origin with the transfer and dropping center; Read the conveying direction, bandwidth direction, and lateral offset of the bearing center relative to the transfer and unloading center of the downstream conveyor at the receiving position. Determine the longitudinal coordinate direction with the conveying direction and the lateral coordinate direction with the bandwidth direction, and record the lateral offset of the bearing center relative to the transfer and unloading center in the lateral coordinate. Read the sampling time, frequency conversion command change process, actual belt speed change process, and material flow change process before the transfer position, and write the frequency conversion command change process, actual belt speed change process, and material flow change process before the transfer position into the same time coordinate according to the sampling time; Based on the actual belt speed change process and sampling interval, the actual conveying displacement of the material peak interval from the upstream conveyor feed side detection position to the unloading center is cumulatively predicted. The initial arrival time of the material peak occupation unit is determined based on the actual conveying displacement. The initial arrival time is corrected based on the material flow change process before the transfer position to obtain the corrected arrival time. The arrival position of the material peak occupancy unit in the vertical coordinate is determined based on the corrected arrival time. The horizontal occupancy range corresponding to the material flow occupancy value is written into the horizontal coordinate, and the corrected arrival time is written into the time sequence coordinate to form the transfer time and space coordinate.

[0006] A further technical improvement of the present invention is that: step one, forming the peak occupancy unit, includes: Read the material flow occupancy values ​​within the predicted material peak interval according to the order of sampling time, and form corresponding material peak occupancy units according to the sampling time corresponding to each material flow occupancy value; Based on the sampling time, actual belt speed change process and sampling interval corresponding to the material flow occupancy value, the actual conveying displacement from the upstream conveyor feed side detection position to the unloading center is accumulated, and the initial arrival time of the corresponding material peak occupancy unit is determined when the accumulated actual conveying displacement reaches the conveying distance from the feed side detection position to the unloading center. Based on the material flow change process before the transfer position corresponding to the initial arrival time, the initial arrival time is corrected to form the corrected arrival time of the corresponding material peak occupancy unit. The arrival position of the corresponding material peak occupancy unit in the longitudinal coordinate is determined based on the corrected arrival time, and the lateral occupancy range of the corresponding material peak occupancy unit in the lateral coordinate is determined based on the material flow occupancy value and the lateral offset of the bearing center relative to the transfer and unloading center. The arrival sequence of each material peak occupancy unit is determined based on the corrected arrival time, and the material flow occupancy value, the corrected arrival time, the arrival position in the vertical coordinate, the horizontal occupancy range in the horizontal coordinate, and the arrival sequence are written into the corresponding material peak occupancy unit.

[0007] A further technical improvement of the present invention is that: in the process of forming the peak occupancy unit in step one, the step of correcting the initial arrival time includes: Read the material flow occupancy value, initial arrival time, and sampling time corresponding to the material peak occupancy unit of the material peak occupancy unit, and read the frequency conversion command change process and the actual belt speed change process; The target belt speed change between the sampling time and the initial arrival time of the peak material occupancy unit is determined according to the frequency conversion command change process, and the target belt speed change is compared with the actual belt speed change process in the same time period to obtain the belt speed comparison result. Read the material flow change process before the transfer position corresponding to the initial arrival time, and compare the material flow occupancy value of the material peak occupancy unit with the material flow occupancy value during the material flow change process before the transfer position to obtain the material flow comparison result; The initial arrival time is corrected by combining the belt speed comparison result and the material flow comparison result. When the correction directions corresponding to the belt speed comparison result and the material flow comparison result are inconsistent, the material flow comparison result is used as the correction basis to form the corrected arrival time of the material peak occupation unit.

[0008] A further technical improvement of the present invention is that step two, which calculates the predicted state of misalignment of the downstream conveyor, includes: The downstream receiving period is determined based on the peak material arrival and occupancy status, and the starting point of the downstream receiving period is taken as the ending time, and the deviation sampling period is selected backward. During the deviation sampling period, the deviation sampling positions of the downstream conveyor along the bandwidth direction are read in the order of sampling time, and the deviation direction and deviation change are determined according to the lateral position difference between adjacent deviation sampling positions. When the offset directions of consecutive adjacent deviation sampling positions are consistent and the amount of offset change does not exceed the deviation change limit, the corresponding deviation sampling position is used as the object of deviation change rate calculation, and the deviation change rate is determined based on the deviation sampling position, the amount of offset change, and the sampling interval that is closest to the starting point of the downstream receiving estimated time period at the formation time. Based on the deviation change rate and the deviation sampling position that is closest to the starting point of the downstream receiving estimation period, the deviation position and offset direction within the downstream receiving estimation period are determined, thus forming the deviation prediction state. When consecutive adjacent deviation sampling positions do not simultaneously satisfy the conditions of consistent deviation direction and deviation change amount not exceeding the deviation change limit, the deviation position in the downstream calculation period is determined by the deviation sampling position whose formation time is closest to the starting point of the downstream calculation period, and the deviation change rate is set to zero to form the deviation prediction state.

[0009] A further technical improvement of the present invention is that the step of determining the candidate differential frequency converter control quantity for forming the material drop overlap adjustment quantity in step three includes: Read the material receiving overlap change corresponding to the current candidate differential frequency converter control quantity, and determine the overlap relationship between the uncovered material peak occupying unit in the initial coverage state of the off-center load and the corrected downstream bearing area based on the material receiving overlap change; When it is determined that all uncovered material peak occupancy units have entered the corrected downstream bearing area based on the changes in material drop overlap, the material drop overlap adjustment amount is formed by the current candidate differential frequency converter control amount, and the generation of candidate differential frequency converter control amounts with further increases in adjustment amplitude is stopped. When determining that the uncovered material peak occupancy units have not all entered the corrected downstream bearing area based on the material drop receiving overlap change, the overlap increase is formed according to the material drop receiving overlap change corresponding to the current candidate differential frequency converter control quantity and the previous candidate differential frequency converter control quantity, and the frequency conversion adjustment completion time corresponding to the current candidate differential frequency converter control quantity is compared with the earliest corrected arrival time in the uncovered material peak occupancy unit. If the overlap increase amount does not reach the overlap increase limit and the frequency conversion adjustment completion time is earlier than the earliest correction time, the material dropping overlap adjustment amount is formed by the previous candidate differential frequency conversion control amount, and the generation of candidate differential frequency conversion control amounts that continue to increase the adjustment amplitude is stopped. When the overlap increase reaches the overlap increase limit and the frequency conversion adjustment completion time is earlier than the earliest correction time, candidate differential frequency conversion control quantities with increased adjustment amplitude are generated.

[0010] A further technical improvement of the present invention is that the step of determining the stable speed limit in step four includes: Read the deviation position and offset direction corresponding to the deviation prediction state, and determine the bearing boundary position of the corrected downstream bearing area on one side of the offset direction; The adjusted occupancy range of the material peak occupancy unit in the bandwidth direction is determined based on the material drop overlap adjustment amount, and the occupancy boundary position on the side closer to the offset direction in the adjusted occupancy range is determined. The remaining bearing distance on the offset side is obtained based on the distance between the occupied boundary position and the bearing boundary position, and the remaining bearing distance on the offset side is compared with the bearing edge retention distance; When the remaining receiving distance on the offset side is not less than the retaining distance at the receiving edge, the upper limit of the allowable speed of the downstream conveyor shall be used as the stable speed limit for receiving. When the remaining receiving distance on the offset side is less than the receiving edge retention distance, the speed limit amount that does not exceed the upper limit of the downstream conveyor's allowable speed is determined based on the difference between the receiving edge retention distance and the remaining receiving distance on the offset side. The speed limit amount is then subtracted from the upper limit of the downstream conveyor's allowable speed to obtain the stable receiving speed limit. The downstream advance acceptance amount is constrained by the stable acceptance speed limit, so that the downstream conveyor speed corresponding to the advance acceptance amount does not exceed the stable acceptance speed limit.

[0011] A further technical improvement of the present invention is that the step of determining the trailing segment corresponding to the upstream delayed release amount in step four includes: Read the remaining gap after deducting the downstream advance acceptance amount and the upstream peak reduction amount in sequence, and read the arrival sequence, corrected arrival time and material flow occupation value of each material peak occupation unit in the predicted material peak interval. Select peak occupancy units from back to front according to arrival order, and accumulate the remaining occupancy amount in the selected peak occupancy units that is not covered by the downstream early acceptance amount and the upstream peak reduction amount. When the accumulated remaining occupancy amount reaches the remaining acceptance gap, the selected peak occupancy unit is determined as the downstream peak occupancy unit. After the downstream receiving estimated time period, based on the corrected downstream receiving area after deducting the material peak occupancy units that have been arranged to be received, the subsequent receiving time period for the material peak occupancy units in the downstream section is determined. Based on the time difference between the corrected arrival time of the peak occupancy unit in the rear section and the starting point of the subsequent receiving period, the upstream delayed release amount corresponding to the peak occupancy unit in the rear section is determined, and the upstream delayed release amount is written into the gap sharing control amount. The release sequence of the peak occupancy units in the downstream segment is delayed according to the upstream delayed release amount, while keeping the release sequence of the peak occupancy units in the predicted peak interval that have not been determined as peak occupancy units in the downstream segment unchanged.

