Six-degree-of-freedom motion platform static load test method and system for analogue simulation

Abstract

The invention provides a six-degree-of-freedom motion platform static load test method and system for analogue simulation, and the method employs a progressive test, starts from a no-load test, gradually increases the load until the load is close to or reaches the ultimate bearing capacity of the platform, captures various changes of the platform from a no-load state to a high-load state, and achieves the simulation of the platform. Comprise stress conditions, structural deformation and levelness changes, the deformation characteristics of the platform under different loads are objectively represented, and the load capacity and stability of the platform are accurately judged. Meanwhile, curve fitting is conducted on the platform state in a stable state after each time of mass loading through the least square method, the function relation between stress, the deformation rate and the like and the load mass is obtained, the performance change rule of the platform is described more accurately, and the performance change rule of the platform can be further calculated based on a fitting equation. The performance of the platform under different load masses is predicted, and powerful data support is provided for design optimization and practical application of the platform.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-degree-of-freedom motion platforms, and in particular to testing the load capacity of platforms, and specifically to a static load testing method and system for a six-degree-of-freedom motion platform for simulation. Background Art

[0002] The six-degree-of-freedom parallel motion platform is the key to the design and development of high-level flight simulators. Through the position and posture control of the six-degree-of-freedom parallel motion platform, the six servo electric cylinders or servo motors of the six-degree-of-freedom parallel motion platform drive the telescopic movement, and control the six degrees of freedom (X, Y, Z, α, β, γ) of the upper platform in space, thereby simulating various spatial motion postures and achieving high-precision and high-fidelity simulation of the flight simulation process of the flight simulator.

[0003] The stability, reliability and motion smoothness of the six-degree-of-freedom parallel motion platform are the key basic technologies for realizing high-level flight simulators. Traditional platform testing obtains simulation and testing capabilities through the input of acceleration, force and displacement, and conducts vibration, durability, abnormal sound and noise tests. The load capacity test, which has a key impact on the reliable operation and stability of the platform itself, often relies on the performance parameters of the motion mechanism such as the linear electric cylinder used to make judgments based on the results of simulation tests, and only applies the limit load of the test results for testing, which makes it difficult to truly reflect the actual load capacity of the platform and the platform deformation rate and stability under different effective loads. Summary of the invention

[0004] In view of the defects and shortcomings of the prior art, according to the first aspect of the present invention, a static load test method for a six-degree-of-freedom motion platform for simulation is proposed, comprising:

[0005] In the initial state without any load, record the initial state data of the platform, and detect and record the initial force of each electric cylinder;

[0006] Check the levelness of the upper platform in the initial state and record the initial levelness;

[0007] Determine the initial loading load and the load loading variation according to the maximum load capacity of all electric cylinders;

[0008] Gradually load the upper platform according to the initial load and the load change;

[0009] After each load is applied, the stability of the platform is determined based on the platform vibration amplitude and force change rate, and the force on the electric cylinder, the structural deformation of the platform, and the level change are tested in the stable state;

[0010] Based on the force of the electric cylinder, the structural deformation of the platform and the horizontal change measured after each load application, the load-force function of the electric cylinder under different loads and the structural deformation function of the platform under different loads are obtained;

[0011] The maximum static load of the motion is obtained and verified based on the load-force function of the electric cylinder under different loads, and the stability of the platform is determined based on the allowable structural deformation rate limit.

[0012] As an optional embodiment, in a stable state of the platform after each load is applied, the center position of the platform is tested for structural deformation and levelness change affected by the applied load;

[0013] The structural deformation is characterized by the vertical displacement Δh of the center position of the above platform;

[0014] The horizontality change is characterized by the horizontal angle change Δθ of the center position of the upper platform.

[0015] As an optional embodiment, when the platform is in a stable state after each load is applied, the force applied to each electric cylinder in the stable state is detected.

