An online monitoring system based on elevator steel wire rope elongation rate

Abstract

The present application belongs to the technical field of elevator safety monitoring, and relates to an online monitoring system based on the elongation of elevator steel wire rope, comprising: a trigger module for monitoring the relative position relationship between the counterweight device and the buffer in the elevator, and sending a trigger signal by using the relative position relationship; a detection module for receiving the trigger signal and calculating the distance between the counterweight device and the buffer; in the distance calculation process, optical compensation is carried out through the ambient temperature and humidity; a data processing module for data processing of the distance values measured multiple times, calculating the elongation by using the distance values processed by data, comparing the elongation and the current distance value with a multi-level threshold judgment function, and obtaining a comparison result; a cloud platform for sending an early warning when the elongation or the buffer distance is abnormal in the comparison result, and drawing a time-elongation and frequency-elongation change curve. The present application is suitable for performance evaluation and safety early warning of elevator steel wire rope.

Description

Technical Field

[0001] This invention relates to the field of elevator safety monitoring technology, and in particular to an online monitoring system based on the elongation rate of elevator wire ropes. Background Technology

[0002] During long-term use, elevator wire ropes undergo length changes due to factors such as initial structural elongation and later wear-induced elongation, directly affecting elevator operational safety. In particular, changes in the counterweight buffer distance can lead to operational instability and buffer failure. The elongation characteristics of wire ropes and their impact on elevator systems have attracted attention from academia and engineering. However, current research and application are clearly disconnected. Wire rope manufacturers, elevator manufacturers, and elevator maintenance companies have different focuses in their practical work, each with its own shortcomings, and lack systematic research and basic data support.

[0003] Steel wire rope manufacturers primarily focus on the impact of material selection, structural design, and manufacturing processes on elongation performance. Existing research published in journals indicates that the core characteristics of steel wire rope traction systems include minimum breaking force, permanent elongation, and dynamic elongation. Understanding and controlling these factors is crucial for extending steel wire rope life and reducing elevator operating costs. Studies on the mechanical properties of steel wire ropes have systematically explored their elastic elongation, structural elongation, modulus of elasticity, and other mechanical properties, pointing out that the elongation characteristics of steel wire ropes are closely related to their internal structure and twisting process.

[0004] At the laboratory testing level, existing technical solutions have explored new methods for testing the elongation at break of steel cables and wire ropes. These methods indicate that elongation at break testing requires specialized fixtures, a large-range extensometer, and precise strain rate control to obtain reliable mechanical property data. However, this research also shows that current laboratory testing primarily targets factory inspections or incoming re-inspections of new ropes, failing to track elongation changes during actual service. This suggests that while manufacturers possess elongation testing capabilities, they lack effective tracking of long-term product usage data, making it difficult to optimize design and processes based on feedback from real-world operating conditions.

[0005] Elevator manufacturers focus on the compatibility between the wire rope and the elevator system, such as setting the counterweight buffer distance and calculating the traction capacity, to ensure the safety performance of the entire elevator when it leaves the factory. Engineering practice shows that the natural elongation of the wire rope directly affects the counterweight buffer distance and leveling accuracy: taking a 15-story passenger elevator as an example, the wire rope length is about 100m in a 2:1 suspension mode, and the elongation can reach 500mm based on a 0.5% elongation, while the buffer distance of a hydraulic buffer is usually only 200~350mm. Excessive elongation may lead to an insufficient counterweight buffer distance or even counterweight bottoming out.

[0006] Regarding the prediction of wire rope fatigue life, existing technologies have explored using artificial neural networks to predict the bending fatigue life of wire ropes. These studies indicate that wire ropes in applications such as elevators and cranes frequently undergo alternating bending motions, leading to accumulated fatigue damage and performance degradation. Early prediction of lifespan can help prevent catastrophic accidents. However, such prediction models are currently mostly in the academic research stage and have not yet been widely applied to the design verification process in elevator manufacturing. This makes it difficult to fully assess the long-term risks associated with wire rope aging during the design phase.

