I / F conversion circuit nonlinearity compensation method based on Gaussian fitting

Abstract

The invention discloses an I / F conversion circuit nonlinearity compensation method based on Gaussian fitting, and the method comprises the following steps: inputting a plurality of groups of positive test currents and negative test currents to an I / F conversion circuit, and sampling and measuring the positive test current and the negative test current of each current point, and the corresponding pulse number; calculating a positive scale factor, a negative scale factor, a positive nonlinearity degree and a negative nonlinearity degree of each current point; performing Gaussian fitting on the positive scale factor, the negative scale factor, the positive test current and the negative test current of each current point obtained by calculation to form compensation coefficients: an offset coefficient, a center coefficient, a width coefficient and an area coefficient; compensating the original pulse number of each current point, and calculating to obtain the compensated pulse number of each current point; and performing nonlinearity calculation on the compensated pulse number to obtain a positive scale factor, a negative scale factor, positive nonlinearity and negative nonlinearity after compensation. According to the invention, the nonlinearity of the I / F conversion circuit can be well reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of analog-digital hybrid applications, and in particular to a method for compensating the non-linearity of an I / F conversion circuit based on Gaussian fitting. Background Art

[0002] The I / F conversion circuit is one of the important components in an inertial navigation system. The I / F conversion circuit converts the output current value of an accelerometer into a digital pulse signal proportional thereto and provides it for use by a navigation computer. Non-linearity characterizes the offset of the scale factor when different currents are input. When the non-linearity is smaller, the offset of the scale factor corresponding to different currents is smaller. In the prior art, the non-linearity of the conversion circuit is generally ensured by hardware, and the index is fixed within a certain range, or compensated by a 10th-order compensation method. The compensation parameters involved are numerous and the logic resources occupied are large, and the non-linearity of the I / F conversion circuit cannot be well compensated. Summary of the Invention

[0003] Based on the above, the object of the present invention is to provide a method for compensating the non-linearity of an I / F conversion circuit based on Gaussian fitting to reduce the non-linearity of the I / F conversion circuit.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for compensating the non-linearity of an I / F conversion circuit based on Gaussian fitting, comprising the following steps:

[0006] Input multiple groups of positive test currents and negative test currents into the I / F conversion circuit, and sample and measure the positive test currents and negative test currents at each current point and the corresponding number of pulses;

[0007] Calculate the positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity at each current point;

[0008] Perform Gaussian fitting on the calculated positive scale factor, negative scale factor, positive test current, and negative test current at each current point to fit and form compensation coefficients: offset coefficient, center coefficient, width coefficient, and area coefficient;

[0009] Compensate the original number of pulses at each current point, and calculate the number of pulses after compensation at each current point;

[0010] Calculate the non-linearity of the number of pulses after compensation to obtain the positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity after compensation.

[0011] As a preferred solution of a non-linearity compensation method for an I / F conversion circuit based on Gaussian fitting, the specific steps for calculating the positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity of each current point before compensation are as follows:

[0012] According to K j+ = F j+ / I j+ Calculate the positive scale factor K j+ , where K j+ is the positive scale factor corresponding to the positive test current I j+ , F j+ is the positive pulse number corresponding to the positive test current I j+ ;

[0013] According to K j- = F j- / I j- Calculate the negative scale factor K j- , where K j- is the negative scale factor corresponding to the negative test current I j- , F j- is the negative pulse number corresponding to the negative test current I j- ;

[0014] According to Obtain the positive non-linearity NL + , K + is the scale factor at the test point of 1 mA, and σ + is the standard deviation of the output positive scale factor;

[0015] According to Obtain the negative non-linearity NL - , K - is the scale factor at the test point of -1 mA, and σ - is the standard deviation of the negative output scale factor.

[0016] As a preferred solution of a non-linearity compensation method for an I / F conversion circuit based on Gaussian fitting, the compensation coefficients formed by fitting include: offset coefficient, center coefficient, width coefficient, and area coefficient:

[0017] According to By substituting the measured test current and the corresponding scale factor into the fitting, obtain the offset coefficient K0, center coefficient A, width coefficient x c , and area coefficient w.