[0016] As an optional embodiment, judging the stability state of the platform based on the platform vibration amplitude and the rate of change of the force includes:

[0017] The vibration amplitude of the platform in each direction collected during each load loading is used to calculate the root mean square value of the vibration amplitude A. RMS :

[0018]

[0019] Among them, A i represents the vibration amplitude detected by the vibration sensor in the i-th direction;

[0020] For the nth loading, the force at the center of the upper platform is measured multiple times using a force sensor. Assuming the force value measured at time t is F(t), the rate of change R(t) of force at the center of the upper platform within the time interval Δt is expressed as:

[0021]

[0022] Based on the set sliding window length T, the average sliding window change rate R at time t avg (t) is expressed as:

[0023]

[0024] In the continuous stable time window length T window For each sampling time t, check the root mean square value A of the vibration amplitude.RMS (t) and the sliding window average change rate R of the force value avg (t) are all less than the set threshold. If so, the current stable state flag stableFlag is set to Ture, indicating that the platform has reached a stable state. Otherwise, if the continuous stable time window length T window If the vibration amplitude or force change rate exceeds the set threshold at any time, the current stable state flag stableFlag is set to False and the timing is restarted until the stability condition is met again.

[0025] As an optional embodiment, for the collected vibration amplitude, outliers are identified and removed by using the 3σ standard, and interpolated and replaced with the mean of adjacent data points;

[0026] For the collected force value F(t), the 3σ standard is used to identify and remove outliers, and the mean of adjacent data points is used for interpolation replacement;

[0027] The noise is then smoothed through a preset filter.

[0028] As an optional embodiment, obtaining the load-force function of the electric cylinder under different loads includes:

[0029] Based on the load mass m of the nth loading n The force of the electric cylinder under the platform is taken as the average value of the electric cylinder force F avg,n ,

[0030] According to the load mass of each load, the force value F of the electric cylinder avg And the load mass m, draw the force value F of the electric cylinder with mass m as the horizontal axis avg The vertical axis is the curve of the electric cylinder force changing with the load mass. The data measured at any nth loading (m n , F avg,n ) are plotted in the coordinate plane to form a scatter plot;

[0031] The curve of the force of the electric cylinder changing with the load mass is fitted by least squares to obtain the load-force fitting function relationship of the electric cylinder under different loads.

[0032] As an optional embodiment, obtaining the platform structure deformation function under different loads includes:

[0033] First, calculate the structural deformation rate of the platform under each load mass:

[0034] (1) For vertical displacement, the structural deformation rate r h，n The calculation is as follows:

[0035]

[0036] Among them, h0 is the initial height of the corresponding part of the platform when it is unloaded, Δh n It represents the vertical displacement of the center position of the upper platform under the nth loading load mass;

[0037] (2) For the change of levelness, the structural deformation rate r θ，n The calculation is as follows:

[0038]

[0039] Among them, θ0 is the initial levelness of the corresponding part of the platform when it is unloaded, Δθ n It represents the horizontal angle change of the center position of the upper platform under the nth loading load mass;

[0040] Then, according to the structural deformation rate under each loading mass and the load mass m, the curves of the structural deformation rate in the vertical and horizontal directions as a function of the load mass are drawn, i.e., r h -m curve and r θ -m curve;

[0041] Finally, the deformation function of the platform structure under different loads is obtained through least squares fitting.

[0042] As an optional embodiment, the obtaining and verifying the maximum static load of the movement based on the load-force function of the electric cylinder under different loads, and determining the stability of the platform according to the allowable structural deformation rate limit, include:

[0043] (1) Determine the safe force limit F of the electric cylinder based on the design parameters of the electric cylinder max ;

[0044] According to the load-force function of the electric cylinder under different loads, calculate when the force = safe force limit F max Load mass m max , as the approximate maximum static load of the platform, and verified by actual measurement;

[0045] (2) Determine the allowable structural deformation rate limit of the platform based on the design requirements of the platform, including:

[0046] For the vertical displacement deformation rate, the allowable limit is r h,lim ; For the horizontal deformation rate, the allowable limit is r θ,lim ;

[0047] Compare the scatter plots of the curves of the structural deformation rate in the vertical and horizontal directions changing with the load mass with the allowable structural deformation rate limit. When the actual deformation rate exceeds the allowable limit under a certain load mass, it indicates that the stability of the platform under the load mass does not meet the requirements.

