A seat dynamic isolation performance evaluation method based on dynamic offset of pressure center

Abstract

The application discloses a seat dynamic isolation performance evaluation method based on pressure center dynamic deviation, relates to the technical field of vehicle seats, and comprises the following steps: laying a flexible film pressure pad on the surface of a cushion of a seat to be evaluated, collecting pressure distribution data under the sitting posture of an occupant, calculating the pressure center coordinates corresponding to each sampling time in real time, collecting the surface electromyography signals of the erector spinae of the lumbar vertebrae of the occupant and vehicle running state data, controlling a vehicle carrying the seat to be evaluated to pass through a standard disturbance section according to preset test conditions, and collecting the continuous change data of the pressure center coordinates, the surface electromyography signals of the erector spinae of the lumbar vertebrae and the vehicle running state data in the driving process of the vehicle. The application collects the pressure center dynamic deviation and electromyography response data of the contact area between the occupant and the seat, constructs a dynamic isolation index D-index, realizes comprehensive evaluation of the dynamic isolation performance of the seat based on the real response of the human body, and supports performance comparison and optimization of different seat schemes.

Description

Technical Field

[0001] This application relates to the field of vehicle seat technology, specifically to a method for evaluating the dynamic vibration isolation performance of seats based on dynamic offset of the pressure center. Background Technology

[0002] With the development of the automotive industry and the increasing demands of users for driving and riding comfort, the dynamic vibration isolation performance of vehicle seats has gradually become an important evaluation indicator in the development of automotive seats. During actual driving, especially when traversing complex road conditions such as uneven surfaces, speed bumps, and continuous undulations, the impact and vibration from the road surface are transmitted to the occupants through the vehicle body, seat frame, and seat cushion, causing body swaying, postural instability, and significant discomfort. Therefore, automotive seats not only need to possess good static support performance but also need to effectively reduce vibration transmission under dynamic vibration environments and help occupants maintain a stable physical state.

[0003] In the development of existing seats, standardized testing methods are typically used to evaluate the vibration damping capability of the seats. The most representative technical solution is the "SEAT factor" (Seat Effective Amplitude Transmissibility) measurement method specified in the international standard ISO 10326-1:2016. This method uses a standardized prosthetic buttock adapter (SAE prosthetic buttock) that conforms to the human body's mass distribution characteristics, with a triaxial accelerometer installed inside the prosthetic buttock and accelerometers also placed at the seat rail positions to acquire the seat input vibration and the seat load-bearing end response signals, respectively. During testing, the prosthetic buttock is placed on the surface of the seat cushion to be evaluated, and the vehicle passes through a standard vibration test section at a specified speed. By collecting the input acceleration signals at the seat rail and the output acceleration signals at the prosthetic buttock, and calculating the amplitude transmission relationship between the two in the frequency range of 1Hz to 20Hz, the SEAT factor is obtained.

[0004] This evaluation index reflects the seat's ability to isolate external vibrations. Generally, the lower the SEAT factor, the more significant the seat's vibration damping effect and the better its dynamic vibration isolation performance. Therefore, the SEAT factor evaluation method based on pseudo-buttock acceleration response has become an important evaluation tool in automotive seat vibration performance testing and engineering development.

[0005] Existing evaluation methods based on the SEAT factor primarily analyze the vibration transmission characteristics of seats. They use a spurious buttock adapter to simulate human mass loading and evaluate the seat's ability to dampen external vibrations using acceleration response. However, because the spurious buttock adapter is a passive mechanical loading device, it cannot reflect the active posture adjustment behavior of real occupants under neuromuscular control during dynamic disturbances. When a vehicle is subjected to complex road surface excitations, real occupants maintain stability through trunk muscle regulation, center of gravity adjustment, and changes in body posture. This type of active human response information cannot be obtained through traditional spurious buttock tests.

[0006] Furthermore, existing methods primarily evaluate vibration transmission characteristics based on vertical vibration transmission properties. However, vibrations in actual vehicle operating environments typically involve combined vertical, longitudinal, and lateral disturbances, and the pressure distribution at the human-seat contact interface dynamically changes with body slippage, tilting, and torsion. Since traditional acceleration evaluation methods cannot capture changes in the pressure center within the human-seat contact area, they cannot directly reflect changes in occupant dynamic stability. Simultaneously, the relationship between seat vibration transmission performance and subjective human comfort is influenced by multiple factors, including physiological responses, posture adjustment capabilities, and the dynamic interaction between the human and seat, leading to discrepancies between some test results and actual riding experiences.

[0007] Therefore, a method is needed to comprehensively evaluate the dynamic vibration isolation performance of seats by combining the dynamic response characteristics of real human bodies.

[0008] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0009] The purpose of this application is to provide a method for evaluating the dynamic vibration isolation performance of seats based on dynamic offset of the pressure center, so as to solve the problems in the background art mentioned above.