[0018] As a preferred solution of a non-linearity compensation method for an I / F conversion circuit based on Gaussian fitting, the specific steps for calculating the pulse number after compensation for each current point are as follows:

[0019] Calculate the number of positive pulses F after compensation j+ ′: F j+ ′ = K j+ ′ × F j+ / K0;

[0020] Calculate the number of negative pulses F after compensation j- ′: F j- ′ = K j- ′ × F j- / K0.

[0021] As a preferred embodiment of the non - linearity compensation method for the I / F conversion circuit based on Gaussian fitting, the compensated scale factor and non - linearity are specifically:

[0022] According to Calculate the compensated positive scale factor;

[0023] According to Calculate the compensated negative scale factor;

[0024] According to NL + ′ = σ + ′ / K + ′, Obtain the compensated positive non - linearity NL + ′, K + ′ is the scale factor at the test point of 1 mA after compensation, and σ + ′ is the standard deviation of the positive scale factor after compensation;

[0025] According to NL - ′ = σ - ′ / K - ′, Obtain the compensated negative non - linearity NL - ′, K - ′ is the scale factor at the test point of - 1 mA after compensation, and σ - ′ is the standard deviation of the negative scale factor after compensation.

[0026] As a preferred embodiment of the non - linearity compensation method for the I / F conversion circuit based on Gaussian fitting, the compensated scale factor and non - linearity are specifically:

[0027] According to Calculate the compensated positive scale factor;

[0028] According to Calculate the compensated negative scale factor;

[0029] According to Obtain the compensated positive non - linearity NL + ′, K+ ′ is the scale factor at the test point of 1 mA after compensation, σ + ′ is the standard deviation of the positive scale factor after compensation;

[0030] According to Obtain the negative non-linearity NL after compensation - ′, K - ′ is the scale factor at the test point of -1 mA after compensation, σ - ′ is the standard deviation of the negative scale factor after compensation.

[0031] As a preferred solution of the non-linearity compensation method for the I / F conversion circuit based on Gaussian fitting, it further includes evaluating the scale factor and non-linearity of the I / F conversion circuit before and after compensation. Specifically, compare the non-linearity NL of the I / F conversion circuit before compensation + and NL + ′. If NL + ′ < NL + , it proves that the compensation method is effective.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention provides a non-linearity compensation method for an I / F conversion circuit based on Gaussian fitting. By calibrating the original pulses obtained from testing, obtaining the fitting parameters according to the Gaussian fitting formula, compensating the original pulses according to the fitting parameters, obtaining the compensated number of pulses, calculating the compensated scale factor and non-linearity, the non-linearity of the I / F conversion circuit is reduced. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments of the present invention. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the content of the embodiments of the present invention and these drawings.

[0035] Figure 1 is the electrical connection diagram provided by the embodiment of the present invention. Detailed Embodiments

[0036] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way limits the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts fall within the scope of protection of the present invention.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0039] A specific embodiment of the present invention provides a method for compensating the non-linearity of an I / F conversion circuit based on Gaussian fitting, including: inputting multiple sets of positive test currents and negative test currents to the I / F conversion circuit, sampling and measuring the positive test currents, negative test currents and corresponding pulse numbers at each current point; calculating the positive scale factor, negative scale factor, positive non-linearity and negative non-linearity at each current point; performing Gaussian fitting on the calculated positive scale factor, negative scale factor, positive test current and negative test current at each current point to form compensation coefficients: offset coefficient, center coefficient, width coefficient, area coefficient; compensating the original pulse numbers at each current point to calculate the compensated pulse numbers at each current point; calculating the non-linearity of the compensated pulse numbers to obtain the compensated positive scale factor, negative scale factor, positive non-linearity and negative non-linearity.

[0040] First, build a test platform. The test equipment includes an I / F conversion circuit board, a current calibration source 5700A, an incubator, a general I / F conversion circuit test bench, and an external power supply. The electrical connections are as Figure 1 shown. The I / F conversion circuit test bench is electrically connected to the I / F conversion circuit, and the I / F conversion circuit is electrically connected to the current calibration source. Place the conversion circuit in the incubator, keep the temperature of the incubator at 25°C, and preheat the conversion circuit for 10 minutes.