[0007] Elevator maintenance companies are responsible for the daily inspection and maintenance of wire ropes, but currently this mainly relies on periodic manual inspections. Practical standards for the inspection and scrapping of wire ropes for lifting machinery specify indicators such as the number of broken wires, the reduction in diameter (scrapping when the nominal diameter decreases by 7%), and the amount of wear (scrapping when the outer wire wear reaches 40% of the diameter), but inspection is still primarily carried out manually by visual inspection and caliper measurement. Existing technical solutions also disclose the use of laser rangefinders to achieve non-contact dynamic measurement of wire rope elongation, providing a new approach to monitoring elongation deformation under impact loads. Existing technical solutions further investigate methods for detecting the thermoelastic effect of wire ropes using infrared thermal imagers, exploring the feasibility of indirectly reflecting load changes through temperature variations. However, these advanced detection technologies have not yet been widely adopted in the elevator maintenance field.

[0008] Regarding innovation in detection methods, existing technologies disclose a patented technology for detecting elevator rope degradation. This technology utilizes the changes in torque current and rope length before and after load changes in the elevator car during stops to estimate the elongation per unit length of rope under a unit tensile force, thus achieving low-cost and accurate degradation detection. While this method provides a technical path for real-time monitoring, it remains in the patent stage and has not yet become a mature product or industry standard.

[0009] In summary, research on wire rope elongation exhibits a fragmented approach: manufacturers focus on new rope performance testing under laboratory conditions; academia concentrates on fatigue life prediction models and dynamic elongation mechanisms; engineering professionals focus on specific issues such as buffer distance deviations caused by elongation and emergency response; and maintenance units still rely primarily on manual inspection, resulting in scattered and discontinuous data. A systematic study of the performance changes throughout the entire life cycle of wire ropes is lacking, and fundamental data is insufficient to provide a scientific basis for early warning and maintenance.

[0010] Furthermore, existing technologies generally suffer from data fragmentation across manufacturing, design, and usage stages: wire rope manufacturers lack feedback on usage data throughout the product's service life, making it difficult to optimize design and processes based on actual working conditions; elevator manufacturers lack accurate predictions of long-term performance changes in wire ropes during design and selection, resulting in blind spots in system compatibility design; maintenance units can only obtain scattered on-site testing data, failing to achieve cross-stage data sharing and systematic analysis, leading to a lack of performance tracking and systematic research throughout the entire lifecycle of wire ropes.

[0011] Therefore, there is an urgent need to establish a system that can monitor the elongation rate of elevator wire ropes in real time and accurately, integrate data resources from manufacturing, design, and use, and achieve cross-stage data sharing and remote monitoring, thereby improving the safety and reliability of elevator operation. Summary of the Invention

[0012] Currently, elevator wire rope elongation detection mainly relies on periodic manual inspections, which suffers from several drawbacks: long inspection cycles, making it impossible to monitor wire rope condition changes in real time; low accuracy of manual inspections, easily affected by subjective factors such as maintenance personnel experience, tools, and operating environment; fragmented and discontinuous inspection data, making it difficult to form effective trend analysis and lifespan prediction; and a lack of remote monitoring and intelligent early warning methods, making it difficult to detect and address safety hazards in a timely manner. To address these problems, this invention aims to provide an online monitoring system based on elevator wire rope elongation rate. This system enables real-time, continuous, and high-precision measurement of wire rope elongation and integrates information from manufacturing, design, and usage stages through a data platform, achieving cross-stage data sharing and remote monitoring. This system can assess the safety status of the wire rope in real time and provide tiered early warnings, providing reliable data for manufacturers to optimize product design, elevator manufacturers to accurately select and verify models, and maintenance units to scientifically formulate maintenance plans and conduct on-demand elevator maintenance, thereby comprehensively improving the safety and reliability of elevator operation.