[0010] To achieve the above objectives, this application provides the following technical solution: a method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center, comprising the following steps: A flexible film pressure pad was laid on the surface of the seat cushion of the seat to be evaluated. Pressure distribution data of the occupant in sitting position was collected, and the pressure center coordinates corresponding to each sampling time were calculated in real time. At the same time, electromyographic signals of the erector spinae muscles of the occupant's lumbar spine and vehicle operation status data were collected. The vehicle equipped with the seat to be evaluated was controlled to pass through a standard disturbed road section under preset test conditions. Continuous change data of the pressure center coordinates, electromyographic signals on the surface of the erector spinae muscles of the lumbar spine, and vehicle operating status data were collected during the vehicle's operation. Dynamic offset characteristic analysis was performed on the continuously changing data of the pressure center coordinates to calculate the root mean square value of the pressure center offset, the peak value of the pressure center offset, and the pressure center return time, which were used to characterize the changes in the body stability of the occupants during dynamic disturbances. Based on the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine during the time period corresponding to the peak of the pressure center offset, the electromyographic integral value is calculated, and the occupant is judged to have engaged in active postural compensation based on the electromyographic integral value. The dynamic vibration isolation index is obtained by normalizing the value of the root mean square of the pressure center offset, the integral value of electromyography, and the preset weight parameters. The dynamic vibration isolation performance of the seat under evaluation is then evaluated based on the dynamic vibration isolation index.

[0011] The flexible film pressure pad adopts a pressure sensor array structure and is set in the human contact area of ​​the seat cushion to be evaluated. It is used to continuously acquire the pressure distribution data of the occupant's buttocks and thighs acting on the surface of the cushion. The sampling frequency of the pressure sensor array is not less than 50Hz.

[0012] The pressure center coordinates include longitudinal coordinates that vary along the vehicle's longitudinal direction and lateral coordinates that vary along the vehicle's lateral direction. By continuously collecting the pressure center coordinates at multiple time points, a dynamic pressure center change trajectory of the occupant-seat contact interface is constructed.

[0013] The standard disturbance road section includes at least one of trapezoidal speed bumps, continuously damaged pavement, and long-wave undulating road, wherein trapezoidal speed bumps are used to generate transient impact excitation, continuously damaged pavement is used to generate continuous random disturbance, and long-wave undulating road is used to generate low-frequency dynamic excitation.

[0014] The root mean square value of the center of pressure offset is used to evaluate the overall swaying state of the occupant's body under the dynamic disturbance of the vehicle. The peak value of the center of pressure offset is used to evaluate the maximum instability response of the occupant caused by a single impact event. The center of pressure recovery time is used to evaluate the time required for the occupant to recover from the offset state to a stable sitting position.

[0015] Matching analysis was performed on the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine and the corresponding time intervals of the pressure center shift peak. By obtaining electromyographic response data within the corresponding time range, it was determined whether the occupant would produce active posture adjustment behavior under the dynamic disturbance of the vehicle.

[0016] The dynamic vibration isolation index is comprehensively evaluated based on the dynamic offset characteristic parameters of the pressure center and the electromyographic response parameters of the human body. The dynamic offset characteristic parameters of the pressure center include the root mean square value of the pressure center offset, and the electromyographic response parameters of the human body include the electromyographic integral value.

[0017] Vehicle operating status data is collected via the vehicle's CAN bus. This data includes vehicle speed information and is used to record the vehicle's operating status during dynamic vibration isolation performance testing.

[0018] When testing different seating options, different seats to be evaluated were installed in the same test vehicle and tested with the same occupants, the same vehicle speed, and the same standard disturbance road section. The dynamic vibration isolation performance of the seats was evaluated by comparing the dynamic vibration isolation index corresponding to different seats.

[0019] The dynamic offset characteristic parameter analysis of the pressure center also includes the analysis of the movement trajectory of the pressure center. By obtaining the direction of position change, movement distance and speed of change of the pressure center during the dynamic disturbance of the vehicle, the analysis can determine the forward and backward movement, left and right offset and posture change of the occupant's body in the seat cushion area.

[0020] The technical effects and advantages provided by this application in the above technical solution are as follows: This application collects pressure distribution data of the contact area between a real occupant and the seat cushion, and uses the dynamic offset of the pressure center as an evaluation index for the seat's dynamic vibration isolation performance, transforming the evaluation object from the traditional mechanical load response to the actual dynamic response state of the human body. Since changes in the pressure center can reflect the changes in the occupant's center of gravity and posture stability when subjected to vehicle vibration disturbances, it can more closely approximate the stability felt by the occupant during actual riding, reducing the bias caused by relying solely on vibration transmission parameters. Simultaneously, by introducing characteristic parameters such as the root mean square value of the pressure center offset, the peak value of the pressure center offset, and the pressure center recovery time, the impact of the seat on the occupant's dynamic stability can be described from multiple aspects, including overall sway, transient impact response, and posture recovery capability.

[0021] This application integrates dynamic pressure center offset data with human electromyography (EMG) response data to construct a dynamic vibration isolation index (D-index), enabling a comprehensive quantitative evaluation of the dynamic vibration isolation performance of vehicle seats. This method can acquire lateral and longitudinal dynamic instability information generated by the occupant's body under complex vehicle disturbance environments, overcoming the limitations of traditional testing methods in reflecting the dynamic changes at the human-seat contact interface. Furthermore, this application can acquire data using existing pressure detection and EMG acquisition devices, requiring only the addition of corresponding data analysis algorithms to achieve dynamic vibration isolation performance evaluation, reducing the need for additional testing equipment. It can also be applied to performance comparisons between different seat designs, providing an evaluation basis for seat structure optimization and comfort development. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0023] Figure 1 This is a flowchart illustrating the method for evaluating the dynamic vibration isolation performance of a seat in this application. Detailed Implementation

[0024] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art.

