A dynamic mechanical detection load adaptive control method for an ergonomic chair

Abstract

The present application relates to the technical field of ergonomic chair detection, and discloses a dynamic mechanical detection load adaptive control method for ergonomic chairs, comprising the following steps: S1, placing the ergonomic chair to be detected on a dynamic mechanical detection platform, applying dynamic load to the chair back through a loading device, and obtaining the rebound characteristic parameters of the equivalent human body waist and back stress working condition or load bearing working condition; S2, pasting a capacitance sensor on the ergonomic chair, applying dynamic load to the chair seat through the loading device, and obtaining the deformation characteristic parameters of the equivalent human body hip stress working condition or load bearing working condition; S3, judging the dynamic mechanical state and the hardness change characteristic of the seat surface and the chair back according to the collected rebound characteristic parameters and deformation characteristic parameters, and generating an adaptive control instruction to control the loading device to adjust the load amplitude, frequency and holding time of the next detection cycle, so as to realize real-time load adaptive adjustment; and S4, when the adaptive control is unavailable or the detection data is abnormal, using a phased update of the loading parameters as a bottom line to complete the dynamic mechanical detection related to human ergonomics of the ergonomic chair.

Description

Technical Field

[0001] This invention relates to the field of ergonomic chair testing technology, and in particular discloses an adaptive control method for dynamic mechanical testing load of ergonomic chairs. Background Technology

[0002] With the increasing number of people working in offices and sitting for long periods, ergonomic chairs, as important pieces of furniture for improving posture and reducing the load on the lower back and hips, are receiving increasing attention for their ergonomic performance. During use, ergonomic chairs need to provide adequate support and cushioning for the lower back and hips; the dynamic mechanical properties of the backrest and seat directly affect user comfort and long-term health benefits.

[0003] Existing testing methods for ergonomic chairs mainly focus on static load testing or unidirectional mechanical performance testing. For example, by applying a constant load or displacement, the deformation, rebound, or stiffness parameters of the chair back or seat are measured. These testing methods can reflect the load-bearing capacity of ergonomic chairs to a certain extent, but they are difficult to simulate the dynamic load changes generated by the human body during actual use, such as the periodic force changes caused by the human body's movements of sitting down, standing up, leaning forward, and leaning back.

[0004] Furthermore, while some existing testing methods incorporate dynamic loading, they typically employ preset fixed loading parameters, such as fixed loading displacement, frequency, or holding time, lacking the ability to adjust the loading conditions in real time based on the test results. When the ergonomic chair being tested exhibits significant differences in material properties, structural form, or hardness, fixed-parameter loading methods are prone to problems such as distorted test results, localized overload, or low testing efficiency, making it difficult to comprehensively and accurately reflect the true mechanical response of the ergonomic chair under equivalent human working conditions.

[0005] Based on the above problems, it is necessary to propose a dynamic mechanical testing method for ergonomic chairs that can simultaneously combine the dynamic rebound characteristics of the chair back and the dynamic deformation characteristics of the seat, and has the ability to adaptively adjust the load, so as to more realistically simulate the ergonomic use conditions and improve the accuracy, stability and applicability of the test results. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a dynamic mechanical testing method for ergonomic chairs that can simultaneously combine the dynamic rebound characteristics of the chair back and the dynamic deformation characteristics of the seat surface, and has the ability to adaptively adjust the load.

[0007] To achieve the above objectives, the present invention provides an adaptive control method for dynamic mechanical testing load of an ergonomic chair, comprising the following steps: S1, placing the ergonomic chair to be tested on a dynamic mechanical testing platform, applying a dynamic load to the chair back using a loading device, and collecting loading force, loading displacement, and corresponding time data during loading and unloading to form a force-displacement-time curve, thereby obtaining the rebound characteristic parameters of the equivalent human lumbar and back stress condition or load-bearing condition; S2, attaching a capacitive sensor to the ergonomic chair, applying a dynamic load to the chair seat using a loading device, and simultaneously collecting loading force, chair seat deformation response signal, and loading load during loading. S3. Based on the collected rebound and deformation parameters, determine the dynamic mechanical state and stiffness variation characteristics of the seat and backrest, and generate adaptive control commands to control the loading device to adjust the load amplitude, frequency and holding time of the next detection cycle, so as to realize real-time adaptive load adjustment; S4. When the adaptive control is unavailable or the detection data is abnormal, the loading parameters are updated in stages as a backup to complete the ergonomic dynamic mechanical detection of the ergonomic chair.

[0008] Furthermore, the loading device applies controlled displacement loading to the chair back along the normal direction of the chair back. The drive end of the loading device is equipped with a displacement sensor to measure the loading displacement Δx. A force sensor is installed between the loading device and the chair back to synchronously collect the loading force F and corresponding time data during the loading and unloading process, forming a force-displacement-time curve.

[0009] Furthermore, the rebound characteristic parameters include rebound displacement Δxr and rebound efficiency coefficient. The rebound time Tr, the rebound displacement Δxr (the difference between the displacement of the chair back at the stable position after unloading and the loading displacement Δx), and the rebound efficiency coefficient are also mentioned. The ratio of the rebound displacement Δxr to the loading displacement Δx is used to characterize the support and rebound capacity of the chair back under the equivalent human lumbar and back stress conditions. The rebound time Tr is the time interval between the start of unloading and the moment when the rate of change of the chair back displacement is lower than the preset threshold.

[0010] Furthermore, the adaptive control includes: when the rebound efficiency coefficient... When the load displacement Δx is below a preset threshold, reduce the load displacement Δx in the next detection cycle; when the rebound efficiency coefficient... If the value exceeds the preset threshold, increase the loading displacement Δx in the next detection cycle.

[0011] Furthermore, step S2 specifically includes: S21, attaching a flexible capacitive sensor to the seat surface of the ergonomic chair; S22, applying a downward force to the flexible capacitive sensor on the seat surface at a speed V, loading it to a preset loading force, the flexible capacitive sensor detects the capacitance change dc, and obtains a force-capacitance-speed curve; S23, calculating the stiffness factor Hz of the ergonomic chair.

