Steel cord belt condition monitoring method based on pcb planar spiral array

Abstract

The application discloses a steel wire rope core belt state monitoring method based on a PCB planar spiral array, and particularly relates to the field of belt intelligent detection, and aims to solve the problem that it is difficult to accurately identify the internal constraint degradation and twitching failure risk of a joint in the existing steel wire rope core belt joint monitoring process; a bipolar differential excitation pair is constructed to obtain a joint area complex impedance differential space sequence, an equivalent magnetic circuit network is established in combination with a joint steel wire braiding structure priori, and a theoretical complex impedance differential space sequence is calculated, so that a complex impedance disturbance field distribution after eliminating the inherent structure response of the joint is obtained; further, a tension-phase response curve is established in combination with a belt real-time tension signal, a micro-motion phase hysteresis amount is extracted, and a joint constraint transmission gradient field is constructed, a high gradient node chain extending along the steel wire extraction direction is identified to determine a through-type twitching channel, and early detection and perception of the twitching failure risk of the belt joint are realized.

Description

Technical Field

[0001] This invention relates to the field of intelligent belt detection technology, and more specifically, to a method for monitoring the condition of steel wire rope core belts based on a PCB planar spiral array. Background Technology

[0002] As the weakest and most prone to failure component in the entire conveyor belt, the belt splice of a steel cord conveyor belt directly affects the safety and continuity of the conveying system. Under long-term alternating loads, starting and braking impact loads, and repeated bending of the rollers, relative slippage, local loosening, and cumulative pulling will gradually occur between the steel cord cores inside the splice. This alters the constraint relationship of the original steel cord braided structure, leading to a decrease in the splice's load-bearing capacity, increased local stress concentration, and a shortened splice life. When the pulling of the steel cords progresses further, it may cause stress imbalance in the steel cords inside the splice, cracking of the adhesive, or even complete failure of the splice, resulting in serious accidents such as conveyor belt tearing, belt breakage, and shutdown.

[0003] Existing engineering sites typically use methods such as manual inspection, shutdown and disassembly inspection, magnetic flux leakage detection, and electromagnetic induction detection to monitor the condition of wire rope core belts. However, in the joint area, due to the complex cross-over relationship of the wire braided structure, the spatial arrangement and magnetic coupling state between different wires will produce significant inherent electromagnetic response characteristics. This results in the detection signal containing both normal joint structural information and abnormal damage information, making it easy for the weak abnormal response generated in the early stage of the pull to be masked by the inherent structural response of the joint.

[0004] Meanwhile, most existing detection methods focus on identifying obvious defects such as broken wires and missing parts. They lack effective monitoring methods for the constraint degradation, micro-motion accumulation, and evolution of the pulling channel before the steel wire pulls. This makes it difficult to accurately reflect the changing trend of the steel wire constraint relationship inside the joint. As a result, the risk of joint pulls is often only discovered after it has developed to a more serious stage. Therefore, there is a need for a steel wire rope core belt condition monitoring method that can combine the structural characteristics of the joint and make a fine identification of the changes in the constraint state of the steel wire inside the joint. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a method for monitoring the condition of a steel wire rope core belt based on a PCB planar helical array to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The method for monitoring the condition of steel wire rope core conveyor belts based on PCB planar helical arrays includes the following steps:

[0008] S1. When the belt joint area travels to the monitoring window of the planar spiral array, two geometrically symmetrical coils in the array are selected to form a bipolar differential excitation pair and fed with equal amplitude and opposite phase AC current.

[0009] S2. When the junction area passes through the differential excitation pair, the induced electromotive force of the two coils is collected synchronously and the complex impedance vector difference is calculated in real time to obtain the complex impedance differential space sequence indexed by the traveling position.

[0010] S3. Based on the index coordinates of the complex impedance difference space sequence, retrieve the equivalent magnetic circuit network established a priori by the joint wire braided structure, and calculate the theoretical complex impedance difference space sequence point by point.

[0011] S4. Subtract the complex impedance difference space sequence from the theoretical complex impedance difference space sequence point by point to separate the complex impedance disturbance field distribution after eliminating the electromagnetic response of the inherent structure of the joint.

[0012] S5. Obtain the real-time tension signal of the belt, divide the loading period from the trough to the peak of the tension, extract the disturbance complex vector corresponding to the index point where the disturbance amplitude exceeds the set threshold, and establish the tension-phase response curve.

[0013] S6. Based on the tension-phase response curve and combined with the spatial topological relationship of each cross node in the prior of the joint wire braided structure, the micro-motion phase hysteresis corresponding to each node is mapped to the constraint topology network, the hysteresis difference between adjacent nodes is calculated and the joint constraint transfer gradient field is constructed.

[0014] S7. Extract the continuously distributed high gradient node chain in the constraint transfer gradient field. When the node chain crosses a preset number of intersection nodes along the wire pulling direction and extends unidirectionally in a continuous running cycle, it is determined that the joint forms a through-type pulling channel.

[0015] As a further aspect of the present invention, in S1, the components constituting the bipolar differential excitation pair specifically include:

[0016] Based on the central axis of symmetry of the wire cross node in the prior art of the wire braided structure of the joint, and combined with the positional calibration relationship between the belt joint area and the planar spiral array within the preset monitoring window, the corresponding array axis of symmetry is determined.

[0017] Two coils that are mirror-symmetrical about the array's axis of symmetry are selected from the planar spiral array as target coils. Excitation currents with equal amplitude and opposite phase are applied to the target coils, driving the corresponding symmetrical wire regions to generate excitation magnetic fields with opposite directions, thus forming a bipolar differential excitation pair.

[0018] As a further aspect of the present invention, in step S2, obtaining the complex impedance differential space sequence indexed by the travel position specifically includes:

[0019] The induced electromotive forces of the two synchronously acquired coils are orthogonally decomposed to obtain their in-phase response components and orthogonal response components relative to the bipolar differential excitation current.

[0020] The in-phase response component is determined as the real part of the corresponding coil coupled complex impedance response, and the quadrature response component is determined as the imaginary part of the corresponding coil coupled complex impedance response. The difference between the real and imaginary parts of the two coil coupled complex impedance responses are calculated respectively, and the difference between the real and imaginary parts is combined to form the complex impedance vector difference.

[0021] The spatial coordinates of the current sampling position in the direction of belt travel are determined based on the belt running speed and the sampling time. The complex impedance vector differences corresponding to each sampling position are arranged in order of spatial coordinates to obtain a complex impedance differential spatial sequence indexed by the position in the direction of belt travel.

