Field calibration and calibration uncertainty evaluation method for rocket sled

Abstract

The invention relates to a field calibration and calibration uncertainty evaluation method for a rocket sled, and belongs to the field of dynamic characteristic calibration. Comprising the following steps: applying excitation signals of different vibration levels to a rocket sled measuring system within a measuring range of an impact sensor of the rocket sled measuring system to respectively obtain a true value of a standard impact sensor and a measured value of the impact sensor of the measuring system; constructing an optimization function between the measuring range and the full scale of the impact sensor of the rocket sled measuring system, and solving the optimization function to obtain a predicted value of the impact sensor of the measuring system; based on the true value of the standard impact sensor and the measured value and the predicted value of the impact sensor of the measuring system, obtaining impact amplitude linearity; excitation signals with different frequencies are applied to the rocket sled measurement system to obtain vibration amplitude frequency response; and carrying out uncertainty evaluation on the impact amplitude linearity and the vibration amplitude frequency response. According to the method, field calibration of the rocket sled measurement system and uncertainty evaluation of the calibration result are realized.

Description

Technical Field

[0001] The invention relates to the field of dynamic characteristic calibration, and in particular to a method for on-site calibration of a rocket sled and calibration uncertainty evaluation. Background Art

[0002] Rocket sleds are mainly used to test the performance indicators of the object being tested during flight. With the rapid development of aerospace and other fields, the speed and accuracy requirements for rocket sleds are becoming higher and higher. Therefore, in order to enable the measurement system on the rocket sled to provide high-precision measurement results, how to accurately calibrate it has become one of the key issues that need to be solved in the development of hypersonic rocket sled test technology.

[0003] At present, the calibration of rocket sled measurement system usually adopts the inspection method, that is, calibration is carried out in the laboratory and then installed on the rocket sled. However, the placement position, installation torque and on-site environment of the rocket sled measurement system sensor will have a great influence on the measurement results, resulting in large errors in the measurement results after the measurement system is calibrated.

[0004] It can be seen that providing a method for on-site calibration of the rocket sled measurement system is an urgent problem that needs to be solved. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a method for on-site calibration and calibration uncertainty evaluation of a rocket sled, so as to solve the problem of lack of on-site calibration method for the rocket sled measurement system.

[0006] The present invention provides a method for on-site calibration of a rocket sled and calibration uncertainty assessment, the method comprising the following steps:

[0007] Within the measurement range of the impact sensor of the rocket sled measurement system, a pulsed impact excitation device is used to apply several excitation signals of different vibration levels to the rocket sled measurement system to obtain the true value of the standard impact sensor and the measured value of the measurement system impact sensor respectively; between the measurement range of the rocket sled measurement system impact sensor and its full scale, an optimization function is constructed based on the true value of the standard impact sensor and the measured value of the measurement system impact sensor, and the predicted value of the measurement system impact sensor is obtained by solving the optimization function; based on the true value of the standard impact sensor, the measured value of the measurement system impact sensor and the predicted value, a linear regression analysis is performed using the least squares method to obtain the slope and intercept of the regression line, and the linearity of the impact amplitude is obtained based on the slope of the regression line and the maximum value of the impact acceleration measurement value or the predicted value;

[0008] Applying a plurality of excitation signals of different frequencies to the rocket sled measurement system through a sinusoidal excitation generating device to obtain the true value of the standard vibration sensor and the measured value of the vibration sensor of the measurement system, and obtaining the vibration amplitude frequency response based on the true value of the standard vibration sensor and the measured value of the vibration sensor of the measurement system;

[0009] Uncertainty assessments were performed on the shock amplitude linearity and vibration amplitude frequency response.

[0010] Furthermore, the slope of the regression line is obtained by the following formula:

[0011]

[0012] Among them, K is the slope of the regression line, a i is the measured value or predicted value of the impact acceleration corresponding to the i-th excitation signal, S i is the sensitivity corresponding to the i-th excitation signal, n is the number of excitation signals, for a i The sensitivity corresponding to the excitation signal is the ratio of the measured value or predicted value of the impact acceleration corresponding to the excitation signal to the true value;

[0013] The intercept of the regression line is obtained by the following formula:

[0014]

[0015] Among them, S0 is the intercept of the regression line, For S i The average value of .

[0016] Furthermore, the linearity of the impact amplitude is obtained by the following formula:

[0017]

[0018] Among them, γ is the linearity of the impact amplitude, a max for a i The maximum value, S n for a max The corresponding sensitivity.