[0012] Furthermore, the dynamic mechanical testing platform includes a frame, a loading device mounted on the frame, and a control unit. The loading device is electrically connected to the control unit. The loading device includes a rebound detection unit and a deformation detection unit. The rebound detection unit is used to detect the rebound characteristics of the ergonomic chair back, and the deformation detection unit is used to detect the softness and hardness of the chair seat.

[0013] Furthermore, the rebound detection unit includes a base, a support frame slidably connected to the base, a first pressure plate and a second pressure plate disposed on the support frame, a lifting assembly on the base, the output end of the lifting assembly being connected to the support frame, the lifting assembly driving the support frame to rise and fall relative to the base, adjusting the height of the first pressure plate and the second pressure plate pressing the chair back to adapt to different models of ergonomic chairs, and a first cylinder and a second cylinder disposed on the support frame, the output shaft of the first cylinder and the output shaft of the second cylinder being connected to the first pressure plate and the second pressure plate respectively.

[0014] Furthermore, the second cylinder is connected to the support frame via a transmission assembly. The transmission assembly includes a displacement motor mounted on the support frame, a screw connected to the output shaft of the displacement motor, and a support plate threadedly connected to the screw. The support plate is slidably connected to the support frame. The displacement motor drives the support plate to slide relative to the support frame, adjusting the pressing height of the second pressure plate. The first pressure plate is shaped to mimic the back of a human body, and the second pressure plate is shaped to mimic the head of a human body.

[0015] Furthermore, the first pressure plate and the second pressure plate are respectively provided with a first pressure sensor for detecting the loading force of the first pressure plate and the second pressure plate, and the support frame is provided with a displacement sensor for detecting the loading displacement of the first pressure plate and the second pressure plate.

[0016] Furthermore, the deformation detection unit includes a third cylinder, a crossbeam slidably connected to the frame, a side detection assembly mounted on the crossbeam, and a third pressure plate. The third cylinder is mounted on the frame, and its output end is connected to the crossbeam. The third pressure plate is slidably connected to the crossbeam. Two sets of side detection assemblies are provided, located at both ends of the crossbeam. Each side detection assembly includes a fourth cylinder and a pressure head connected to the output end of the fourth cylinder. The pressure head is used to press the side of the ergonomic chair. The third pressure plate mimics the shape of a human buttock. The third pressure plate and the pressure head are equipped with second pressure sensors for detecting the loading force of the third pressure plate and the pressure head. The chair seat is equipped with a capacitive sensor for detecting the deformation of the chair seat. The frame is equipped with a speed sensor for detecting the pressing speed of the third pressure plate and the pressure head.

[0017] The beneficial effects of this invention are as follows: By acquiring the rebound characteristic parameters and deformation characteristic parameters of the chair back, the chair back and seat are tested on the same dynamic mechanical testing platform, so that the rebound response of the chair back and the deformation response of the seat are analyzed under the same dynamic loading conditions; compared with the existing technology where the chair back test and the seat hardness test are independent, this invention can form a unified ergonomic dynamic mechanical evaluation system, improving the consistency and comparability of the test results; The invention calculates the rebound displacement Δxr and rebound efficiency coefficient by collecting force-displacement-time curves during loading and unloading processes. The rebound time Tr characterizes the dynamic response of the chair back under equivalent human lumbar and back stress conditions from multiple dimensions; the rebound displacement Δxr characterizes the elastic recovery capability of the structure, and the rebound efficiency coefficient... The rebound time Tr is used to characterize the proportion of effective rebound in the loaded displacement, and to characterize the dynamic response rhythm and damping characteristics of the structure. By combining multiple parameters to judge the dynamic mechanical state, compared with the method of evaluating only a single deformation amount or stiffness value, it can more comprehensively and accurately reflect the dynamic support performance of the ergonomic chair. Adaptive control commands are generated based on the rebound and deformation characteristics parameters to adjust the loading displacement Δx, loading frequency, and holding time of the next detection cycle in real time. This allows the loading conditions to be dynamically adjusted according to the actual mechanical response of the ergonomic chair being tested. Compared with detection methods with fixed loading parameters, this invention can avoid overload or underload problems, improve detection efficiency and safety, and enhance the compatibility between different models of ergonomic chairs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the dynamic mechanical testing platform of the present invention; Figure 2 This is a schematic diagram of the rebound detection unit of the present invention; Figure 3 This is a schematic diagram of the deformation detection unit of the present invention; Figure 4 for Figure 3 A magnified view of part A in the diagram.

[0019] The reference numerals in the figures include: 1. Frame; 2. Loading device; 3. Control unit; 4. Springback detection unit; 5. Deformation detection unit; 6. Base; 7. Support frame; 8. First pressure plate; 9. Second pressure plate; 10. Lifting assembly; 11. Transmission assembly; 12. Displacement motor; 13. Screw; 14. Support plate; 15. Third cylinder; 16. Crossbeam; 17. Side detection assembly; 18. Third pressure plate; 19. Fourth cylinder; 20. Pressure head; 21. First cylinder; 22. Second cylinder. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0021] Please see Figures 1 to 4 As shown, the present invention discloses an adaptive control method for dynamic mechanical testing load of an ergonomic chair, comprising the following steps: S1, placing the ergonomic chair to be tested on a dynamic mechanical testing platform, applying a dynamic load to the chair back using a loading device 2, and collecting loading force, loading displacement, and corresponding time data during loading and unloading to form a force-displacement-time curve, thereby obtaining the rebound characteristic parameters of the equivalent human lumbar and back stress condition or load-bearing condition; S2, attaching a capacitive sensor to the ergonomic chair, applying a dynamic load to the chair seat using the loading device 2, and simultaneously collecting the loading force, chair seat deformation response signal, and loading speed during the loading process. S3. Based on the collected rebound and deformation parameters, determine the dynamic mechanical state and hardness variation characteristics of the seat and backrest, and generate adaptive control commands to control the loading device 2 to adjust the load amplitude, frequency and holding time of the next detection cycle, so as to realize real-time adaptive load adjustment; S4. When the adaptive control is unavailable or the detection data is abnormal, the loading parameters are updated in stages as a backup to complete the ergonomic dynamic mechanical detection of the ergonomic chair.

