A method and apparatus for monitoring the fatigue of office chair bottom casters during testing

Abstract

This invention relates to a monitoring method for fatigue testing of casters at the bottom of office chairs. By specifically collecting and comparing driving force data and base rotation data during the linear motion phase after caster direction adjustment, the method can quickly identify any abnormality in any of the casters through a warning message indicating that the data difference exceeds a threshold. This method offers the advantage of flexible control over the experimental process and avoids invalid testing. This invention also relates to a fatigue testing device for office chair casters, integrating multiple functions such as a horizontal testing platform, load simulation, motion guidance, power drive, data acquisition, and intelligent control into one unit, offering the advantages of high integration and concentrated functionality.

Description

Technical Field

[0001] This invention relates to the field of furniture testing technology, and in particular to a monitoring method and equipment for testing the fatigue of casters at the bottom of office chairs. Background Technology

[0002] Office chairs, as common equipment in modern offices, receive significant attention for their quality and performance. QB / T 2280-2016, "Office Furniture - Office Chairs," clearly specifies the mechanical properties of office chairs, including durability requirements such as the reciprocating wear of casters. As a critical component of office chairs, the fatigue and durability of casters directly affect the chair's lifespan and safety. Problems with the casters can lead to difficulty in moving the chair or even tipping over, threatening the user's safety.

[0003] Currently, fatigue testing of office chair casters has received some attention. This typically involves using counterweights to simulate human weight, pushing the chair in a reciprocating motion to test caster durability, checking for easy loosening or detachment, and smooth rotation. However, existing testing methods and equipment have several shortcomings. For example, most current methods struggle to accurately monitor subtle changes in casters during testing, failing to detect early abnormalities. These issues are often only noticed after severe wear or damage, failing to meet practical testing needs and resulting in lengthy testing processes.

[0004] Currently, various caster fatigue testing devices exist on the market, but they generally suffer from low levels of integration. Many devices can only perform a single function; for example, some devices can only perform static load tests, observing the caster's pressure resistance by loading heavy objects, but cannot simultaneously simulate the dynamic movement of the caster. On the other hand, some devices with dynamic testing capabilities often lack accurate load simulation and data acquisition systems, making it difficult to accurately assess the fatigue level of casters in actual use. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides, on the one hand, a monitoring method for fatigue testing of the casters at the bottom of office chairs that allows for flexible control of the experimental process and avoids invalid testing; on the other hand, it provides a fatigue testing device for the casters at the bottom of office chairs that uses the aforementioned monitoring method.

[0006] The technical solution of this invention is as follows:

[0007] A method for monitoring the fatigue of casters at the bottom of an office chair includes the following steps:

[0008] Record the number of times the casters move during the experiment;

[0009] Data acquisition steps: Synchronously acquire data for the first condition and the second condition. The data for the first condition is the driving force data when the office chair maintains linear motion after the direction of movement is adjusted. The data for the second condition is the base rotation data when the office chair maintains linear motion after the direction is adjusted.

[0010] First condition determination step: Set a first time window, collect the driving force value within the first time window, compare it with the driving force value within the previous first time window, and when the difference exceeds the preset threshold, generate the first warning information;

[0011] Second condition determination step: Set a second time window, collect the base rotation angle value within the second time window, compare it with the corresponding value within the previous second time window, and when the difference exceeds the preset threshold, a second warning message is generated;

[0012] Command output steps: The host computer receives the first or second warning information and issues the corresponding command.

[0013] Preferably, the first time window is defined as starting from the point where the caster has completed its movement direction adjustment and has traveled 40 centimeters, and ending at 60 centimeters.

[0014] The second time window is defined as the starting point when the caster's movement direction is adjusted, and the ending point when the caster finishes its one-way movement in that direction.

[0015] In any of the above schemes, it is preferred that, in the first condition determination step, driving force data of at least 5 adjacent movements are collected to form a dataset, and the mean of the driving force data is calculated and compared with the mean of the driving force dataset of the previous at least 5 adjacent movements.

[0016] In the second condition determination step, the base rotation angle values ​​of at least 5 adjacent movements are collected to form a dataset, and the average base rotation angle value is calculated and compared with the average base rotation data set of the previous at least 5 adjacent movements.

[0017] Preferably, any of the above schemes also includes a data storage step, which stores all data samples collected within each first time window and second time window for subsequent fatigue trend analysis.