[0022] As a further aspect of the present invention, in step S3, calculating the theoretical complex impedance difference space sequence specifically includes:

[0023] Based on the index coordinates of the complex impedance differential space sequence, the spatial coordinates, diameters, and cross-node connection relationships of each wire rope core in the corresponding section of the joint wire braided structure are retrieved point by point.

[0024] An equivalent magnetic circuit network is constructed using each wire segment as a unit. The network branch parameters include the longitudinal magnetic reluctance determined by the wire segment size and nominal permeability, the cross node contact magnetic reluctance given by the nominal contact state, and the magnetic coupling coefficient calculated geometrically from the relative positions of the wire and the two coils.

[0025] Using the excitation magnetomotive force of the bipolar differential excitation pair as the network excitation source, the magnetic flux distribution corresponding to each wire segment is obtained by solving the magnetic potential distribution of each node in the equivalent magnetic circuit network.

[0026] The induced electromotive force of the two coils at each index coordinate is calculated from the magnetic flux of each wire segment to obtain the coupled complex impedance of the two coils. The real and imaginary differences of the coupled complex impedance of the two coils are combined to form the theoretical complex impedance vector difference at the corresponding index coordinates. All theoretical complex impedance vector differences are arranged according to spatial index to obtain the theoretical complex impedance difference spatial sequence.

[0027] As a further aspect of the present invention, step S4, which involves subtracting the complex impedance difference space sequence from the theoretical complex impedance difference space sequence point by point, specifically includes:

[0028] For the complex impedance vector difference at each index position in the complex impedance difference space sequence, the real and imaginary parts are subtracted from the real and imaginary parts of the theoretical complex impedance vector difference at the same index position in the theoretical complex impedance difference space sequence, respectively, to obtain the complex impedance disturbance vector. All complex impedance disturbance vectors are arranged in the order of index coordinates to form the complex impedance disturbance field distribution.

[0029] As a further aspect of the present invention, in step S5, establishing the tension-phase response curve specifically includes:

[0030] The fundamental component synchronized with the belt's operating cycle is extracted from the real-time tension signal of the belt. The interval between two consecutive zero crossings of the fundamental component is taken as the single tension cycle period. The time period in which the tension value monotonically increases from the minimum value to the maximum value within the single tension cycle period is divided into the loading period.

[0031] During the loading period, based on the time correspondence between the tension sampling time and the acquisition time of the complex impedance differential space sequence, the perturbation complex vector corresponding to each index point where the perturbation amplitude exceeds the preset noise threshold is found, and the phase angle of each perturbation complex vector is extracted.

[0032] The tension-phase response curve is obtained by arranging the data points in ascending order of tension value and connecting them with the tension value as the horizontal axis variable and the phase angle of the perturbation complex vector at the corresponding time as the vertical axis variable.

[0033] As a further aspect of the present invention, in step S6, constructing the joint constraint transfer gradient field specifically includes:

[0034] At the end of a single tension cycle, the difference between the termination phase value and the initial phase value is calculated as the net phase offset, and the irreversible residual component that the termination phase value has not returned to the initial phase value within the set neighborhood is determined as the micro-motion phase hysteresis of the corresponding index point.

[0035] Based on the spatial position of each cross node in the prior of the joint wire braided structure, the corresponding node influence area is established. Each index point in the complex impedance disturbance field distribution is mapped to the corresponding node influence area. All micro-phase hysteresis values ​​mapped to the same node influence area are fused to obtain the node hysteresis value of the corresponding cross node.

[0036] Each intersection node is used as a node of the wire-constrained topology network, and the wire segments between the intersection nodes are used as edges of the wire-constrained topology network. The difference in hysteresis between two adjacent intersection nodes is divided by the projected length of the corresponding wire segment along the wire extraction direction as the constraint gradient value of the corresponding edge. All constraint gradient values ​​are arranged according to the connection relationship of each edge in the wire-constrained topology network to form the joint constraint transfer gradient field.

[0037] As a further aspect of the present invention, in S7, determining that the joint forms a through-type pumping channel specifically includes:

[0038] In the joint constraint transfer gradient field, the intersection node whose constraint transfer gradient value exceeds the quantile of the statistical distribution of the gradient field itself is determined as a high gradient node. Starting from each high gradient node, the adjacent high gradient nodes are searched along the connection relationship of the intersection nodes in the prior of the joint wire braid structure and connected in sequence to form a high gradient node chain.

[0039] Calculate the angle between the extension direction of each high gradient node chain and the axial direction of the wire rope core at the intersection node, and take the node chain with the angle lower than the set adjacency consistency threshold as the effective node chain extending along the wire pull-out direction.

[0040] The effective node chain obtained in the current operating cycle is spatially superimposed and compared with the effective node chain in the previous operating cycle. When the displacement of the chain end node along the wire pulling direction extends unidirectionally in the continuous operating cycle and the number of cross nodes crossed by the node chain increases, it is determined that the joint forms a through-type pulling channel.

[0041] The technical effects and advantages of the present invention regarding the condition monitoring method for steel wire rope core conveyor belts based on PCB planar helical arrays are as follows:

[0042] This invention, when a belt conveyor passes through a PCB planar spiral array, acquires the complex impedance differential space sequence corresponding to the joint area by constructing a bipolar differential excitation pair. Combined with the prior knowledge of the joint's wire braided structure, an equivalent magnetic circuit network is established. Forward modeling is performed on the theoretical complex impedance differential space sequence under no-damage conditions. The complex impedance disturbance field distribution is obtained by comparing the measured response with the theoretical response point by point, effectively separating the electromagnetic response of the joint's inherent structure from the abnormal disturbance response. This avoids interference from the complex braided structure on the anomaly identification results, improving the accuracy of identifying abnormal states inside the joint. Furthermore, a tension-phase response curve is constructed based on the belt's tension variation process to extract... The micro-motion phase hysteresis reflects the cumulative characteristics of micro-motion between steel wires, and the constraint transfer gradient field of the joint is constructed by utilizing the cross node topological relationship in the prior of the joint steel wire braid structure. The local abnormal response is mapped to the change of constraint transfer state inside the joint, realizing the early identification of the constraint degradation process before the formation of steel wire pull. At the same time, by identifying the high gradient node chain in the constraint transfer gradient field and its extension characteristics in continuous operation cycle, the formation process of the pull channel inside the joint is dynamically tracked, thereby realizing early warning of the risk of steel wire pull failure, improving the sensitivity, accuracy and timeliness of steel wire rope core belt joint condition monitoring, and reducing the risk of sudden belt breakage and joint failure. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the steel wire rope core belt condition monitoring method based on PCB planar spiral array according to the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] Figure 1 The present invention provides a method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array, which includes the following steps:

[0047] S1. When the belt joint area travels to the monitoring window of the planar spiral array, two geometrically symmetrical coils in the array are selected to form a bipolar differential excitation pair and fed with equal amplitude and opposite phase AC current.