[0013] To achieve the above objectives, the present invention provides the following solution: An online monitoring system based on the elongation rate of elevator wire ropes includes: The trigger module is used to monitor the relative positional relationship between the counterweight and the buffer in the elevator, and to issue a trigger signal based on the relative positional relationship. The detection module is used to receive the trigger signal and calculate the distance between the counterweight device and the buffer; during the distance calculation process, optical compensation is performed based on the ambient temperature and humidity. The data processing module is used to process the distance values ​​measured multiple times, calculate the elongation rate using the processed distance values, and compare the elongation rate and the current distance value with a multi-level threshold judgment function to obtain the comparison result. The cloud platform is used to issue warnings when the elongation or buffer distance is abnormal in the comparison results, and to plot the time-elongation and frequency-elongation curves.

[0014] Optionally, calculating the distance between the counterweight and the buffer includes: ; in, This is the distance between the counterweight and the buffer after optical compensation. The distance between the counterweight and the buffer before optical compensation. For refractive index, The ambient temperature at the time of measurement. The ambient air pressure at the time of measurement The ambient humidity at the time of measurement The refractive index is given at standard atmospheric pressure.

[0015] Optionally, the refractive index includes: ; in, This is the water vapor pressure measured at the time.

[0016] Optionally, the data processing module includes: The data processing unit is used to filter the distance values ​​measured multiple times to obtain a distance sequence; The data judgment unit is used to calculate the elongation rate using the current distance value of the distance sequence, and compare the elongation rate and the current distance value with a multi-level threshold judgment function to obtain the comparison result.

[0017] Optionally, calculating the elongation includes: ; in, Elongation The distance between the counterweight and the buffer was measured at the initial installation stage. This is the currently measured distance between the counterweight and the buffer. This refers to the wire rope ratio. To increase the height of the elevator.

[0018] Optionally, the multi-level threshold determination function includes: ; in, This is a multi-level threshold determination function. Elongation For the safety determination of the buffer distance, To pay attention to the threshold, For warning thresholds, This is the alarm threshold.

[0019] Optionally, the buffer distance safety determination includes: ; in, The rated speed of the elevator, It is the acceleration due to gravity. For safety margin.

[0020] Optionally, plotting the time-elongation curve includes: ; ; in, For the first Elongation after treatment Let elongation be a function of the rate of change. For time variables, Elongation It is a time constant. For the first Elongation after treatment For the first Elongation after treatment For the first Secondary original elongation. For the first Secondary original elongation. For the first Next and first The time interval between times For monitoring duration.

[0021] Optionally, plotting the frequency-elongation variation curve includes: ; in, The frequency-elongation curve is shown. To accumulate the number of runs, , , For fitting parameters, This represents the initial elongation.

[0022] The beneficial effects of this invention are as follows: High real-time performance: This invention triggers data acquisition every time the counterweight approaches the buffer, achieving continuous monitoring throughout the entire cycle, timely detection of changes in wire rope elongation, and elimination of detection blind spots.

[0023] Accurate data: This invention uses high-precision laser ranging and temperature and humidity environmental compensation to reduce measurement errors, and the elongation calculation accuracy can reach the millimeter level; automatic counting avoids errors from manual recording.

[0024] Intelligent early warning: This invention uses trend curves generated in the cloud and set multi-level thresholds to detect potential safety hazards (such as sudden changes in elongation rate) in advance, enabling predictive maintenance.

[0025] Remote monitoring: This invention supports real-time viewing via mobile phone and computer, facilitating centralized management of multiple elevators by maintenance units, reducing the frequency of on-site inspections, and improving work efficiency.