[0018] Preferably, in any of the above schemes, the instruction includes at least pausing the test, issuing an alarm, generating an abnormal data report, or creating a video.

[0019] A fatigue testing device for the bottom casters of an office chair includes a horizontal testing platform, a support rod, weights, a guide mechanism, a drive mechanism, and a control unit;

[0020] The weight is placed on the top of the support rod. The caster to be tested is connected to the connecting seat at the bottom of the support rod. A connecting sleeve is slidably connected to the support rod. An angle measuring sensor is set between the connecting sleeve and the support rod.

[0021] The guiding mechanism includes a connecting rod, one end of which is connected to the connecting sleeve, and the other end of which is slidably connected to the horizontal test platform;

[0022] The driving mechanism includes a drive motor and a drive rod. One end of the drive rod is connected to the connecting sleeve via a pressure sensor. The drive motor provides power for the reciprocating motion of the caster to be tested via a transmission rod.

[0023] The angle measuring sensor, pressure sensor, and drive motor are electrically connected to the control unit.

[0024] Preferably, the drive unit is an electric motor, and a rack is provided at the drive rod, with the electric motor providing power to the drive rod through gear meshing.

[0025] In any of the above embodiments, the preferred embodiment is that the angle measuring sensor includes a transmitter, a receiver, and a measuring disk. The measuring disk has holes evenly distributed around its circumference for the transmitter rays to pass through. The transmitter, the receiver, and the connecting sleeve are fixedly connected relative to each other, and the measuring disk and the support rod are fixedly connected.

[0026] In any of the above embodiments, it is preferred that an outer sleeve is fitted on the outer wall of the support rod, a receiving groove is provided at the connecting sleeve, the bottom end of the outer sleeve is rotatably connected to the connecting sleeve via the receiving groove, and a spring is provided between the outer sleeve and the support rod.

[0027] In any of the above embodiments, it is preferred that bearings are provided between the parts where the outer sleeve contacts the bottom of the container and between the parts where the outer sleeve contacts the inner wall of the container.

[0028] Compared with existing technologies, the monitoring method for fatigue testing of the casters at the bottom of office chairs in this invention specifically collects and compares the driving force data and base rotation data during the linear motion phase after the casters are adjusted. When any one of the casters malfunctions, it can be quickly identified through a warning message indicating that the data difference exceeds a threshold. Measures can be taken promptly based on the warning message (such as pausing the test, marking abnormal points, etc.), without waiting for all casters to fail or complete a fixed number of reciprocating movements before terminating the experiment. This avoids the impact of a single damaged caster on the testing accuracy of other casters, reduces unnecessary repetitive testing, and reasonably shortens the overall experimental cycle while ensuring test effectiveness.

[0029] The fatigue testing device for the bottom casters of office chairs of this invention integrates multiple functions such as a horizontal testing platform, load simulation (weights, support rods), motion guidance (guide mechanism), power drive (drive mechanism), data acquisition (angle measurement sensor, pressure sensor), and intelligent control (control unit). The components are organically combined through connecting sleeves, connecting rods, and other structures, and the entire process of testing from load application and motion drive to data monitoring can be completed without additional scattered equipment, simplifying the complexity of the testing system. Therefore, it has the beneficial effects of high integration and concentrated functions. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the monitoring method for fatigue testing of the casters at the bottom of the office chair according to the present invention.

[0031] Figure 2 This is a flowchart illustrating a preferred embodiment of the monitoring method for fatigue testing of the casters at the bottom of an office chair according to the present invention.

[0032] Figure 3 This is a flowchart illustrating a preferred embodiment of the monitoring method for fatigue testing of the casters at the bottom of an office chair according to the present invention, specifically the second condition determination.

[0033] Figure 4 This is a graph showing the relationship between the driving force and the position of the base during a single reciprocating motion of each caster under normal working conditions, based on the monitoring method for fatigue testing of the casters at the bottom of the office chair according to the present invention.

[0034] Figure 5 This is a graph showing the relationship between the driving force and the position of the base during a single reciprocating motion when any caster malfunctions during the fatigue test of the casters at the bottom of the office chair according to the monitoring method of the present invention.

[0035] Figure 6 This is a graph showing the relationship between the base deflection angle and the base position during a single reciprocating motion of each caster under normal working conditions, based on the monitoring method for fatigue testing of the casters at the bottom of the office chair according to the present invention.