[0019] Furthermore, the vibration amplitude frequency response is obtained by the following formula:

[0020]

[0021] Among them, δ a is the vibration amplitude frequency response, x i is the measured value of the vibration amplitude corresponding to the i-th excitation signal, x r is the true value of the vibration amplitude corresponding to the i-th excitation signal.

[0022] Furthermore, the uncertainty includes: the uncertainty u introduced by measurement repeatability A , uncertainty u1 introduced by standard sensor, uncertainty u2 introduced by transfer characteristics of rocket sled measurement system, uncertainty u3 introduced by signal conditioning unit, uncertainty u4 introduced by data acquisition system, uncertainty u5 introduced by stability of excitation source, uncertainty u6 introduced by waveform distortion of excitation source, uncertainty u7 introduced by random interference signal.

[0023] Furthermore, the uncertainty of the impact amplitude linearity and the vibration amplitude frequency response is obtained by the following formula:

[0024]

[0025] Furthermore, the uncertainty introduced by measurement repeatability is obtained by the following formula:

[0026]

[0027] Among them, m is the number of excitation signals, y i is the vibration amplitude or the measured value of the impact acceleration corresponding to the i-th excitation signal, for y i The average value of

[0028] u1-u7 is obtained by the following formula:

[0029]

[0030] Among them, U i % is u i The corresponding error rate, λ i for u i The corresponding coefficient.

[0031] Furthermore, between the measurement range of the impact sensor of the rocket sled measurement system and its full range, an optimization function is constructed based on the true value of the standard impact sensor and the measurement value of the impact sensor of the measurement system, and the predicted value of the impact sensor of the measurement system is obtained by solving the optimization function, including:

[0032] Step S101, constructing a time domain output response function of the impact sensor of the measurement system based on the linear time-invariant system principle, and obtaining a discretized frequency domain output response function;

[0033] Step S102, obtaining a replacement vector of each parameter in the frequency domain output response function based on the frequency domain complex transfer function of the frequency domain output response function;

[0034] Step S103, constructing a truth matrix based on the true value of the shock acceleration of the standard shock sensor, and constructing a measurement shock acceleration matrix containing uncertainty based on the measured value of the shock acceleration of the shock sensor of the measurement system;

[0035] Step S104, constructing an optimization function based on the measured impact acceleration matrix and the truth matrix, solving the optimization function using the least squares method to obtain estimated values ​​of the parameters in the frequency domain output response function, and obtaining estimated values ​​of the parameters of the time domain output response function by replacing the vector and the estimated values; between the measurement range of the impact sensor of the rocket sled measurement system and its full range, obtaining the predicted impact acceleration of the measurement system impact sensor by using the time domain output response function and the estimated values ​​of its parameters.

[0036] Furthermore, the frequency domain complex transfer function is:

[0037]

[0038] Wherein, H() is the complex transfer function in the frequency domain, i is the imaginary unit, S() is the amplitude function of the transfer function, φ() is the phase function of the transfer function, ω is the response frequency, δ is the damping coefficient of the shock sensor, ω0 is the installation resonant frequency of the shock sensor, and ε is the inherent characteristic constant of the shock sensor.

[0039] Furthermore, the parameters of the discretized frequency domain output response function are obtained by the following method:

[0040]

[0041] Where T is the sampling interval, b, c1, and c2 are the parameters of the discretized frequency domain output response function.

[0042] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0043] 1. The present invention realizes the on-site calibration of the rocket sled measurement system by obtaining the impact amplitude linearity and the vibration amplitude frequency response.

[0044] 2. The present invention solidifies the boundary conditions of the rocket sled measurement system, thereby constructing the time domain output response function of the rocket sled measurement system sensor based on the principle of linear time invariant system, and takes into account the structural characteristics of the sensor itself through the parameters of the time domain output response function, providing a basis for accurately predicting the impact acceleration of the rocket sled.

[0045] 3. The present invention constructs an optimization function and uses the least squares method to solve the optimization function to obtain the estimated values ​​of the parameters in the frequency domain output response function, and obtains the predicted impact acceleration of the measurement system sensor based on the estimated values ​​of the parameters, thereby solving the problem that the impact acceleration of the rocket sled measurement system sensor cannot obtain the full-scale calibration value during on-site calibration.

[0046] 4. The present invention realizes the uncertainty evaluation of the field calibration results of the rocket sled measurement system by calculating the uncertainty of the impact amplitude linearity and the vibration amplitude frequency response.