[0026] Data accumulation: This invention provides steel wire rope manufacturers with real service data to help optimize products; it provides elevator design units with long-term performance data to guide selection and design verification; and it provides basic data support for maintenance units to scientifically formulate replacement cycles. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the overall structure of an online monitoring system based on the elongation rate of elevator wire rope according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the workflow of an online monitoring system based on the elongation rate of elevator wire ropes, according to an embodiment of the present invention. Figure 3 This is a partial enlarged view of the installation location of the triggering and detection module in an embodiment of the present invention. Detailed Implementation

[0029] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1-2As shown, this embodiment discloses an online monitoring system based on the elongation rate of elevator wire ropes, including: a trigger module for monitoring the relative positional relationship between the counterweight device and the buffer in the elevator, and issuing a trigger signal based on the relative positional relationship; a detection module for receiving the trigger signal and calculating the distance between the counterweight device and the buffer; optical compensation is performed during the distance calculation process using ambient temperature and humidity; a data processing module for processing the distance values ​​measured multiple times, calculating the elongation rate using the processed distance values, comparing the elongation rate and the current distance value with a multi-level threshold judgment function to obtain the comparison result; and a cloud platform for issuing an early warning when the elongation rate or buffer distance is abnormal in the comparison result, and plotting the time-elongation rate and frequency-elongation rate change curves.

[0032] Specifically, this embodiment discloses an online monitoring system based on the elongation rate of elevator wire ropes, including: like Figure 3 As shown, the trigger module is the "sensory nerve ending" of the entire monitoring system, undertaking the crucial functions of system startup control and measurement timing synchronization. This module employs non-contact magnetic induction technology and is installed near the elevator counterweight buffer to monitor the relative positional relationship between the counterweight and the buffer in real time. When the elevator reaches the bottom terminal station and the counterweight approaches the buffer to a set distance, the module immediately generates a trigger signal, waking up the detection module which is in low-power standby mode and initiating the complete distance measurement, environmental parameter acquisition, and data processing process.

[0033] When the counterweight approaches the counterweight buffer, the trigger module detects a trigger signal, and its trigger threshold is determined according to the following formula. Based on the calculated magnetic flux density threshold of the magnetic sensor, the specifications of the permanent magnet (sintered NdFeB) and the installation position of the trigger module are selected. Magnetic flux density calculation: ; Where B is the magnetic flux density (T); H / m is the free permeability; m is the magnetic moment (A·m). 2 ); Distance (m); The angle between the magnetic moment and the line connecting the measurement point.

[0034] Trigger threshold determination function: ; =1 indicates that the trigger signal is valid, that is, the counterweight has been detected to be close to the buffer to the set position, and the system starts the subsequent measurement; =0 indicates that the trigger signal is invalid, meaning that the counterweight has not reached the trigger position, and the system remains in standby or reset state.

[0035] Trigger distance estimation: ; in, For trigger signal state, To enable the threshold, To close the threshold, As a reference magnetic field, Hysteresis (hysteresis width) The trigger distance is the straight-line distance from the surface of the permanent magnet to the sensing surface of the sensor.

[0036] The detection module is the "sensory center" of the entire monitoring system, undertaking three core functions: high-precision geometric measurement, environmental parameter sensing, and operational status recording. Specifically, it includes: a Time-of-Flight (TOF) laser sensor for measuring the distance between the counterweight and the buffer; a temperature and humidity sensor to collect ambient temperature and humidity data to compensate for errors caused by changes in air refractive index in laser ranging; and a counting unit to record the cumulative number of triggering cycles. The measurement light uses the 940nm near-infrared band, balancing the high quantum efficiency of the silicon detector with its invisibility to the naked eye (for safety). This module responds to the triggering module's activation signal, completing the precise measurement of the distance between the counterweight and the buffer in an extremely short time (less than 30ms). The measured value is obtained according to the formula: ; in, For measuring distance; , where is the speed of light in vacuum; Δt is the round-trip flight time of the laser (s).