[0036] Figure 7 This is a graph showing the relationship between the base deflection angle and the base position during a single reciprocating motion when any caster malfunctions during the fatigue test of the bottom casters of the office chair according to the monitoring method of the present invention.

[0037] Figure 8 This is a schematic diagram of the fatigue testing device for the bottom casters of the office chair according to the present invention.

[0038] Figure 9 This is a schematic diagram of the angle measuring sensor and the support rod working together in the fatigue testing device for the bottom casters of the office chair of this invention.

[0039] Figure 10This is a schematic diagram showing the cooperation of the support rod, connecting sleeve, and outer sleeve of the fatigue testing device for the bottom casters of the office chair of the present invention.

[0040] Figure 11 yes Figure 10 A schematic diagram of the AA cross-section of the embodiment shown.

[0041] Explanation of the labels in the diagram:

[0042] 101-Motor; 102-Guide rod; 103-Slide rail; 104-Pressure sensor; 105-Pattern; 106-Connecting sleeve; 107-Connecting rod; 108-Horizontal test platform; 109-Support rod; 110-Base; 111-Drive rod; 112-Receiver; 113-Transmitter; 114-Measuring plate; 115-Spring; 116-Baffle; 117-First bearing; 118-Second bearing; 119-Outer sleeve; 120-Receiver groove. Detailed Implementation

[0043] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1:

[0045] This method applies to the fatigue test of the casters at the bottom of office chairs on an unobstructed horizontal test platform 108, as specified in QT / T2280.6.6.6-2016.

[0046] like Figure 1 In the illustrated embodiment, the number of caster movements refers to the total number of forward and backward movements during the test process. That is, each forward and backward movement of the caster under test is counted as a movement.

[0047] Understandably, office chair casters typically use swivel casters. Their structure includes a base, a swivel caster, and the swivel caster is rotatably connected to the base. The base is also rotatably connected to the bottom of the office chair. The rotation center lines of the base and the swivel caster are spatially perpendicular and spaced apart. When swivel casters are installed at the base 110 of the office chair, five casters are typically used, evenly distributed across the bottom of the chair to ensure stability.

[0048] During the test, driven by external force, the office chair will reciprocate between two points A and B. While the office chair is reciprocating between points A and B, the data acquisition steps simultaneously collect data for the first condition and the second condition. The data for the first condition is the driving force data when the base 110 maintains linear motion after the movement direction is adjusted. The data for the second condition is the rotation data of the base 110 when the casters are adjusting their direction.

[0049] Specifically, the driving force data can be collected using a pressure sensor 104, and the rotation data of the base 110 can be collected using an angle sensor.

[0050] like Figure 4-7 As shown, during the movement from point A to point B or from point B to point A, the uneven force on each caster at the beginning of the movement will cause each caster to adjust its direction relative to the base 110 in the initial stage. At the same time, external force is required to achieve acceleration in both the initial and final stages. Therefore, under the influence of these two factors, the office chair will require a large driving force in both the initial and final stages.

[0051] in, Figure 4 'a' represents the driving force required by the base 110 at each stage of the movement from point A to point B when all casters are in normal working condition. The X-axis represents the position of the base 110, and the Y-axis represents the driving force value.

[0052] Figure 4 b represents the driving force required by the base 110 at each stage of the movement from point B to point A when all casters are in normal working condition. The X-axis represents the position of the base 110, and the Y-axis represents the driving force value.

[0053] Figure 5 c represents the driving force required by the base 110 at each stage of the movement from point A to point B when any caster malfunctions. The X-axis represents the position of the base 110, and the Y-axis represents the driving force value.

[0054] Figure 5 d represents the driving force required by the base 110 at each stage when point B moves towards point A due to an abnormality in the working condition of any caster. The X-axis represents the position of the base 110, and the Y-axis represents the driving force value.

[0055] Figure 6 e represents the deflection angle of base 110 at each stage of the movement from point A to point B when all casters are in normal working condition. The X-axis represents the position of base 110, and the Y-axis represents the deflection angle.

[0056] Figure 6f represents the deflection angle of base 110 at each stage of the movement from point B to point A when all casters are in normal working condition. The X-axis represents the position of base 110, and the Y-axis represents the deflection angle.

[0057] Figure 7 g represents the deflection angle of base 110 at each stage when point A moves from point B due to an abnormality in the working condition of any caster. The X-axis represents the position of base 110, and the Y-axis represents the deflection angle.