[0047] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0049] Figure 1 It is a flow chart of a method for field calibration and calibration uncertainty assessment of a rocket sled according to an embodiment of the present invention;

[0050] Figure 2 4 is a block diagram of a rocket sled measurement system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0052] A specific embodiment of the present invention discloses a method for on-site calibration of a rocket sled and calibration uncertainty assessment. Figure 1 As shown, the method comprises the following steps:

[0053] Step S1, within the measurement range of the impact sensor of the rocket sled measurement system, apply several excitation signals of different vibration levels to the rocket sled measurement system through a pulsed impact excitation device to obtain the true value of the standard impact sensor and the measured value of the measurement system impact sensor respectively; between the measurement range of the rocket sled measurement system impact sensor and its full scale, construct an optimization function based on the true value of the standard impact sensor and the measured value of the measurement system impact sensor, and obtain the predicted value of the measurement system impact sensor by solving the optimization function; based on the true value of the standard impact sensor, the measured value and the predicted value of the measurement system impact sensor, use the least squares method to perform linear regression analysis to obtain the slope and intercept of the regression line, and obtain the impact amplitude linearity based on the slope of the regression line and the maximum value of the impact acceleration measurement value or predicted value;

[0054] Step S2, applying a plurality of excitation signals of different frequencies to the rocket sled measurement system through a sinusoidal excitation generating device to obtain the true value of the standard vibration sensor and the measurement value of the vibration sensor of the measurement system, and obtaining the vibration amplitude frequency response based on the true value of the standard vibration sensor and the measurement value of the vibration sensor of the measurement system;

[0055] Step S3: performing uncertainty evaluation on the impact amplitude linearity and the vibration amplitude frequency response.

[0056] Specifically, in step S1, Figure 2 As shown, the rocket sled measurement system includes a trigger device, a data acquisition system, a signal conditioning unit, an impact sensor and a vibration sensor. When the excitation source applies an excitation signal to the rocket sled, the trigger device triggers the data acquisition system, so that the data acquisition system starts to record the response of the impact sensor or the vibration sensor; the excitation source includes a pulsed impact excitation device and a sinusoidal excitation generating device. At this time, the impact sensor or the vibration sensor outputs a corresponding response signal according to the excitation generated by the excitation source, and the response signal is converted into a voltage signal by the signal conditioning unit and then input into the data acquisition system.

[0057] Furthermore, before applying the excitation signal through the excitation source, it is necessary to determine the boundary conditions of the rocket sled measurement system, and the boundary conditions of the rocket sled measurement system include: the impact sensor of the rocket sled measurement system and the standard impact sensor of the pulse impact excitation device are fixed with the same installation torque and screws to be rigidly connected; the vibration sensor of the rocket sled measurement system and the standard vibration sensor of the sinusoidal excitation generating device are fixed with the same installation torque and screws to be rigidly connected; the boundary conditions of the measurement system and the excitation source are solidified.

[0058] It can be understood that the measurement system and the excitation source are in the same environmental conditions. When their boundary conditions are solidified by the above method, they constitute a linear time-invariant system. For a linear time-invariant system, a sufficient condition for the stability of its input and output states is that its zero input system is stable. When the impact sensor and vibration sensor of the rocket sled measurement system and the standard sensor of the excitation source use the same installation torque and installation method, the zero input system of the measurement system and the excitation source is stable.

[0059] Furthermore, a measurement range of the impact sensor of the rocket sled measurement system is set. Within the measurement range, L excitation signals are applied to the rocket sled measurement system in sequence at different frequencies and amplitudes to obtain L true values ​​of the standard impact sensor and L measurement values ​​of the measurement system impact sensor.

[0060] It should be noted that the full scale of the impact sensor of the rocket sled measurement system is obtained according to the technical specifications, and the measurement range is set according to the full scale. Exemplarily, the measurement range is set to 75% of the full scale. It is understandable that due to the influence of environmental factors, the impact sensor of the rocket sled measurement system cannot obtain the full-scale measurement value, so a reasonable measurement range is set and the measurement value of the impact acceleration is obtained within the measurement range, and then the predicted value of the impact acceleration between the measurement range and the full scale is obtained according to the true value and measurement value of the impact acceleration, so as to realize the full-scale field calibration of the rocket sled impact acceleration. Excitation signals of different vibration levels are applied to the rocket sled measurement system, that is, excitation signals are applied to the rocket sled measurement system at different frequencies and amplitudes. The standard impact sensor outputs a corresponding response signal to the excitation signal, and the response signal is converted into a voltage signal by a signal conditioning unit. The voltage signal is the true value of the impact acceleration of the standard impact sensor, including amplitude and phase information. Similarly, the impact sensor of the rocket sled measurement system outputs a corresponding response signal to the excitation signal, and the response signal is converted into a voltage signal by the signal conditioning unit. The voltage signal is the measurement value of the impact acceleration of the impact sensor of the measurement system.