[0022] The loading device 2 applies controlled displacement loading to the chair back along the normal direction of the chair back. The drive end of the loading device 2 is equipped with a displacement sensor to measure the loading displacement Δx. A force sensor is set between the loading device 2 and the chair back to synchronously collect the loading force F and the corresponding time data during the loading and unloading process, forming a force-displacement-time curve.

[0023] Specifically, the loading device 2 applies controlled displacement loading to the chair back along the normal direction of the chair back. This technical feature clarifies the direction and method by which the loading device 2 applies dynamic load to the ergonomic chair back. This ensures a high degree of consistency between the loading direction and the force direction experienced by the human back during actual use, effectively avoiding measurement distortion caused by deviations in the loading direction, thus more realistically simulating ergonomic stress conditions. For example, this can be achieved using a robotic arm or linear guide system in conjunction with the loading head. The robotic arm controls the movement trajectory of its end effector (loading head) through programming, ensuring it is always perpendicular to the chair back surface for displacement loading. Alternatively, a pneumatic or hydraulic cylinder can be used as the loading device 2. By adjusting the installation angle of the cylinder, the axis of its piston rod is aligned with the normal direction of the chair back. Precise control of the intake / exhaust or oil intake / return volume of the cylinder achieves precise control of the piston rod displacement, thereby achieving controlled displacement loading.

[0024] The driving end of the loading device 2 is equipped with a displacement sensor to measure the loaded displacement Δx. This technical feature clearly defines the installation position of the displacement sensor and its measurement object. This allows for the direct and accurate acquisition of displacement change data applied by the loading device 2, providing a basis for subsequent calculation of rebound characteristic parameters. For example, the displacement sensor can be a linear displacement sensor, such as a draw-wire displacement sensor or an LVDT (linear variable differential transformer), which directly measures the linear displacement of the driving end. Alternatively, a grating ruler or encoder can be used. The grating ruler is directly mounted on the moving part of the driving end and measures the displacement through optical principles; the encoder is usually connected to the rotating shaft of the drive motor and indirectly calculates the linear displacement by measuring the rotation angle.

[0025] A force sensor is installed between the loading device 2 and the chair back, a technical feature that clearly defines the sensor's installation location. This allows for real-time and accurate measurement of the force applied to the chair back by the loading device 2, forming a complete force-displacement relationship when combined with displacement data. For example, the force sensor can be a piezoelectric force sensor or a resistance strain gauge force sensor, which is typically installed at the interface between the loading head of the loading device 2 and the chair back to directly sense the loading force. Alternatively, a multi-axis force sensor can be used, measuring not only normal force but also shear force to more comprehensively reflect the stress on the chair back.

[0026] During loading and unloading, the loading force F and corresponding time data are simultaneously acquired to form a force-displacement-time curve. This technical feature describes the timing and results of data acquisition. This ensures a high degree of synchronization between force, displacement, and time data, enabling accurate analysis of the transient response of the chair back during dynamic loading and unloading, and providing a continuous and consistent data foundation for the precise calculation of rebound characteristic parameters. For example, this can be achieved using a data acquisition card (DAQ card) with dedicated software. The DAQ card has multiple synchronous sampling channels, which can simultaneously connect to displacement and force sensors and perform synchronous data acquisition at a preset sampling frequency. Alternatively, an integrated test and control system can be used. This system typically includes a built-in sensor interface, a high-speed data processor, and a real-time operating system, capable of synchronously triggering sensor data acquisition with microsecond-level or even lower latency.

[0027] Through the above technical solution, the loading device 2 applies controlled displacement loading along the normal direction of the chair back, ensuring a high degree of consistency between the loading direction and the actual force direction of the human back, effectively avoiding measurement distortion caused by deviation in the loading direction. Simultaneously, a displacement sensor is installed at the drive end of the loading device 2, enabling direct and accurate measurement of the loading displacement Δx, eliminating errors that may be introduced by indirect measurement. A force sensor is installed between the loading device 2 and the chair back, realizing direct and real-time measurement of the loading force F. More importantly, the loading force F, loading displacement Δx, and corresponding time data are simultaneously collected during loading and unloading, forming a force-displacement-time curve, ensuring a high degree of synchronization and correlation between force, displacement, and time data. This precise loading method and synchronous data acquisition mechanism significantly improve the accuracy and reliability of the loading force and loading displacement data, thereby enabling more accurate acquisition of the rebound characteristic parameters of the equivalent human back force or load-bearing conditions. This provides a solid data foundation for subsequent judgment of the dynamic mechanical state and softness / hardness changes of the seat surface and chair back, thus improving the accuracy and reliability of the entire dynamic mechanical testing method.

[0028] The rebound characteristic parameters include rebound displacement Δxr, rebound efficiency coefficient η, and rebound time Tr. Rebound displacement Δxr is the difference between the displacement corresponding to the stable position of the chair back after unloading and the loading displacement Δx. Rebound efficiency coefficient η is the ratio of rebound displacement Δxr to loading displacement Δx, which is used to characterize the support and rebound ability of the chair back under equivalent human lumbar and back stress conditions. Rebound time Tr is the time interval between the start of unloading and the moment when the rate of change of chair back displacement is lower than a preset threshold.

[0029] Specifically, rebound characteristic parameters refer to a set of physical quantities used to quantify and describe the ability and efficiency of an ergonomic chair back to recover its original or stable state after being subjected to dynamic loads. These parameters comprehensively reflect the influence of the elasticity, damping, and structural design of the chair back material on the lumbar support and cushioning performance of the human body. Possible implementation methods include, but are not limited to: obtaining them through analysis and calculation of the force-displacement-time curves collected in step S1; or monitoring the dynamic response of the chair back during loading and unloading processes in real time through a dedicated sensor array, and extracting parameters in combination with algorithms.