[0012] Compared with the prior art, the present invention has the following beneficial effects: This invention establishes the determination of peak material arrival based on the joint correction of actual belt speed changes and material flow changes before the transfer position. This can reduce the early or late deviations that occur when the arrival time is calculated only based on the target frequency or fixed belt speed. Therefore, the peak material arrival time, arrival sequence and occupancy range on which subsequent speed control is based can be closer to the actual feeding process of the upstream conveyor, avoiding the generation of mismatched upstream and downstream speed control actions when the peak material has not yet arrived or has arrived early. Furthermore, this invention introduces the bearing area after deviation in the downstream bearing judgment, so that the lateral occupancy range of the material peak can be compared with the actual bearing boundary of the downstream conveyor; for the uncovered part on the left or right side caused by deviation, its position and occupancy can be identified before generating the frequency conversion control command, so that the speed control is no longer based solely on the nominal bandwidth or rated bearing capacity of the downstream conveyor, but can reflect the actual material receiving status at the transfer position, thereby reducing the probability of material peak edge falling outward, local accumulation and instantaneous insufficient bearing. On the other hand, when there are still uncovered parts after the material overlap adjustment, the present invention decomposes the remaining acceptance gap into control results corresponding to downstream early acceptance, upstream peak reduction, upstream delayed release, and prohibition of frequency increase, so that the uncovered part is no longer handled by a single speed increase or a single speed decrease action. Through this sharing method, the remaining acceptance risk can be converted into a frequency timing constraint that can be issued, so that the upstream release rhythm and the downstream acceptance rhythm form a corresponding relationship within the same transfer period, reducing the continuous conveying interruption caused by the concentrated release of material peaks. Attached Figure Description

[0013] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0014] Figure 1 This is a schematic diagram of the method logic of the present invention. Detailed Implementation

[0015] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0016] Please see Figure 1 As shown, this invention provides a conveyor frequency conversion speed control method based on material flow prediction, including: Step 1: Establish the transfer time and space coordinates at the transfer position of the upstream conveyor and the downstream conveyor, collect the material flow occupancy value, frequency conversion command change process and actual belt speed change process of the upstream conveyor, identify the predicted material peak interval, form the predicted material peak interval into material peak occupancy units according to the sampling time sequence, and correct the arrival time sequence and occupancy status of the material peak occupancy units to form the material peak arrival occupancy status. In this embodiment, step one is used to establish a transfer spatiotemporal coordinate system at the transfer positions of the upstream and downstream conveyors, and to determine the predicted material peak interval, material peak occupancy unit, and material peak arrival and occupancy status within this transfer spatiotemporal coordinate system. The feed-side detection position of the upstream conveyor and the material flow acquisition position before the transfer position are determined during equipment installation and calibration. Both are recorded along the conveying centerline of the upstream conveyor at a longitudinal distance relative to the unloading center, and the recorded values ​​are saved in mm. The feed-side detection position is located before the unloading center and is used to collect the material flow occupancy value entering the upstream conveyor. The material flow acquisition position before the transfer position is close to the unloading center and is still located before the unloading center, used to form the material flow change process before the transfer position. The conveying distance from the feed-side detection position to the unloading center is measured along the conveying centerline of the upstream conveyor during equipment installation and calibration, and is used as a comparison object to determine whether the material peak occupancy unit has reached the unloading center when accumulating the actual conveying displacement.

[0017] The material flow occupancy value is obtained by multiplying the lateral coverage width of the material in the bandwidth direction by the average height of the material layer within that lateral coverage width, and recorded in mm². The lateral coverage width is determined by the projected boundary of the material in the bandwidth direction, and the average height of the material layer is obtained by averaging the height values ​​of each height sampling point within that lateral coverage width. When collecting the material flow occupancy value, the sampling time, the lateral coverage start point, and the lateral coverage end point are saved simultaneously; the lateral coverage start point and the lateral coverage end point are recorded in mm, and are first saved with the bandwidth centerline of the corresponding sampling position as a reference, and then converted to the lateral coordinates of the transfer spatiotemporal coordinates when written to the material peak occupancy unit.

[0018] When establishing the spatiotemporal coordinates for material transfer, the unloading center of the upstream conveyor at the transfer location and the bearing center of the downstream conveyor at the receiving location are read. The unloading center is determined by the intersection of the conveying centerline of the unloading end of the upstream conveyor and the axis of the unloading end roller; the bearing center is determined by the intersection of the centerline of the bearing surface of the downstream conveyor in the bandwidth direction and the material receiving area. The unloading center is projected onto the bearing surface of the downstream conveyor along the material dropping direction to form the transfer material dropping center, and the origin of the coordinate system is determined by the transfer material dropping center. The conveying direction of the downstream conveyor at the receiving location is used as the longitudinal coordinate direction, and the bandwidth direction is used as the transverse coordinate direction; at the same time, the transverse offset of the bearing center relative to the transfer material dropping center in the bandwidth direction is read and recorded in the transverse coordinate system. Therefore, the arrival position and transverse occupancy range of subsequent material peak occupancy units are both referenced to the same transfer material dropping center.

[0019] In the time dimension, the frequency converter command output cycle, actual belt speed acquisition cycle, and material flow acquisition cycle, which were written before step one, are read and used to form continuous sampling times according to a uniform sampling interval. The sampling interval is recorded in seconds, taking the maximum cycle among the frequency converter command output cycle, actual belt speed acquisition cycle, and material flow acquisition cycle; for example, when the frequency converter command output cycle is 0.2s, the actual belt speed acquisition cycle is 0.1s, and the material flow acquisition cycle is 0.2s, the sampling interval is 0.2s. At each sampling time, the target frequency value and the time when the target frequency value is formed of the upstream conveyor are read to form the frequency converter command change process; the actual belt speed value of the upstream conveyor is read to form the actual belt speed change process; and the material flow occupancy value at the material flow acquisition position before the feed side detection position and the transfer position is read to form the corresponding material flow change record. The above data are written to the same time-series coordinate according to the sampling time, so that subsequent arrival calculation and arrival correction can be performed under the same time reference.

[0020] The predicted peak material range is identified based on the material flow occupancy value detected at the feed side. First, a stable feeding period is read during the current feeding process. This stable feeding period is a continuous sampling period where no frequency adjustment occurs during the frequency conversion command changes, and the difference in actual belt speed values ​​between adjacent sampling times does not exceed the belt speed stability limit. The actual belt speed value is recorded in m / s. The actual belt speed acquisition resolution is determined by the actual belt speed acquisition parameters written before step one, and serves as the minimum speed change that can distinguish the actual belt speed value. The belt speed stability limit is obtained by multiplying the actual belt speed acquisition resolution by the belt speed stability factor. The belt speed stability factor is written according to the allowable noise range of the actual belt speed acquisition; in this embodiment, the belt speed stability factor is 2. If a stable feeding period can be formed during the current feeding process, the peak material identification threshold is determined based on the average material flow occupancy value within this stable feeding period and the maximum difference between each material flow occupancy value and this average value.

[0021] If the current feeding process has not yet formed a stable feeding period, the material flow occupancy values ​​saved within the most recent N sampling times are read. The peak material identification threshold is determined based on the average of these N sampling times and the maximum difference between each material flow occupancy value and this average. N is the sliding sampling number for peak material identification, determined based on the sampling interval and the number of consecutive samples required to determine the start and end points of the predicted peak interval, and is not less than the sum of the number of consecutive samples required to determine the start and end points; in this embodiment, N is 10. If the saved material flow occupancy values ​​are less than N sampling times, all saved material flow occupancy values ​​are used to form the peak material identification threshold. Therefore, a stable feeding period is used to improve the stability of the peak material identification threshold, but it is not used as a trigger condition for predicting peak interval identification.

[0022] After determining the peak material identification threshold, the material flow occupancy values ​​at the feed-side detection positions are read in chronological order of sampling time. The material flow change between adjacent sampling times is calculated, and the direction of material flow change at the corresponding sampling time is determined based on whether the material flow change is positive or negative. The start and end points of the predicted peak material interval are confirmed using the number of consecutive peak material judgments, which is no less than 2, and is written according to the material flow acquisition cycle and the duration of material flow fluctuations. In this embodiment, the number of consecutive peak material judgments is 2. When the material flow occupancy value reaches the peak material identification threshold, and the direction of material flow change is upward in all sampling times that reach the consecutive peak material judgment number, the earliest sampling time in this consecutive sampling time is determined as the start point of the predicted peak material interval. The material flow occupancy value continues to be read from this start point. When the material flow occupancy value falls below the peak material identification threshold, and the direction of material flow change no longer remains upward in all sampling times that reach the consecutive peak material judgment number, the corresponding first sampling time is determined as the end point of the predicted peak material interval. Once both the start and end points are formed, the continuous sampling period between them is written into the predicted peak material interval. Continuous sampling data where only the start point has formed but the end point has not yet been formed is initially saved as a pending interval and not written into the predicted peak material interval. The pending interval stores the start time, each sampling time, and the corresponding material flow occupancy value, and continues to receive frequency conversion command changes and actual belt speed changes as the sampling time changes. Once the end point is formed, this pending interval is then written into the predicted peak material interval. The predicted peak material interval stores the interval start point, interval end point, each sampling time within the interval, the corresponding material flow occupancy value at each sampling time, the lateral coverage start point, and the lateral coverage end point.

[0023] After forming the predicted peak material range, the material flow occupancy value within the range is read in chronological order of sampling time, and the material flow occupancy value corresponding to each sampling time is formed into a peak material occupancy unit. Each peak material occupancy unit stores the corresponding sampling time, material flow occupancy value, lateral coverage start point, lateral coverage end point, and sampling position. For any peak material occupancy unit, starting from the sampling time corresponding to that peak material occupancy unit, the actual conveying displacement from the upstream conveyor feed side detection position to the unloading center is accumulated based on the actual belt speed change process and sampling interval. The conveying displacement within each sampling interval is calculated by multiplying the actual belt speed value corresponding to that sampling interval by the sampling interval, converting it to mm, and then participating in the accumulation. When the accumulated actual conveying displacement reaches the conveying distance from the feed side detection position to the unloading center, the corresponding sampling time is determined as the initial arrival time of that peak material occupancy unit. This initial arrival time reflects the actual conveying progress of the upstream conveyor, not the theoretical conveying progress at the target frequency.