[0041] Input multiple sets of positive test currents and negative test currents to the I / F conversion circuit, 1 mA, 5 mA, 10 mA, 15 mA, 20 mA, 30 mA, 40 mA, 50 mA, 60 mA, 70 mA, 80 mA positive current I j+ and -1 mA, -5 mA, -10 mA, -15 mA, -20 mA, -30 mA, -40 mA, -50 mA, -60 mA, -70 mA, -80 mA negative current I j- . At the same time, use the general I / F conversion circuit test bench to measure the output pulse numbers corresponding to the positive test currents and negative test currents respectively. The sampling time for each current point is shown in Table 1.

[0042] Table 1 is the corresponding table of test current and sampling time

[0043]

[0044]

[0045] Calculate the positive scale factor, negative scale factor, positive non-linearity and negative non-linearity at each current point before compensation. Among them, according to K j+ =F j+ / I j+ calculate the positive scale factor, negative scale factor, positive non-linearity and negative non-linearity at each current point; according to Kj- = F j- / I j- Calculate the negative scale factor K j- , where K j- is the negative scale factor corresponding to the negative test current I j- , F j- is the number of negative pulses corresponding to the negative test current I j- .

[0046] The calculation process of the positive non-linearity is as follows:

[0047] NL + = σ + / K +

[0048]

[0049] where the positive non-linearity is NL + , K + is the scale factor at the test point of 1 mA, and σ + is the standard deviation of the positive output scale factor.

[0050] The calculation process of the negative non-linearity is as follows:

[0051] NL - = σ - / K - ,

[0052]

[0053] where the negative non-linearity is NL - , K - is the scale factor at the test point of -1 mA, and σ - is the standard deviation of the negative output scale factor.

[0054] Taking the input current I j+ as the independent variable and the scale factors K j+ at different current points as the dependent variable, perform Gaussian fitting on the calculated positive scale factors, negative scale factors, positive test currents, and negative test currents at each current point as follows:

[0055]

[0056] In the formula, K0 is the offset coefficient, A is the center coefficient, x c is the width coefficient, and w is the area coefficient,

[0057] Substitute the output pulse numbers of the positive test current and negative test current sampled before compensation, draw a graph, and fit a curve to separately obtain the compensation coefficients: K0 offset coefficient, A center coefficient, xc Width coefficient, w area coefficient. The more output pulses of the positive test current and the negative test current obtained by sampling before compensation, the more accurate the fitting.

[0058] Compensate the original pulse numbers of each current point, calculate the pulse numbers after compensation for each current point, calculate the positive pulse numbers after compensation and the positive scale factor after compensation:

[0059]

[0060] F j+ ′ = K j+ ′ × F j+ / K0;

[0061] Wherein, K j+ ′ is the positive scale factor after compensation, F j+ ′ is the positive pulse number after compensation.

[0062] Calculate the negative pulse number after compensation and the negative scale factor after compensation:

[0063]

[0064] F j- ′ = K j- ′ × F j- / K0

[0065] Wherein, K j- ′ is the negative scale factor after compensation, F j- ′ is the negative pulse number after compensation.

[0066] Calculate the non-linearity of the pulse number after compensation. Among them, the process of obtaining the positive non-linearity after compensation is:

[0067] NL + ′NL + ′ = σ + ′ / K + ′

[0068]

[0069] In the formula, the positive non-linearity is NL + ′, K + ′ is the scale factor at 1 mA of the test point after compensation, σ + ′ is the standard deviation of the positive scale factor after compensation.

[0070] The process of obtaining the negative non-linearity after compensation is:

[0071] NL - ′ = σ - ′ / K - ′

[0072]

[0073] In the formula, the negative non-linearity is NL - ′, K - ′ is the scale factor at the test point of -1 mA after compensation, and σ - ′ is the standard deviation of the negative scale factor after compensation.

[0074] Compare the non-linearity NL + of the I / F conversion circuit before compensation and the non-linearity NL + ′ of the I / F conversion circuit after compensation. According to the results, evaluate the optimization degree. If NL + ′ < NL + , it proves that the compensation method is effective, and the non-linearity compensation method of the I / F conversion circuit based on Gaussian fitting can well reduce the non-linearity of the I / F conversion circuit.