[0025] This application provides, as follows: Figure 1 The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center, as shown, includes the following steps: A flexible film pressure pad was laid on the surface of the seat cushion of the seat to be evaluated. Pressure distribution data of the occupant in sitting position was collected, and the pressure center coordinates corresponding to each sampling time were calculated in real time. At the same time, electromyographic signals of the erector spinae muscles of the occupant's lumbar spine and vehicle operation status data were collected. The vehicle equipped with the seat to be evaluated was controlled to pass through a standard disturbed road section under preset test conditions. Continuous change data of the pressure center coordinates, electromyographic signals on the surface of the erector spinae muscles of the lumbar spine, and vehicle operating status data were collected during the vehicle's operation. Dynamic offset characteristic analysis was performed on the continuously changing data of the pressure center coordinates to calculate the root mean square value of the pressure center offset, the peak value of the pressure center offset, and the pressure center return time, which were used to characterize the changes in the body stability of the occupants during dynamic disturbances. Based on the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine during the time period corresponding to the peak of the pressure center offset, the electromyographic integral value is calculated, and the occupant is judged to have engaged in active postural compensation based on the electromyographic integral value. The dynamic vibration isolation index is obtained by normalizing the value of the root mean square of the pressure center offset, the integral value of electromyography, and the preset weight parameters. The dynamic vibration isolation performance of the seat under evaluation is then evaluated based on the dynamic vibration isolation index.

[0026] Specific Implementation Method 1: This implementation method provides a seat dynamic vibration isolation performance evaluation method based on dynamic offset of the pressure center. This method is used to evaluate the ability of a car seat to maintain occupant posture stability and riding comfort when subjected to dynamic excitations such as road vibration and impact disturbances during vehicle operation. This implementation method differs from the traditional seat vibration isolation evaluation method based on the pseudo-buttock acceleration transmissibility. By collecting information on the pressure distribution changes in the contact area between the actual occupant and the seat cushion, it obtains the dynamic mechanical response of the human-seat contact interface and uses the dynamic offset characteristics of the pressure center to evaluate the seat's dynamic vibration isolation performance.

[0027] In the specific implementation process, the first step is to prepare the seat to be evaluated for testing. A flexible film pressure pad is laid on the main contact area of ​​the human body on the seat cushion, ensuring that the flexible film pressure pad covers the effective contact area between the occupant's buttocks and thighs and the seat cushion. The flexible film pressure pad adopts an array-type pressure detection structure composed of multiple pressure sensing units, with a pressure sensing array density of no less than 32×32, enabling continuous acquisition of the pressure distribution of the human body acting on the seat cushion surface; the pressure sampling frequency is no less than 50Hz to meet the real-time detection requirements of human body pressure changes during vehicle dynamic vibration. By collecting contact pressure data between the human body and the seat in a normal sitting posture using the flexible film pressure pad, the pressure values ​​corresponding to different spatial positions and the pressure change process are obtained.

[0028] During pressure data acquisition, the pressure pad acquisition software calculates the position of the resultant force exerted by the human body on the seat cushion surface based on the position coordinates of each pressure sampling point and the pressure value at the corresponding sampling time, obtaining the pressure center coordinates at each sampling time in real time. The pressure center coordinates include the longitudinal coordinate X and the lateral coordinate Y. The longitudinal coordinate X reflects the change in the pressure center generated by the occupant's body along the front-to-back direction of the vehicle, while the lateral coordinate Y reflects the change in the pressure center generated by the occupant's body along the left-to-right direction of the vehicle. By continuously acquiring the pressure center coordinates at multiple sampling times, a dynamic pressure center change trajectory can be formed, which is used to describe the change in the occupant's center of gravity and the dynamic interaction between the human body and the seat contact interface during vehicle vibration.

[0029] Simultaneously, during the acquisition of pressure center data, electromyographic (EMG) signals from the surface of the erector spinae muscles of the occupant's lumbar spine were collected to obtain information on the occupant's active regulatory response when subjected to vehicle dynamic disturbances. EMG signals from the erector spinae muscles reflect the degree of muscle activity during the occupant's trunk stability control. When the vehicle is impacted by road surfaces, causing the occupant's body to shift, the occupant may actively contract their back muscles to adjust their posture. Therefore, changes in EMG signals can serve as an important basis for judging the occupant's active posture compensation behavior. In addition, vehicle operating status data, including vehicle speed and other information, was simultaneously acquired from the vehicle's CAN bus to record the vehicle's operating status during dynamic testing and to assist in analyzing changes in the seat's dynamic vibration isolation performance under different vehicle operating conditions.

[0030] After deploying the testing equipment, the test occupant is seated in a relaxed posture on the seat to be evaluated, maintaining a normal driving posture with hands lightly placed on their thighs. This avoids the occupant actively supporting themselves or adjusting their posture, which could interfere with the test results. The pressure center changes during the test are primarily attributed to vehicle dynamic disturbances and seat support characteristics. The vehicle operates under preset test conditions, passing through a standard disturbance road section at a constant speed to conduct dynamic excitation tests on the seat and occupant. The standard disturbance road section includes various road conditions that can generate typical vehicle vibration responses, such as trapezoidal speed bumps, continuously damaged road surfaces, and long-wave undulating roads.