[0061] Furthermore, between the measurement range of the impact sensor of the rocket sled measurement system and its full range, an optimization function is constructed based on the true value of the standard impact sensor and the measurement value of the impact sensor of the measurement system, and the predicted value of the impact sensor of the measurement system is obtained by solving the optimization function, including:

[0062] Step S101, constructing a time domain output response function of the impact sensor of the measurement system based on the linear time-invariant system principle, and obtaining a discretized frequency domain output response function;

[0063] Step S102, obtaining a replacement vector of each parameter in the frequency domain output response function based on the frequency domain complex transfer function of the frequency domain output response function;

[0064] Step S103, constructing a truth matrix based on the true value of the shock acceleration of the standard shock sensor, and constructing a measurement shock acceleration matrix containing uncertainty based on the measured value of the shock acceleration of the shock sensor of the measurement system;

[0065] Step S104, constructing an optimization function based on the measured impact acceleration matrix and the truth matrix, solving the optimization function using the least squares method to obtain estimated values ​​of the parameters in the frequency domain output response function, and obtaining estimated values ​​of the parameters of the time domain output response function by replacing the vector and the estimated values; between the measurement range of the impact sensor of the rocket sled measurement system and its full range, obtaining the predicted impact acceleration of the measurement system impact sensor by using the time domain output response function and the estimated values ​​of its parameters.

[0066] Specifically, in step S101, the time domain output response function of the impact sensor of the measurement system is:

[0067]

[0068] Where y(t) is the output value of the impact sensor, is the first-order derivative of the output value of the shock sensor, is the second-order derivative of the output value of the shock sensor, δ is the damping coefficient of the shock sensor, ω0 is the installation resonant frequency of the shock sensor, ε is the inherent characteristic constant of the shock sensor, and x(t) is the input value of the shock sensor.

[0069] It can be understood that based on the linear time-invariant system principle, a mathematical model is used to describe the input-output characteristics of the impact sensor, that is, the time-domain output response function. In addition, considering the structural characteristics of the impact sensor itself, a set of parameters of the model is used to represent the structural characteristics of the sensor. The present invention solidifies the boundary conditions of the rocket sled measurement system, thereby constructing the time-domain output response function of the rocket sled measurement system sensor based on the linear time-invariant system principle, and takes into account the structural characteristics of the sensor itself through the parameters of the time-domain output response function, providing a basis for accurately predicting the impact acceleration of the rocket sled.

[0070] Specifically, for the linear time-invariant system, its transfer function can be obtained based on the above function formula, and the transfer function is inversely calculated, Z-transformed, and sampled to obtain a discretized frequency domain output response function.

[0071] The complex transfer function in the frequency domain is:

[0072]

[0073] Where H() is the complex transfer function in the frequency domain, i is the imaginary unit, S() is the amplitude function of the transfer function, φ() is the phase function of the transfer function, and ω is the response frequency.

[0074] Taking the inverse of the transfer function yields:

[0075]

[0076] Where G() is the inverse of the complex transfer function and s is the Laplace factor.

[0077] The Laplace factor s in the above formula is z-transformed by the following method:

[0078]

[0079] Where z is the z-transform factor and T is the sampling interval.

[0080] Furthermore, the discretized frequency domain output response function is:

[0081] y k +c1y k-1 +c2y k-2 = b(a k +2a k-1 +a k-2 ),

[0082] Among them, y k is the output of the impact sensor at time k; a k is the input of the shock sensor at time k, b, c1, c2 are the parameters of the discretized frequency domain output response function.

[0083] Specifically, the parameters of the discretized frequency domain output response function are obtained by the following method:

[0084]

[0085] It is understandable that the full scale of impact acceleration is usually 20g to 10000g. The above parameters can be determined by rigidly mounting the impact sensor on a pneumatic impact standard device in the laboratory and measuring the linearity of the impact amplitude within the full scale range. It can be seen from the discretized frequency domain output response function that the above parameters are closely related to the sampling interval. According to the sampling law, in order to prevent the influence of uncertainty caused by the first-order resonant frequency of the impact sensor, the sampling frequency should be higher than 5 times the first-order resonant frequency. Preferably, the sampling frequency is higher than 10 times the first-order resonant frequency.