[0048] S2. When the junction area passes through the differential excitation pair, the induced electromotive force of the two coils is collected synchronously and the complex impedance vector difference is calculated in real time to obtain the complex impedance differential space sequence indexed by the traveling position.

[0049] S3. Based on the index coordinates of the complex impedance difference space sequence, retrieve the equivalent magnetic circuit network established a priori by the joint wire braided structure, and calculate the theoretical complex impedance difference space sequence point by point.

[0050] S4. Subtract the complex impedance difference space sequence from the theoretical complex impedance difference space sequence point by point to separate the complex impedance disturbance field distribution after eliminating the electromagnetic response of the inherent structure of the joint.

[0051] S5. Obtain the real-time tension signal of the belt, divide the loading period from the trough to the peak of the tension, extract the disturbance complex vector corresponding to the index point where the disturbance amplitude exceeds the set threshold, and establish the tension-phase response curve.

[0052] S6. Based on the tension-phase response curve and combined with the spatial topological relationship of each cross node in the prior of the joint wire braided structure, the micro-motion phase hysteresis corresponding to each node is mapped to the constraint topology network, the hysteresis difference between adjacent nodes is calculated and the joint constraint transfer gradient field is constructed.

[0053] S7. Extract the continuously distributed high gradient node chain in the constraint transfer gradient field. When the node chain crosses a preset number of intersection nodes along the wire pulling direction and extends unidirectionally in a continuous running cycle, it is determined that the joint forms a through-type pulling channel.

[0054] In S1, a bipolar differential excitation pair is formed.

[0055] Obtain the structural design data of the current wire rope core belt joint. This data includes at least the wire rope core arrangement sequence, spatial positions of cross nodes, wire overlap length, and weaving direction information. Based on the distribution of all cross nodes along the joint width, statistically analyze the mirror correspondence of each cross node relative to the geometric center of the joint. For cross node pairs that form a corresponding mirror relationship, extract the midpoint of their connecting line. Fit the joint's central symmetry axis based on the midpoints of all connecting lines, and use this central symmetry axis as the reference axis in the prior art of the wire rope braided structure. Subsequently, during the equipment installation phase, establish the positional calibration relationship between the planar helical array and the conveyor belt's running trajectory. Specifically, this is achieved by having a standard joint sample pass through the monitoring window in its rated operating state, recording the position coordinates corresponding to the joint's leading edge entering the monitoring window, the center position reaching the center of the monitoring window, and the trailing edge leaving the monitoring window. Simultaneously, record the fixed coordinates of the center points of each coil in the planar helical array, thereby establishing a coordinate mapping relationship between the joint's structural coordinate system and the array coordinate system. After completing the coordinate mapping, project the joint's central symmetry axis onto the array coordinate system to obtain the corresponding array symmetry axis. To prevent belt misalignment from causing coordinate shifts, belt edge position data is collected synchronously during actual operation. The projection position of the joint's central axis of symmetry in the array coordinate system is then corrected in real time based on the deviation of the edge position relative to the installation reference. When the belt exhibits lateral shift, the position of the array's axis of symmetry is synchronously corrected according to the actual shift amount, ensuring that the subsequently selected mirror coil always corresponds to the symmetrical wire region in the joint structure.

[0056] After determining the symmetry axis of the array, the center coordinates and geometric dimensions of all coils in the planar spiral array are read. The vertical distance from the center of each coil to the symmetry axis is calculated using the array symmetry axis as a reference. Mirror coil pairs are selected based on the principle of equal distance and location on both sides of the symmetry axis. When multiple mirror coil pairs meet the conditions, the coil combination covering the central area of ​​the joint and having the most corresponding wire crossing nodes is prioritized as the target coil to ensure that the detection area covers the structural area where wire pulling is most likely to occur. After determining the target coil, a reference excitation signal is generated through the same AC excitation source, and then two excitation currents with a 180-degree phase difference are generated by the inverting drive unit. These two excitation currents are fed into the two target coils respectively. To ensure that the two coils receive consistent excitation energy, the DC resistance and AC impedance of the two target coils are measured before excitation. The compensation parameters in the drive circuit are adjusted according to the measurement results to ensure that the effective current values ​​flowing through the two coils are consistent. During excitation, the actual current waveforms of the two coils are continuously monitored, and the amplitude difference between the two coil currents is calculated. When the amplitude difference exceeds the allowable deviation range determined by the drive circuit calibration results, current compensation is immediately performed to restore the symmetry of the two excitation currents. Two coils are located on opposite sides of the array's axis of symmetry and are subjected to excitation currents flowing in opposite directions, forming excitation magnetic fields in opposite directions in the symmetrical wire regions corresponding to the joints.

[0057] In step S2, a complex impedance differential space sequence indexed by the travel position is obtained.

[0058] The bipolar differential excitation continuously acquires the induced electromotive force (EMF) waveforms of the two target coils during operation, while simultaneously recording the reference waveform of the excitation current. To ensure that the subsequent decomposition results strictly correspond to the excitation state, the reference phase for each sampling period is first determined based on the excitation current waveform, and the acquired induced EMF waveforms are periodically aligned according to the reference phase. For cases with sampling clock drift, the sampling time axis is corrected by comparing the position offset of the reference phase in multiple consecutive excitation periods to ensure consistency of the reference phase for each sampling period. After alignment, using the excitation current reference phase as the zero-phase reference, orthogonal decomposition is performed on the induced EMFs of the two coils to obtain the response component that changes in the same direction as the excitation current and the response component that differs from the excitation current phase by a quarter of a period. Subsequently, periodic averaging is performed on the in-phase and orthogonal response components to eliminate the fluctuations caused by single-period random disturbances. To avoid interference from local abnormal spikes in the decomposition results, the distribution of the response components within multiple consecutive sampling periods is statistically analyzed before periodic averaging, and data points deviating from the median value beyond the statistical fluctuation range of the historical stable operation phase are discarded. After component extraction, the in-phase response component is mapped to the real part of the coupled complex impedance response, and the quadrature response component is mapped to the imaginary part of the coupled complex impedance response. Complex impedance response records for the two coils at the current sampling position are then established. Subsequently, a difference operation is performed on the real and imaginary parts of the complex impedance responses of the two coils to obtain the real and imaginary differences at the corresponding sampling positions. Since the difference results directly reflect the response differences between the symmetrical regions on both sides of the connector structure, common-mode response components caused by changes in ambient temperature, power supply fluctuations, and overall wire magnetic properties can be synchronously canceled out. Finally, the real and imaginary differences are combined in complex number form to form the complex impedance vector difference corresponding to the current sampling position.