[0048] According to a second aspect of the present invention, a computer system is provided, comprising:

[0049] one or more processors;

[0050] A memory stores operable instructions, which, when executed by the one or more processors, cause the one or more processors to perform operations, including the process of executing the aforementioned six-degree-of-freedom motion platform static load testing method for simulation.

[0051] The static load test method for the six-degree-of-freedom motion platform used for simulation by the above embodiment adopts a progressive test, starting from a no-load test, and gradually increasing the load until it approaches or reaches the ultimate load-bearing capacity of the platform, so as to fully understand the performance of the platform under different load conditions, capture various changes in the platform from no load to high load, including stress conditions, structural deformation and horizontal changes, objectively characterize the deformation characteristics of the platform under different loads, and accurately judge the load capacity and stability of the platform. At the same time, the least squares method is used to curve fit the state of the platform in a stable state after each mass loading, and the mathematical relationship between the stress, deformation rate, etc. and the load mass is obtained, which more accurately describes the performance change law of the platform, and can further predict the performance of the platform under different load masses based on the fitting equation, providing strong data support for the design optimization and practical application of the platform.

[0052] Compared with the prior art, the static load testing method and system of the six-degree-of-freedom motion platform for simulation of the present invention have the following significant advantages:

[0053] (1) The initial loading load and the load loading variation are determined according to the maximum load capacity of all electric cylinders, and then the platform load capacity test is performed by actual step-by-step loading and actual testing, rather than using simulation results. The progressive loading method of the present invention can systematically obtain the performance data of the platform under different load conditions, and can depict in detail the curve of the platform performance changing with the load, rather than focusing only on individual load points, so as to fully understand the load characteristics of the platform; combined with the force of the electric cylinder in the stable state, the structural deformation of the platform and the level change after each load loading, the problem of focusing only on a single indicator is avoided, and the performance of the platform under static load is comprehensively evaluated from multiple dimensions;

[0054] (2) In view of the shortcomings of the traditional observation method (such as waiting for 5 minutes after loading, but different masses of loads and different states of the platform require different stabilization times) to determine the stability of the platform, the present invention uses the platform vibration amplitude and force change rate to determine the stability of the platform, because the stability of the platform not only involves whether the force is balanced, but also is related to the vibration condition. The vibration amplitude reflects the dynamic balance of the platform as a whole, and the force change rate can reflect the stability of the force during the loading process. By combining the two, the stabilization time required for the platform under each load can be determined more accurately according to the actual situation, and the stability of the platform under different loading mass conditions can be more accurately determined;

[0055] (3) By setting the length of the stable time window, the vibration amplitude and the rate of change of force are continuously checked within this time range to see if they are less than the set threshold. If they exceed the threshold, the timing is reset until the conditions are met again and the state is determined to be stable. This not only takes into account the continuity of the stable state, but also adapts to the short-term fluctuations that may occur in the platform during the loading process, thus avoiding misjudgment due to accidental factors and improving the accuracy of the stable state judgment.

[0056] It should be understood that all combinations of the aforementioned concepts and the additional concepts described in more detail below can be considered as part of the inventive subject matter of the present disclosure as long as such concepts are not mutually inconsistent. In addition, all combinations of the claimed subject matter are considered as part of the inventive subject matter of the present disclosure.

[0057] The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in each figure may be represented by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0059] Figure 1 It is a flow chart of a static load testing method of a six-degree-of-freedom motion platform for simulation according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to better understand the technical content of the present invention, specific embodiments are given and described as follows in conjunction with the accompanying drawings.

[0061] Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways, because the concepts and embodiments disclosed by the present invention are not limited to any implementation. In addition, some aspects disclosed by the present invention can be used alone or in any appropriate combination with other aspects disclosed by the present invention.