[0086] Specifically, in step S102, since the main frequency component of the impact sensor is a high-frequency signal, its frequency domain complex transfer function can be obtained based on the frequency domain output response function. The frequency domain complex transfer function of the frequency domain output response function is:

[0087]

[0088] Where, Ω = ω / f s =ωT is the angular frequency after sampling and normalization.

[0089] Taking the inverse of the frequency domain complex transfer function yields:

[0090]

[0091] Furthermore, by comparing the above two formulas, a replacement vector can be obtained, and the formula of the replacement vector is:

[0092] v T =[v1, v2, v3] = [1 / b, c1 / b, c2 / b],

[0093] Among them, v T is the replacement vector.

[0094] Specifically, in step S103, the true value of the shock acceleration of the standard shock sensor is expressed as: T =[a1, a2, …, a L ], where a L is the Lth shock acceleration true value of the standard shock sensor.

[0095] Furthermore, the truth matrix is:

[0096]

[0097] Among them, H is the truth matrix, a(ω L ) is the true value of the impact acceleration of the Lth excitation signal.

[0098] It should be noted that the truth value matrix is ​​constructed according to the L truth values ​​of the standard shock sensor obtained in step S1.

[0099] Specifically, the measured value of the impact acceleration of the impact sensor of the measurement system is expressed as: G(ω)=[G1, G2, ..., G L ]. According to historical experience, the corresponding uncertainty is set as u ω =[u1,u2,…,u L ], where u L is the standard uncertainty of the Lth response value.

[0100] Furthermore, the measured impact acceleration matrix is:

[0101]

[0102] Among them, y is the measured impact acceleration matrix, Re is the real part, Im is the imaginary part, G L is the Lth response value after adding uncertainty, exp is an exponential function with e as the base, j is an imaginary number, is the phase of the Lth response value after adding uncertainty.

[0103] Furthermore, the uncertainty vector is obtained by the following method:

[0104]

[0105] Among them, u i is the standard uncertainty corresponding to the ith response value, G i is the ith response value, is the phase of the i-th response value, σ is the shock acceleration amplitude random variable of the normal distribution, and ∈ is the phase random variable of the normal distribution.

[0106] It is understandable that according to public literature and historical experience data, it can be found that the response of the impact sensor obeys a normal distribution, and the standard deviation is the standard uncertainty of its response. The present invention takes uncertainty into account when constructing the impact acceleration measurement matrix, so that the uncertainty is taken into account when predicting the impact acceleration, thereby improving the accuracy of the prediction.

[0107] Specifically, in step S104, the optimization function is:

[0108]

[0109] in, Outputs estimates of the parameters in the frequency-domain response function.

[0110] Specifically, the covariance matrix of the parameter estimation values ​​in the frequency domain output response function, that is, the uncertainty of the parameter estimation values, is obtained by the following method:

[0111]

[0112] in, for The covariance matrix, H T is the transformed rank of the truth matrix, V y is the covariance matrix of y, V y -1 V y The inverse matrix of .

[0113] It can be understood that the estimated values ​​of the parameters in the frequency domain output response function can be obtained by solving the optimization function using the least square method.

[0114] Specifically, after solving the estimated values ​​of each parameter in the frequency domain, the estimated values ​​of v1, ν2, and ν3 are obtained by using the replacement vector, and then the estimated values ​​of each parameter in the time domain output response function are obtained by the following formula.

[0115] Furthermore, the estimated values ​​of the time domain output response function parameters are:

[0116]

[0117] Where T is the sampling interval.

[0118] It should be noted that the estimated values ​​of the parameters in the frequency domain output response function are replaced by the replacement vector to obtain the estimated values ​​of the parameters in the time domain output response function. Substituting the estimated values ​​of the parameters in the time domain output response function into the time domain output response function, the predicted optimal impact acceleration of the impact sensor of the measurement system can be obtained. The present invention obtains the measurement value of the rocket sled measurement system sensor through a number of different excitation signals, that is, the impact acceleration is predicted based on the true value and the measurement value obtained in the field environment, thereby improving the prediction accuracy. The present invention obtains the estimated values ​​of the parameters in the frequency domain output response function by constructing an optimization function and solving the optimization function using the least squares method, and obtains the predicted impact acceleration of the measurement system sensor based on the estimated values ​​of the parameters, thereby solving the problem that the impact acceleration of the rocket sled measurement system sensor cannot obtain the full-scale calibration value during field calibration.

[0119] Specifically, between the measurement range of the impact sensor of the rocket sled measurement system and its full scale, L′ excitation signals with different frequencies and amplitudes are selected, and L′ predicted values ​​corresponding to the impact sensor of the measurement system are obtained based on the above method.