[0037] Since the time of flight of light is affected by ambient temperature, humidity, and air pressure, optical compensation is required for the measured values, determined according to Edlén's refractive index equation. The formula is: ; in, The refractive index; The ambient temperature at the time of measurement; Ambient air pressure during measurement; The ambient humidity at the time of measurement; The water vapor pressure at the time of measurement is determined by the formula: ; in, Let be the saturated water vapor pressure, a function of temperature, obtained using the Magnus-Tetens formula. The formula is: ; After light compensation, the final measurement value is: ; in, , is the refractive index under standard atmospheric pressure (15℃, 0.101325MPa, dry air).

[0038] During the measurement process, the cumulative number of triggers is recorded simultaneously to provide data support for lifetime prediction.

[0039] Data processing module: Receives data from the detection module, filters the distance values ​​collected multiple times to suppress impulse noise, and improves the stability of elongation calculation. ; After compensating for environmental parameters, the elongation rate of the wire rope is calculated based on the initial installation distance, and it is determined whether it exceeds the preset threshold.

[0040] ; If the distance between the counterweight and the buffer (reference value) is measured at the initial installation stage. (mm), the currently measured distance between the counterweight and the buffer. (mm), elevator lifting height (m), wire rope ratio (winding ratio) The elongation of the wire rope is as follows: ; The formula for calculating elongation is: ; The denominator is multiplied by 2 because the length of the counterweight side wire rope changes to half that of the car side (the counterweight stroke is 1 / 2 of the car stroke). Cumulative elongation provides support for assessing the overall aging and damage level of wire ropes, and offers a scientific basis for decisions on on-demand maintenance and replacement. ; in: Elastic elongation (recoverable); Plastic elongation (permanent).

[0041] Threshold determination and hierarchical early warning: Multi-level threshold determination function: Set the threshold parameter: Note the threshold. =0.5%: When the cumulative elongation of the wire rope reaches 0.5%, the system issues a "caution" warning, prompting maintenance personnel to pay attention to the elongation trend of the wire rope and strengthen daily inspections.

[0042] Warning threshold =1.0%: When the cumulative elongation reaches 1.0%, the system issues a "warning" warning, recommending that the maintenance unit arrange professional testing, assess the condition of the wire rope, and plan subsequent maintenance.

[0043] alarm threshold =1.5%: When the cumulative elongation rate reaches 1.5%, the system issues an "alarm" warning, indicating that the wire rope has significantly elongated and poses a safety hazard. The elevator must be stopped immediately for inspection or the wire rope must be replaced.

[0044] ; Buffer distance safety determination: ; in Elevator rated speed (m / s) Gravitational acceleration Safety margin.

[0045] Storage module: This module is responsible for temporarily storing measurement data, managing historical records, and supporting breakpoint resume. Located between the detection module and the data transmission module, it acts as a buffer node for data flow, ensuring that critical measurement data is not lost in the event of network interruptions, power fluctuations, or system anomalies, and is fully uploaded to the cloud platform after communication is restored. This invention uses the W25Q128, which has a storage capacity of 16Mbytes.

[0046] Data Transmission Module: The data transmission module serves as the "communication bridge" of the monitoring system, undertaking four core functions: edge data uploading to the cloud, remote command reception, device status synchronization, and network anomaly recovery. This module transmits data to the cloud platform via a wireless communication network (supporting 4G / 5G, Wi-Fi, or NB-IoT), using MQTT (Message Queuing Telemetry Transport) as the core communication protocol. It achieves efficient, reliable, and low-power data interaction with the cloud platform based on a publish / subscribe model.

[0047] Cloud platform: Establishes a database to store historical data, i.e., records of each trigger: trigger timestamp, cumulative number of triggers (frequency), distance between counterweight and buffer after filtering and compensation, temperature and humidity values; calculates derived values: instantaneous elongation rate, cumulative elongation rate (relative to the initial installation value), buffer distance (i.e., the measured distance value); elevator basic information: elevator unique identifier, wire rope model and parameters, installation date, initial installation distance. Buffer distance safety threshold Warning records include: the warning level (normal / attention / warning / alarm), trigger time, and processing status (processed / unprocessed) for each trigger. This data is stored chronologically, supporting long-term tracking and trend analysis, and generating "time-elongation rate" and "frequency-elongation rate" curves.