[0059] After obtaining the complex impedance vector difference corresponding to each sampling moment, a mapping relationship between the sampling moment and the belt running position is established. In specific implementation, a position encoder is installed at the end of the drive roller shaft, and the encoder output pulse signal maintains a fixed correspondence with the roller rotation angle. Based on the roller's outer diameter and the transmission relationship between the belt and the roller, the cumulative number of encoder pulses is converted into the actual belt travel distance, and the cumulative displacement value corresponding to each sampling moment is recorded. To avoid the influence of local elastic elongation of the belt on the position conversion results, a displacement correction table is established using standard joint samples during the equipment installation and commissioning phase. The encoder-converted displacement and the actual distance traveled by the joint are calibrated, and displacement compensation is performed according to the calibration results during operation. Subsequently, using the position when the leading edge of the joint enters the monitoring window as the spatial coordinate origin, the cumulative displacement corresponding to each sampling moment is converted into spatial coordinate values ​​in the joint's local coordinate system. For the complex impedance vector difference obtained within the same sampling period, it is bound and stored with the corresponding spatial coordinates to form a position-response corresponding data set. Since the sampling frequency is fixed during actual operation, while the belt running speed may fluctuate slightly, the spatial interval between different sampling points is not completely consistent. To address this issue, the spatial intervals between consecutive sampling points are statistically analyzed. When the distance between adjacent sampling points exceeds the allowable interval determined based on the average spacing of the wire crossing nodes, interpolation compensation is performed between adjacent data points to maintain the continuity of the spatial sequence. After mapping the positions of all sampling points, all complex impedance vector differences are rearranged in ascending order of spatial coordinates to form a spatial response sequence consistent with the actual structural distribution of the belt joint. For the same joint that repeatedly passes through the monitoring window, the spatial coordinates are uniformly aligned based on the identification position of the joint's leading edge, ensuring that the complex impedance differential spatial sequences obtained in different operating cycles always correspond to the same structural position.

[0060] In S3, the theoretical complex impedance differential space sequence is calculated.

[0061] The prior knowledge of the braided steel wire joint structure is stored in the form of a structural parameter table. This table records the node identifier, three-dimensional coordinates, corresponding wire core identifier, wire direction vector, and wire diameter information for each wire crossing node, as well as the wire connection relationship between any two crossing nodes. When a certain index coordinate in the complex impedance differential space sequence is read, the belt travel direction position corresponding to that index coordinate is used as the retrieval reference. All wire segments and crossing nodes currently within the effective range of the bipolar differential excitation pair are extracted from the structural parameter table. The effective range is determined by multiplying the center distance between the two target coils by a coverage correction factor, which is statistically obtained during the equipment calibration phase based on the magnetic field diffusion range of the standard joint sample. Subsequently, the wire portion between any two adjacent crossing nodes is defined as a wire segment unit, and a corresponding branch is established for each wire segment unit. For each wire segment unit, the length of the wire segment is calculated by reading the coordinates of its two intersecting nodes, the cross-sectional area of ​​the wire is calculated based on the wire diameter, and the longitudinal magnetic reluctance of the wire segment is determined by combining the nominal permeability of the corresponding wire material under undamaged conditions; the nominal permeability is the incremental permeability obtained by actual measurement of a wire rope core sample of the same specification at the detection excitation frequency. For each intersecting node, the corresponding contact magnetic reluctance is determined based on the contact state file formed during the initial manufacturing stage of the joint. The contact state file is established through structural inspection after the joint vulcanization is completed, and is divided into three levels according to the wire contact area and compression state: full contact, partial contact, and weak contact, with each level corresponding to a fixed contact magnetic reluctance value. Subsequently, the magnetic coupling coefficient between each wire segment and the two target coils is calculated. Specifically, the geometric center coordinates of the wire segments and the center coordinates of the two target coils are read, the spatial offset and directional angle between the wire segments and the coils are calculated, and the wire segments are equivalent to magnetic dipoles located at their geometric centers. The normal magnetic flux distribution generated by these magnetic dipoles in the corresponding coil plane is calculated, and an area integration operation is performed on the coil-covered area. The ratio of the integral result to the magnetic moment of the magnetic dipole is determined as the corresponding magnetic coupling coefficient. After all parameter calculations are completed, the intersection nodes are used as network nodes, and the wire segments are used as network branches. The longitudinal magnetic reluctance, contact magnetic reluctance, and magnetic coupling coefficient are written into the corresponding branch parameters to form an equivalent magnetic circuit network corresponding to the current index coordinates.

[0062] After constructing the equivalent magnetic circuit network, the excitation parameters corresponding to the current bipolar differential excitation are read. The number of turns of the two target coils is multiplied by the excitation current amplitude to obtain the corresponding excitation magnetomotive force (MTF). The first target coil corresponds to the forward excitation MMF, and the second target coil corresponds to the reverse excitation MMF. Subsequently, based on the actual positions of the two target coils in the local coordinate system of the joint, the corresponding excitation MMFs are applied to the branch regions of the wire segments with the highest coupling degree with the target coils, and these are used as the boundary excitation conditions of the equivalent magnetic circuit network. After the excitation conditions are applied, a magnetic flux conservation relationship is established for each node in the equivalent magnetic circuit network. Specifically, the magnetic flux of all branches connected to the node is counted, and the total inflow magnetic flux is equal to the total outflow magnetic flux as the node constraint condition. For any branch, its branch magnetic flux is determined by the magnetic potential difference between the nodes at both ends of the branch and the corresponding branch magnetic reluctance. For branches containing excitation MMFs, the corresponding excitation MMF is superimposed on the node magnetic potential difference before calculating the branch magnetic flux. A set of nodal magnetic potential equations is established based on the magnetic flux conservation relationship corresponding to all nodes. The unknowns in the equations are the magnetic potential values ​​of each node, and the equation coefficients are determined by the reciprocals of the magnetic reluctance of each branch. Then, a sparse matrix solution method is used to solve the nodal magnetic potential equations to obtain the magnetic potential distribution results for all intersecting nodes. After obtaining the nodal magnetic potentials, the magnetic potential values ​​of the nodes at both ends of each wire segment branch are read one by one. The corresponding node magnetic potential difference is calculated, and the longitudinal magnetic flux in the wire segment is obtained by dividing the node magnetic potential difference by the longitudinal magnetic reluctance of the wire segment. For contact branches at intersecting nodes, the coupling magnetic flux between nodes is obtained by dividing the magnetic potential difference between the nodes at both ends of the contact branch by the corresponding contact magnetic reluctance. After completing the traversal of all branches, the magnetic flux distribution result of the wire segment corresponding to the current index coordinate is formed.