[0030] The rebound displacement Δxr is a key indicator for measuring the actual degree of recovery of the chair back after unloading. It represents the difference between the final position of the chair back after dynamic loading and subsequent unloading to a stable state and the maximum displacement during loading. This parameter directly reflects the elastic recovery capability of the chair back material and the restoring performance of the structure after dynamic deformation. Possible implementation methods include, but are not limited to: continuously monitoring the position of the chair back after unloading using a displacement sensor until it stabilizes, recording the stable position, and calculating the difference with the loaded displacement Δx; or capturing the motion trajectory of the chair back during unloading using a high-speed camera system and combining it with image processing technology to accurately calculate the stable position.

[0031] The rebound efficiency coefficient η is an important dimensionless parameter characterizing the support and rebound capacity of a chair back under equivalent human lumbar and back stress conditions. It quantifies the energy dissipation and recovery efficiency of the chair back during dynamic loading cycles by measuring the ratio of the rebound displacement Δxr to the loading displacement Δx. A higher rebound efficiency coefficient generally means that the chair back can absorb impact more effectively and recover quickly, providing continuous support for the user. Possible implementation methods include, but are not limited to: directly calculating the coefficient mathematically after obtaining the rebound displacement Δxr and loading displacement Δx; or calculating and displaying the coefficient in real time through a data processing module integrated into the detection system.

[0032] Rebound time (Tr) is a time-dimensional parameter used to evaluate the dynamic response speed and stability of the chair back. It is defined as the time interval from the start of unloading to the moment when the rate of displacement change of the chair back falls below a preset threshold. This parameter reflects the time required for the chair back to recover from a state of stress deformation to a stable state, and is crucial for evaluating the performance of the chair back under rapid, repetitive loading scenarios. Possible implementation methods include, but are not limited to: continuously collecting chair back displacement data through displacement sensors, combining it with timestamps to calculate the rate of displacement change, recording the time point when the rate first falls below the preset threshold, and calculating the difference with the start of unloading; or using signal processing techniques to differentiate the displacement-time curve and identify the time point when the rate of displacement change tends to stabilize.

[0033] The adaptive control includes: when the rebound efficiency coefficient η is lower than a preset threshold, reducing the loading displacement Δx in the next detection cycle; when the rebound efficiency coefficient η is higher than the preset threshold, increasing the loading displacement Δx in the next detection cycle.

[0034] Specifically, the rebound efficiency coefficient η is a key parameter characterizing the support and rebound capacity of a chair back under equivalent human lumbar and back stress conditions. It is quantified by the ratio of the rebound displacement Δxr to the loading displacement Δx, reflecting the energy dissipation and recovery characteristics of the chair back material and structure during dynamic loading-unloading cycles. In practical applications, the rebound efficiency coefficient η can be determined in several ways. For example, its ratio can be directly calculated by real-time monitoring of the loading displacement Δx and the stable rebound displacement Δxr of the chair back after unloading. Alternatively, it can be indirectly evaluated by combining the hysteresis loop area of ​​the force-displacement curve. For instance, the energy loss can be reflected by calculating the ratio of the area enclosed by the unloading curve and the loading curve to the total area under the loading curve, thus inferring the rebound efficiency.

[0035] When the rebound efficiency coefficient η is lower than a preset threshold, it indicates that the backrest's rebound capability is insufficient or its energy dissipation is large, potentially indicating problems such as excessive softness or inadequate support. In this case, reducing the loading displacement Δx in the next detection cycle is to avoid applying excessive stress to the backrest, preventing potential structural damage or material fatigue, while also allowing for more precise detection of its mechanical response within a smaller deformation range. For example, the control unit 3 can reduce the displacement output command of the loading device 2 by a fixed step or a percentage according to a preset adjustment strategy. Alternatively, based on the deviation of η from the threshold, a proportional or PID control algorithm can be used to dynamically calculate the reduction in loading displacement Δx, achieving smoother and more precise adjustment.

[0036] When the rebound efficiency coefficient η is higher than the preset threshold, it indicates that the chair back has a strong rebound capability, which may indicate that it is too stiff or provides too much support, or that the current loading displacement Δx has not fully stimulated its dynamic mechanical performance. In this case, increasing the loading displacement Δx in the next testing cycle aims to more comprehensively evaluate the support and rebound characteristics of the chair back within a larger deformation range, ensuring that the test results fully reflect its true performance under equivalent human working conditions. For example, the control unit 3 can increase the displacement output command of the loading device 2 by a fixed step or a percentage according to a preset adjustment strategy. Alternatively, based on the deviation of η from the threshold, a proportional or PID control algorithm can be used to dynamically calculate the increase in loading displacement Δx to achieve a more ideal testing condition.

[0037] In some embodiments of this application, step S2 is proposed to obtain the deformation characteristic parameters of the ergonomic chair seat surface. However, in this process, due to the lack of specific implementation details, such as how to attach the sensor, how to apply the dynamic load, and how to calculate the softness and hardness factor, the detection results may be inaccurate or unable to effectively reflect the deformation response characteristics during the dynamic loading process, thereby affecting the comprehensive analysis of the equivalent human buttock stress condition.

[0038] In this regard, this application further proposes that step S2 specifically includes: S21, attaching a flexible capacitive sensor to the seat surface of the ergonomic chair; S22, applying a downward force to the flexible capacitive sensor on the seat surface at a speed V, loading to a preset loading force, the flexible capacitive sensor detects the capacitance change dc, and obtains a force-capacitance-speed curve; S23, calculating the stiffness factor Hz of the ergonomic chair.

[0039] Specifically, in step S21, a flexible capacitive sensor is attached to the seat surface of the ergonomic chair. This flexible capacitive sensor is designed to accurately capture minute deformations of the seat surface during stress. Its implementation can be, but is not limited to: one method is to use a capacitive thin-film sensor with high flexibility and extensibility, directly attached to the seat surface using a special adhesive, allowing it to closely conform to the seat surface curve and generate capacitance changes with seat surface deformation; another method is to integrate a flexible capacitive sensor array into a thin fabric or polymer substrate, and then lay or embed this integrated layer under the surface material of the ergonomic chair seat to achieve deformation monitoring of a larger area or a finer region of the seat surface.