[0031] The trapezoidal speed bump is used to simulate the transient impact vibration generated when a vehicle passes over a sudden obstacle. The height of the trapezoidal speed bump can be set to 30mm, and the width can be set to 300mm. The continuously damaged road surface is used to simulate the situation where a vehicle is subjected to continuous random disturbances during long-term driving. The road smoothness can be based on road conditions with an International Roughness Index (IRI) of approximately 4.0 to 6.0. The long-wave undulating road is used to simulate the occupant's body stability response under low-frequency, large-amplitude vehicle posture changes. By setting different types of standard disturbance road sections, the impact of the seat on the occupant's body stability under different dynamic excitation conditions can be comprehensively obtained.

[0032] During the vehicle's passage through a standard disturbance section, data on the pressure center coordinate changes output by the flexible film pressure pad, electromyographic signals on the surface of the erector spinae muscles of the lumbar spine, and vehicle operating status data were continuously collected. Based on the collected time series of pressure center coordinates, the variation patterns of the pressure center during dynamic disturbances were analyzed. Since the pressure center typically experiences only minor fluctuations within a small range when the occupant's body is in a stable state, but when the vehicle experiences strong vibrations or impacts, the occupant's body will move forward and backward, shift laterally, or tilt, leading to a redistribution of pressure in the contact area between the body and the seat, causing a significant shift in the pressure center. Therefore, the dynamic changes in the pressure center directly reflect the occupant's body stability under vehicle vibration conditions.

[0033] Furthermore, dynamic offset features were extracted from the continuously changing pressure center coordinates, and the root mean square value (COP_RMS) of the pressure center offset was calculated. COP_RMS reflects the overall sway amplitude of the occupant's body under continuous vehicle vibration by statistically analyzing the root mean square value of the pressure center coordinate changes throughout the entire test journey. A larger COP_RMS value indicates a larger range of changes in the occupant's center of gravity during the test, suggesting a weaker ability of the seat to maintain dynamic stability. Conversely, a smaller COP_RMS value indicates that the occupant's body can maintain a relatively stable state, indicating better dynamic support from the seat.

[0034] Simultaneously, the maximum offset distance of the center of pressure, COP_peak, in a single impact event is calculated. COP_peak describes the maximum degree of displacement of the occupant's body when the vehicle is subjected to a transient impact, and can reflect the seat's ability to suppress sudden vibration events. When a road impact causes a rapid and significant shift in the center of pressure, it indicates that the occupant's body has become significantly unstable. This parameter can effectively capture the dynamic displacement phenomenon of the human body that is difficult to directly reflect using traditional acceleration evaluation methods.

[0035] The center-of-pressure recovery time, T_return, is further calculated. This time represents the time required for the center of pressure to recover from its maximum offset state to its initial stable range, and is used to evaluate the occupant's posture recovery capability after being subjected to dynamic disturbances. A shorter T_return indicates that the occupant can quickly return to a stable sitting posture, and the seat has good dynamic support and comfort. A longer T_return indicates that the occupant needs a longer time to readjust their body posture after being disturbed, suggesting weaker dynamic stability of the seat.

[0036] After obtaining the dynamic offset characteristic parameters of the center of pressure, time-matching analysis was performed on the electromyographic (EMG) signals of the erector spinae muscles of the lumbar spine, which were acquired simultaneously, based on the time interval corresponding to the peak offset COP_peak. EMG signals within the time period corresponding to the event of maximum center of pressure offset were extracted, and the integrated EMG value iEMG_peak within that time range was calculated to evaluate whether the occupant maintained body stability through active muscle regulation. When a significant offset of the center of pressure occurred, and a significant increase in the EMG signal of the erector spinae muscles of the lumbar spine was observed, it indicated that the occupant had engaged in active posture compensation behavior, i.e., the body resisted instability caused by vehicle vibration through muscle contraction.

[0037] Furthermore, the severity of dynamic disturbance events is determined based on changes in electromyographic (EMG) integral values. When the EMG response ratio R within the time period corresponding to the peak pressure center shift is greater than a preset threshold (e.g., R > 1.5), the disturbance is considered to have not only caused mechanical shift of the human body but also induced significant active postural compensation behavior, thus classifying the event as a severe instability event. By jointly analyzing pressure center change information and EMG response information, the shortcomings of evaluating human response solely based on mechanical vibration parameters can be avoided, improving the consistency between the seat's dynamic vibration isolation performance evaluation results and the actual occupant experience.

[0038] Finally, the obtained root mean square value of pressure center offset (COP_RMS) and electromyographic integral value (iEMG_peak) are normalized and fused according to preset weight parameters to construct the dynamic vibration isolation index (D-index), a comprehensive index for evaluating the dynamic vibration isolation performance of the seat. The formula for calculating the dynamic vibration isolation index (D-index) is: D-index = k × [normalized (COP_RMS) × α + normalized (iEMG_peak) × (1-α)], where k is the vehicle model calibration coefficient, used to correct the evaluation results according to the seat development requirements of different vehicle models; α is the weighting coefficient, used to adjust the proportion of the dynamic offset parameter of pressure center and the electromyographic response parameter in the comprehensive evaluation results. α is preferably set to 0.7 to make the evaluation results more focused on the dynamic stability changes of the human body-seat contact interface. By calculating the dynamic vibration isolation index (D-index) corresponding to different seat schemes and comparing the index differences between the various seat schemes, a quantitative evaluation of the dynamic vibration isolation performance of the seat can be achieved. Among them, the lower the D-index value, the smaller the change in the occupant pressure center during vehicle dynamic disturbance, the lower the need for active posture adjustment of the human body, the stronger the ability of the seat to maintain the stability of the occupant's body, and the better the dynamic vibration isolation performance.