[0063] After obtaining the magnetic flux distribution of the wire segment corresponding to the current index coordinates, the linkage magnetic flux contribution of all wire segments to the first and second target coils is calculated. Specifically, for any wire segment, its magnetic flux and the magnetic coupling coefficient with the corresponding target coil are read. The magnetic flux of the wire segment is multiplied by the magnetic coupling coefficient to obtain the partial linkage magnetic flux formed by the wire segment to the target coil. Then, an accumulation operation is performed on all wire segments within the effective coverage area of ​​the target coil to obtain the total linkage magnetic flux of the corresponding target coil. According to the electromagnetic induction relationship, the induced electromotive force of the corresponding coil is determined by the rate of change of the total linkage magnetic flux with time. Under AC steady-state conditions, the amplitude of the corresponding induced electromotive force is obtained by multiplying the total linkage magnetic flux by the excitation angular frequency, and the phase information of the induced electromotive force is determined by combining the reference phase of the excitation current. Then, the theoretical coupling complex impedance of the coil is determined by the ratio between the induced electromotive force of the corresponding coil and the excitation current, where the real part of the complex impedance corresponds to the response component in phase with the excitation current, and the imaginary part of the complex impedance corresponds to the response component orthogonal to the excitation current. After solving the theoretical coupling complex impedance of the two target coils, the real and imaginary parts of the theoretical coupling complex impedance of the first and second target coils are extracted respectively. The difference between their real parts is calculated to obtain the real part difference of the theoretical complex impedance, and the difference between their imaginary parts is calculated to obtain the imaginary part difference of the theoretical complex impedance. The real and imaginary part differences of the theoretical complex impedance are combined to form the theoretical complex impedance vector difference corresponding to the current index coordinate. Subsequently, according to the index coordinate order in the complex impedance difference space sequence, the magnetic flux calculation, linkage magnetic flux accumulation, induced electromotive force solution, and theoretical complex impedance solution process are repeated for all index positions to obtain a set of theoretical complex impedance vector differences covering the entire junction region. All theoretical complex impedance vector differences are arranged in the order of spatial coordinates from front to back to form the theoretical complex impedance difference space sequence.

[0064] In step S4, the complex impedance differential space sequence is subtracted from the theoretical complex impedance differential space sequence point by point.

[0065] Spatial coordinate alignment is performed on the measured complex impedance differential spatial sequence and the theoretical complex impedance differential spatial sequence. The positional identifiers corresponding to each index coordinate in the two sequences are checked one by one. When it is found that individual index positions are not completely corresponding due to sampling interpolation or spatial resampling, position remapping is performed on the theoretical complex impedance differential spatial sequence based on the spatial interval between adjacent index coordinates, ensuring that the two sequences maintain a corresponding relationship in the same spatial coordinate system. After coordinate alignment, the measured complex impedance vector difference and the theoretical complex impedance vector difference corresponding to each index position are read sequentially. The measured complex impedance vector difference includes the measured real part difference and the measured imaginary part difference, while the theoretical complex impedance vector difference includes the theoretical real part difference and the theoretical imaginary part difference. Then, the measured real part difference is subtracted from the theoretical real part difference to obtain the perturbation real part corresponding to that index position, and the measured imaginary part difference is subtracted from the theoretical imaginary part difference to obtain the perturbation imaginary part corresponding to that index position. The perturbation real part and the perturbation imaginary part are combined to form the complex impedance perturbation vector for the corresponding index position. Since the theoretical complex impedance differential space sequence has already characterized the inherent electromagnetic response characteristics of the joint wire braided structure under the non-pulling state, the complex impedance disturbance vector retained after subtraction reflects the degree of deviation of the actual state of the joint from the prior model of the structure.

[0066] After completing the differential calculation for all index positions, a continuity check is performed on the obtained complex impedance disturbance vectors, and the variation amplitude of disturbance vectors at adjacent index positions is statistically analyzed. When an isolated abrupt change occurs at a certain index position and no corresponding change occurs at its immediate or adjacent positions, the original induced potential sampling data corresponding to that position is read for verification. If it is confirmed to be an instantaneous sampling interference, the interpolation result of the disturbance vectors at adjacent index positions is used for correction. Subsequently, all complex impedance disturbance vectors are arranged in order from front to back according to the index coordinates, maintaining the correspondence with the actual spatial position of the joint, forming a complex impedance disturbance field distribution covering the entire joint area. Each index position corresponds to a complex impedance disturbance vector, and each complex impedance disturbance vector simultaneously retains disturbance amplitude information and disturbance phase information to characterize the deviation of the local electromagnetic response of the wire structure at that position relative to the undamaged state.

[0067] In step S5, a tension-phase response curve is established.

[0068] The real-time tension signal of the belt is continuously acquired by a tension detection unit located at the tensioning device. The acquired data is stored together with the complex impedance detection data according to the timestamp. To extract the tension component that represents the periodic force changes of the belt, the original tension signal is first subjected to DC bias removal processing. The average tension value within the current sampling window is used as the static tension reference, and this static tension reference is subtracted from the original tension signal to obtain a tension change signal that only reflects periodic fluctuations. Subsequently, the fundamental frequency of the tension is determined according to the drive drum speed or the belt running cycle, and the fundamental frequency of the tension change signal is extracted. The first-order periodic component synchronized with the belt running cycle is retained, and asynchronous components caused by local drum vibration, idler impact, and instantaneous load disturbance are filtered out. After the fundamental frequency extraction is completed, two adjacent zero-crossing points in the same direction in the fundamental frequency component are read, and the time interval between the two zero-crossing points is determined as a single tension cycle. For each single tension cycle, the minimum and maximum points of the fundamental frequency component of the tension are searched within the cycle, and the time period from the minimum to the maximum value of the tension is determined as the loading period. If a non-monotonic sampling point is caused by a local drop within the same period, the local drop point is smoothed and corrected according to the overall upward direction of the tension fundamental component. The correction range is limited to the area between two adjacent sampling points to avoid instantaneous interference disrupting the continuity of the loading period. After the loading period is determined, its start time, end time, corresponding tension minimum and maximum values ​​are recorded, and this period is used as the data intercept interval for the tension-phase response curve.