[0120] Furthermore, the least squares method was used for linear regression analysis, and the slope of the regression line was obtained by the following formula:

[0121]

[0122] Among them, K is the slope of the regression line, a i is the measured value or predicted value of the impact acceleration corresponding to the i-th excitation signal, S i is the sensitivity corresponding to the i-th excitation signal, n is the number of excitation signals, for a i The average value of .

[0123] It should be noted that n is the sum of L and L′. The sensitivity corresponding to the excitation signal is the ratio of the impact acceleration measurement value or predicted value corresponding to the excitation signal to the true value.

[0124] Furthermore, the intercept of the regression line is obtained by the following formula:

[0125]

[0126] Among them, S0 is the intercept of the regression line, For S i The average value of .

[0127] Furthermore, the linearity of the impact amplitude is obtained by the following formula:

[0128]

[0129] Among them, γ is the linearity of the impact amplitude, a max for a i The maximum value, S n for a max The corresponding sensitivity.

[0130] Specifically, in step S2, L3 excitation signals are applied to the rocket sled measurement system at different frequencies in turn to obtain L3 true values ​​of the standard vibration sensor and L3 measurement values ​​of the vibration sensor of the measurement system.

[0131] It should be noted that the standard vibration sensor outputs a corresponding response signal to the excitation signal, and the response signal is converted into a voltage signal by the signal conditioning unit, and the voltage signal is the true value of the vibration amplitude of the standard vibration sensor. Similarly, the rocket sled measurement system vibration sensor outputs a corresponding response signal to the excitation signal, and the response signal is converted into a voltage signal by the signal conditioning unit, and the voltage signal is the measured value of the vibration amplitude of the measurement system vibration sensor.

[0132] Furthermore, the vibration amplitude frequency response is obtained by the following formula:

[0133]

[0134] Among them, δ a is the vibration amplitude frequency response, x i is the measured value of the vibration amplitude corresponding to the i-th excitation signal, x r is the true value of the vibration amplitude corresponding to the i-th excitation signal.

[0135] It should be noted that when the rocket sled is running, its impact acceleration and vibration amplitude are strongly correlated with its running speed. Therefore, the linearity of the impact amplitude obtained from the impact acceleration and the vibration amplitude frequency response obtained from the vibration amplitude are important indicators for the calibration of the rocket sled. Since the placement, installation torque and on-site environment of the rocket sled measurement system sensor will have a great influence on the sensor's measurement results, the characteristics of the rocket sled measurement system sensor are unknown. The sensitivity, impact amplitude linearity and vibration amplitude frequency response are calibrated through the above method, thereby completing the on-site calibration of the rocket sled measurement system.

[0136] It can be understood that the present invention achieves on-site calibration of the rocket sled measurement system by obtaining the impact amplitude linearity and the vibration amplitude frequency response.

[0137] Specifically, in step S3, the uncertainty includes: the uncertainty u introduced by measurement repeatability A , uncertainty u1 introduced by standard sensor, uncertainty u2 introduced by transfer characteristics of rocket sled measurement system, uncertainty u3 introduced by signal conditioning unit, uncertainty u4 introduced by data acquisition system, uncertainty u5 introduced by stability of excitation source, uncertainty u6 introduced by waveform distortion of excitation source, uncertainty u7 introduced by random interference signal.

[0138] Furthermore, the uncertainty of the impact amplitude linearity and the vibration amplitude frequency response is obtained by the following formula:

[0139]

[0140] Specifically, the uncertainty introduced by measurement repeatability is obtained by the following formula:

[0141]

[0142] Among them, m is the number of excitation signals, y i is the vibration amplitude or the measured value of the impact acceleration corresponding to the i-th excitation signal, for y i The average value of .

[0143] u1-u7 is obtained by the following formula:

[0144]

[0145] Among them, U i % is u i The corresponding error rate, λ i for u i The corresponding coefficient.

[0146] Exemplarily, the uncertainty of the vibration amplitude frequency response is calculated by the above formula. Assuming m=10, the corresponding vibration amplitude measurement values ​​are shown in the following table:

[0147] Table 1 Measurement values ​​of vibration amplitude

[0148] Number of measurements Vibration amplitude measurement value (mm) 1 100.21 2 100.14 3 100.08 4 100.11 5 100.19 6 100.35 7 100.24 8 100.31 9 100.52 10 100.37