[0024] After determining the initial arrival time, the material flow occupancy value, initial arrival time, and corresponding sampling time of the material peak occupancy unit are read. The frequency conversion command change process and actual belt speed change process between the corresponding sampling time and the initial arrival time are also read. Based on the target frequency value during the frequency conversion command change process and the pre-calibrated frequency-belt speed correspondence, the target belt speed change is determined. The frequency-belt speed correspondence is obtained from the upstream conveyor's no-load calibration and is used to store the correspondence between the target frequency value and the stable belt speed value. When the target frequency value is between two adjacent frequency points, linear interpolation is performed based on the stable belt speed values ​​of the two adjacent frequency points to obtain the target belt speed value corresponding to the target frequency value. The target belt speed change is formed from the target belt speed values ​​at continuously sampled times.

[0025] Subsequently, the actual belt speed value is compared with the target belt speed value at each sampling time to obtain the belt speed difference. The belt speed difference is the actual belt speed value minus the target belt speed value. The belt speed difference is retrieved backward from the sampling time corresponding to the initial arrival time. When the belt speed difference for K consecutive sampling times, including that sampling time, is less than 0 and its absolute value reaches the actual belt speed acquisition resolution, a belt speed comparison result pointing to arrival delay correction is formed. When the belt speed difference for K consecutive sampling times, including that sampling time, is greater than 0 and its absolute value reaches the actual belt speed acquisition resolution, a belt speed comparison result pointing to arrival advance correction is formed. K is the number of consecutive belt speed deviation judgments, K is not less than 2, and is written according to the actual belt speed acquisition cycle and the duration of belt speed acquisition noise; in this embodiment, K is 2. When forming the belt speed comparison result, the earliest sampling time among the K consecutive sampling times is taken as the starting point of the difference duration, the sampling time corresponding to the initial arrival time is taken as the ending point of the difference duration, and the number of sampling intervals between the starting point and the ending point of the difference duration is multiplied by the sampling interval to obtain the belt speed deviation duration. If the above conditions are not met, the belt speed comparison results will not indicate an advance or delay correction.

[0026] To avoid relying solely on belt speed calculations, the material flow change process before the transfer position is used for secondary correction. Centered on the initial arrival time, the material flow occupancy value before the transfer position is read for M consecutive sampling times before and after it, forming the arrival correction reading period. M is the arrival correction extended sampling number, determined based on the belt speed convergence sampling number adjusted by the most recent frequency conversion command. The belt speed convergence sampling number is obtained by comparing the actual belt speed value with the stable belt speed value at the corresponding target frequency value: when the difference between the two does not exceed the actual belt speed acquisition resolution for K consecutive sampling times, the number of sampling intervals from the adjustment from the frequency conversion command to that moment is taken as the belt speed convergence sampling number, and this belt speed convergence sampling number is taken as M; if no frequency conversion command adjustment occurs between the sampling time corresponding to the material peak occupancy unit and the initial arrival time, M is set to 1. If the M sampling times after the initial arrival time have not yet been formed, the arrival correction and writing of the material peak occupancy unit are temporarily suspended until all sampling times within the arrival correction reading period have been formed.

[0027] During the arrival and correction reading period, the material flow occupancy value before the transfer position is read, and the difference in material flow occupancy values ​​between adjacent sampling times is calculated to determine the direction of material flow change before the transfer position. The material flow occupancy value of the peak occupancy unit is compared with the material flow occupancy value before the transfer position at each sampling time within the reading period to obtain the material flow difference. The material flow difference and the material flow occupancy value are recorded using the same units. Among the sampling times where the direction of material flow change before the transfer position is consistent with the direction of material flow change of the peak occupancy unit within the predicted peak interval, the sampling time with the smallest material flow difference is selected as the corresponding material flow time. If there are multiple sampling times with the same and smallest material flow difference, one of the sampling times is selected as the corresponding material flow time in the order from the last to the first. If there are no sampling times with the same direction of material flow change within the reading period, the initial arrival time is used as the corresponding material flow time. When the material flow time is later than the initial arrival time, the material flow comparison result indicates a delayed arrival correction; when the material flow time is earlier than the initial arrival time, the material flow comparison result indicates an early arrival correction; when the two are the same, the material flow comparison result does not indicate an early or delayed correction.

[0028] The initial arrival time is then corrected based on the belt speed comparison result and the material flow comparison result. When both point to the same correction direction, the absolute value of the time difference between the corresponding material flow time and the initial arrival time is compared with the belt speed deviation duration. The shorter of the two times is taken as the arrival correction amount, and the initial arrival time is moved according to the correction direction to form the corrected arrival time. When both point to different correction directions, the material flow comparison result is used as the correction basis, and the corresponding material flow time is determined as the corrected arrival time. If only the material flow comparison result points to an earlier or later correction, the corresponding material flow time is determined as the corrected arrival time; if only the belt speed comparison result points to an earlier or later correction, the initial arrival time is moved according to the belt speed deviation duration to form the corrected arrival time; if neither points to an earlier or later correction, the initial arrival time remains unchanged. This correction method is adopted to simultaneously utilize the actual belt speed response of the upstream conveyor and the actual material flow change before the transfer position, and to prioritize the material flow change closer to the unloading center when the two are inconsistent.

[0029] After obtaining the corrected arrival time, the coordinates of the transfer and unloading center in the vertical coordinate are used as the arrival position of the corresponding material peak occupancy unit in the vertical coordinate, and this arrival position is written in correspondence with the corrected arrival time. The lateral coverage start and lateral coverage end points corresponding to the material flow occupancy value are respectively superimposed with the lateral offset of the bearing center relative to the transfer and unloading center to obtain the lateral occupancy range of the corresponding material peak occupancy unit in the horizontal coordinate. The arrival sequence is determined according to the corrected arrival times of each material peak occupancy unit from first to last; when multiple material peak occupancy units have the same corrected arrival time, the arrival sequence is determined according to the corresponding sampling times from first to last. The material flow occupancy value, corrected arrival time, arrival position in the vertical coordinate, lateral occupancy range in the horizontal coordinate, and arrival sequence are written into the corresponding material peak occupancy unit as the corrected arrival sequence and occupancy status of that material peak occupancy unit.

[0030] Finally, all peak occupancy units within the predicted peak range are read, arranged according to arrival sequence, and the corrected arrival time, arrival position in the vertical coordinate, lateral occupancy range in the horizontal coordinate, material flow occupancy value, and arrival sequence of each peak occupancy unit are written into the peak arrival and occupancy status. This peak arrival and occupancy status is used for subsequent determination of downstream load-bearing calculation periods, correction of downstream load-bearing areas, and formation of initial off-center load coverage.

[0031] Step 2: Determine the downstream load-bearing time period based on the material peak arrival and occupancy status, correct the downstream load-bearing area based on the predicted deviation status of the downstream conveyor, and compare the material peak arrival and occupancy status with the corrected downstream load-bearing area to form the initial off-center load coverage status. In this embodiment, after reading the arrival and occupancy status of the material peak, the corrected arrival time, arrival position in the vertical coordinate, horizontal occupancy range, and material flow occupancy value of each material peak occupancy unit are read according to the arrival sequence. The corrected arrival time of the material peak occupancy unit with the earliest arrival sequence is taken as the starting point of the downstream receiving and calculation period. The time corresponding to the extended sampling number is extended backward from the corrected arrival time of the material peak occupancy unit with the latest arrival sequence, and is taken as the end point of the downstream receiving and calculation period. The extended sampling number is determined according to the number of continuous material peak judgments used when predicting the end point of the material peak interval in step one, and is not less than the number of continuous material peak judgments. In this embodiment, the same sampling number as the number of continuous material peak judgments is used. Through this processing, the downstream receiving and calculation period covers the arrival process of each material peak occupancy unit within the predicted material peak interval, and serves as the time range for subsequent deviation prediction and bearing area correction.

[0032] After determining the downstream receiving and calculation period, the starting point of this downstream receiving and calculation period is used as the ending time, and a deviation sampling period is selected backward. Deviation acquisition parameters are written by the deviation acquisition component at the downstream conveyor receiving position during equipment installation and calibration, including at least the deviation sampling interval and deviation sampling position resolution; wherein, the deviation sampling interval is recorded in seconds (s), and the deviation sampling position resolution represents the smallest distinguishable lateral position change at the deviation sampling position. The number of consecutive deviation change observations is determined based on the deviation sampling interval and the shortest observation time required for continuous deviation changes, and is written before executing step two; in this embodiment, the number of consecutive deviation change observations is 3. The length of the deviation sampling period is determined by the deviation sampling interval and the number of consecutive deviation change observations, ensuring that the period can accommodate at least the number of deviation sampling positions for consecutive deviation change observations. The deviation sampling position is formed by the lateral offset of the centerline of the actual belt width of the downstream conveyor at the receiving position relative to the bearing center, with the lateral position recorded in millimeters (mm); deviation sampling positions formed later than the starting point of the downstream receiving and calculation period do not participate in this deviation prediction. The deviation sampling position is written into the same time-series coordinate formed in step one according to its formation time, so that the deviation sampling position can correspond to the corrected arrival time of each material peak occupation unit through the time difference.

[0033] During the misalignment sampling period, the misalignment sampling positions are read sequentially according to the sampling time, and the lateral position difference between adjacent misalignment sampling positions is calculated. The lateral position difference is the difference between the previous and subsequent misalignment sampling positions. When the lateral position difference is positive, the sampling offset direction is the positive direction of the lateral coordinate; when the lateral position difference is negative, the sampling offset direction is the negative direction of the lateral coordinate; when the lateral position difference is 0, it is not included in the judgment of the consistency of the sampling offset direction. The amount of offset change is obtained from the absolute value of the lateral position difference, and its length dimension is consistent with the misalignment sampling position. The allowable lateral jump variable within a single misalignment sampling interval is determined by the maximum continuous lateral displacement within a single misalignment sampling interval recorded during the commissioning operation of the downstream conveyor, and the allowable variation parameter of misalignment is pre-written according to the actual belt speed range of the downstream conveyor. When executing step two, the most recent actual belt speed value of the downstream conveyor formed before the start of the downstream receiving and calculation period is read, and the corresponding lateral jump variable is read according to the belt speed range in which the actual belt speed value is located. The larger value between the misalignment sampling position resolution and the lateral jump variable is determined as the misalignment mutation limit.