[0039] Through the above implementation methods, this method utilizes the pressure center changes and human muscle response information generated by real occupants in a dynamic vibration environment to replace the traditional evaluation method based on the transmission rate of false buttock acceleration. It realizes the transformation from evaluating the vibration transmission performance of the seat to evaluating the dynamic interaction performance of the human body and the seat, and can more comprehensively and accurately reflect the dynamic vibration isolation capability of the car seat in the actual use environment.

[0040] Specific Implementation Method Two: This implementation method provides a method for comparing the dynamic vibration isolation performance of different seat designs based on the dynamic offset characteristics of the pressure center. It is used to quantitatively evaluate the dynamic vibration isolation performance of different seat structures, materials, and support forms under the same vehicle operating conditions and occupant response conditions. This implementation method is mainly applied to the selection of solutions, structural optimization, and performance verification in the automotive seat development process. By establishing standardized test conditions, it reduces the impact of differences in vehicle structure, driving conditions, and individual human differences on the test results, enabling a more accurate reflection of the differences in dynamic vibration isolation performance between different seat designs.

[0041] In the specific implementation process, multiple seat designs to be evaluated are first selected, and each design is sequentially installed in the same test vehicle for testing. Different seat designs may include cushion structures formed from different foam materials, seat support structures with different hardness gradients, seat structures with different side wing covering forms, and other seat design schemes that affect the human body's support status. By using the same test vehicle for testing, testing errors caused by differences in vehicle body structural stiffness, suspension system parameters, vehicle mass distribution, and vibration transmission paths between different vehicles can be avoided, allowing the test results to more accurately reflect the impact of the seat's own structure on the dynamic stability of the human body.

[0042] When testing different seating configurations, the same occupant was selected as the test subject, maintaining the same test posture and seating position. During the test, the occupant maintained a natural and relaxed sitting posture as preset requirements, avoiding any active adjustments to body posture, changes in sitting position, or active support that could cause additional interference. This ensured that the human body response was primarily determined by the vehicle vibration excitation and the seat support performance. Simultaneously, the vehicle test speed, road disturbance conditions, data acquisition equipment parameters, and test procedures were uniformly set. For example, the vehicle passed through the same standard disturbance road section at the same speed, the flexible membrane pressure pad used the same sampling frequency to collect pressure distribution data, and the electromyographic signals of the erector spinae muscles of the lumbar spine were recorded synchronously using the same acquisition method. By establishing a consistent test environment, it can be ensured that the differences in pressure center changes, human muscle responses, and dynamic vibration isolation indices generated by different seating configurations mainly stem from changes in the seat's own structural performance, rather than changes in test conditions.

[0043] During testing of each seating configuration, a flexible film pressure pad was installed in the human contact area of ​​the corresponding seat cushion. A pressure sensor array continuously collected data on the pressure distribution changes between the occupant's buttocks and thighs and the seat. Based on the position coordinates and pressure values ​​of each pressure sampling point, the flexible film pressure pad calculated the pressure center coordinate sequence throughout the vehicle's dynamic disturbance process. The pressure center coordinates include the X-coordinate, which varies along the vehicle's longitudinal direction, and the Y-coordinate, which varies along the vehicle's lateral direction. By continuously recording the trajectory of the pressure center coordinate changes, the pattern of the occupant's center of gravity change under vehicle vibration can be obtained.

[0044] Because vehicles experience dynamic disturbances in different directions when traversing varying road conditions, occupants may experience dynamic changes such as forward / backward movement, lateral shifting, and torso twisting, leading to a redistribution of contact pressure between the occupant and the seat. When the occupant's body remains stable, the center of pressure exerted on the seat cushion surface typically varies within a small range. However, when the vehicle experiences a strong impact or continuous vibration, the occupant's posture is affected, causing a significant shift in the center of pressure. Therefore, analyzing the pressure center coordinate sequence can directly reflect the dynamic mechanical interaction between the occupant and the seat interface, and evaluate the ability of different seating designs to support occupant stability.

[0045] Furthermore, dynamic offset feature calculations were performed on the pressure center coordinate sequences collected during the testing of different seating configurations, yielding three dynamic feature parameters: the root mean square value of pressure center offset (COP_RMS), the peak value of pressure center offset (COP_peak), and the pressure center return time (T_return). COP_RMS describes the degree of continuous change in the pressure center throughout the vehicle's dynamic testing process, reflecting the overall swaying amplitude of the occupant's body. A smaller COP_RMS for a particular seating configuration indicates that the seat can reduce the change in the occupant's center of gravity caused by vehicle vibration, allowing the occupant to maintain a more stable sitting posture; a larger COP_RMS indicates that the seat's dynamic support for the human body is insufficient, making the occupant more prone to continuous swaying.

[0046] COP_peak is used to evaluate the maximum dynamic displacement of the human body when a vehicle is subjected to a transient impact. For example, when a vehicle goes over a trapezoidal speed bump or a local road protrusion, the human body will experience a sudden impact. If the seat's coverage and support are insufficient, the occupant's body will experience a significant inertial displacement, leading to a noticeable shift in the center of pressure. By comparing the COP_peak values ​​of different seat designs, the ability of different seats to suppress sudden vibration events can be determined.