[0062] {Example 1}

[0063] Combined with Figure 1 As shown, the static load testing method of a six-degree-of-freedom motion platform for simulation according to an embodiment of the present invention includes:

[0064] In the initial state without any load, record the initial state data of the platform, and detect and record the initial force of each electric cylinder;

[0065] Check the levelness of the upper platform in the initial state and record the initial levelness;

[0066] Determine the initial loading load and the load loading variation according to the maximum load capacity of all electric cylinders;

[0067] Gradually load the upper platform according to the initial load and the load change;

[0068] After each load is applied, the stability of the platform is determined based on the platform vibration amplitude and force change rate, and the force on the electric cylinder, the structural deformation of the platform, and the level change are tested in the stable state;

[0069] Based on the force of the electric cylinder, the structural deformation of the platform and the horizontal change measured after each load application, the load-force function of the electric cylinder under different loads and the structural deformation function of the platform under different loads are obtained;

[0070] The maximum static load of the motion is obtained and verified based on the load-force function of the electric cylinder under different loads, and the stability of the platform is determined based on the allowable structural deformation rate limit.

[0071] As an optional embodiment, the load is equivalent to a uniform load and loaded at the center of the upper platform.

[0072] As an optional embodiment, in a stable state of the platform after each load is applied, the center position of the platform is tested for structural deformation and levelness change affected by the applied load;

[0073] The structural deformation is characterized by the vertical displacement Δh of the center position of the above platform;

[0074] The horizontality change is characterized by the horizontal angle change Δθ of the center position of the upper platform.

[0075] As an optional embodiment, when the platform is in a stable state after each load is applied, the force applied to each electric cylinder in the stable state is detected.

[0076] As an optional embodiment, judging the stability state of the platform based on the platform vibration amplitude and the rate of change of the force includes:

[0077] The vibration amplitude of the platform in each direction collected during each load loading is used to calculate the root mean square value of the vibration amplitude A. RMS :

[0078]

[0079] Among them, A i represents the vibration amplitude detected by the vibration sensor in the i-th direction;

[0080] For the nth loading, the force at the center of the upper platform is measured multiple times using a force sensor. Assuming the force value measured at time t is F(t), the rate of change R(t) of force at the center of the upper platform within the time interval Δt is expressed as:

[0081]

[0082] Based on the set sliding window length T, the average sliding window change rate R at time t avg (t) is expressed as:

[0083]

[0084] In the continuous stable time window length T window For each sampling time t, check the root mean square value A of the vibration amplitude. RMS (t) and the sliding window average change rate R of the force value avg (t) are all less than the set threshold. If so, the current stable state flag stableFlag is set to Ture, indicating that the platform has reached a stable state. Otherwise, if the continuous stable time window length T window If the vibration amplitude or force change rate exceeds the set threshold at any time, the current stable state flag stableFlag is set to False and the timing is restarted until the stability condition is met again.

[0085] As an optional embodiment, for the collected vibration amplitude, outliers are identified and removed by using the 3σ standard, and interpolated and replaced with the mean of adjacent data points;

[0086] For the collected force value F(t), the 3σ standard is used to identify and remove outliers, and the mean of adjacent data points is used for interpolation replacement;

[0087] The noise is then smoothed through a preset filter.

[0088] As an optional embodiment, obtaining the load-force function of the electric cylinder under different loads includes:

[0089] Based on the load mass m of the nth loading n The force of the electric cylinder under the platform is taken as the average value of the electric cylinder force F avg,n ;

[0090] According to the load mass of each load, the force value F of the electric cylinder avg And the load mass m, draw the force value F of the electric cylinder with mass m as the horizontal axis avg The vertical axis is the curve of the electric cylinder force changing with the load mass. The data measured at any nth loading (m n , F avg,n ) are plotted in the coordinate plane to form a scatter plot;

[0091] The curve of the force of the electric cylinder changing with the load mass is fitted by least squares to obtain the load-force fitting function relationship of the electric cylinder under different loads.