[0034] Starting from the deviation sampling position whose formation time is closest to and no later than the start of the downstream bearing calculation period, read the sampling offset direction and offset change between adjacent deviation sampling positions, and determine this deviation sampling position as the prediction starting position. If no deviation sampling position is formed within the deviation sampling period, read the most recently saved deviation sampling position before executing step two as the prediction starting position; if no saved deviation sampling position still exists, use the lateral coordinate position corresponding to the bearing center as the prediction starting position.

[0035] After the prediction starting position is determined, a deviation change rate is generated based on the continuous changes in the deviation sampling positions. If there are fewer than two deviation sampling positions, the deviation change rate is set to 0, and the prediction starting position is used as the starting value for the deviation position corresponding to each material peak occupancy unit. If there are at least two deviation sampling positions, it is first determined whether the sampling offset directions of consecutive adjacent deviation sampling positions formed forward from the prediction starting position are consistent. If the sampling offset directions are inconsistent, the deviation change rate is set to 0, and the prediction starting position is used as the holding position for subsequent deviation position calculations. If the sampling offset directions are consistent, continue to compare the offset changes between adjacent off-track sampling positions; if none of the offset changes exceed the off-track sudden change limit, determine the off-track change rate by taking the group of adjacent off-track sampling positions closest to the starting point of the downstream receiving calculation period. The off-track change rate is obtained by dividing the offset change between the group of adjacent off-track sampling positions by the off-track sampling interval, and is recorded as the directional off-track change rate in combination with the sampling offset direction of the group of adjacent off-track sampling positions; if any offset change exceeds the off-track sudden change limit, set the off-track change rate to 0.

[0036] Subsequently, each peak occupancy unit is read according to its arrival sequence, and the time difference between the corresponding corrected arrival time and the starting point of the downstream receiving estimated time period is calculated. This time difference is multiplied by the deviation change rate and then added to the prediction starting position to obtain the deviation position of the peak occupancy unit at its corrected arrival time; when the deviation change rate is 0, the corresponding deviation position remains the prediction starting position. Then, the predicted offset direction is determined according to the sign of the deviation position relative to the bearing center: when the deviation position is on the positive side of the horizontal coordinate, the predicted offset direction is the positive direction of the horizontal coordinate; when the deviation position is on the negative side of the horizontal coordinate, the predicted offset direction is the negative direction of the horizontal coordinate; when the deviation position coincides with the bearing center, the predicted offset direction is no offset. The prediction starting position, deviation change rate, arrival sequence of each peak occupancy unit, corrected arrival time, corresponding deviation position, and corresponding predicted offset direction are written into the deviation prediction status.

[0037] After the deviation prediction state is established, the original downstream bearing area of ​​the downstream conveyor at the receiving position is read. The original downstream bearing area is determined by the effective bandwidth boundary of the downstream conveyor bearing surface and the longitudinal bearing range at the receiving position; the effective bandwidth boundary includes the left lateral boundary and the right lateral boundary, both recorded in mm along the lateral coordinate during equipment installation and calibration; the start and end points of the longitudinal bearing range are determined along the longitudinal coordinate during equipment installation and calibration. Since the deviation prediction state represents the offset of the downstream conveyor along the bandwidth direction, this step corrects the lateral boundary of the original downstream bearing area according to the deviation position, while the longitudinal bearing range remains unchanged. For each material peak occupancy unit, based on the deviation position in the deviation prediction state corresponding to its corrected arrival time, the left and right lateral boundaries of the original downstream bearing area are superimposed on the deviation position to obtain the translated left and right lateral boundaries, forming the corrected downstream bearing area corresponding to that material peak occupancy unit. The corrected downstream bearing area saves the arrival sequence of the corresponding material peak occupancy unit, the corrected arrival time, the translated left lateral boundary, the translated right lateral boundary, and the longitudinal bearing range of the original downstream bearing area. It is only available for reading during the current downstream bearing calculation period for the initial coverage status of off-center load and subsequent adjustment processing.

[0038] Finally, the arrival and occupancy status of the material peak is compared with the corrected downstream carrying area to form the initial coverage status of the off-center load. Both covered and uncovered records are established according to the arrival sequence of the material peak occupancy units. Each material peak occupancy unit is read according to its arrival sequence, and the corresponding corrected downstream carrying area is read. The arrival position in the vertical coordinate and the lateral occupancy range in the horizontal coordinate of the material peak occupancy unit are compared with the corresponding corrected downstream carrying area's vertical carrying area, the translated left lateral boundary, and the translated right lateral boundary. If the arrival position of the material peak occupancy unit falls within the vertical carrying area, and the left boundary of the lateral occupancy range is greater than or equal to the translated left lateral boundary, and the right boundary is less than or equal to the translated right lateral boundary, then the material peak occupancy unit is written into the covered record.

[0039] If the arrival position of a peak material occupancy unit does not fall within the longitudinal bearing area, the peak material occupancy unit is written to the uncovered record. The uncovered record saves the arrival sequence, corrected arrival time, material flow occupancy value, arrival position in the longitudinal coordinate, lateral occupancy range in the lateral coordinate, and the corresponding corrected left lateral boundary, right lateral boundary, and longitudinal bearing area in the downstream bearing area, and saves the uncovered type as longitudinal uncovered. If the arrival position of a peak material occupancy unit falls within the longitudinal bearing area, but the lateral occupancy range exceeds the translated left lateral boundary or the translated right lateral boundary, the peak material occupancy unit is written to the uncovered record. When the left boundary of the lateral occupied range is smaller than the translated left lateral boundary, the uncovered left direction, the uncovered left lateral range formed between the left boundary of the lateral occupied range and the translated left lateral boundary, and the translated left lateral boundary are saved in the uncovered record. When the right boundary of the lateral occupied range is larger than the translated right lateral boundary, the uncovered right direction, the uncovered right range formed between the translated right lateral boundary and the right boundary of the lateral occupied range, and the translated right lateral boundary are saved in the uncovered record. The covered and uncovered records together form the initial coverage state of the off-center load, where the uncovered records are used as adjustment objects for subsequent generation of candidate differential frequency converter control quantities.

[0040] Step 3: Taking the uncovered material peak occupancy unit in the initial coverage state of off-center load as the adjustment object, generate candidate differential frequency converter control quantities, and calculate the material drop overlap change corresponding to the candidate differential frequency converter control quantities to form the material drop overlap adjustment quantity. In this embodiment, the uncovered records in the initial coverage state of the off-center load are read, and the corrected arrival time, material flow occupancy value, arrival position in the longitudinal coordinate, and lateral occupancy range in the transverse coordinate of the uncovered material peak occupancy unit are obtained according to the arrival sequence. The corresponding corrected left lateral boundary, right lateral boundary, and longitudinal bearing range in the downstream bearing area are also obtained. The time of entering step three is read and aligned with the frequency converter command output cycle to form the adjustment start time. Subsequently, the frequency converter status record corresponding to the adjustment start time is read to obtain the current output frequency of the upstream conveyor and the current output frequency of the downstream conveyor. Simultaneously, the frequency converter control parameters written before executing step three are read. These parameters include frequency adjustment resolution, minimum output frequency of the upstream conveyor, maximum output frequency of the upstream conveyor, minimum output frequency of the downstream conveyor, maximum output frequency of the downstream conveyor, frequency change rate of the upstream frequency converter, and frequency change rate of the downstream frequency converter.

[0041] If the uncovered record is empty, a zero adjustment amount is generated as the material drop overlap adjustment amount. This zero adjustment amount saves the upstream conveyor candidate frequency adjustment amount as 0, the downstream conveyor candidate frequency adjustment amount as 0, and the adjustment amplitude sequence as 0. The current output frequency of the upstream conveyor is written as the upstream candidate output frequency, and the current output frequency of the downstream conveyor is written as the downstream candidate output frequency into the corresponding candidate differential frequency converter control amount. At the same time, the corresponding material drop overlap change is saved as an empty record, and the generation and selection of subsequent candidate differential frequency converter control amounts are no longer executed. If there are uncovered records, the earliest corrected arrival time is taken as the earliest corrected arrival time to determine whether the candidate adjustment can be completed before the material peak arrives.

[0042] Candidate differential frequency converter control quantities are formed step-by-step according to the adjustment magnitude sequence. The adjustment magnitude sequence starts from 0 and increases incrementally; when the adjustment magnitude sequence is 0, the candidate frequency adjustment quantities for both the upstream and downstream conveyors are 0. When the adjustment magnitude sequence is greater than 0, the adjustment magnitude sequence is multiplied by the frequency adjustment resolution to obtain the current adjustment magnitude; the current adjustment magnitude is subtracted from the current output frequency of the upstream conveyor to obtain the upstream candidate output frequency, and its lower limit is limited by the lowest output frequency of the upstream conveyor; the current adjustment magnitude is added to the current output frequency of the downstream conveyor to obtain the downstream candidate output frequency, and its upper limit is limited by the highest output frequency of the downstream conveyor. The difference between the upstream candidate output frequency and the current output frequency of the upstream conveyor forms the upstream candidate frequency adjustment quantity, and the difference between the downstream candidate output frequency and the current output frequency of the downstream conveyor forms the downstream candidate frequency adjustment quantity. The candidate differential frequency converter control quantities are only used for overlap relationship calculation and candidate selection in this step and are not issued and executed in this step.