[0047] T_return is used to evaluate the time required for an occupant to recover to a stable state after being disturbed. Different seat designs vary in cushion support stiffness, foam material damping characteristics, and the degree of body coverage, resulting in differences in the speed at which the body recovers to a stable state after being subjected to vehicle dynamics. A shorter T_return indicates that the seat can quickly limit changes in body posture and help the occupant return to a stable sitting position; a longer T_return indicates that the body requires a longer time to adjust its posture, suggesting relatively weaker dynamic stability performance of the seat.

[0048] After calculating the dynamic shift parameters of the center of pressure, electromyographic (EMG) signals on the surface of the erector spinae muscles of the lumbar spine were further collected and analyzed. The EMG response was used as an auxiliary indicator to evaluate the human body's active posture adjustment ability. When the vehicle is subjected to vibration, if the occupant only experiences a change in the center of pressure, while the EMG signal on the surface of the erector spinae muscles of the lumbar spine changes little, it indicates that the human body is mainly affected by the vehicle's mechanical disturbance and does not produce significant active posture adjustment behavior. If the center of pressure shifts significantly, and the lumbar EMG signal increases synchronously, it indicates that the occupant needs to actively contract the lumbar and back muscles to adjust their posture in order to maintain body stability. This situation reflects that the seat has failed to adequately suppress the human body's dynamic instability.

[0049] Furthermore, a comprehensive evaluation model is established based on the dynamic offset parameters of the pressure center and the electromyographic response parameters. First, the COP_RMS and iEMG_peak data corresponding to different seating schemes are normalized to eliminate the influence of differences in the dimensions of different parameters on the evaluation results. Then, based on preset weight parameters, the dynamic offset characteristics of the human body interface and the active adjustment response characteristics of the human body are fused and calculated to obtain the dynamic vibration isolation index D-index of the corresponding seating scheme. The formula for calculating the dynamic vibration isolation index D-index is: D-index=k×[normalized(COP_RMS)×α+normalized(iEMG_peak)×(1-α)], where k is the vehicle model calibration coefficient, used to adjust the evaluation results according to different vehicle development needs; α is the weight parameter, used to adjust the proportion of the dynamic offset index of the pressure center and the electromyographic response index in the comprehensive evaluation results. Through the dynamic vibration isolation index D-index, the actual dynamic response of the human body can be transformed into a quantifiable evaluation index, thereby avoiding the problem that traditional evaluation of seat performance based solely on vibration transmissibility cannot reflect changes in human stability.

[0050] After completing tests on all seat designs, the dynamic vibration isolation indices (D-index) for each design were compared and analyzed. The dynamic vibration isolation performance of different seat designs was ranked and evaluated based on the index values. A lower D-index indicates a smaller shift in the occupant's center of pressure during vehicle dynamic disturbances, a lower need for active posture adjustment, a stronger ability of the seat to maintain occupant stability, and superior dynamic vibration isolation performance. This method provides objective quantitative evidence for selecting different structural, material, and support designs during automotive seat development, improving the efficiency of dynamic comfort development.

[0051] This implementation method performs dynamic pressure center offset analysis on multiple seating designs under uniform vehicle, occupant, and road disturbance conditions. It uses the actual human body response as the basis for evaluating the dynamic vibration isolation performance of the seats, thus transforming the traditional evaluation of seat vibration transmission performance into an evaluation of the dynamic interaction performance between the human body and the seat. This method can more accurately reflect the differences in dynamic stability of different seating designs in actual use environments. This approach is applicable not only to performance comparisons during the automotive seat development stage but also to applications such as seat structure optimization, material selection, and pre-mass production performance verification.

[0052] Specific Implementation Method Three: This implementation method provides an extended application scheme for a dynamic stability evaluation method based on the concept of dynamic pressure center analysis. This implementation method is a further extension of the aforementioned method for evaluating the dynamic vibration isolation performance of seats based on dynamic pressure center offset. Its core idea is to obtain the dynamic offset characteristics of the pressure center by utilizing the pressure distribution change information on the support interface, and to quantitatively evaluate the dynamic stability performance of the support structure by analyzing the changes in the center of gravity, posture, and stability recovery ability of the supported object under dynamic loads. This method is not limited to the automotive seat field but is applicable to any application scenario that requires evaluating the "ability of the support surface to maintain the stability of the object under dynamic loads." Compared to traditional evaluation methods based on single-point vibration transmission, single acceleration response, or local force detection, this implementation method obtains the dynamic pressure changes of the entire contact interface and analyzes the object's stability from the perspective of interface dynamic mechanical interaction, which is closer to the human experience or equipment operating state during actual use.

[0053] In the application scenario of evaluating the dynamic vibration isolation performance of automotive seats, this method collects contact pressure distribution data between the human body and the seat cushion using a flexible pressure detection structure. Based on the pressure distribution changes at different sampling times, the pressure center position exerted by the human body on the seat surface is calculated, and the dynamic offset pattern of the pressure center caused by vehicle vibration input is further analyzed. When a vehicle is subjected to road impacts, continuous bumps, or complex road disturbances, the occupant's body will move forward and backward, shift left and right, and change torso posture due to inertia, causing a redistribution of contact pressure between the human body and the seat, thus leading to a change in the pressure center position. By analyzing dynamic characteristic parameters such as the pressure center offset amplitude, offset peak, and recovery time, the seat's ability to support human posture stability can be determined. Simultaneously, the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine can be combined to assist in judging whether the human body engages in active posture adjustment behavior, thereby comprehensively evaluating the seat's dynamic vibration isolation capability under real occupant conditions.