[0069] Each index point in the complex impedance disturbance field distribution simultaneously stores its spatial coordinates, acquisition time, real part of the disturbance, and imaginary part of the disturbance. Upon entering the loading period, based on the timestamp correspondence between the tension sampling time and the complex impedance acquisition time, each complex impedance disturbance index point is matched to the tension value at the same or most recently synchronized time. When the tension sampling frequency and the complex impedance sampling frequency are inconsistent, the tension value is interpolated according to the linear relationship between two adjacent tension sampling points, ensuring that each disturbance index point corresponds to a specific tension value. Subsequently, the amplitude of the complex impedance disturbance vector corresponding to each index point is calculated. The amplitude is determined by both the real and imaginary parts of the disturbance, and is compared with a noise threshold. The noise threshold is determined during the no-load background sampling stage before the belt joint enters the monitoring window. Specifically, it is calculated by adding three times the standard deviation to the mean and standard deviation of the complex impedance disturbance amplitude during the statistical background stage, using this threshold to eliminate invalid disturbance points caused solely by circuit noise, environmental electromagnetic interference, or background fluctuations. For index points where the disturbance amplitude exceeds the noise threshold, the real and imaginary parts of the disturbance are read, and the phase angle of the complex disturbance vector is calculated according to the arctangent relationship between the imaginary part and the real part. When the real part of the disturbance is zero or close to zero, a four-quadrant arctangent algorithm is used to determine the phase angle to avoid phase quadrant discrimination errors. After the phase angle is extracted, the tension value corresponding to each valid disturbance index point within the same loading period is used as the horizontal axis variable, and the disturbance phase angle corresponding to that index point is used as the vertical axis variable to form tension-phase data points. When there are multiple valid disturbance index points near the same tension value, they are weighted and fused according to the disturbance amplitude of the index points to obtain the representative phase angle corresponding to that tension value. The index point with the larger disturbance amplitude contributes more to the representative phase angle. Finally, all tension-phase data points are arranged in ascending order of tension value and connected sequentially to form a tension-phase response curve. This curve reflects the response process of the complex impedance disturbance phase changing with the force state during tension loading.

[0070] In S6, a joint constraint transfer gradient field is constructed.

[0071] For each valid disturbance index point with an established tension-phase response curve, the initial phase value at the start of a single tension cycle and the termination phase value at the end of that cycle are read. Since the tension cycle includes both tension loading and unloading, the termination phase value reflects whether the index point has returned to its pre-cycle state after a complete stress cycle. During calculation, the phase angle of the same index point at consecutive sampling times is first processed by phase expansion. When the phase angle crosses the ±180 degree boundary, the phase angle is corrected according to the continuous direction of phase change of adjacent sampling points to avoid false phase shifts caused by angle jumps. Then, the termination phase value is subtracted from the initial phase value to obtain the net phase shift of the index point in a single tension cycle. The neighborhood range is not obtained statistically during the repeated operation phase of the sample without a pull-out joint; specifically, the phase regression error of the same specification without a pull-out joint is collected over at least thirty tension cycle cycles, and the sum of the mean of the absolute values ​​of the phase regression errors and three times the standard deviation is taken as the set neighborhood range. If the termination phase value of the current index point falls within the set neighborhood range corresponding to the initial phase value, the phase change of the index point is determined to be an elastic recoverable response, and the irreversible residual component is not extracted; if the termination phase value exceeds the neighborhood range, the phase offset exceeding the neighborhood range is taken as the irreversible residual component, and the irreversible residual component is determined as the micro-motion phase hysteresis of the index point.

[0072] The spatial coordinates of each cross node and the connection relationships between adjacent cross nodes in the prior art of the braided steel wire structure of the joint are read, and a node influence region is established with each cross node as the center. The node influence region is determined according to the structural coverage of the cross node in the belt travel direction and belt width direction. The influence boundary in the belt travel direction is taken as the midpoint between the cross node and the adjacent cross nodes before and after it, and the influence boundary in the belt width direction is taken as the midpoint between the cross node and the adjacent steel wire cross nodes on the left and right. For cross nodes located at the edge of the joint, the joint boundary is used as the boundary of the influence region. In this way, each cross node corresponds to a spatial region that does not overlap with adjacent nodes, so that index points in the complex impedance disturbance field can be assigned to the determined cross nodes according to their spatial positions. After the node influence region is established, the effective index points in the complex impedance disturbance field distribution are read one by one, and the node influence region they fall into is determined according to their spatial coordinates. The micro-phase hysteresis corresponding to the index point is written into the candidate hysteresis set of the corresponding cross node. For index points that fall on the boundary of the region, they are assigned according to their distance from the center of the adjacent cross node, and the side with the smaller distance is taken as the node to which the index point belongs. Subsequently, all micro-motion phase hysteresis values ​​in the candidate hysteresis value set of the same cross node are fused. During fusion, the perturbation amplitude of the index point is used as the weight. The perturbation amplitude is calculated from the real and imaginary parts of the corresponding complex impedance perturbation vector. The micro-motion phase hysteresis value of each index point is multiplied by the corresponding perturbation amplitude, summed, and then divided by the sum of all perturbation amplitudes to obtain the node hysteresis value of that cross node. When there are no valid index points exceeding the noise threshold within the influence area of ​​a certain cross node, the node hysteresis value is recorded as zero and the empty response mark is retained, indicating that no identifiable irreversible micro-motion response was detected at that node in the current tension cycle.

[0073] Based on the cross-node connection relationships recorded in the prior art of the braided steel wire joint structure, a steel wire constraint topology network is constructed. Each cross-node corresponds to a network node, and a network edge is established between any two adjacent cross-nodes connected along the same steel wire core. This network edge corresponds to a steel wire segment inside the actual joint. For each network edge, the nodal hysteresis of its two cross-nodes is read, and the difference between the two nodal hysteresis is calculated. This difference represents the change in the residual response of the constraint micro-motion at both ends of the same steel wire segment. Subsequently, the three-dimensional orientation vector of the steel wire segment corresponding to the network edge is read, and the steel wire extraction direction vector of the joint is read. The projected length of the steel wire segment in the extraction direction is calculated. The projected length is determined by multiplying the actual length of the steel wire segment by the cosine of the angle between the steel wire segment orientation and the extraction direction. When the projected length is less than the minimum effective length determined based on the joint structure resolution, the network edge is marked as a transverse transition edge and does not participate in the constraint gradient calculation along the extraction direction to avoid amplifying local noise due to an excessively small denominator. For each network edge involved in the calculation, the constraint gradient value of that edge is obtained by dividing the difference in hysteresis between the two endpoints by the projected length of the wire segment along the wire extraction direction. The sign of the constraint gradient value preserves the directional relationship between the two endpoints: a positive value indicates that the node hysteresis increases along the wire extraction direction, and a negative value indicates that the node hysteresis increases in the opposite direction. After calculating the constraint gradients of all network edges, the constraint gradient values ​​are arranged according to the connection relationship of each edge in the wire constraint topology network, forming the joint constraint transmission gradient field. This gradient field is not a single numerical set, but rather an edge state distribution consistent with the wire braiding topology. Each edge corresponds to a constraint gradient value and a direction identifier, representing the transmission and change of micro-motion hysteresis within the joint along the wire constraint path.