[0092] As an optional embodiment, obtaining the platform structure deformation function under different loads includes:

[0093] First, calculate the structural deformation rate of the platform under each load mass:

[0094] (1) For vertical displacement, the structural deformation rate r h，n The calculation is as follows:

[0095]

[0096] Among them, h0 is the initial height of the corresponding part of the platform when it is unloaded, Δh n It represents the vertical displacement of the center position of the upper platform under the nth loading load mass;

[0097] (2) For the change of levelness, the structural deformation rate r θ，n The calculation is as follows:

[0098]

[0099] Among them, θ0 is the initial levelness of the corresponding part of the platform when it is unloaded, Δθ n It represents the horizontal angle change of the center position of the upper platform under the nth loading load mass;

[0100] Then, according to the structural deformation rate under each loading mass and the load mass m, the curves of the structural deformation rate in the vertical and horizontal directions as a function of the load mass are drawn, i.e., r h -m curve and r θ -m curve;

[0101] Finally, the deformation function of the platform structure under different loads is obtained through least squares fitting.

[0102] As an optional embodiment, the aforementioned obtaining and verifying the maximum static load of the movement based on the load-force function of the electric cylinder under different loads, and determining the stability of the platform according to the allowable structural deformation rate limit, include:

[0103] (1) Determine the safe force limit F of the electric cylinder based on the design parameters of the electric cylinder max ;

[0104] According to the load-force function of the electric cylinder under different loads, calculate when the force = safe force limit F max Load mass m max , as the approximate maximum static load of the platform, and verified by actual measurement;

[0105] (2) Determine the allowable structural deformation rate limit of the platform based on the design requirements of the platform, including:

[0106] For the vertical displacement deformation rate, the allowable limit is r h,lim ; For the horizontal deformation rate, the allowable limit is r θ,lim ;

[0107] Compare the scatter plots of the curves of the structural deformation rate in the vertical and horizontal directions changing with the load mass with the allowable structural deformation rate limit. When the actual deformation rate exceeds the allowable limit under a certain load mass, it indicates that the stability of the platform under the load mass does not meet the requirements.

[0108] {Example 2}

[0109] In this embodiment, we will explain in more detail the implementation process of the six-degree-of-freedom motion platform static load testing method of the present invention in combination with specific examples.

[0110] In this embodiment, a six-degree-of-freedom parallel motion platform is used as an example. It consists of an upper platform and a lower platform. Six electric cylinders are used between the upper platform and the lower platform as a linear motion mechanism to drive the upper platform to move. High-precision force sensors are installed at the connection between the electric cylinder and the platform and at the center of the upper platform to measure the force state. The force sensor needs to be calibrated to meet the measurement accuracy requirements.

[0111] 1. Test process and data recording

[0112] (I) Initial no-load test

[0113] When no load is applied, the initial state data of the platform is recorded.

[0114] The initial force of the electric cylinder is measured by a force sensor and the data is recorded.

[0115] Use measuring tools to recheck the levelness of the platform and the dimensions of the structure to ensure they match the initial inspection results.

[0116] (II) Step-by-step loading test

[0117] (1) Determine the initial loading load and the load loading variation according to the maximum load capacity of all electric cylinders. In this embodiment, the six electric cylinders are of the same model and have the same design parameters and performance parameters.

[0118] The initial loading load is determined based on the maximum load capacity of all electric cylinders and a certain proportion of the total maximum load capacity of all electric cylinders. This proportion is usually determined as 20%-50%.

[0119] The load change is determined by the percentage of a single electric cylinder, which is usually 5%-10%.

[0120] In an embodiment of the present invention, the load adopts a hydraulic loading system, and the load is applied according to a set rule during the platform test.

[0121] (2) Then, starting from the initial loading load, the load is gradually loaded in order from small to large, and the load is evenly placed in the load installation area of ​​the upper platform, located at the center of the upper platform (within the circular range with the center point as the radius, and the radius of the circle is gradually expanded according to different load masses).

[0122] As mentioned above, after each load is applied, the vibration amplitude and force change rate of the monitoring platform are used to determine whether the platform has reached a stable state, and the stabilization time is dynamically determined. Thus, the force of the electric cylinder, the structural deformation of the platform, and the level change in the stable state are measured for subsequent force analysis and deformation analysis.

[0123] (3) Based on the force of the electric cylinder, the structural deformation of the platform and the horizontal change measured after each load application, the load-force function of the electric cylinder under different loads and the structural deformation function of the platform under different loads are obtained.