[0043] For any current candidate differential frequency converter control variable, the frequency band speed correspondences of the upstream conveyor and the downstream conveyor are read respectively. The frequency band speed correspondence of the upstream conveyor adopts the frequency band speed correspondence already formed in step one; the frequency band speed correspondence of the downstream conveyor is formed by the downstream conveyor during equipment installation and calibration, and the formation method is consistent with the calibration method of the frequency band speed correspondence of the upstream conveyor in step one. Starting from the self-adjustment start time, the expected frequency value is formed point by point according to the sampling interval formed in step one: within each sampling interval, starting from the expected frequency value of the previous sampling time, the frequency value increases or decreases towards the candidate output frequency according to the corresponding strain gauge frequency change rate. The frequency change amplitude within a single sampling interval does not exceed the product of the corresponding strain gauge frequency change rate and the sampling interval; the expected frequency value remains unchanged after reaching the candidate output frequency. Then, according to the frequency band speed correspondence, the expected frequency value of each sampling time is converted into the expected belt speed value, and the expected belt speed change corresponding to the upstream and downstream conveyors is formed by the expected belt speed values ​​of continuous sampling times.

[0044] For each uncovered peak occupancy unit, based on the conveying distance from the feed-side detection position to the unloading center determined in step one, and the actual conveying displacement accumulated by the peak occupancy unit from the corresponding sampling time to the adjustment start time, determine its remaining conveying displacement that has not yet reached the unloading center at the adjustment start time. When the remaining conveying displacement is greater than 0, the conveying displacement is accumulated according to the upstream expected belt speed change corresponding to the current candidate differential frequency converter control quantity, starting from the adjustment start time according to the sampling interval formed in step one; the conveying displacement within each sampling interval is formed by multiplying the upstream expected belt speed value corresponding to the sampling interval by the sampling interval, and the time corresponding to when the accumulated value reaches the remaining conveying displacement is taken as the adjusted arrival time of the uncovered peak occupancy unit. When the remaining conveying displacement is not greater than 0, the corrected arrival time of the uncovered peak occupancy unit remains unchanged.

[0045] The longitudinal carrying capacity movement of the downstream conveyor is formed by accumulating the difference between the downstream expected belt speed value and the belt speed value corresponding to the current output frequency between the adjustment start time and the adjusted arrival time. During discrete calculation, the sampling interval formed in step one is used as the accumulation unit. The belt speed difference within each sampling interval is multiplied by the sampling interval and then accumulated. The accumulated result is used as the longitudinal carrying capacity movement superimposed along the longitudinal coordinate direction. The adjusted arrival time and the longitudinal carrying capacity movement are written into the calculation result of the current candidate differential frequency converter control quantity. This longitudinal carrying capacity movement is only used for calculating the adjusted carrying capacity range corresponding to the current candidate differential frequency converter control quantity and does not cover the longitudinal carrying capacity range in the corrected downstream carrying area already saved in step two. When generating the next candidate differential frequency converter control quantity, the movement calculation is still performed again from the longitudinal carrying capacity range saved in step two.

[0046] Then, the material receiving overlap change corresponding to the current candidate differential frequency converter control quantity is calculated. For an uncovered material peak occupying unit, its arrival position in the longitudinal coordinate remains unchanged as written in step two, and the adjusted arrival time is used to select the corresponding longitudinal receiving movement amount. Based on this longitudinal receiving movement amount, the longitudinal receiving range in the corresponding corrected downstream bearing area is moved along the longitudinal coordinate to obtain the adjusted bearing range; the lateral boundary still adopts the translated left lateral boundary and the translated right lateral boundary in the corrected downstream bearing area.

[0047] The arrival position of the peak material occupancy unit is compared longitudinally with the adjusted receiving range, and its lateral occupancy range is compared laterally with the translated left and right lateral boundaries. When the arrival position falls within the adjusted receiving range, a longitudinal overlap result is formed; the intersection between the lateral occupancy range and the translated left and right lateral boundaries forms the overlapping lateral range, and the portion of the lateral occupancy range that does not enter this intersection forms the non-overlapping lateral range. The overlapping occupancy amount is calculated by multiplying the proportion of the overlapping lateral range in the lateral occupancy range by the material flow occupancy value of the peak material occupancy unit; the non-overlapping occupancy amount is calculated by multiplying the proportion of the non-overlapping lateral range in the lateral occupancy range by the material flow occupancy value of the peak material occupancy unit. If no longitudinal overlap result is formed, the overlapping occupancy amount of the peak material occupancy unit is set to 0, and the non-overlapping occupancy amount is taken as the material flow occupancy value of the peak material occupancy unit. The overlapping occupancy amount, non-overlapping occupancy amount, overlapping lateral range, non-overlapping lateral range, and corresponding candidate differential frequency converter control values ​​of each uncovered peak material occupancy unit are jointly written into the material receiving overlap change.

[0048] Read the material receiving overlap change corresponding to the current candidate differential frequency converter control quantity, and determine whether all of them have entered the corrected downstream bearing area based on the non-overlapping occupancy of each uncovered material peak occupancy unit. If the non-overlapping occupancy of each uncovered material peak occupancy unit is 0, then write the current candidate differential frequency converter control quantity and its corresponding material receiving overlap change into the material receiving overlap adjustment quantity, and end this round of candidate search.

[0049] If there are still non-overlapping occupancy units, the necessity and feasibility of further amplification of the current candidate are determined. For initial candidates with an adjustment amplitude sequence of 0, the candidate differential frequency converter control quantity corresponding to the next adjustment amplitude sequence is directly generated. For non-initial candidates, the material receiving overlap change corresponding to the current candidate differential frequency converter control quantity and the previous candidate differential frequency converter control quantity are read, and the overlap increase is formed by the difference between the two corresponding overlap occupancy quantities. When there are multiple uncovered material peak occupancy units, the overlap increase of each uncovered material peak occupancy unit is calculated separately, and the minimum value is taken as the overlap increase of the current candidate differential frequency converter control quantity, so that the judgment of further amplification is based on the material peak occupancy unit with the lowest overlap improvement amplitude.

[0050] The overlap increase ratio is written before executing step three according to the minimum overlap change recognition requirement corresponding to the frequency adjustment resolution. In this embodiment, it is set to 10%. This value means that when the increase in the overlap occupancy of the current candidate relative to the previous candidate reaches 10% of the corresponding non-overlapping occupancy, the current candidate meets the overlap improvement condition for further amplification. For each uncovered peak occupancy unit, the non-overlapping occupancy under the differential frequency converter control of the previous candidate is multiplied by the overlap increase ratio to form the overlap increase limit of the uncovered peak occupancy unit. When there are multiple uncovered peak occupancy units, the minimum value among the overlap increase limits is taken as the overlap increase limit of the current candidate differential frequency converter control, so that the overall judgment stops and the peak occupancy unit that first reaches the minimum effective increase requirement is used as the comparison object.

[0051] Simultaneously, the upstream adjustment duration is calculated based on the absolute value of the candidate frequency adjustment amount of the upstream conveyor and the frequency change rate of the upstream inverter. Similarly, the downstream adjustment duration is calculated based on the absolute value of the candidate frequency adjustment amount of the downstream conveyor and the frequency change rate of the downstream inverter. The longer of the two values ​​is then superimposed on the adjustment start time to form the inverter adjustment completion time corresponding to the current candidate differential inverter control amount. This inverter adjustment completion time is then compared with the earliest corrected arrival time.

[0052] If the overlap increase does not simultaneously reach the overlap increase limit and the frequency conversion adjustment completion time is earlier than the earliest correction arrival time, then the preceding candidate differential frequency conversion control quantity and its corresponding material receiving overlap change are jointly written into the material receiving overlap adjustment quantity, and the current round of candidate search ends. If both of the above conditions are met, and the upstream candidate output frequency does not reach the minimum output frequency of the upstream conveyor and the downstream candidate output frequency does not reach the maximum output frequency of the downstream conveyor, then candidate differential frequency conversion control quantities with increased adjustment amplitude are generated, and the corresponding material receiving overlap change is repeatedly calculated. If both of the above conditions are met, but the upstream candidate output frequency has reached the minimum output frequency of the upstream conveyor, or the downstream candidate output frequency has reached the maximum output frequency of the downstream conveyor, then the current candidate differential frequency conversion control quantity and its corresponding material receiving overlap change are jointly written into the material receiving overlap adjustment quantity, and the current round of candidate search ends.

[0053] Step 4: Determine the receiving gap based on the material drop overlap adjustment amount. Under the constraints of the downstream conveyor's allowable speed limit and the receiving stable speed limit defined by the deviation prediction state, form the downstream advance receiving amount. Then, deduct the downstream advance receiving amount, the upstream peak reduction amount, and the delayed coverage occupancy amount corresponding to the upstream delayed release amount in sequence from the receiving gap. For the part that is still not covered after deduction, form a prohibited frequency increase state to obtain the gap sharing control amount. In this embodiment, the candidate differential frequency converter control quantity in the material drop overlap adjustment quantity, the material drop overlap change corresponding to the candidate differential frequency converter control quantity, and the adjustment start time used in step three to form the material drop overlap adjustment quantity are read. The non-overlapping occupancy quantity, overlapping lateral range, non-overlapping lateral range, corrected arrival time, material flow occupancy value, and corresponding corrected downstream carrying area of ​​each uncovered material peak occupancy unit are read according to the arrival sequence. The portion of non-overlapping occupancy quantity greater than 0 is accumulated to form a carrying gap; material peak occupancy units with a non-overlapping occupancy quantity of 0 do not participate in this carrying gap calculation. If the carrying gap is 0, the downstream advance carrying amount, carrying stability speed limit, upstream peak reduction amount, upstream delayed release amount, delayed coverage occupancy amount, and final remaining uncovered occupancy amount are all set to 0, and the above zeroing results and the no-remaining-gap flag are written into the gap sharing control quantity; the no-remaining-gap flag is used to indicate that after this gap sharing, there is no remaining uncovered portion that needs to be processed by prohibiting frequency increase. When the gap is 0, the process of calculating the sharing of downstream early acceptance, upstream peak reduction and upstream delayed release will no longer be formed.