[0058] Figure 7 h represents the deflection angle of base 110 at each stage when point B moves towards point A due to an abnormality in the working condition of any caster. The X-axis represents the position of base 110, and the Y-axis represents the deflection angle.

[0059] like Figure 1 As shown, in the determination steps of the first and second conditions, a first window time and a second window time are set to prevent interference with the accuracy of the determination and to facilitate data statistics. The determination method for the first condition is to collect the driving force value within the first time window and compare it with the driving force value within the previous first time window. When the difference exceeds a preset threshold, a first warning message is generated.

[0060] The second condition determination method is to collect the base rotation value within the second time window and compare it with the corresponding value within the previous second time window. When the difference exceeds the preset threshold, a second warning message is generated. The base rotation data within the second window time is the base rotation speed or rotation angle.

[0061] The determination of the first window time and the second window time can be achieved using a position sensor or a time relay. Specifically, the position of the base 110 can be detected by the position sensor, or the time relay can be used based on the speed characteristics of the reciprocating motion of the base 110.

[0062] The driving force data within the first window time period can be obtained using a segmented average and then averaged algorithm. The base rotation data within the second window time period can be obtained using a cumulative rotation algorithm. It should be noted that the driving force data of base 110 and the base rotation angle are both absolute values ​​when compared.

[0063] like Figure 1 As shown, the host computer receives the first or second warning message and issues corresponding instructions. These instructions include at least pausing the test, issuing an alarm, generating an abnormal data report, or creating a video.

[0064] Example 2:

[0065] Based on Example 1, in order to prevent interference with the accuracy of the determination of the first and second conditions, constraints are imposed on the first and second time windows in this example.

[0066] The statistical results are shown in the table below, based on the statistics of the position of the base 110 and the average driving force when each caster changes from normal working condition to abnormal working condition.

[0067] Table 1 shows the statistical values ​​of the base position and average driving force when the casters change from normal working condition to abnormal working condition.

[0068]

[0069] Table 2: Statistics of the base position and rotation angle when the casters change from normal working condition to abnormal working condition.

[0070]

[0071]

[0072] By analyzing the data in Table 1, combined with Figure 4 , 5 The driving force characteristics of each caster under normal working conditions and when any caster malfunctions are shown. The first time window is defined as the starting point when the caster has completed its movement direction adjustment and has traveled 40 centimeters, and the ending point is 60 centimeters.

[0073] By analyzing the data in Table 2, combined with Figure 6 , 7 The characteristics of the rotation angle of the base 110 at different positions when any caster malfunctions under normal working conditions are shown. The second time window is the starting point of the caster's movement direction adjustment and the ending point of the caster's one-way movement in that direction.

[0074] Example 3:

[0075] Based on Example 2, such as Figure 2 , 3 As shown, to prevent false alarms in the first and second warning messages due to accidentally high values ​​during the determination of the first and second conditions, the data characteristics of each stage in Tables 1 and 2 are considered. In the first condition determination step, driving force data from at least five adjacent movements are collected to form a dataset, and the mean of the driving force data is calculated and compared with the mean of the driving force dataset from the previous at least five adjacent movements.

[0076] In the second condition determination step, the base rotation angle values ​​of at least 5 adjacent movements are collected to form a dataset, and the average base rotation angle value is calculated and compared with the average base rotation data set of the previous at least 5 adjacent movements.

[0077] Example 4:

[0078] Based on any of the embodiments 1-3, in order to facilitate the subsequent analysis of test data, this embodiment also adds a data storage step. In the specific test, all data samples collected in each first time window and second time window are stored for subsequent fatigue trend analysis.

[0079] Example 5:

[0080] A fatigue testing device for the bottom casters of an office chair is used to perform the monitoring method for fatigue testing of the bottom casters of an office chair in any of the above embodiments.

[0081] like Figure 8 As shown, the horizontal test platform 108 is used for both the sliding of casters and the installation of various functional components. The horizontal test platform 108 includes a support frame and a panel. The support frame can be welded from steel bars or angle steel, and the panel can be made of stainless steel.

[0082] The bottom end of the support rod 109 is connected to a connecting seat, and at least five mounting seats are evenly distributed along the center of the connecting seat. The caster to be tested is installed at each mounting seat. A tray 105 is provided at the top end of the support rod 109, and the weight is movably mounted on the tray 105. The weight applies a force to the base 110 through the support rod 109.