[0124] As an example, based on the load mass loaded each time and the corresponding average force of the electric cylinder, data is sorted to form a one-to-one correspondence table in a tabular form.

[0125] Then choose drawing software (such as Origin, Matlab, etc.) or spreadsheet software (such as Excel) to draw the curve. Take the load mass as the horizontal coordinate and the average force of the electric cylinder as the vertical coordinate to determine the range of the coordinate axis. The coordinate axis range should be able to cover all data points and leave a certain margin to facilitate observation of the trend of the curve. Plot each group of data points in the data table on the coordinate plane to form a scatter plot, which intuitively shows the distribution of the force of the electric cylinder with the change of load mass.

[0126] Finally, by selecting a linear function or a quadratic relationship function, the function fitting of the electric cylinder force and load mass is performed using a data table according to the least squares fitting principle.

[0127] In the example of the present invention, the fitting process is further described by taking the fitting of a linear function as an example, as follows:

[0128] For a first fitting function F avg =a×m+b, the residual sum of squares is expressed as:

[0129]

[0130] Among them, parameters a and b are the coefficients to be fitted;

[0131] Find the partial derivatives of parameters a and b respectively:

[0132]

[0133] The following system of equations is obtained:

[0134]

[0135] By solving the equation group, the values ​​of fitting coefficients a and b are obtained.

[0136] Furthermore, the fitting results can be evaluated by calculating the goodness of fit index to determine the coefficient R 2 For example:

[0137]

[0138] in, is the sample mean of the average force of the electric cylinder. The value range of is between 0 and 1. The closer it is to 1, the better the fitting effect.

[0139] Based on the fitted equation, the force of the electric cylinder under other load masses can be predicted, providing a basis for the design, control and performance evaluation of the platform. New When , the corresponding electric cylinder force prediction value is calculated by fitting equation.

[0140] (iii) Obtaining and verifying the maximum static load of the motion based on the load-force function of the electric cylinder under different loads, and determining the stability of the platform based on the platform structure deformation function under different loads and the allowable structural deformation rate limit of the platform.

[0141] As mentioned above, (1) according to the design parameters of the electric cylinder, determine the safe force limit F of the electric cylinder. max ;

[0142] According to the load-force function of the electric cylinder under different loads, calculate when the force = safe force limit F max Load mass m max , as the approximate maximum static load of the platform, and verified by actual measurement;

[0143] (2) Determine the allowable structural deformation rate limit of the platform based on the design requirements of the platform, including:

[0144] For the vertical displacement deformation rate, the allowable limit is r h,lim ; For the horizontal deformation rate, the allowable limit is r θ,lim ;

[0145] Compare the scatter plots of the curves of the structural deformation rate in the vertical and horizontal directions changing with the load mass with the allowable structural deformation rate limit. When the actual deformation rate exceeds the allowable limit under a certain load mass, it indicates that the stability of the platform under the load mass does not meet the requirements.

[0146] {Example 3}

[0147] In the above-mentioned embodiment of the present invention, after each load is applied, the vibration amplitude and force change rate of the platform are used to determine whether the platform has reached a stable state, and the stabilization time is dynamically determined. The specific implementation includes the following process:

[0148] (1) Pre-set the sampling frequency to accurately capture the platform vibration and force change information. The sampling frequency can be set to 100 Hz-1000 Hz according to the platform vibration frequency characteristics and force change speed.

[0149] (2) The collected vibration amplitude and force change rate data are time-stamped to facilitate subsequent analysis of the platform status at different times.

[0150] (3) Preprocessing the sampled vibration amplitude and force change rate data, including outlier removal and smoothing aluminum foil denoising, to remove outliers caused by sensor failure or electromagnetic interference, and to smooth the measurement noise caused by the electronic noise of the sensor and the system vibration parameters.

[0151] The filter can select a suitable filtering method according to the characteristics of the force signal, such as mean filtering, median filtering, etc.

[0152] (4) When vibration sensors are installed in multiple directions, the root mean square (RMS) value of the vibration amplitude measured by each sensor is calculated to comprehensively evaluate the overall vibration level of the platform.