[0054] In the application of dynamic stability evaluation for athletic shoes, flexible pressure detection structures can be placed inside the insole or in the foot contact area. By collecting data on the pressure distribution changes between the foot and the shoe sole during human movement, a dynamic model of the foot pressure center change during exercise can be established. During dynamic motion events such as running landing, jumping impact, and rapid turning, the human foot is subjected to significant instantaneous impact forces and directional changes, causing the foot pressure distribution to change with the adjustment of the body's center of gravity. By calculating the foot pressure center offset amplitude, peak pressure center offset, and pressure center recovery speed, the support effect of the shoe sole structure on the dynamic stability of the human foot can be evaluated. For example, during running landing, if the midsole structure can effectively disperse the impact load, resulting in a small range of change in the foot pressure center and a rapid recovery to a stable area, it indicates that the shoe sole structure has good dynamic stability performance. Conversely, if the pressure center experiences a large offset and a long recovery time, it indicates that the shoe sole structure lacks sufficient stability control during human movement. This evaluation method can provide a quantitative evaluation basis for the selection of athletic shoe sole materials, midsole structure design, and cushioning performance optimization.

[0055] In the application scenario of dynamic comfort evaluation of bicycle saddles, pressure detection structures can be installed on the surface of the bicycle saddle or placed in the contact area between the rider's buttocks and the saddle. By continuously collecting the pressure changes between the rider's buttocks and the saddle during riding, the dynamic interaction between the rider and the saddle can be analyzed. When a bicycle passes over speed bumps, potholes, or continuously vibrating road sections, the rider's buttocks are affected by external impacts, resulting in up-and-down vibrations, lateral swaying, and adjustments to the body's center of gravity, causing a dynamic shift in the center of pressure on the buttocks. By acquiring the trajectory of the change in the center of pressure on the buttocks and calculating the magnitude of the pressure center shift, peak change, and recovery time, the impact of different saddle structures, filling materials, and support forms on the rider's stability and comfort can be evaluated. This method can overcome the shortcomings of traditional bicycle saddle evaluation methods that rely solely on static pressure distribution or subjective feelings, achieving saddle performance analysis based on the real dynamic response of the human body.

[0056] In wheelchair anti-rollover stability evaluation applications, the dynamic changes in the center of pressure can be used to determine the trend of the user's center of gravity changes during wheelchair operation and to evaluate the impact of the wheelchair structure on the user's posture maintenance ability. When the wheelchair traverses uneven surfaces, ramps, turning areas, or is subjected to external disturbances, the user's body may shift laterally, causing changes in the pressure distribution between the body and the wheelchair seat. By collecting pressure change data in the seat area and calculating the direction of movement, offset distance, and recovery process of the body's center of pressure, it is possible to determine whether the user has a potential risk of instability. When the center of pressure continuously shifts in a certain direction and cannot recover quickly, it indicates reduced user stability, and the wheelchair structure may require further optimization, such as adjusting the seat support area, adding lateral support structures, or optimizing the chassis stability design. This method can provide data support for wheelchair safety performance evaluation and anti-rollover structure design.

[0057] In the evaluation of industrial vibration damping platforms, this method can also be applied to the evaluation of support structures for precision instruments, testing equipment, or other equipment requiring stable operation. Traditional evaluation methods for industrial vibration damping platforms typically use parameters such as equipment vibration acceleration and displacement response to judge the damping effect. However, the operational stability requirements of some precision equipment depend not only on the vibration amplitude but also on changes in the force on the equipment's support area and the overall posture stability of the equipment. Therefore, a pressure detection structure can be set up between the equipment and the vibration damping platform. By collecting data on pressure distribution changes in the equipment's support area, the dynamic shift of the pressure center at the support interface can be calculated when the equipment is affected by external vibrations. When the pressure center shift is small and can quickly recover to a stable state during equipment operation, it indicates that the vibration damping platform can effectively maintain equipment stability; when the pressure center changes significantly or shifts continuously, it indicates that the vibration damping platform's ability to maintain the dynamic stability of the equipment is insufficient. This method allows for the evaluation of the stability effect of industrial vibration damping platforms from the perspective of the mechanical response of the support interface.

[0058] Furthermore, the dynamic analysis method for the pressure center in this embodiment can also adjust parameters according to different applications. For example, in human-related applications, the pressure acquisition area and evaluation index weights can be adjusted based on factors such as human body mass, contact area, and motion state; in equipment stability evaluation, the pressure detection range and dynamic evaluation parameters can be adjusted based on equipment weight, support type, and vibration environment characteristics. The dynamic characteristic parameters of the pressure center can include not only the root mean square value of pressure center offset, peak value of pressure center offset, and pressure center recovery time, but can also be further extended to the length of the pressure center trajectory, the pressure center movement speed, the direction of pressure center change, and the stability parameters of the pressure center trajectory, thereby more comprehensively describing the interaction between the object and the support interface under dynamic load.

[0059] In this embodiment, the core of the dynamic offset evaluation method for the pressure center lies in transforming the traditional evaluation method based on single-point vibration transmission characteristics into one based on the dynamic mechanical interaction of the interface by acquiring the dynamic pressure distribution changes on the support interface. Traditional evaluation methods typically focus on the vibration amplitude or acceleration changes at a certain detection point, while this method focuses on the overall stress state changes of the supported object. By reflecting the change in the position of the pressure center, it reflects the object's attitude stability in a dynamic environment, thus more accurately describing the true response state of the supported object after being subjected to dynamic disturbances.