[0149] The corresponding vibration amplitude has an average value of 100.25 and a standard deviation of 1.36×10 -1 ,u A 1.36×10 -3 According to the standard vibration sensor traceability evaluation, U1% is 5%. Assuming λ1 is 2, u1 is 2.5×10 -2 According to the statistical data, the influence of the transfer characteristics of the rocket sled measurement system on the measured value of the vibration amplitude is less than 1.5%, so U2% is set to 1.5%, assuming that λ2 is So u2 is 8.66×10 -3 Assuming that the upper limit of the error of the signal conditioning unit is 0.2%, we set U3% to 0.2% and λ3 to So u3 is 1.2×10 -3 ; Assuming that the upper limit of the error of the data acquisition system is 0.1%, we set U4% to 0.1% and λ4 to So u4 is 5.8×10 -4 According to the statistical data, the influence of the stability of the sine excitation generator is less than 2.5%, so U5% is set to 2.5%, assuming that λ5 is So u5 is 1.44×10 -2 Assuming that the upper limit of the error of the waveform distortion of the sinusoidal excitation generator is 3%, U6% is set to 3%, and λ6 is So u6 is 1.73×10 -2 According to the statistical data, the impact of random interference signals is less than 2.2%, so U7% is set to 2.2%, assuming that λ7 is So u7 is 1.27×10 -2 , then the uncertainty of the vibration amplitude frequency response u c ≈3.75%.

[0150] It should be noted that, similar to the uncertainty in calculating the vibration amplitude frequency response, when calculating the uncertainty of the shock amplitude linearity using the above formula, the average value and standard deviation of the corresponding shock acceleration measurement value are obtained to obtain u A. According to the traceability evaluation of the standard impact sensor, U1% is obtained, and thus u1 is obtained; according to the statistical data, the influence of the transfer characteristics of the rocket sled measurement system on the measured value of the impact acceleration is obtained, and U2% is set to obtain u2; according to the upper limit of the error of the signal conditioning unit, U3% is set to obtain u3; according to the upper limit of the error of the data acquisition system, U4% is set to obtain u4; according to the statistical data, the influence of the stability of the pulsed impact excitation device is obtained, and U5% is set to obtain u5; according to the upper limit of the error of the waveform distortion of the pulsed impact excitation device, U6% is set to obtain u6; according to the statistical data, the influence of the random interference signal is obtained, and U7% is set to obtain u7, and based on u A And u1-u7 obtains the uncertainty of the linearity of the impact amplitude.

[0151] It can be understood that the present invention achieves uncertainty assessment of the field calibration results of the rocket sled measurement system by calculating the uncertainty of the impact amplitude linearity and the vibration amplitude frequency response.

[0152] Compared with the prior art, the on-site calibration and calibration uncertainty assessment method of the rocket sled provided by the present invention has the following beneficial effects:

[0153] 1. The present invention realizes the on-site calibration of the rocket sled measurement system by obtaining the impact amplitude linearity and the vibration amplitude frequency response.

[0154] 2. The present invention solidifies the boundary conditions of the rocket sled measurement system, thereby constructing the time domain output response function of the rocket sled measurement system sensor based on the principle of linear time invariant system, and takes into account the structural characteristics of the sensor itself through the parameters of the time domain output response function, providing a basis for accurately predicting the impact acceleration of the rocket sled.

[0155] 3. The present invention constructs an optimization function and uses the least squares method to solve the optimization function to obtain the estimated values ​​of the parameters in the frequency domain output response function, and obtains the predicted impact acceleration of the measurement system sensor based on the estimated values ​​of the parameters, thereby solving the problem that the impact acceleration of the rocket sled measurement system sensor cannot obtain the full-scale calibration value during on-site calibration.

[0156] 4. The present invention realizes the uncertainty evaluation of the field calibration results of the rocket sled measurement system by calculating the uncertainty of the impact amplitude linearity and the vibration amplitude frequency response.

[0157] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0158] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for on-site calibration of a rocket sled and calibration uncertainty assessment, characterized in that: The method comprises the following steps: Within the measurement range of the impact sensor of the rocket sled measurement system, a pulsed impact excitation device is used to apply several excitation signals of different vibration levels to the rocket sled measurement system to obtain the true value of the standard impact sensor and the measured value of the measurement system impact sensor respectively; between the measurement range of the rocket sled measurement system impact sensor and its full scale, an optimization function is constructed based on the true value of the standard impact sensor and the measured value of the measurement system impact sensor, and the predicted value of the measurement system impact sensor is obtained by solving the optimization function; based on the true value of the standard impact sensor, the measured value of the measurement system impact sensor and the predicted value, a linear regression analysis is performed using the least squares method to obtain the slope and intercept of the regression line, and the linearity of the impact amplitude is obtained based on the slope of the regression line and the maximum value of the impact acceleration measurement value or the predicted value; Applying a plurality of excitation signals of different frequencies to the rocket sled measurement system through a sinusoidal excitation generating device to obtain the true value of the standard vibration sensor and the measured value of the vibration sensor of the measurement system, and obtaining the vibration amplitude frequency response based on the true value of the standard vibration sensor and the measured value of the vibration sensor of the measurement system; Uncertainty assessments were performed on the shock amplitude linearity and vibration amplitude frequency response.

2. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 1, characterized in that: The slope of the regression line is obtained by the following formula: Among them, K is the slope of the regression line, a i is the measured value or predicted value of the impact acceleration corresponding to the i-th excitation signal, S i is the sensitivity corresponding to the i-th excitation signal, n is the number of excitation signals, for a i The sensitivity corresponding to the excitation signal is the ratio of the measured value or predicted value of the impact acceleration corresponding to the excitation signal to the true value; The intercept of the regression line is obtained by the following formula: Among them, S0 is the intercept of the regression line, For S i The average value of .

3. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 2, characterized in that: The linearity of the impact amplitude is obtained by the following formula: Among them, γ is the linearity of the impact amplitude, a max for a i The maximum value, S n for a max The corresponding sensitivity.

4. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 1, characterized in that: The vibration amplitude frequency response is obtained by the following formula: Among them, δ a is the vibration amplitude frequency response, x i is the measured value of the vibration amplitude corresponding to the i-th excitation signal, x r is the true value of the vibration amplitude corresponding to the i-th excitation signal.

5. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 1, characterized in that: The uncertainty includes: the uncertainty introduced by the measurement repeatability u A , uncertainty u1 introduced by standard sensor, uncertainty u2 introduced by transfer characteristics of rocket sled measurement system, uncertainty u3 introduced by signal conditioning unit, uncertainty u4 introduced by data acquisition system, uncertainty u5 introduced by stability of excitation source, uncertainty u6 introduced by waveform distortion of excitation source, uncertainty u7 introduced by random interference signal.

6. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 5, characterized in that: The uncertainty of the shock amplitude linearity and vibration amplitude frequency response is obtained by the following formula:

7. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 5, characterized in that: The uncertainty introduced by measurement repeatability is obtained by the following formula: Among them, m is the number of excitation signals, y i is the vibration amplitude or the measured value of the impact acceleration corresponding to the i-th excitation signal, for y i The average value of u1-u7 is obtained by the following formula: Among them, U i % is u i The corresponding error rate, λ i for u i The corresponding coefficient.

8. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 1, characterized in that: The method of constructing an optimization function between the measurement range of the impact sensor of the rocket sled measurement system and its full range based on the true value of the standard impact sensor and the measurement value of the impact sensor of the measurement system, and solving the optimization function to obtain the predicted value of the impact sensor of the measurement system includes: Step S101, constructing a time domain output response function of the impact sensor of the measurement system based on the linear time-invariant system principle, and obtaining a discretized frequency domain output response function; Step S102, obtaining a replacement vector of each parameter in the frequency domain output response function based on the frequency domain complex transfer function of the frequency domain output response function; Step S103, constructing a truth matrix based on the true value of the shock acceleration of the standard shock sensor, and constructing a measurement shock acceleration matrix containing uncertainty based on the measured value of the shock acceleration of the shock sensor of the measurement system; Step S104, constructing an optimization function based on the measured impact acceleration matrix and the truth matrix, solving the optimization function using the least squares method to obtain estimated values ​​of the parameters in the frequency domain output response function, and obtaining estimated values ​​of the parameters of the time domain output response function by replacing the vector and the estimated values; between the measurement range of the impact sensor of the rocket sled measurement system and its full range, obtaining the predicted impact acceleration of the measurement system impact sensor by using the time domain output response function and the estimated values ​​of its parameters.

9. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 8, characterized in that: The complex transfer function in the frequency domain is: Wherein, H() is the complex transfer function in the frequency domain, i is the imaginary unit, S() is the amplitude function of the transfer function, φ() is the phase function of the transfer function, ω is the response frequency, δ is the damping coefficient of the shock sensor, ω0 is the installation resonant frequency of the shock sensor, and ε is the inherent characteristic constant of the shock sensor.

10. The method for on-site calibration and calibration uncertainty assessment of a rocket sled according to claim 9, characterized in that: The parameters of the discretized frequency domain output response function are obtained by the following method: Where T is the sampling interval, b, c1, and c2 are the parameters of the discretized frequency domain output response function.

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