[0153] Assume that there are n vibration sensors (same model and accuracy) set in a total of n directions, and the vibration amplitudes measured by them are A1, A2, ..., A n , then the root mean square value of the vibration amplitude is A RMS The calculation is as follows:

[0154]

[0155] (5) Calculation of force change rate

[0156] For the nth loading, the force at the center of the upper platform is measured multiple times using a force sensor. Assuming the force value measured at time t is F(t), the rate of change R(t) of force at the center of the upper platform within the time interval Δt is expressed as:

[0157]

[0158] Based on the set sliding window length T, the average sliding window change rate R at time t avg (t) is expressed as:

[0159]

[0160] (6) Dynamic judgment of stable time

[0161] First, set the vibration amplitude threshold A threshold (such as 0.1mm) and the force change rate threshold R threshold (such as 0.5%), set the stable time window length T window (For example, the number of time points corresponding to 1 minute is determined according to the sampling frequency), set the current stable state flag stableFlag, the default is False;

[0162] Then, after each load is applied to the platform, the vibration amplitude and rate of change of force are monitored in real time:

[0163] For each sampling time t, check the root mean square value A of the vibration amplitude RMS Is (t) less than A? threshold , and the average rate of change of the sliding window of force R avg Is (t) less than R? threshold :

[0164] - If in continuous T window If the above two judgment conditions are met within the time, the current stable state flag stableFlag is set to Ture, and the current time is recorded as the time when the platform reaches the stable state;

[0165] - If the vibration amplitude or force change rate exceeds the threshold at any time during the monitoring process, the current stable state flag stableFlag is set to False and the timing is restarted until the stability condition is met again.

[0166] Therefore, through the above steps, the time required for the platform to reach a stable state under each different load is dynamically determined according to the actual vibration conditions of the platform and the change in force, providing an accurate time basis for subsequent testing and analysis.

[0167] {Example 4}

[0168] In conjunction with the implementation of the static load testing method for a six-degree-of-freedom motion platform for simulation in the above embodiment, according to an embodiment of the present invention, a computer system is further provided, comprising: one or more processors and a memory.

[0169] It should be understood that the aforementioned memory can be used to store operable instructions, which, when executed by one or more processors, enable one or more processors to perform the following operations, including the process of executing the static load testing method of the six-degree-of-freedom motion platform for simulation simulation of the aforementioned embodiment.

[0170] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims

1. A static load test method for a six-degree-of-freedom motion platform for simulation, characterized in that: include: In the initial state without any load, record the initial state data of the platform, and detect and record the initial force of each electric cylinder; Check the levelness of the upper platform in the initial state and record the initial levelness; Determine the initial loading load and the load loading variation according to the maximum load capacity of all electric cylinders; Gradually load the upper platform according to the initial load and the load change; After each load is applied, the stability of the platform is determined based on the platform vibration amplitude and force change rate, and the force on the electric cylinder, the structural deformation of the platform, and the level change are tested in the stable state; Based on the force of the electric cylinder, the structural deformation of the platform and the horizontal change measured after each load application, the load-force function of the electric cylinder under different loads and the structural deformation function of the platform under different loads are obtained; The maximum static load of the motion is obtained and verified based on the load-force function of the electric cylinder under different loads, and the stability of the platform is determined based on the allowable structural deformation rate limit.

2. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: The load is equivalent to a uniform load and loaded at the center of the upper platform.

3. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: In the stable state of the platform after each loading, the center position of the above platform is tested for structural deformation and horizontal changes affected by the loaded load; The structural deformation is characterized by the vertical displacement Δh of the center position of the above platform; The horizontality change is characterized by the horizontal angle change Δθ of the center position of the upper platform.

4. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: When the platform is in a stable state after each load is applied, the force of each electric cylinder in the stable state is detected.

5. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: The determining of the platform stability state based on the platform vibration amplitude and the rate of change of the force comprises: The vibration amplitude of the platform in each direction collected during each load loading is used to calculate the root mean square value of the vibration amplitude A. RMS : Among them, A i represents the vibration amplitude detected by the vibration sensor in the i-th direction; For the nth loading, the force at the center of the upper platform is measured multiple times using a force sensor. Assuming the force value measured at time t is F(t), the rate of change R(t) of force at the center of the upper platform within the time interval Δt is expressed as: Based on the set sliding window length T, the average sliding window change rate R at time t avg (t) is expressed as: In the continuous stable time window length T window For each sampling time t, check the root mean square value A of the vibration amplitude. RMS (t) and the sliding window average change rate R of the force value avg (t) are all less than the set threshold. If so, the current stable state flag stableFlag is set to Ture, indicating that the platform has reached a stable state. Otherwise, if the continuous stable time window length T window If the vibration amplitude or force change rate exceeds the set threshold at any time, the current stable state flag stableFlag is set to False and the timing is restarted until the stability condition is met again.

6. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 5, characterized in that: For the vibration amplitude collected, outliers were identified and removed using the 3σ standard, and interpolated with the mean of adjacent data points; For the collected force value F(t), the 3σ standard is used to identify and remove outliers, and the mean of adjacent data points is used for interpolation replacement; The noise is then smoothed through a preset filter.

7. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: The step of obtaining the load-force function of the electric cylinder under different loads includes: Based on the load mass m of the nth loading n The force of the electric cylinder under the platform is taken as the average value of the electric cylinder force F avg,n , According to the load mass of each load, the force value F of the electric cylinder avg And the load mass m, draw the force value F of the electric cylinder with mass m as the horizontal axis avg The vertical axis is the curve of the electric cylinder force changing with the load mass. The data measured at any nth loading (m n , F avg,n ) are plotted in the coordinate plane to form a scatter plot; The curve of the force of the electric cylinder changing with the load mass is fitted by least squares to obtain the load-force fitting function relationship of the electric cylinder under different loads.

8. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: Obtain the platform structure deformation function under different loads, including: First, calculate the structural deformation rate of the platform under each load mass: (1) For vertical displacement, the structural deformation rate r h，n The calculation is as follows: Among them, h0 is the initial height of the corresponding part of the platform when it is unloaded, Δh n It represents the vertical displacement of the center position of the upper platform under the nth loading load mass; (2) For the change of levelness, the structural deformation rate r θ，n The calculation is as follows: Among them, θ0 is the initial levelness of the corresponding part of the platform when it is unloaded, Δθ n It represents the horizontal angle change of the center position of the upper platform under the nth loading load mass; Then, according to the structural deformation rate under each loading mass and the load mass m, the curves of the structural deformation rate in the vertical and horizontal directions as a function of the load mass are drawn, i.e., r h -m curve and r θ -m curve; Finally, the deformation function of the platform structure under different loads is obtained through least squares fitting.

9. The static load testing method for a six-degree-of-freedom motion platform for simulation according to claim 1, characterized in that: The method of obtaining and verifying the maximum static load of the movement based on the load-force function of the electric cylinder under different loads, and determining the stability of the platform according to the allowable structural deformation rate limit, includes: (1) Determine the safe force limit F of the electric cylinder based on the design parameters of the electric cylinder max ; According to the load-force function of the electric cylinder under different loads, calculate when the force = safe force limit F max Load mass m max , as the approximate maximum static load of the platform, and verified by actual measurement; (2) Determine the allowable structural deformation rate limit of the platform based on the design requirements of the platform, including: For the vertical displacement deformation rate, the allowable limit is r h,lim ; For the horizontal deformation rate, the allowable limit is r θ,lim ; Compare the scatter plots of the curves of the structural deformation rate in the vertical and horizontal directions changing with the load mass with the allowable structural deformation rate limit. When the actual deformation rate exceeds the allowable limit under a certain load mass, it indicates that the stability of the platform under the load mass does not meet the requirements.

10. A computer system, characterized in that: include: one or more processors; A memory storing operable instructions, wherein when the instructions are executed by the one or more processors, the one or more processors are caused to perform operations, wherein the operations include the process of executing the static load testing method for a six-degree-of-freedom motion platform for simulation as described in any one of claims 1 to 9.

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