[0074] In step S7, it is determined that the joint forms a through-type pumping channel.

[0075] The current running cycle's corresponding joint constraint transfer gradient field is read, and the constraint gradient values ​​corresponding to all network edges are extracted. To avoid misjudgments caused by the fixed threshold being affected by different joint structures, different load conditions, and different usage stages, all constraint gradient values ​​in the current gradient field are statistically sorted and arranged into a gradient distribution sequence in ascending order of absolute value. The upper quantile position of the gradient distribution sequence is then determined. The upper quantile position is determined based on the initial joint calibration stage; in this embodiment, 90% of the upper quantile positions are used, meaning that the constraint gradient values ​​in the first 10% of the gradient distribution are considered abnormally enhanced gradient regions. After determining the upper quantile positions, all intersection nodes in the wire constraint topology network are traversed, and it is counted whether there are any constraint gradient values ​​exceeding the corresponding upper quantile position among the network edges directly connected to each intersection node. When at least one network edge connected to a certain intersection node exceeds the upper quantile position, the intersection node is marked as a high-gradient node, and its node number, spatial coordinates, and corresponding constraint gradient value are recorded. Subsequently, an adjacency list is established based on the node connection relationships in the prior knowledge of the joint wire braided structure. The adjacency list records the set of intersection nodes directly connected to each intersection node. Starting with each high-gradient node, the search proceeds layer by layer along the adjacency list to find directly connected high-gradient nodes. When adjacent nodes are also marked as high-gradient nodes, they are added to the same node chain, and the search continues forward. The search terminates when a non-high-gradient node is encountered. After deduplication of all search paths, consecutively connected high-gradient nodes are arranged in the actual connection order to form corresponding high-gradient node chains. For cases with branching structures, the high-gradient node chains corresponding to each branch path are retained, and the number of nodes, spatial coverage, and the positions of the first and last nodes in the chain are recorded to form the high-gradient node chain set corresponding to the current running cycle.

[0076] For each node chain, the overall extension direction is calculated. Specifically, the spatial coordinates of the first and last nodes of the node chain are read, and the direction of the line connecting the first and last nodes is taken as the overall extension direction vector of the node chain. Then, all intersection nodes in the node chain are traversed, and the axial direction vector of the corresponding wire rope core at that intersection node is read. The angle between the extension direction vector of the node chain and the axial direction vector of the wire rope is calculated. For the same node chain, all angles are averaged to obtain the average direction angle of the node chain. The adjacency consistency threshold is established using a baseline dataset of non-pulling samples during the joint factory acceptance stage. This threshold is obtained by statistically analyzing the angle distribution between the wire path inside a normal joint and the node chain direction. In this embodiment, the 95th percentile of the normal state angle distribution is taken as the adjacency consistency threshold. When the average direction angle of the node chain is lower than this adjacency consistency threshold, the node chain is determined to be consistent with the actual force transmission direction of the wire rope and is identified as a valid node chain extending along the wire extraction direction. For node chains with angles exceeding the adjacency consistency threshold, they are considered discrete abnormal chains formed by local random disturbances and do not participate in subsequent extraction channel identification. After completing the screening of valid node chains, the valid node chain records saved in the previous running cycle are read, and spatial overlay comparison is performed based on the spatial coordinates of the cross nodes. Specifically, node matching is performed between the valid node chains of the current running cycle and the historical valid node chains. When the proportion of overlapping nodes in the two node chains exceeds the pre-calculated chain matching standard, the two are determined to be the same evolutionary chain. For successfully matched node chains, the projected coordinates of the current cycle's chain-end node and the previous cycle's chain-end node in the wire extraction direction are read, and the displacement increment between them is calculated. When the displacement increment remains in the same direction for multiple consecutive running cycles without reverse retraction, it is determined that the chain-end node continues to expand along the wire extraction direction. At the same time, the number of cross nodes crossed by the node chain is counted. When the number of cross nodes contained in the current cycle's node chain is greater than the number of cross nodes in the corresponding node chain of the previous cycle, the node chain coverage area is recorded as expanded. If the node chain simultaneously satisfies two conditions—the continuous expansion of the chain-end nodes along the wire extraction direction and the continuous increase in the number of covered cross nodes—it is determined that a stable, through-type extraction channel has been formed inside the joint, and the spatial position, expansion direction, and coverage range of the corresponding node chain are output as extraction failure monitoring results.

[0077] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. The semiconductor medium can be a solid-state drive.

[0078] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0079] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0080] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0081] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0082] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0083] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0084] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0085] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array, characterized in that, Includes the following steps: S1. When the belt joint area travels to the monitoring window of the planar spiral array, two geometrically symmetrical coils in the array are selected to form a bipolar differential excitation pair and fed with equal amplitude and opposite phase AC current. S2. When the junction area passes through the differential excitation pair, the induced electromotive force of the two coils is collected synchronously and the complex impedance vector difference is calculated in real time to obtain the complex impedance differential space sequence indexed by the traveling position. S3. Based on the index coordinates of the complex impedance difference space sequence, retrieve the equivalent magnetic circuit network established a priori by the joint wire braided structure, and calculate the theoretical complex impedance difference space sequence point by point. S4. Subtract the complex impedance difference space sequence from the theoretical complex impedance difference space sequence point by point to separate the complex impedance disturbance field distribution after eliminating the electromagnetic response of the inherent structure of the joint. S5. Obtain the real-time tension signal of the belt, divide the loading period from the trough to the peak of the tension, extract the disturbance complex vector corresponding to the index point where the disturbance amplitude exceeds the set threshold, and establish the tension-phase response curve. S6. Based on the tension-phase response curve and combined with the spatial topological relationship of each cross node in the prior of the joint wire braided structure, the micro-motion phase hysteresis corresponding to each node is mapped to the constraint topology network, the hysteresis difference between adjacent nodes is calculated and the joint constraint transfer gradient field is constructed. At the end of a single tension cycle, the difference between the termination phase value and the initial phase value is calculated as the net phase offset, and the irreversible residual component that the termination phase value has not returned to the initial phase value within the set neighborhood is determined as the micro-motion phase hysteresis of the corresponding index point. Based on the spatial position of each cross node in the prior of the joint wire braided structure, the corresponding node influence area is established. Each index point in the complex impedance disturbance field distribution is mapped to the corresponding node influence area. All micro-phase hysteresis values ​​mapped to the same node influence area are fused to obtain the node hysteresis value of the corresponding cross node. The fundamental component synchronized with the belt's operating cycle is extracted from the real-time tension signal of the belt. The interval between two consecutive zero crossings of the fundamental component is taken as the single tension cycle period. Based on the tension-phase response curve, effective disturbance index points are screened. The phase angle of the disturbance complex vector corresponding to the effective disturbance index point at the beginning of the single tension cycle period is read as the initial phase value. The termination phase value is the phase angle of the disturbance complex vector corresponding to the same index point at the end of the same single tension cycle period. S7. Extract the continuously distributed high gradient node chain in the constraint transfer gradient field. When the node chain crosses a preset number of intersection nodes along the wire pulling direction and extends unidirectionally in a continuous running cycle, it is determined that the joint forms a through-type pulling channel.

2. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In S1, the bipolar differential excitation pair specifically includes: Based on the central axis of symmetry of the wire cross node in the prior art of the wire braided structure of the joint, and combined with the positional calibration relationship between the belt joint area and the planar spiral array within the preset monitoring window, the corresponding array axis of symmetry is determined. Two coils that are mirror-symmetrical about the array's axis of symmetry are selected from the planar spiral array as target coils. Excitation currents with equal amplitude and opposite phase are applied to the target coils, driving the corresponding symmetrical wire regions to generate excitation magnetic fields with opposite directions, thus forming a bipolar differential excitation pair.

3. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S2, obtaining the complex impedance differential space sequence indexed by the travel position specifically includes: The induced electromotive forces of the two synchronously acquired coils are orthogonally decomposed to obtain their in-phase response components and orthogonal response components relative to the bipolar differential excitation current. The in-phase response component is determined as the real part of the corresponding coil coupled complex impedance response, and the quadrature response component is determined as the imaginary part of the corresponding coil coupled complex impedance response. The difference between the real and imaginary parts of the two coil coupled complex impedance responses are calculated respectively, and the difference between the real and imaginary parts is combined to form the complex impedance vector difference. The spatial coordinates of the current sampling position in the direction of belt travel are determined based on the belt running speed and the sampling time. The complex impedance vector differences corresponding to each sampling position are arranged in order of spatial coordinates to obtain a complex impedance differential spatial sequence indexed by the position in the direction of belt travel.

4. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S3, the calculation of the theoretical complex impedance differential space sequence specifically includes: Based on the index coordinates of the complex impedance differential space sequence, the spatial coordinates, diameters, and cross-node connection relationships of each wire rope core in the corresponding section of the joint wire braided structure are retrieved point by point. An equivalent magnetic circuit network is constructed using each wire segment as a unit. The network branch parameters include the longitudinal magnetic reluctance determined by the wire segment size and nominal permeability, the cross node contact magnetic reluctance given by the nominal contact state, and the magnetic coupling coefficient calculated geometrically from the relative positions of the wire and the two coils. Using the excitation magnetomotive force of the bipolar differential excitation pair as the network excitation source, the magnetic flux distribution corresponding to each wire segment is obtained by solving the magnetic potential distribution of each node in the equivalent magnetic circuit network. The induced electromotive force of the two coils at each index coordinate is calculated from the magnetic flux of each wire segment to obtain the coupled complex impedance of the two coils. The real and imaginary differences of the coupled complex impedance of the two coils are combined to form the theoretical complex impedance vector difference at the corresponding index coordinates. All theoretical complex impedance vector differences are arranged according to spatial index to obtain the theoretical complex impedance difference spatial sequence.

5. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S4, subtracting the complex impedance difference space sequence from the theoretical complex impedance difference space sequence point by point specifically includes: For the complex impedance vector difference at each index position in the complex impedance difference space sequence, the real and imaginary parts are subtracted from the real and imaginary parts of the theoretical complex impedance vector difference at the same index position in the theoretical complex impedance difference space sequence, respectively, to obtain the complex impedance disturbance vector. All complex impedance disturbance vectors are arranged in the order of index coordinates to form the complex impedance disturbance field distribution.

6. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S5, establishing the tension-phase response curve specifically includes: The period during which the tension value monotonically increases from its minimum to its maximum value within a single tension cycle is defined as the loading period. During the loading period, based on the time correspondence between the tension sampling time and the acquisition time of the complex impedance differential space sequence, the perturbation complex vector corresponding to each index point where the perturbation amplitude exceeds the preset noise threshold is found, and the phase angle of each perturbation complex vector is extracted. The tension-phase response curve is obtained by arranging the data points in ascending order of tension value and connecting them with the tension value as the horizontal axis variable and the phase angle of the perturbation complex vector at the corresponding time as the vertical axis variable.

7. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S6, constructing the joint constraint transfer gradient field specifically includes: Each intersection node is used as a node of the wire-constrained topology network, and the wire segments between the intersection nodes are used as edges of the wire-constrained topology network. The difference in hysteresis between two adjacent intersection nodes is divided by the projected length of the corresponding wire segment along the wire extraction direction as the constraint gradient value of the corresponding edge. All constraint gradient values ​​are arranged according to the connection relationship of each edge in the wire-constrained topology network to form the joint constraint transfer gradient field.

8. The method for monitoring the condition of a steel wire rope core conveyor belt based on a PCB planar helical array according to claim 1, characterized in that, In step S7, determining that the joint forms a through-type pumping channel specifically includes: In the joint constraint transfer gradient field, the intersection node whose constraint transfer gradient value exceeds the quantile of the statistical distribution of the gradient field itself is determined as a high gradient node. Starting from each high gradient node, the adjacent high gradient nodes are searched along the connection relationship of the intersection nodes in the prior of the joint wire braid structure and connected in sequence to form a high gradient node chain. Calculate the angle between the extension direction of each high gradient node chain and the axial direction of the wire rope core at the intersection node, and take the node chain with the angle lower than the set adjacency consistency threshold as the effective node chain extending along the wire pull-out direction. The effective node chain obtained in the current operating cycle is spatially superimposed and compared with the effective node chain in the previous operating cycle. When the displacement of the chain end node along the wire pulling direction extends unidirectionally in the continuous operating cycle and the number of cross nodes crossed by the node chain increases, it is determined that the joint forms a through-type pulling channel.

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