[0040] In step S22, a downward force is applied to the flexible capacitive sensor on the seat surface at a speed V, loading to a preset loading force. The flexible capacitive sensor detects the capacitance change dc, resulting in a force-capacitance-velocity curve. This step aims to simulate the dynamic loading process when a human sits down and simultaneously acquire multi-dimensional data. The force can be applied in two ways: one is by pressing the flexible capacitive sensor on the seat surface downwards at a preset constant or variable speed V using a loading device 2 (e.g., a loading head driven by a servo motor or pneumatic cylinder). The loading head is typically designed to mimic the shape of a human buttock to ensure realistic loading. Another method is to utilize a high-precision robotic arm equipped with a pressure sensor and a loading plate at its end. The robotic arm is programmed to move downwards at a precise speed V until the preset loading force is reached. During the loading process, the flexible capacitive sensor continuously outputs a capacitance change signal dc, while the force sensor on the loading device 2 records the loading force, and the displacement sensor or encoder on the loading device 2 records the loading speed V. All this data is collected synchronously and integrated to form a force-capacitance-velocity curve reflecting the dynamic response of the seat surface.

[0041] In step S23, the stiffness factor (Hz) of the ergonomic chair is calculated. This stiffness factor (Hz) is a key indicator for quantifying the dynamic mechanical properties of the seat surface. Its calculation can be achieved in two ways: First, based on the force-capacitance-velocity curve obtained in step S22, a specific algorithm model can be used. For example, the slope, hysteresis loop area, or energy dissipation characteristics of the curve within a specific loading range can be analyzed, and combined with the loading speed V, the stiffness factor (Hz) can be derived. This factor comprehensively reflects the seat surface's support, cushioning, and resilience. Second, a machine learning-based predictive model can be established. This model learns from a large amount of force-capacitance-velocity curve data of ergonomic chairs with known stiffness levels, thereby automatically calculating and outputting the corresponding stiffness factor (Hz) based on new detection curves.

[0042] Through the above technical solution, this application can solve the problem of inaccurate acquisition of seat deformation characteristic parameters in the prior art. First, a flexible capacitive sensor is attached to the seat surface, directly attached to the detection area, which can sensitively monitor minute deformations, avoid external interference, and provide a reliable source of deformation response signals. Second, a force is applied to a preset loading force at a speed V to simulate the dynamic process of a real human sitting down, while simultaneously detecting the capacitance change dc, forming a force-capacitance-velocity curve. This curve comprehensively reflects the dynamic characteristics of deformation during the loading process by integrating force, capacitance, and velocity, overcoming the limitations of single-parameter detection. Finally, the softness / hardness factor Hz is calculated based on this curve to quantify the softness / hardness level of the seat surface, providing a standardized evaluation basis for subsequent adaptive control and ensuring the consistency and comparability of deformation characteristic parameters. The entire solution, through the close connection between steps, realizes a complete process from data acquisition to parameter calculation, significantly improving the accuracy and practicality of detection, and making the analysis of the equivalent human buttock stress conditions more comprehensive and in-depth.

[0043] In some embodiments of this application, the dynamic mechanical testing platform includes a frame 1, a loading device 2 and a control unit 3 mounted on the frame 1. The loading device 2 is electrically connected to the control unit 3. The loading device 2 includes a rebound detection unit 4 and a deformation detection unit 5. The rebound detection unit 4 is used to detect the rebound characteristics of the ergonomic chair back, and the deformation detection unit 5 is used to detect the softness and hardness of the chair seat.

[0044] Control unit 3 is the brain of the dynamic mechanics testing platform, responsible for coordinating the entire testing process, data processing, and command generation. It receives real-time data from sensors, analyzes it according to preset testing logic and adaptive algorithms, and sends control commands to loading device 2. Control unit 3 can be implemented based on an industrial programmable logic controller (PLC), enabling complex logic control and data acquisition through programming; alternatively, it can employ an industrial computer (IPC)-based control system, utilizing a high-performance processor for real-time data processing and algorithm calculations, and providing a more flexible human-machine interface. The electrical connection between loading device 2 and control unit 3 is fundamental for real-time data and command transmission. This connection ensures that control unit 3 can promptly acquire the operating status and sensor data of loading device 2 and quickly send precise control signals to loading device 2. The electrical connection can be implemented via wired methods, such as using industrial Ethernet, CAN bus, or RS485 communication protocols for data transmission; or via wireless communication modules (such as Wi-Fi or Bluetooth) to improve system flexibility and deployment convenience.

[0045] The rebound detection unit 4 includes a base 6, a support frame 7 slidably connected to the base 6, a first pressure plate 8 and a second pressure plate 9 set on the support frame 7. The base 6 is provided with a lifting assembly 10, the output end of the lifting assembly 10 is connected to the support frame 7, and the lifting assembly 10 drives the support frame 7 to rise and fall relative to the base 6, adjusting the height of the first pressure plate 8 and the second pressure plate 9 pressing the chair back to adapt to different models of ergonomic chairs. The support frame 7 is provided with a first cylinder 21 and a second cylinder 22, the output shaft of the first cylinder 21 and the output shaft of the second cylinder 22 are respectively connected to the first pressure plate 8 and the second pressure plate 9.

[0046] Specifically, the rebound detection unit 4 is part of the loading device 2 of the dynamic mechanical testing platform. Its core function is to simulate the support and rebound effect of the human lower back on the chair back and to accurately collect relevant data. The base 6, as the basic support structure of the rebound detection unit 4, is used to fix the entire detection unit and provide a stable mounting platform. It is typically made of high-strength materials to ensure the stability and rigidity of the structure during dynamic loading. The support frame 7 is a key component that bears the pressure plate and cylinder. It is connected to the base 6 via a sliding mechanism, allowing the support frame 7 to move vertically relative to the base 6. This sliding connection can be achieved using linear guides and sliders, or through rollers and guide grooves, ensuring the stability and positioning accuracy of the support frame 7 during lifting and lowering.