[0083] The connecting sleeve 106 can move linearly under the constraint of the guiding mechanism. Specifically, the guiding mechanism includes a connecting rod 107, one end of which is fixedly connected to the connecting sleeve 106. Slides 103 are provided on both sides of the horizontal test platform 108, and the other end of the connecting rod 107 is slidably connected to the slides 103 on the horizontal test platform 108.

[0084] The connecting sleeve 106 is fitted onto the support rod 109 and can rotate and slide freely between them. During the specific test, the support rod 109 reciprocates along a straight line under the constraint of the connecting sleeve 106. In order to improve the tightness between the connecting sleeve 106 and the support rod 109 and reduce the friction between them during relative movement, the contact area between the connecting sleeve 106 and the support rod 109 is coated with polytetrafluoroethylene.

[0085] The drive mechanism provides power for the movement of the support rod 109, causing the caster under test to reciprocate along a preset trajectory at the horizontal test platform 108. Specifically, the drive mechanism includes a drive motor and a drive rod 111. One end of the drive rod 111 is connected to a pressure sensor 104 and a connecting sleeve 106. The pressure sensor 104 can collect the driving force of the drive mechanism in real time.

[0086] like Figure 9 As shown, the angle measuring sensor is used to measure the angle of rotation of the base 110 during the test. One optional form of the angle measuring sensor includes a transmitter 113, a receiver 112, and a measuring disk 114. The measuring disk 114 has circumferentially distributed apertures for the rays from the transmitter 113 to pass through. The transmitter 113, receiver 112, and connecting sleeve 106 are fixedly connected relative to each other. The measuring disk 114 and support rod 109 are fixedly connected. In use, the rotation data of the base 110 during the test can be calculated based on the number of times the laser is blocked and the included angle between two adjacent apertures at the measuring disk 114.

[0087] The control unit is equipped with several I / O interfaces, and the angle measuring sensor, pressure sensor 104, and drive motor are electrically connected to the corresponding I / O interfaces of the control unit. The control unit can collect rotation data of the base 110 and data from the pressure sensor 104 during the test, and issue commands to the drive motor to execute actions.

[0088] The control unit can be a microcontroller or a programmable logic controller (PLC).

[0089] Example 6:

[0090] Based on Example 5, such as Figure 8 As shown, to prevent noise generated during the use of the pneumatic push rod, the drive motor is preferably a motor 101, and a rack is provided at the drive rod 111. The motor 101 provides power to the drive rod 111 through gear meshing. A guide rod 102 is provided at the horizontal test platform 108, and the drive rod 111 is slidably connected to the guide rod 102 to guide the drive rod 111.

[0091] Example 7:

[0092] Based on Example 5 or 6, such as Figure 10 , 11 As shown, to facilitate the disassembly of the casters at the connecting seat, an outer sleeve 119 is fitted onto the outer wall of the support rod 109, and a receiving groove 120 is provided at the connecting sleeve 106 to accommodate the bottom of the outer sleeve 119. The bottom of the outer sleeve 119 is inserted into the receiving groove 120 and can be rotatably connected to the connecting sleeve 106.

[0093] Spring 115 is used to lift support rod 109 when disassembling caster. The connection between outer tube 119, support rod 109 and spring 115 is as follows: a baffle 116 is provided on the outer wall of outer tube 119, and spring 115 is sleeved on the baffle 116 of outer tube 119. When the tray 105 on support rod 109 is connected to support rod 109, the two ends of spring 115 abut against baffle 116 and tray 105 respectively.

[0094] When a weight is placed on the tray 105 during use, the weight's gravity compresses the spring 115, causing the caster at the base 110 to contact the horizontal testing platform 108. When the weight is removed, the spring force of the spring 115 causes the support rod 109 to spring up, at which point the base 110 moves away from the horizontal testing platform 108, making it easier to disassemble the caster to be tested.

[0095] It should be noted that, considering the spring force of spring 115, the mass of the weights should be increased to meet the standard requirements for fatigue testing of the casters at the bottom of office chairs in QT / T2280.6.6.6-2016.

[0096] Example 8:

[0097] Based on Example 7, such as Figure 10 , 11 As shown, during the test, in order to reduce the friction between the outer sleeve 119 and the connecting sleeve 106 when they rotate relative to each other, bearings are provided between the parts where the outer sleeve 119 and the bottom of the trough 120 contact each other, and between the parts where the outer sleeve 119 and the inner wall of the trough 120 contact each other.