[0054] If the gap is greater than 0, for the uncovered material peak occupancy unit participating in the gap calculation, its overlapping and non-overlapping horizontal ranges are read, and the union of the two in the horizontal coordinate is taken as the adjusted occupancy range. The minimum horizontal coordinate value of this union is taken as the left boundary, and the maximum horizontal coordinate value is taken as the right boundary. Then, the deviation prediction state formed in step two is read, and the corresponding deviation position and predicted offset direction are obtained according to the arrival sequence of the uncovered material peak occupancy unit. When the predicted offset direction is the positive direction of the horizontal coordinate, the right horizontal boundary of the corresponding corrected downstream bearing area is read as the bearing boundary position, the right boundary of the adjusted occupied area is taken as the occupancy boundary position, and the remaining bearing distance on the offset side is obtained by subtracting the occupancy boundary position from the bearing boundary position. When the predicted offset direction is the negative direction of the horizontal coordinate, the left horizontal boundary of the translated area is read as the bearing boundary position, the left boundary of the adjusted occupied area is taken as the occupancy boundary position, and the remaining bearing distance on the offset side is obtained by subtracting the bearing boundary position from the occupancy boundary position. When the predicted offset direction is no offset, the left and right horizontal boundaries of the translated area are read respectively, and the side closer to the adjusted occupied area is taken as the bearing boundary position. The side of the adjusted occupied area that is closer to the bearing boundary position is taken as the occupancy boundary position, and the absolute value of the difference between the two is used to form the remaining bearing distance on the offset side. If the remaining bearing distance on the offset side is less than 0, the remaining bearing distance on the offset side is set to 0.

[0055] Read the maximum allowable speed and the edge retention distance of the downstream conveyor. The maximum allowable speed of the downstream conveyor is determined by the downstream conveyor operating parameters written before step four. The edge retention distance is determined based on the maximum allowable lateral offset recorded during the commissioning operation of the downstream conveyor and is written before step four, recorded in mm; this edge retention distance represents the minimum safe distance that needs to be maintained at the edge of the downstream bearing area under misalignment conditions.

[0056] The remaining receiving distance on the offset side is compared with the reserved distance at the receiving edge. When the remaining receiving distance on the offset side is not less than the reserved distance at the receiving edge, the upper limit of the downstream conveyor's allowable speed is used as the stable receiving speed limit. When the remaining receiving distance on the offset side is less than the reserved distance at the receiving edge, the difference is divided by the reserved distance at the receiving edge to obtain the edge deficiency ratio. The speed limit is then calculated by multiplying the upper limit of the downstream conveyor's allowable speed by the edge deficiency ratio. When the speed limit exceeds the upper limit of the downstream conveyor's allowable speed, the upper limit of the downstream conveyor's allowable speed is used as the speed limit. The stable receiving speed limit is obtained by subtracting the speed limit from the upper limit of the downstream conveyor's allowable speed. When there are multiple uncovered material peak occupancy units, corresponding stable receiving speed limits are formed for each unit, and the minimum value among them is used as the stable receiving speed limit for this gap sharing.

[0057] After the stable speed limit for receiving material is established, the corrected arrival times of each uncovered material peak occupancy unit involved in the receiving gap calculation are read, and the earliest corrected arrival time is determined as the earliest corrected arrival time used in this step. The most recent actual belt speed value of the downstream conveyor formed before the start of the downstream receiving estimation period is read, and the smaller value between the stable speed limit for receiving material and the maximum allowable speed of the downstream conveyor is taken as the maximum available speed of the downstream. The non-negative duration between the earliest corrected arrival time and the end of the downstream receiving estimation period is taken as the advance receiving time. The available speed difference is obtained by subtracting the actual belt speed of the downstream conveyor from the maximum available speed; if the available speed difference is less than 0, it is set to 0. Based on the available speed difference and the advance receiving time, the new receiving length is formed.

[0058] For the uncovered peak occupancy unit corresponding to the receiving gap, its non-overlapping occupancy amount is read, and the longitudinal receiving range in the corresponding corrected downstream bearing area is read. Since the longitudinal receiving movement only changes the position of the longitudinal receiving range and does not change the length of the longitudinal receiving range, the distance between the end point and the start point of the longitudinal receiving range is taken as the longitudinal length of the receiving range. When the longitudinal length of the receiving range is 0, the occupancy amount of the corresponding peak occupancy unit that can be covered by downstream in advance is set to 0; when the longitudinal length of the receiving range is greater than 0, the newly added receiving length is divided by the longitudinal length of the receiving range to obtain the newly added receiving ratio. When the newly added receiving ratio exceeds 1, it is taken as 1. Then, the newly added receiving ratio is multiplied by the corresponding non-overlapping occupancy amount to obtain the occupancy amount of the peak occupancy unit that can be covered by downstream in advance. The coverable occupancy amount of each peak occupancy unit is accumulated to form the downstream advance receiving amount; when the downstream advance receiving amount exceeds the receiving gap, the receiving gap is taken as the downstream advance receiving amount. The portion of the shortfall after deducting the downstream advance acceptance amount forms the first remaining shortfall, and the downstream advance acceptance amount and its corresponding acceptance stability speed limit are written into the shortfall sharing control amount.

[0059] If the first remaining gap is 0, then the upstream peak reduction amount, the second remaining gap, the upstream delayed release amount, the delayed coverage occupancy amount, and the final remaining uncovered occupancy amount are all set to 0, and the above zeroing results and the no remaining gap flag are written into the gap sharing control quantity. If the first remaining gap is greater than 0, then the current output frequency of the upstream conveyor, the upstream candidate output frequency, and the upstream conveyor candidate frequency adjustment amount are obtained from the read candidate differential frequency control quantities. Based on the upstream conveyor frequency-speed correspondence already used in step three, the belt speed value corresponding to the current output frequency of the upstream conveyor and the belt speed value corresponding to the upstream candidate output frequency are determined respectively. The upstream belt speed reduction amount is obtained by subtracting the latter from the former. When the upstream belt speed reduction amount is less than 0, it is set to 0. The upstream release reduction length is formed by the duration between the earliest corrected arrival time and the end of the downstream receiving calculation period, which is the duration of the upstream release reduction amount. This upstream release reduction length is used to determine the upstream peak reduction amount, which represents the material conveying length reduced by the upstream conveyor due to deceleration during this period.

[0060] Read the sampling times of the first and last peak occupancy units within the predicted peak occupancy interval in Step 1, and accumulate the actual conveying displacement between them according to the actual belt speed change process and sampling interval formed in Step 1. Use this actual conveying displacement as the conveying length corresponding to the predicted peak occupancy interval. When this conveying length is 0, the upstream peak reduction amount is set to 0. When the conveying length corresponding to the predicted peak occupancy interval is greater than 0, divide the upstream release reduction length by this conveying length to obtain the peak reduction ratio. If the peak reduction ratio exceeds 1, set it to 1. Read the non-overlapping occupancy corresponding to the first remaining receiving gap according to the arrival sequence, and perform a weighted calculation of the peak reduction ratio based on the actual material flow occupancy value ratio of each peak occupancy unit to form the peak reduction occupancy amount corresponding to each peak occupancy unit. Accumulate all peak reduction occupancy amounts to form the upstream peak reduction amount. When the upstream peak reduction amount exceeds the first remaining receiving gap, take the first remaining receiving gap as the upstream peak reduction amount. The portion of the first remaining receiving gap after deducting the upstream peak reduction amount forms the second remaining receiving gap, and the upstream peak reduction amount is written into the gap sharing control amount.

[0061] The covered peak occupancy corresponding to the downstream advance acceptance and upstream peak reduction is deducted in order of arrival. When the same peak occupancy unit is partially deducted, the covered occupancy and remaining occupancy of that peak occupancy unit are saved. If the second remaining acceptance gap is 0, the upstream delayed release, delayed coverage occupancy, and final remaining uncovered occupancy are all set to 0, and the above zeroing results and the no remaining gap indicator are written into the gap sharing control quantity.

[0062] If the second remaining gap is greater than 0, the subsequent segment corresponding to the upstream delayed release is determined. The arrival sequence, corrected arrival time, and material flow occupancy value of each peak occupancy unit within the predicted peak range are read. Peak occupancy units are selected from back to front according to the arrival sequence, and the remaining occupancy not covered by downstream advance reception and upstream peak reduction in the selected peak occupancy units is accumulated. When the accumulated remaining occupancy reaches the second remaining gap, the selected peak occupancy units are determined as subsequent segment peak occupancy units. For each subsequent segment peak occupancy unit, the occupancy already covered by downstream advance reception and upstream peak reduction is read. The material flow occupancy value of the subsequent segment peak occupancy unit is subtracted from the covered occupancy to obtain the occupancy to be delayed. The occupancy to be delayed of each subsequent segment peak occupancy unit is accumulated to form the cumulative value of the occupancy to be delayed.

[0063] Subsequently, starting from the end of the downstream receiving calculation period, candidate subsequent receiving periods are generated backward according to the sampling interval formed in step one. Each candidate subsequent receiving period uses the shifted left and right lateral boundaries in the corrected downstream carrying area corresponding to the material peak occupancy unit with the latest arrival sequence. The downstream candidate output frequency is obtained from the read candidate differential frequency converter control values; the downstream conveyor frequency-speed correspondence already used in step three is read, and the downstream expected belt speed within the candidate subsequent receiving period is determined based on the downstream candidate output frequency; the longitudinal receiving length is determined based on the downstream expected belt speed and the duration of the candidate subsequent receiving period.