[0048] The system issues warnings when elongation or buffer distance is abnormal, issuing different levels of warnings according to rules. After each data acquisition and processing, the cloud platform analyzes the cumulative elongation. Perform multi-level logical judgments based on the current buffer distance: <0.5%, normal, no warning; 0.5% ≤ <1.0%, Note: Significant elongation of the wire rope is observed; close monitoring is recommended. 1.0% ≤ <1.5%, Warning: Elongation exceeds the normal range; professional testing should be arranged. If the elongation is ≥1.5%, an alarm is triggered indicating severely excessive elongation, requiring immediate elevator shutdown for inspection or replacement of the wire rope. The platform can also store basic elevator information, wire rope model, and installation date, and use historical data to predict the remaining lifespan of the wire rope.

[0049] Time-elongation curve: ; ; Frequency-elongation curve ( - curve): ; in: This represents the cumulative number of runs. , , The fitting parameters are determined using the least squares method. Initial elongation.

[0050] Data viewing terminals include mobile apps, WeChat mini programs, or web pages, supporting real-time data display, historical curve queries, and receiving tiered early warning information (such as alerts, warnings, and alarms), and can be linked with the maintenance task dispatch system.

[0051] System working principle: When the elevator counterweight approaches the buffer, the magnetic sensor triggers the system to start; the laser sensor starts measuring distance and records the ambient temperature, humidity and number of triggers; the data is processed locally (filtering, compensation, elongation calculation) and then packaged and uploaded to the cloud; the cloud platform performs data analysis and curve plotting, and if the elongation exceeds the standard or the buffer distance is abnormal, the system issues an alarm through the terminal.

[0052] Alternative solutions: The triggering module can employ a photoelectric sensor (triggered by the light shield on the counterweight) or a mechanical contact switch (a micro switch for counterweight collision). Data transmission can utilize Wi-Fi (suitable for scenarios with good network coverage) or NB-IoT (suitable for shafts without 4G / 5G signals). Data processing can be entirely completed in the cloud, with the local system only responsible for collecting and transmitting raw data, simplifying on-site hardware. In the event of a communication interruption, the system can activate a local audible and visual alarm module, issuing an alarm on-site based on the judgment result of the data processing module.

[0053] (1) Multi-module collaborative automated monitoring system architecture: This embodiment proposes for the first time a wire rope elongation monitoring system that integrates a trigger module, detection module, data processing module, storage module, data sending module, cloud platform and data viewing terminal, realizing full-process automation from sensing, processing, transmission to early warning.

[0054] (2) Low-power wake-up mechanism based on magnetic induction trigger: This embodiment adopts non-contact magnetic induction technology, which is installed near the counterweight buffer to realize automatic wake-up and measurement start when the counterweight approaches the buffer, thereby reducing system power consumption and improving system response efficiency.

[0055] (3) Fusion of high-precision laser ranging and environmental parameter compensation: This embodiment combines time-of-flight laser sensor + temperature and humidity sensor + air pressure compensation algorithm (Edlén equation) to achieve distance measurement with millimeter-level accuracy and eliminate the influence of environmental factors on the measurement results.

[0056] (4) Multi-level threshold determination and graded early warning mechanism for elongation rate: In this embodiment, three levels of thresholds are set: attention (0.5%), warning (1.0%), and alarm (1.5%). Combined with the buffer distance safety determination formula, graded early warning and safety status assessment are realized.

[0057] (5) The cloud platform generates “time-elongation” and “frequency-elongation” hyperbolas: In this embodiment, the ε-t curve and ε-N curve are constructed through the cloud database to realize the visualization analysis of the elongation trend of the wire rope and the prediction of its remaining life.