[0075] Note that the above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described here. Various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, it can also include more other equivalent embodiments, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for compensating the non-linearity of an I / F conversion circuit based on Gaussian fitting, characterized in that, Including the following steps: Input multiple sets of positive test currents and negative test currents to the I / F conversion circuit, and sample and measure the positive test currents, negative test currents at each current point and the corresponding number of pulses; Calculate the positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity at each current point; Perform Gaussian fitting on the calculated positive scale factor, negative scale factor, positive test current, and negative test current at each current point to fit and form compensation coefficients: offset coefficient, center coefficient, width coefficient, area coefficient; Compensate the original number of pulses at each current point, and calculate the compensated number of pulses at each current point; Perform non-linearity calculation on the compensated number of pulses to obtain the compensated positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity.

2. The non-linearity compensation method for the I / F conversion circuit based on Gaussian fitting according to claim 1, characterized in that The specific calculation of the positive scale factor, negative scale factor, positive non-linearity, and negative non-linearity at each current point before compensation is as follows: According to K j+ = F j+ / I j+ Calculate the positive scale factor K j+ , where K j+ is the positive scale factor corresponding to the positive test current I j+ , F j+ is the positive pulse number corresponding to the positive test current I j+ ; According to K j- = F j- / I j- Calculate the negative scale factor K j- , where K j- is the negative scale factor corresponding to the negative test current I j- , F j- is the negative pulse number corresponding to the negative test current I j- ; According to NL + = σ + / K + , Obtain the positive non-linearity NL + , K + is the scale factor at the test point of 1 mA, and σ + is the standard deviation of the output positive scale factor; According to NL - = σ - / K - , Obtain the negative non-linearity NL - , K - is the scale factor at the test point of -1 mA, and σ - is the standard deviation of the negative output scale factor.

3. The non-linearity compensation method of the I / F conversion circuit based on Gaussian fitting according to claim 1 or 2, characterized in that The fitting to form compensation coefficients: offset coefficient, center coefficient, width coefficient, area coefficient includes: According to The offset coefficient K0, the center coefficient A, and the width coefficient x are obtained by fitting the measured test current and the corresponding scale factor obtained by sampling c , and the area coefficient w.

4. The method for compensating the non-linearity of the I / F conversion circuit based on Gaussian fitting according to claim 2 or 3, characterized in that, The specific calculation of the compensated number of pulses at each current point is as follows: Calculate the compensated positive pulse number F j+ ': F j+ ' = K j+ ' × F j+ / K0; Calculate the number of negative pulses F after compensation j- ': F j- ' = K j- ' × F j- / K0.

5. The method for compensating the non-linearity of the I / F conversion circuit based on Gaussian fitting according to claims 2-3, characterized in that, The specific obtaining of the compensated scale factor and non-linearity is as follows: According to calculate the compensated positive scale factor; According to Calculate the compensated negative scale factor; According to NL + ′ = σ + ′ / K + ′, Obtain the compensated positive non-linearity NL + ′, K + ′ is the scale factor at the test point of 1 mA after compensation, and σ + ′ is the standard deviation of the positive scale factor after compensation; According to NL - ′ = σ - ′ / K - ′, Obtain the compensated negative non-linearity NL - ′, K - ′ is the scale factor at the test point of -1 mA after compensation, and σ - ′ is the standard deviation of the negative scale factor after compensation.

6. The non-linearity compensation method of the I / F conversion circuit based on Gaussian fitting according to claim 4, characterized in that The specific obtaining of the compensated scale factor and non-linearity is as follows: According to Calculate the compensated positive scale factor; According to Calculate the compensated negative scale factor; According to NL + ′ = σ + ′ / K + ′, Obtain the compensated positive non-linearity NL + ′, K + ′ is the scale factor at the test point of 1 mA after compensation, and σ + ′ is the standard deviation of the positive scale factor after compensation; According to NL - ′ = σ - ′ / K - ′, Obtain the compensated negative non-linearity NL - ′, K - ′ is the scale factor at the test point of -1 mA after compensation, and σ - ′ is the standard deviation of the negative scale factor after compensation.

7. The non-linearity compensation method for the I / F conversion circuit based on Gaussian fitting according to claim 1, characterized in that, It also includes evaluating the scale factor and non-linearity of the I / F conversion circuit before and after contrast compensation, specifically comparing the non-linearity NL + and NL + ′, if NL + ′ < NL + , it proves that the compensation method is effective.

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