[0047] A lifting assembly 10 is mounted on the base 6, which is the core mechanism for adjusting the vertical height of the support frame 7. This assembly can take various forms; for example, it can be a screw-nut mechanism driven by a motor, rotating the screw to move the nut and the connected support frame 7 up and down; it can also be a hydraulic cylinder or pneumatic cylinder, using fluid pressure to drive a piston rod to raise and lower the support frame 7; or it can be a gear and rack mechanism, with a motor driving the gear to move the rack and support frame 7 up and down. The output end of the lifting assembly 10 is mechanically connected to the support frame 7 to transmit the lifting driving force, ensuring that the movement of the lifting assembly 10 can be directly and accurately converted into the vertical displacement of the support frame 7. The lifting assembly 10 drives the support frame 7 to rise and fall relative to the base 6, allowing the support frame 7 to move vertically upwards or downwards under the guidance of the base 6. This action is the basis for adjusting the height of the pressure plate. By driving the support frame 7 to rise and fall through the lifting component 10, the vertical position of the first pressure plate 8 and the second pressure plate 9 installed on the support frame 7 can be adjusted simultaneously, thereby adjusting the height of the first pressure plate 8 and the second pressure plate 9 pressing the chair back, so that the pressure plate can be accurately aligned with different force areas of the ergonomic chair back, ensuring the accuracy of the loading position, and thus adapting to different models of ergonomic chairs.

[0048] The second cylinder 22 is connected to the support frame 7 via the transmission assembly 11. The transmission assembly 11 includes a displacement motor 12 mounted on the support frame 7, a screw 13 connected to the output shaft of the displacement motor 12, and a support plate 14 threadedly connected to the screw 13. The support plate 14 is slidably connected to the support frame 7. The displacement motor 12 drives the support plate 14 to slide relative to the support frame 7, adjusting the pressing height of the second pressure plate 9. The first pressure plate 8 is shaped to mimic the back of a human body, and the second pressure plate 9 is shaped to mimic the head of a human body.

[0049] The first pressure plate 8 and the second pressure plate 9 are respectively equipped with pressure sensors for detecting the loading force of the first pressure plate 8 and the second pressure plate 9, and the support frame 7 is equipped with displacement sensors for detecting the loading displacement of the first pressure plate 8 and the second pressure plate 9.

[0050] The deformation detection unit 5 includes a third cylinder 15, a crossbeam 16 slidably connected to the frame 1, a side detection component 17 disposed on the crossbeam 16, and a third pressure plate 18. The third cylinder 15 is disposed on the frame 1, and the output end of the third cylinder 15 is connected to the crossbeam 16. The third pressure plate 18 is slidably connected to the crossbeam 16. There are two sets of side detection components 17, which are located at both ends of the crossbeam 16. The side detection component 17 includes a fourth cylinder 19 and a pressure head 20 connected to the output end of the fourth cylinder 19. The pressure head 20 is used to press the side of the ergonomic chair. The third pressure plate 18 imitates the shape of the human buttocks. Pressure sensors for detecting the loading force of the third pressure plate 18 and the pressure head 20 are provided on the third pressure plate 18 and the pressure head 20. A capacitive sensor for detecting the deformation of the chair seat is provided on the seat. A speed sensor for detecting the pressing speed of the third pressure plate 18 and the pressure head 20 is provided on the frame 1.

[0051] The two sets of side detection components 17, located at opposite ends of the crossbeam 16, are designed to enable simultaneous or independent detection of both sides of the ergonomic chair seat. This symmetrical layout more comprehensively simulates the lateral support and pressure exerted on the seat by the sides of the buttocks or outer thighs, avoiding the limitations of single-point detection and thus obtaining more realistic lateral deformation data. The two sets of side detection components 17 can employ independent drive and sensing systems for their respective loading and data acquisition; alternatively, they can be linked together to maintain a degree of synchronous movement while still independently acquiring data. Their installation positions should ensure coverage of the side areas of a typical ergonomic chair seat. The fourth cylinder 19, acting as the drive source for the side detection components 17, drives the pressure head 20 to apply precise lateral loads to the sides of the ergonomic chair. The pressure head 20, being the component directly in contact with the side of the ergonomic chair, should have a shape and material that helps simulate the contact characteristics of the human body under lateral force. This design allows the side detection components 17 to independently perform lateral loading and detection. The fourth cylinder 19 can be a small pneumatic cylinder or an electric actuator, providing controllable lateral thrust. The pressure head 20 can be designed with a certain curvature to better conform to the side curves of the ergonomic chair, and can be made of elastic materials such as rubber or silicone to reduce damage to the seat material and improve the realism of the contact. The pressure head 20 acts directly on the side of the ergonomic chair, and its function is to apply lateral pressure to simulate the lateral support or compression effect of the buttocks or outer thighs against the edge of the seat when the human body is in a sitting posture. This is crucial for evaluating the lateral support performance of the seat and the deformation response of the material under lateral loads. The pressure head 20 can be designed as a replaceable module to adapt to the shape and material of different ergonomic chair sides. Its pressing action can be achieved by the extension and retraction of the fourth cylinder 19, and the pressing force and displacement can be precisely controlled by the control system.

[0052] Pressure sensors can be thin-film pressure sensors, piezoelectric sensors, or strain gauge sensors. They should be integrated inside or on the surface of the pressure plate and pressure head 20 and calibrated to ensure measurement accuracy. Sensor data is transmitted to the control unit 3 for processing via wired or wireless means.

[0053] Capacitive sensors, such as flexible capacitive sensors, can be directly attached to or embedded in the surface or interior of the chair seat. These sensors are thin and flexible, and do not significantly alter the original mechanical properties of the chair seat. The sensors should be placed in key stress areas to comprehensively capture deformation information.