[0058] (6) Data sharing and closed-loop feedback mechanism across links: This embodiment not only serves the maintenance unit, but also feeds the data back to the manufacturing and design units, forming a data closed loop of "design-manufacturing-use-optimization" to support product optimization and design verification.

[0059] (7) Multi-terminal collaboration and maintenance task linkage: This embodiment supports real-time viewing and early warning reception via mobile APP, WeChat mini program and web page, and can be linked with the maintenance task dispatch system to realize intelligent and on-demand maintenance.

[0060] (8) Dual protection of breakpoint resume and local alarm: The data transmission module of this embodiment has the function of breakpoint resume. When communication is interrupted, the local sound and light alarm module can be activated to ensure that the system still has basic early warning capabilities in abnormal situations.

[0061] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An online monitoring system based on the elongation rate of elevator wire ropes, characterized in that, include: The trigger module is used to monitor the relative positional relationship between the counterweight and the buffer in the elevator, and to issue a trigger signal based on the relative positional relationship. The detection module is used to receive the trigger signal and calculate the distance between the counterweight device and the buffer; During the distance calculation process, optical compensation is performed using ambient temperature and humidity. The data processing module is used to process the distance values ​​measured multiple times, calculate the elongation rate using the processed distance values, and compare the elongation rate and the current distance value with a multi-level threshold judgment function to obtain the comparison result. The cloud platform is used to issue warnings when the elongation or buffer distance is abnormal in the comparison results, and to plot the time-elongation and frequency-elongation curves.

2. The online monitoring system based on elevator wire rope elongation according to claim 1, characterized in that, Calculating the distance between the counterweight and the buffer includes: ； in, This is the distance between the counterweight and the buffer after optical compensation. The distance between the counterweight and the buffer before optical compensation. For refractive index, The ambient temperature at the time of measurement. The ambient air pressure at the time of measurement The ambient humidity at the time of measurement The refractive index is given at standard atmospheric pressure.

3. The online monitoring system based on elevator wire rope elongation according to claim 2, characterized in that, The refractive index includes: ； in, This is the water vapor pressure measured at the time.

4. The online monitoring system based on elevator wire rope elongation according to claim 1, characterized in that, The data processing module includes: The data processing unit is used to filter the distance values ​​measured multiple times to obtain a distance sequence; The data judgment unit is used to calculate the elongation rate using the current distance value of the distance sequence, and compare the elongation rate and the current distance value with a multi-level threshold judgment function to obtain the comparison result.

5. The online monitoring system based on elevator wire rope elongation according to claim 4, characterized in that, Calculating the elongation includes: ； in, Elongation The distance between the counterweight and the buffer was measured at the initial installation stage. This is the currently measured distance between the counterweight and the buffer. This refers to the wire rope ratio. To increase the height of the elevator.

6. The online monitoring system based on elevator wire rope elongation according to claim 4, characterized in that, The multi-level threshold determination function includes: ； in, This is a multi-level threshold determination function. Elongation For the safety determination of the buffer distance, To pay attention to the threshold, For warning thresholds, This is the alarm threshold.

7. The online monitoring system based on elevator wire rope elongation according to claim 6, characterized in that, The buffer distance safety determination includes: ； in, The rated speed of the elevator, It is the acceleration due to gravity. For safety margin.

8. The online monitoring system based on elevator wire rope elongation according to claim 1, characterized in that, Plotting the time-elongation curve includes: ； ； in, For the first Elongation after treatment Let elongation be a function of the rate of change. For time variables, Elongation It is a time constant. For the first Elongation after treatment For the first Elongation after treatment For the first Secondary original elongation. For the first Secondary original elongation. For the first Next and first The time interval between times For monitoring duration.

9. The online monitoring system based on the elongation rate of elevator wire rope according to claim 1, characterized in that, Plotting the frequency-elongation variation curve includes: ； in, The frequency-elongation curve is shown. To accumulate the number of runs, , , For the fitting parameters, This represents the initial elongation.

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