[0060] By fusing dynamic characteristic parameters of the pressure center with auxiliary response parameters, a quantitative evaluation of the dynamic performance of different support structures can be achieved. For example, in the automotive seating industry, the dynamic vibration isolation performance of different seating designs can be evaluated; in the athletic footwear industry, the dynamic stability capability of different sole structures can be evaluated; in the bicycle saddle industry, the comfort of different saddle designs can be evaluated; in the wheelchair industry, the safety and stability performance of different structural designs can be evaluated; and in the industrial vibration reduction field, the ability of different vibration reduction platforms to ensure the stable operation of precision equipment can be evaluated. Therefore, this method can improve the consistency between dynamic performance evaluation results and actual user experience, providing effective data for product design and performance optimization involving dynamic support, dynamic vibration isolation, and dynamic stability control in various fields.

[0061] The foregoing has only described certain exemplary embodiments of this application by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of this application. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of this application.

Claims

1. A method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center, characterized in that, Includes the following steps: A flexible film pressure pad was laid on the surface of the seat cushion of the seat to be evaluated. Pressure distribution data of the occupant in sitting position was collected, and the pressure center coordinates corresponding to each sampling time were calculated in real time. At the same time, electromyographic signals of the erector spinae muscles of the occupant's lumbar spine and vehicle operation status data were collected. The vehicle equipped with the seat to be evaluated was controlled to pass through a standard disturbed road section under preset test conditions. Continuous change data of the pressure center coordinates, electromyographic signals on the surface of the erector spinae muscles of the lumbar spine, and vehicle operating status data were collected during the vehicle's operation. Dynamic offset characteristic analysis is performed on the continuously changing data of the pressure center coordinates to calculate the root mean square value of the pressure center offset, the peak value of the pressure center offset, and the pressure center return time. Based on the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine during the time period corresponding to the peak of the pressure center offset, the electromyographic integral value is calculated, and the occupant is judged to have engaged in active postural compensation based on the electromyographic integral value. The dynamic vibration isolation index is obtained by normalizing the value of the root mean square of the pressure center offset, the integral value of electromyography, and the preset weight parameters. The dynamic vibration isolation performance of the seat under evaluation is then evaluated based on the dynamic vibration isolation index.

2. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center as described in claim 1, characterized in that, The flexible film pressure pad adopts a pressure sensor array structure and is set in the human contact area of ​​the seat cushion to be evaluated. It is used to continuously acquire the pressure distribution data of the occupant's buttocks and thighs acting on the surface of the cushion. The sampling frequency of the pressure sensor array is not less than 50Hz.

3. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center as described in claim 1, characterized in that, The pressure center coordinates include longitudinal coordinates that vary along the vehicle's longitudinal direction and lateral coordinates that vary along the vehicle's lateral direction. By continuously collecting the pressure center coordinates at multiple time points, a dynamic pressure center change trajectory of the occupant-seat contact interface is constructed.

4. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center as described in claim 1, characterized in that, The standard disturbance road section includes at least one of trapezoidal speed bumps, continuously damaged pavement, and long-wave undulating road, wherein trapezoidal speed bumps are used to generate transient impact excitation, continuously damaged pavement is used to generate continuous random disturbance, and long-wave undulating road is used to generate low-frequency dynamic excitation.

5. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 3, characterized in that, The root mean square value of the center of pressure offset is used to evaluate the overall swaying state of the occupant's body under the dynamic disturbance of the vehicle. The peak value of the center of pressure offset is used to evaluate the maximum instability response of the occupant caused by a single impact event. The center of pressure recovery time is used to evaluate the time required for the occupant to recover from the offset state to a stable sitting position.

6. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 1, characterized in that, Matching analysis was performed on the electromyographic signals on the surface of the erector spinae muscles of the lumbar spine and the corresponding time intervals of the pressure center shift peak. By obtaining electromyographic response data within the corresponding time range, it was determined whether the occupant would produce active posture adjustment behavior under the dynamic disturbance of the vehicle.

7. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 5, characterized in that, The dynamic vibration isolation index is comprehensively evaluated based on the dynamic offset characteristic parameters of the pressure center and the electromyographic response parameters of the human body. The dynamic offset characteristic parameters of the pressure center include the root mean square value of the pressure center offset, and the electromyographic response parameters of the human body include the electromyographic integral value.

8. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 1, characterized in that, Vehicle operating status data is collected via the vehicle's CAN bus. This data includes vehicle speed information and is used to record the vehicle's operating status during dynamic vibration isolation performance testing.

9. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 1, characterized in that, When testing different seating options, different seats to be evaluated were installed in the same test vehicle and tested with the same occupants, the same vehicle speed, and the same standard disturbance road section. The dynamic vibration isolation performance of the seats was evaluated by comparing the dynamic vibration isolation index corresponding to different seats.

10. The method for evaluating the dynamic vibration isolation performance of a seat based on dynamic offset of the pressure center according to claim 7, characterized in that, The dynamic offset characteristic parameter analysis of the pressure center also includes the analysis of the movement trajectory of the pressure center. By obtaining the direction of position change, movement distance and speed of change of the pressure center during the dynamic disturbance of the vehicle, the analysis can determine the forward and backward movement, left and right offset and posture change of the occupant's body in the seat cushion area.

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