[0054] The speed sensor can be a laser rangefinder, encoder, or Hall effect sensor. A laser rangefinder can directly measure the instantaneous speed of the pressure plate or pressure head 20; an encoder can be mounted on a drive cylinder or motor to obtain speed by calculating the rate of displacement change; a Hall effect sensor can calculate speed by detecting changes in the magnetic field. The sensor should be installed in a position that accurately reflects the movement speed of the pressure plate / pressure head 20.

[0055] The rebound detection unit 4 plays a role in testing the chair back performance. The rebound detection unit 4 includes a base 6, a support frame 7 slidably connected to the base 6, and a first pressure plate 8 and a second pressure plate 9 mounted on the support frame 7. A lifting assembly 10 on the base 6 drives the support frame 7 to rise and fall, adjusting the height at which the first and second pressure plates 8 and 9 press against the chair back to adapt to different models of ergonomic chairs. The support frame 7 is equipped with a first cylinder 21 and a second cylinder 22, whose output shafts are connected to the first and second pressure plates 8 and 9, respectively. The first pressure plate 8 mimics the shape of a human back, and the second pressure plate 9 mimics the shape of a human head. A loading device 2 applies controlled displacement loading to the chair back along the normal direction of the chair back. During loading and unloading, a displacement sensor on the support frame 7 measures the loading displacement Δx, while pressure sensors on the first and second pressure plates 8 and 9 simultaneously collect the loading force F and corresponding time data. These data are recorded in real time, forming a force-displacement-time curve. By analyzing this curve, the system obtains the rebound characteristic parameters of the equivalent human lumbar and back stress or load-bearing conditions, including the rebound displacement Δxr, the rebound efficiency coefficient η, and the rebound time Tr. The rebound displacement Δxr is the difference between the displacement corresponding to the stable position of the chair back after unloading and the loaded displacement Δx; the rebound efficiency coefficient η is the ratio of the rebound displacement Δxr to the loaded displacement Δx, used to characterize the support and rebound capacity of the chair back under the equivalent human lumbar and back stress conditions; the rebound time Tr is the time interval between the start of unloading and the moment when the rate of change of the chair back displacement falls below a preset threshold. This dynamic loading and detailed parameter acquisition overcomes the limitations of existing technologies where static or single dynamic loading cannot realistically simulate the dynamic stress conditions of the human body, providing a more comprehensive evaluation of chair back performance.

[0056] Subsequently, the deformation characteristics of the chair seat are tested. Flexible capacitive sensors are precisely attached to the seat surface of the ergonomic chair. The deformation detection unit 5 includes a third cylinder 15, a crossbeam 16 slidably connected to the frame 1, two sets of side detection components 17 mounted on the crossbeam 16, and a third pressure plate 18. The third cylinder 15 is mounted on the frame 1, and its output end is connected to the crossbeam 16. The third pressure plate 18 is slidably connected to the crossbeam 16, mimicking the shape of a human buttocks. The two sets of side detection components 17 are located at both ends of the crossbeam 16, each component including a fourth cylinder 19 and a pressure head 20 connected to the output end of the fourth cylinder 19. The pressure head 20 is used to press the side of the ergonomic chair. The loading device 2 applies downward force to the flexible capacitive sensors on the seat surface at a preset speed V, loading to a preset loading force. During the loading process, pressure sensors on the third pressure plate 18 and pressure head 20 synchronously collect the loading force, while a capacitance sensor on the seat detects the seat deformation response signal (capacitance change DC). A speed sensor on the frame 1 detects the pressing speed of the third pressure plate 18 and pressure head 20. These data form a force-capacitance-speed curve, from which the stiffness factor (Hz) of the ergonomic chair is calculated, thereby obtaining deformation characteristic parameters under equivalent human buttock stress or load-bearing conditions. This dynamic loading combined with multi-dimensional data acquisition overcomes the shortcomings of existing technologies where seat surface detection is mostly based on single loading or quasi-static loading, and can more accurately reflect the true response of the seat surface under dynamic stress.

[0057] After acquiring the rebound characteristic parameters of the chair back and the deformation characteristic parameters of the chair seat, the control unit 3 determines the dynamic mechanical state and stiffness variation characteristics of the seat and chair back based on these data. For example, if the rebound efficiency coefficient η is detected to be lower than a preset threshold (indicating insufficient support or rebound capacity of the chair back), or the stiffness factor Hz exceeds the ideal range (indicating that the seat surface is too soft or too hard), the control unit 3 generates adaptive control commands. These commands control the loading device 2 to adjust the load amplitude, frequency, and holding time of the next detection cycle. Specifically, when the rebound efficiency coefficient η is lower than the preset threshold, the system will reduce the loading displacement Δx of the next detection cycle; when the rebound efficiency coefficient η is higher than the preset threshold, the system will increase the loading displacement Δx of the next detection cycle. In this way, real-time adaptive load adjustment is achieved, ensuring that the detection process can be optimized according to the actual characteristics of the ergonomic chair under test, avoiding the problems of distorted detection results or low efficiency caused by fixed loading parameters in the prior art, and realizing unified control of the chair back rebound performance and seat surface stiffness detection.

[0058] Furthermore, to ensure the continuity and reliability of the testing, the system automatically activates a fallback mechanism when the adaptive control function becomes unavailable (e.g., sensor failure or control algorithm malfunction) or when abnormal testing data occurs. In this case, the system will update the loading parameters in stages, for example, by performing tests according to a preset loading sequence covering a wide range of operating conditions, to complete the ergonomic dynamic mechanical testing of the ergonomic chair. This fallback strategy effectively solves the problem of the lack of a stable and reliable anomaly handling mechanism in existing technologies, ensuring the smooth progress of the testing process.