[0098] The above-described embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for monitoring the fatigue of casters at the bottom of an office chair, characterized in that, Includes the following steps: Record the number of times the casters move during the experiment; Data acquisition steps: Synchronously acquire data for the first condition and the second condition. The data for the first condition is the driving force data when the office chair maintains linear motion after the direction of movement is adjusted. The data for the second condition is the base rotation data when the office chair maintains linear motion after the direction is adjusted. First condition determination step: Set a first time window, collect the driving force value within the first time window, compare it with the driving force value within the previous first time window, and when the difference exceeds the preset threshold, generate the first warning information; Second condition determination step: Set a second time window, collect the base rotation angle value within the second time window, compare it with the corresponding value within the previous second time window, and when the difference exceeds the preset threshold, a second warning message is generated; Command output steps: The host computer receives the first or second warning information and issues the corresponding command.

2. The monitoring method for fatigue testing of the casters at the bottom of an office chair as described in claim 1, characterized in that, The first time window is defined as starting from the point when the caster has completed its direction of motion adjustment and has traveled 40 centimeters, and ending at 60 centimeters. The second time window is defined as the starting point when the caster's movement direction is adjusted, and the ending point when the caster finishes its one-way movement in that direction.

3. The monitoring method for fatigue testing of the casters at the bottom of an office chair as described in claim 2, characterized in that, In the first condition determination step, driving force data of at least 5 adjacent motions are collected to form a dataset, and the mean of the driving force data is calculated and compared with the mean of the driving force dataset of the previous at least 5 adjacent motions. In the second condition determination step, the base rotation angle values ​​of at least 5 adjacent movements are collected to form a dataset, and the average base rotation angle value is calculated and compared with the average base rotation data set of the previous at least 5 adjacent movements.

4. The monitoring method for fatigue testing of the casters at the bottom of an office chair as described in claim 1, characterized in that, It also includes a data storage step, which stores all data samples collected within each first and second time window for subsequent fatigue trend analysis.

5. The monitoring method for fatigue testing of the casters at the bottom of an office chair as described in claim 1, characterized in that, The instructions include at least pausing the test, issuing an alarm, generating an anomaly data report, or creating a video.

6. A fatigue testing device for the casters at the bottom of an office chair, characterized in that, It includes a horizontal test platform (108), a support rod (109), weights, a guide mechanism, a drive mechanism, and a control unit; The weight is set on the top of the support rod (109), the caster to be tested is connected to the connecting seat at the bottom of the support rod (109), the connecting sleeve (106) is slidably connected to the support rod (109), and an angle measuring sensor is set between the connecting sleeve (106) and the support rod (109). The guiding mechanism includes a connecting rod (107), one end of which is connected to a connecting sleeve (106), and the other end is slidably connected to a horizontal test platform (108); The driving mechanism includes a drive motor and a drive rod (111). One end of the drive rod (111) is connected to a pressure sensor (104) and a connecting sleeve (106). The drive motor provides power for the reciprocating motion of the caster to be tested via a transmission rod. The angle measuring sensor, pressure sensor (104), and drive motor are electrically connected to the control unit.

7. The fatigue testing device for the bottom casters of office chairs as described in claim 6, characterized in that, The drive unit is a motor (101), and a rack is provided at the drive rod (111). The motor (101) provides power to the drive rod (111) through gear meshing.

8. The fatigue testing device for the bottom casters of office chairs as described in claim 6, characterized in that, The angle measurement sensor includes a transmitter (113), a receiver (112), and a measuring disk (114). The measuring disk (114) has holes evenly distributed around its circumference for the rays from the transmitter (113) to pass through. The transmitter (113), the receiver (112), and the connecting sleeve (106) are fixedly connected to each other. The measuring disk (114) and the support rod (109) are fixedly connected.

9. The fatigue testing device for the bottom casters of office chairs as described in claim 5 or 6, characterized in that, An outer sleeve (119) is fitted on the outer wall of the strut (109), and a groove (120) is provided at the connecting sleeve (106). The bottom end of the outer sleeve (119) is rotatably connected to the connecting sleeve (106) via the groove (120). A spring (115) is provided between the outer sleeve (119) and the strut (109).

10. The fatigue testing device for the bottom casters of an office chair as described in claim 9, characterized in that, Bearings are provided at the contact points between the bottom of the outer tube (119) and the container (120), and at the contact points between the inner walls of the outer tube (119) and the container (120).

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