[0064] Based on the longitudinal bearing length, the translated left lateral boundary, and the translated right lateral boundary, a candidate bearing space for the candidate subsequent bearing period is formed. The lateral occupancy range and the amount to be postponed for each downstream peak occupancy unit are read. The intersection of the lateral occupancy range of the downstream peak occupancy unit and the lateral boundary of the candidate bearing space is calculated to obtain the subsequent overlapping lateral range. The proportion of the subsequent overlapping lateral range in the lateral occupancy range of the downstream peak occupancy unit is multiplied by the amount to be postponed for that downstream peak occupancy unit to form the bearable bearing capacity for that downstream peak occupancy unit for the candidate subsequent bearing period. The bearable bearing capacity corresponding to each downstream peak occupancy unit is accumulated to obtain the subsequent bearable bearing capacity. When the subsequent bearable bearing capacity reaches the cumulative value of the amount to be postponed, the corresponding candidate subsequent bearing period is determined as the subsequent bearing period.

[0065] The search endpoint for candidate subsequent carrying periods is formed by extending the time corresponding to the number of extended samples from the latest corrected arrival time of the material peak occupancy unit in the trailing segment. If the subsequent carrying capacity has not yet reached the cumulative value of the delayed occupancy when the search reaches the search endpoint, the candidate subsequent carrying period with the largest subsequent carrying capacity is selected as the subsequent carrying period. If multiple candidate subsequent carrying periods have the same maximum subsequent carrying capacity, the candidate subsequent carrying period with the shortest duration is selected as the subsequent carrying period, and this maximum subsequent carrying capacity is taken as the maximum delayed coverage occupancy corresponding to the subsequent carrying period. In another embodiment, the most recently formed deviation sampling position before the period can be reread within the subsequent carrying period, and the corrected downstream carrying area corresponding to the subsequent period can be formed according to the deviation prediction method in step two.

[0066] Based on the time difference between the start of the subsequent receiving period and the corrected arrival time of the peak occupancy unit in the subsequent segment, the upstream delayed release amount corresponding to that peak occupancy unit is formed; if the time difference is less than 0, the corresponding upstream delayed release amount is set to 0. The corrected arrival time of the peak occupancy unit in the subsequent segment is superimposed with the corresponding upstream delayed release amount to form the delayed arrival time, and this delayed arrival time is used as the delayed release sequence of the peak occupancy unit in the subsequent segment; peak occupancy units in the predicted peak interval that are not determined to be peak occupancy units in the subsequent segment are still released using their corrected arrival time as the release sequence. The arrival sequence, corresponding upstream delayed release amount, and delayed release sequence of the peak occupancy unit in the subsequent segment are associated and written into the gap sharing control quantity. The minimum value among the subsequent acceptable occupancy amount, the cumulative value of the occupancy amount to be delayed, and the second remaining accepting gap corresponding to the subsequent receiving period is used as the delayed coverage occupancy amount; this delayed coverage occupancy amount is used as the accepting gap deduction amount corresponding to the upstream delayed release amount and is written into the gap sharing control quantity.

[0067] The remaining amount after deducting the downstream advance acceptance amount, the upstream peak reduction amount, and the delayed coverage amount from the acceptance gap is taken as the final remaining uncovered occupancy amount. If the final remaining uncovered occupancy amount is greater than 0, the peak occupancy unit corresponding to the final remaining uncovered occupancy amount is written into the prohibited frequency increase state; if the final remaining uncovered occupancy amount is 0, the no remaining gap indicator is written into the gap sharing control amount. When the prohibited frequency increase state is formed, the prohibited frequency increase state saves the arrival sequence, the corrected arrival time, the remaining uncovered occupancy amount, and the period during which the upstream conveyor frequency increase is prohibited from being increased for the corresponding peak occupancy unit; the period of action is based on the adjustment start time used when the current material drop overlap adjustment amount is formed in step three, and ends with the latest corrected arrival time of the peak occupancy unit corresponding to the remaining uncovered occupancy amount. The downstream advance acceptance amount, the acceptance stable speed limit, the upstream peak reduction amount, the arrival sequence of the peak occupancy unit in the trailing section, the upstream delayed release amount, the delayed release sequence, the delayed coverage occupancy amount, the prohibited frequency increase status, and the final remaining uncovered occupancy amount are all written into the gap sharing control amount for subsequent reading when generating dual-end differential frequency converter control instructions.

[0068] Step 5: Generate a dual-end differential frequency converter control command based on the material overlap adjustment amount and the gap sharing control amount, and control the upstream and downstream conveyors according to the dual-end differential frequency converter control command; In this embodiment, the candidate differential frequency converter control quantities in the material drop overlap adjustment quantity are read, as well as the adjustment start time used in step three to form the current material drop overlap adjustment quantity. The upstream candidate output frequency and downstream candidate output frequency are obtained from the candidate differential frequency converter control quantities. The end point of the downstream receiving calculation period formed in step two is read, and the downstream advance receiving quantity, receiving stability speed limit, upstream peak reduction quantity, upstream delayed release quantity, no remaining gap indicator, prohibited frequency increase state, and final remaining uncovered occupancy quantity in the gap sharing control quantity are read. Using the adjustment start time to the end point of the downstream receiving calculation period as the basic action period, the upstream candidate output frequency and downstream candidate output frequency are written into the basic frequency converter control record. The no remaining gap indicator is only used to indicate that it is not necessary to generate an action period that prohibits the upstream conveyor from increasing its frequency, and does not affect the formation of the control records corresponding to the downstream advance receiving quantity and the upstream peak reduction quantity.

[0069] When the downstream advance acceptance amount is greater than 0, read the acceptance stability speed limit value used in step four when the downstream advance acceptance amount is formed, and read the downstream conveyor frequency belt speed correspondence already used in step three; among the output frequencies that do not exceed the downstream candidate output frequency and whose corresponding belt speed does not exceed the acceptance stability speed limit value, select the output frequency with the largest value as the downstream advance acceptance control frequency, and write it and the basic action period into the downstream advance acceptance control record.

[0070] When the upstream peak reduction amount is greater than 0, the upstream candidate output frequency is used as the upstream peak reduction control frequency, and it is written into the upstream peak reduction control record along with the basic action period. For the downstream peak occupancy unit with upstream delayed release amount, its corrected arrival time, corresponding upstream delayed release amount, and delayed release sequence are read according to the arrival sequence. If the corresponding upstream delayed release amount is greater than 0, the delayed control period is taken from the corrected arrival time to the delayed arrival time corresponding to the delayed release sequence. During this period, the output frequency of the upstream conveyor is limited to no higher than the upstream candidate output frequency, forming a delayed control record.

[0071] If a frequency upscaling prohibition state is detected, its effective period is read, and the upstream execution frequency corresponding to the start of this effective period is determined based on the existing basic frequency converter control record, upstream peak shaving control record, and delayed control record. If the start point does not fall within the effective period of the aforementioned control records, the target output frequency of the most recently completed upstream control record before the start point is read. If the target output frequency still does not exist, the actual output frequency of the most recently formed upstream conveyor before the start point is read. This upstream execution frequency is used as the upper limit of the output frequency corresponding to the frequency upscaling prohibition state, ensuring that the upstream conveyor does not execute frequency upscaling commands higher than this upper limit during this effective period. A frequency upscaling prohibition control record is then formed based on the effective period and the upper limit of the output frequency in the frequency upscaling prohibition state.

[0072] Subsequently, the basic frequency converter control records, downstream advance acceptance control records, upstream peak shaving control records, delayed control records, and prohibition of frequency increase control records are sorted and merged according to the start of the action period. When multiple control records exist upstream at the same time, the record with the lowest target output frequency is taken as the upstream execution frequency; if the target output frequencies are the same, the record with the latest end of the action period is taken as the upstream execution frequency. Downstream, when the basic frequency converter control records and downstream advance acceptance control records overlap, the downstream advance acceptance control frequency is taken as the downstream execution frequency, and for other periods, the downstream candidate output frequency is taken as the downstream execution frequency. After merging, upstream frequency timing records and downstream frequency timing records are formed, and written into the dual-end differential frequency converter control instructions. The dual-end differential frequency converter control instructions save the conveyor identifier, the start of the action period, the end of the action period, the target output frequency, and the arrival sequence of the corresponding peak occupancy unit; when corresponding to multiple peak occupancy units, an arrival sequence set is written; when not corresponding to a single peak occupancy unit, an empty arrival sequence record is written. The dual-end differential frequency converter control command is sent to the frequency converter control terminals of the upstream and downstream conveyors for execution from the start time of adjustment.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A conveyor variable frequency speed control method based on material flow prediction, characterized in that, include: Step 1: Establish the transfer time and space coordinates at the transfer position of the upstream conveyor and the downstream conveyor, collect the material flow occupancy value, frequency conversion command change process and actual belt speed change process of the upstream conveyor, identify the predicted material peak interval, form the predicted material peak interval into material peak occupancy units according to the sampling time sequence, and correct the arrival time sequence and occupancy status of the material peak occupancy units to form the material peak arrival occupancy status. Step 2: Determine the downstream load-bearing time period based on the material peak arrival and occupancy status, correct the downstream load-bearing area based on the predicted deviation status of the downstream conveyor, and compare the material peak arrival and occupancy status with the corrected downstream load-bearing area to form the initial off-center load coverage status. Step 3: Taking the uncovered material peak occupancy unit in the initial coverage state of off-center load as the adjustment object, generate candidate differential frequency converter control quantities, and calculate the material drop overlap change corresponding to the candidate differential frequency converter control quantities to form the material drop overlap adjustment quantity. Step 4: Determine the receiving gap based on the material drop overlap adjustment amount. Under the constraints of the downstream conveyor's allowable speed limit and the receiving stable speed limit defined by the deviation prediction state, form the downstream advance receiving amount. Then, deduct the downstream advance receiving amount, the upstream peak reduction amount, and the delayed coverage occupancy amount corresponding to the upstream delayed release amount in sequence from the receiving gap. For the part that is still not covered after deduction, form a prohibited frequency increase state to obtain the gap sharing control amount. Step 5: Generate a dual-end differential frequency converter control command based on the material drop overlap adjustment amount and the gap sharing control amount, and control the upstream and downstream conveyors according to the dual-end differential frequency converter control command.

2. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step one, establishing the spatiotemporal coordinates of the transit, includes: Read the unloading center of the upstream conveyor at the transfer position and the bearing center of the downstream conveyor at the receiving position, project the unloading center onto the bearing surface of the downstream conveyor to form the transfer and dropping center, and determine the coordinate origin with the transfer and dropping center; Read the conveying direction, bandwidth direction, and lateral offset of the bearing center relative to the transfer and unloading center of the downstream conveyor at the receiving position. Determine the longitudinal coordinate direction with the conveying direction and the lateral coordinate direction with the bandwidth direction, and record the lateral offset of the bearing center relative to the transfer and unloading center in the lateral coordinate. Read the sampling time, frequency conversion command change process, actual belt speed change process, and material flow change process before the transfer position, and write the frequency conversion command change process, actual belt speed change process, and material flow change process before the transfer position into the same time coordinate according to the sampling time; Based on the actual belt speed change process and sampling interval, the actual conveying displacement of the material peak interval from the upstream conveyor feed side detection position to the unloading center is cumulatively predicted. The initial arrival time of the material peak occupation unit is determined based on the actual conveying displacement. The initial arrival time is corrected based on the material flow change process before the transfer position to obtain the corrected arrival time. The arrival position of the material peak occupancy unit in the vertical coordinate is determined based on the corrected arrival time. The horizontal occupancy range corresponding to the material flow occupancy value is written into the horizontal coordinate, and the corrected arrival time is written into the time sequence coordinate to form the transfer time and space coordinate.

3. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step one, forming the peak occupancy unit, includes: Read the material flow occupancy values ​​within the predicted material peak interval according to the order of sampling time, and form corresponding material peak occupancy units according to the sampling time corresponding to each material flow occupancy value; Based on the sampling time, actual belt speed change process and sampling interval corresponding to the material flow occupancy value, the actual conveying displacement from the upstream conveyor feed side detection position to the unloading center is accumulated, and the initial arrival time of the corresponding material peak occupancy unit is determined when the accumulated actual conveying displacement reaches the conveying distance from the feed side detection position to the unloading center. Based on the material flow change process before the transfer position corresponding to the initial arrival time, the initial arrival time is corrected to form the corrected arrival time of the corresponding material peak occupancy unit. The arrival position of the corresponding material peak occupancy unit in the longitudinal coordinate is determined based on the corrected arrival time, and the lateral occupancy range of the corresponding material peak occupancy unit in the lateral coordinate is determined based on the material flow occupancy value and the lateral offset of the bearing center relative to the transfer and unloading center. The arrival sequence of each material peak occupancy unit is determined based on the corrected arrival time, and the material flow occupancy value, the corrected arrival time, the arrival position in the vertical coordinate, the horizontal occupancy range in the horizontal coordinate, and the arrival sequence are written into the corresponding material peak occupancy unit.

4. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, In the process of forming the peak material occupancy unit in step one, the step of arrival correction for the initial arrival time includes: Read the material flow occupancy value, initial arrival time, and sampling time corresponding to the material peak occupancy unit of the material peak occupancy unit, and read the frequency conversion command change process and the actual belt speed change process; The target belt speed change between the sampling time and the initial arrival time of the peak material occupancy unit is determined according to the frequency conversion command change process, and the target belt speed change is compared with the actual belt speed change process in the same time period to obtain the belt speed comparison result. Read the material flow change process before the transfer position corresponding to the initial arrival time, and compare the material flow occupancy value of the material peak occupancy unit with the material flow occupancy value during the material flow change process before the transfer position to obtain the material flow comparison result; The initial arrival time is corrected by combining the belt speed comparison result and the material flow comparison result. When the correction directions corresponding to the belt speed comparison result and the material flow comparison result are inconsistent, the material flow comparison result is used as the correction basis to form the corrected arrival time of the material peak occupation unit.

5. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step two involves calculating the predicted misalignment state of the downstream conveyor, including: The downstream receiving period is determined based on the peak material arrival and occupancy status, and the starting point of the downstream receiving period is taken as the ending time, and the deviation sampling period is selected backward. During the deviation sampling period, the deviation sampling positions of the downstream conveyor along the bandwidth direction are read in the order of sampling time, and the deviation direction and deviation change are determined according to the lateral position difference between adjacent deviation sampling positions. When the offset directions of consecutive adjacent deviation sampling positions are consistent and the amount of offset change does not exceed the deviation change limit, the corresponding deviation sampling position is used as the object of deviation change rate calculation, and the deviation change rate is determined based on the deviation sampling position, the amount of offset change, and the sampling interval that is closest to the starting point of the downstream receiving estimated time period at the formation time. Based on the deviation change rate and the deviation sampling position that is closest to the starting point of the downstream receiving estimation period, the deviation position and offset direction within the downstream receiving estimation period are determined, thus forming the deviation prediction state. When consecutive adjacent deviation sampling positions do not simultaneously satisfy the conditions of consistent deviation direction and deviation change amount not exceeding the deviation change limit, the deviation position in the downstream calculation period is determined by the deviation sampling position whose formation time is closest to the starting point of the downstream calculation period, and the deviation change rate is set to zero to form the deviation prediction state.

6. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step three, which involves determining the candidate differential frequency converter control values ​​for forming the material overlap adjustment amount, includes: Read the material receiving overlap change corresponding to the current candidate differential frequency converter control quantity, and determine the overlap relationship between the uncovered material peak occupying unit in the initial coverage state of the off-center load and the corrected downstream bearing area based on the material receiving overlap change; When it is determined that all uncovered material peak occupancy units have entered the corrected downstream bearing area based on the changes in material drop overlap, the material drop overlap adjustment amount is formed by the current candidate differential frequency converter control amount, and the generation of candidate differential frequency converter control amounts with further increases in adjustment amplitude is stopped. When determining that the uncovered material peak occupancy units have not all entered the corrected downstream bearing area based on the material drop receiving overlap change, the overlap increase is formed according to the material drop receiving overlap change corresponding to the current candidate differential frequency converter control quantity and the previous candidate differential frequency converter control quantity, and the frequency conversion adjustment completion time corresponding to the current candidate differential frequency converter control quantity is compared with the earliest corrected arrival time in the uncovered material peak occupancy unit. If the overlap increase amount does not reach the overlap increase limit and the frequency conversion adjustment completion time is earlier than the earliest correction time, the material dropping overlap adjustment amount is formed by the previous candidate differential frequency conversion control amount, and the generation of candidate differential frequency conversion control amounts that continue to increase the adjustment amplitude is stopped. When the overlap increase reaches the overlap increase limit and the frequency conversion adjustment completion time is earlier than the earliest correction time, candidate differential frequency conversion control quantities with increased adjustment amplitude are generated.

7. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step four, which involves determining the stable speed limit, includes: Read the deviation position and offset direction corresponding to the deviation prediction state, and determine the bearing boundary position of the corrected downstream bearing area on one side of the offset direction; The adjusted occupancy range of the material peak occupancy unit in the bandwidth direction is determined based on the material drop overlap adjustment amount, and the occupancy boundary position on the side closer to the offset direction in the adjusted occupancy range is determined. The remaining bearing distance on the offset side is obtained based on the distance between the occupied boundary position and the bearing boundary position, and the remaining bearing distance on the offset side is compared with the bearing edge retention distance; When the remaining receiving distance on the offset side is not less than the retaining distance at the receiving edge, the upper limit of the allowable speed of the downstream conveyor shall be used as the stable speed limit for receiving. When the remaining receiving distance on the offset side is less than the receiving edge retention distance, the speed limit amount that does not exceed the upper limit of the downstream conveyor's allowable speed is determined based on the difference between the receiving edge retention distance and the remaining receiving distance on the offset side. The speed limit amount is then subtracted from the upper limit of the downstream conveyor's allowable speed to obtain the stable receiving speed limit. The downstream advance acceptance amount is constrained by the stable acceptance speed limit, so that the downstream conveyor speed corresponding to the advance acceptance amount does not exceed the stable acceptance speed limit.

8. The conveyor frequency conversion speed control method based on material flow prediction according to claim 1, characterized in that, Step four, which determines the trailing segment corresponding to the upstream delayed release, includes: Read the remaining gap after deducting the downstream advance acceptance amount and the upstream peak reduction amount in sequence, and read the arrival sequence, corrected arrival time and material flow occupation value of each material peak occupation unit in the predicted material peak interval. Select peak occupancy units from back to front according to arrival order, and accumulate the remaining occupancy amount in the selected peak occupancy units that is not covered by the downstream early acceptance amount and the upstream peak reduction amount. When the accumulated remaining occupancy amount reaches the remaining acceptance gap, the selected peak occupancy unit is determined as the downstream peak occupancy unit. After the downstream receiving estimated time period, based on the corrected downstream receiving area after deducting the material peak occupancy units that have been arranged to be received, the subsequent receiving time period for the material peak occupancy units in the downstream section is determined. Based on the time difference between the corrected arrival time of the peak occupancy unit in the rear section and the starting point of the subsequent receiving period, the upstream delayed release amount corresponding to the peak occupancy unit in the rear section is determined, and the upstream delayed release amount is written into the gap sharing control amount. The release sequence of the peak occupancy units in the downstream segment is delayed according to the upstream delayed release amount, while keeping the release sequence of the peak occupancy units in the predicted peak interval that have not been determined as peak occupancy units in the downstream segment unchanged.

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