[0059] Using the above methods, the ergonomic chair manufacturer can comprehensively and accurately evaluate the performance of ergonomic chairs in dynamic usage scenarios, providing reliable data support for product optimization and significantly improving the authenticity, adaptability, and reliability of the testing.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dynamic mechanical detection load adaptive control method for an ergonomic chair, characterized in that, Includes the following steps: S1. Place the ergonomic chair to be tested on the dynamic mechanical testing platform. Apply dynamic load to the backrest through the loading device (2). Collect loading force, loading displacement and corresponding time data during loading and unloading to form a force-displacement-time curve and obtain the rebound characteristic parameters of the equivalent human back and waist stress conditions or load conditions. S2. Attach a capacitive sensor to the ergonomic chair. Apply dynamic load to the seat through the loading device (2). Collect loading force, seat deformation response signal and loading speed data synchronously during loading to form a force-capacitance-speed curve and obtain the deformation characteristic parameters of the equivalent human buttock stress conditions or load conditions. S3. Based on the collected rebound characteristic parameters and deformation characteristic parameters, determine the dynamic mechanical state and softness / hardness change characteristics of the seat surface and backrest, and generate adaptive control commands to control the loading device (2) to adjust the load amplitude, frequency and holding time of the next testing cycle to achieve real-time adaptive load adjustment. S4. When adaptive control is unavailable or the detection data is abnormal, a phased update of the loading parameters is used as a fallback to complete the ergonomic dynamic mechanical testing of the ergonomic chair.

2. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 1, characterized in that: The loading device (2) applies controlled displacement loading to the chair back along the normal direction of the chair back. The drive end of the loading device (2) is equipped with a displacement sensor to measure the loading displacement Δx. A force sensor is set between the loading device (2) and the chair back to synchronously collect the loading force F and the corresponding time data during the loading and unloading process, forming a force-displacement-time curve.

3. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 2, characterized in that: The rebound characteristic parameters include rebound displacement Δxr, rebound efficiency coefficient η, and rebound time Tr. Rebound displacement Δxr is the difference between the displacement corresponding to the stable position of the chair back after unloading and the loading displacement Δx. Rebound efficiency coefficient η is the ratio of rebound displacement Δxr to loading displacement Δx, which is used to characterize the support and rebound ability of the chair back under equivalent human lumbar and back stress conditions. Rebound time Tr is the time interval between the start of unloading and the moment when the rate of change of chair back displacement is lower than a preset threshold.

4. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 3, characterized in that: The adaptive control includes: when the rebound efficiency coefficient η is lower than a preset threshold, reducing the loading displacement Δx in the next detection cycle; when the rebound efficiency coefficient η is higher than the preset threshold, increasing the loading displacement Δx in the next detection cycle.

5. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 1, characterized in that: Step S2 specifically includes: S21, attaching a flexible capacitive sensor to the seat surface of the ergonomic chair; S22, applying a downward force to the flexible capacitive sensor on the seat surface at a speed V, loading to a preset loading force, the flexible capacitive sensor detects the capacitance change dc, and obtains a force-capacitance-speed curve; S23, calculating the stiffness factor Hz of the ergonomic chair.

6. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 1, characterized in that: The dynamic mechanical testing platform includes a frame (1), a loading device (2) and a control unit (3) mounted on the frame (1). The loading device (2) is electrically connected to the control unit (3). The loading device (2) includes a rebound detection unit (4) and a deformation detection unit (5). The rebound detection unit (4) is used to detect the rebound characteristics of the ergonomic chair back, and the deformation detection unit (5) is used to detect the softness and hardness of the chair seat.

7. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 6, characterized in that: The rebound detection unit (4) includes a base (6), a support frame (7) set on the base (6), a first pressure plate (8) and a second pressure plate (9) set on the support frame (7). The base (6) is provided with a lifting assembly (10). The output end of the lifting assembly (10) is connected to the support frame (7). The lifting assembly (10) drives the support frame (7) to rise and fall relative to the base (6). The height of the first pressure plate (8) and the second pressure plate (9) is adjusted to press the chair back, adapting to different models of ergonomic chairs. The support frame (7) is provided with a first cylinder (21) and a second cylinder (22). The output shaft of the first cylinder (21) and the output shaft of the second cylinder (22) are respectively connected to the first pressure plate (8) and the second pressure plate (9).

8. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 7, characterized in that: The second cylinder (22) is connected to the support frame (7) via the transmission assembly (11). The transmission assembly (11) includes a displacement motor (12) mounted on the support frame (7), a screw (13) connected to the output shaft of the displacement motor (12), and a support plate (14) threadedly connected to the screw (13). The support plate (14) is slidably connected to the support frame (7). The displacement motor (12) drives the support plate (14) to slide relative to the support frame (7) to adjust the pressing height of the second pressure plate (9). The first pressure plate (8) is shaped to mimic the back of a human body, and the second pressure plate (9) is shaped to mimic the head of a human body.

9. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 7, characterized in that: The first pressure plate (8) and the second pressure plate (9) are each equipped with a first pressure sensor for detecting the loading force of the first pressure plate (8) and the second pressure plate (9), and the support frame (7) is equipped with a displacement sensor for detecting the loading displacement of the first pressure plate (8) and the second pressure plate (9).

10. The adaptive control method for dynamic mechanical detection load of an ergonomic chair according to claim 6, characterized in that: The deformation detection unit (5) includes a third cylinder (15), a crossbeam (16) slidably connected to the frame (1), a side detection assembly (17) mounted on the crossbeam (16), and a third pressure plate (18). The third cylinder (15) is mounted on the frame (1), and its output end is connected to the crossbeam (16). The third pressure plate (18) is slidably connected to the crossbeam (16). The side detection assembly (17) has two sets, which are located at both ends of the crossbeam (16). (17) Includes a fourth cylinder (19) and a pressure head (20) connected to the output end of the fourth cylinder (19). The pressure head (20) is used to press the side of the ergonomic chair. The third pressure plate (18) imitates the shape of the human buttocks. The third pressure plate (18) and the pressure head (20) are provided with a second pressure sensor for detecting the loading force of the third pressure plate (18) and the pressure head (20). The chair seat is provided with a capacitive sensor for detecting the deformation of the chair seat. The frame (1) is provided with a speed sensor for detecting the pressing speed of the third pressure plate (18) and the pressure head (20).

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