Measuring method, device and circuit based on eddy current encoder and encoder

Abstract

The invention relates to the technical field of eddy current encoders, and discloses a measurement method, device and circuit based on an eddy current encoder, and an encoder. The measurement method based on the eddy current encoder comprises the following steps: in a starting stage of the eddy current encoder, determining a dominant frequency and an amplitude and an initial phase value corresponding to the dominant frequency from a first orthogonal signal group output by the eddy current encoder, and according to the dominant frequency and the amplitude and the initial phase value corresponding to the dominant frequency, determining the amplitude and the initial phase value corresponding to the dominant frequency; generating a second orthogonal signal group; and under the condition of an operation stage of the eddy current encoder, taking the second orthogonal signal group as a reference signal of a third orthogonal signal group output by the eddy current encoder, and performing digital signal processing to obtain a physical quantity measurement value. And more accurate measurement can be realized at least by constructing a reference signal with a better phase error compensation effect.

Description

Technical Field

[0001] The present application relates to the technical field of eddy current encoders, and in particular to a measurement method, device, circuit and encoder based on eddy current encoders. Background Art

[0002] Eddy current encoders are widely used in rotary position measurement scenarios and are particularly suitable for contactless, high-precision angle detection in harsh environments. These encoders typically generate a phase-orthogonal sensing signal (sin / cos waveform) by exciting the induction coil. This signal is sampled and conditioned by the front-end, then fed into a solver chip for real-time angle calculation.

[0003] In practical systems, the amplitude, frequency, and phase of the raw signal output by an eddy current encoder can vary non-ideally due to factors such as coil structure, noise interference, and sampling drift, affecting the accuracy of angle calculations. Therefore, eddy current encoders typically incorporate a self-calibration mechanism to construct a reference signal to compensate for phase errors caused by these factors, improving measurement performance.

[0004] However, the current solution of compensating phase errors through reference signals still does not provide satisfactory improvement in measurement. Summary of the Invention

[0005] The embodiments of the present application provide a measurement method, device, circuit and encoder based on an eddy current encoder, which at least helps to achieve more accurate measurement by constructing a reference signal with better phase error compensation effect.

[0006] According to some embodiments of the present application, a first aspect of the embodiments of the present application provides a measurement method based on an eddy current encoder, comprising: in the startup phase of the eddy current encoder, determining the main frequency and the amplitude and initial phase value corresponding to the main frequency from the first orthogonal signal group output by the eddy current encoder, and generating a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; in the operation phase of the eddy current encoder, using the second orthogonal signal group as a reference signal of the third orthogonal signal group output by the eddy current encoder, and performing digital signal processing to obtain a physical quantity measurement value.

[0007] According to some embodiments of the present application, the second aspect of the embodiments of the present application further provides a measuring device based on an eddy current encoder, including: a first processing module, used to determine the main frequency and the amplitude and initial phase value corresponding to the main frequency from the first orthogonal signal group output by the eddy current encoder during the startup phase of the eddy current encoder, and generate a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; a second processing module, used to use the second orthogonal signal group as a reference signal for the third orthogonal signal group output by the eddy current encoder during the operation phase of the eddy current encoder, and perform digital signal processing to obtain physical quantity measurement values.

[0008] According to some embodiments of the present application, the third aspect of the embodiments of the present application further provides an integrated circuit, comprising: a receiving module, an analog signal processing module and a digital signal processing module connected in sequence; wherein the receiving module is configured to obtain the signal generated on the receiving coil in the eddy current encoder and output it to the analog signal processing module; the analog signal processing module is configured to sample the received signal to obtain a first orthogonal signal group or a third orthogonal signal group, and output it to the digital signal processing module, wherein the first orthogonal signal group is the sampling result of the startup phase, and the third orthogonal signal group is the sampling result of the operation phase; the digital signal processing module is configured to determine the main frequency and the amplitude and initial phase value corresponding to the main frequency from the received first orthogonal signal group, and generate a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; use the second orthogonal signal group as a reference signal for the received third orthogonal signal group, and perform digital signal processing to obtain physical quantity measurement values.

[0009] According to some embodiments of the present application, the fourth aspect of the embodiments of the present application further provides an eddy current encoder, comprising: a carrier; an excitation coil and a receiving coil, which are arranged on the carrier; an integrated circuit, which is arranged on the carrier and connected to the output end of the receiving coil, wherein the integrated circuit is the integrated circuit as described in the third aspect.

[0010] The technical solution provided in the embodiments of this application has at least the following advantages: In the startup phase of the eddy current encoder, the main frequency and the amplitude and initial phase value main frequency corresponding to the main frequency of the encoder are determined from the first orthogonal signal group output by the encoder eddy current encoder to generate a second orthogonal signal group as a reference signal for the startup phase, rather than pre-extracting the main frequency and then constructing the reference signal when needed. This allows the main frequency and the reference signal to be acquired in a consistent eddy current encoder state, especially when the reference signal is acquired in the startup phase before the start of the operating phase. This can accurately describe the state of the eddy current encoder in the operating phase, thereby providing a better phase error compensation effect for the operating phase, and can more accurately and reliably provide a reference for digital signal processing based on the third orthogonal signal group, thereby obtaining a more accurate physical quantity measurement value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0012] Figure 1 is a flow chart of a measurement method based on an eddy current encoder provided in one embodiment of the present application; Figure 2 1 is a schematic diagram of signal comparison involved in a measurement method based on an eddy current encoder provided in another embodiment of the present application; Figure 3 A measurement method based on an eddy current encoder provided in another embodiment of the present application involves an amplitude spectrum of a signal in a first orthogonal signal group; Figure 4 A measurement method based on an eddy current encoder provided in another embodiment of the present application involves a phase spectrum of a signal in a first orthogonal signal group; Figure 5 A measurement method based on an eddy current encoder provided in another embodiment of the present application involves an amplitude spectrum of a signal in a second orthogonal signal group; Figure 6 A measurement method based on an eddy current encoder provided in another embodiment of the present application involves a phase spectrum of a signal in a second orthogonal signal group; Figure 7 1 is a flow chart of determining the main frequency involved in a measurement method based on an eddy current encoder provided in another embodiment of the present application; Figure 8 is a flow chart of a measurement method based on an eddy current encoder provided in another embodiment of the present application; Figure 9 is a structural schematic diagram of a reference signal construction device for an eddy current encoder provided in another embodiment of the present application; Figure 10It is a schematic structural diagram of an integrated circuit provided in another embodiment of the present application. DETAILED DESCRIPTION

[0013] As can be seen from the background art, the existing solution of compensating phase error through reference signal still does not provide satisfactory improvement effect on measurement.

[0014] After analysis, it was found that the reason for the above problem is at least that: in order to be able to construct a reference signal in time when needed, the existing solution usually completes the main frequency estimation in advance before using the eddy current encoder for measurement, and then constructs the reference signal based on the previously estimated main frequency when using the eddy current encoder for measurement, so as to reduce the overhead of main frequency estimation when using the eddy current encoder for measurement, and construct the reference signal more quickly, perform digital signal processing, and achieve measurement. In other words, the main frequency estimation and the use of the main frequency are at different stages. Between these two stages, the factors that cause the phase error of the eddy current encoder may be different, and the degree of influence of the same influencing factor on the phase error may also be different. Therefore, the pre-estimated main frequency may not accurately reflect the current phase error, resulting in poor compensation effect, and the improvement effect on the measurement does not meet the expectations.

[0015] Based on this, an embodiment of the present application provides a measurement method, device, circuit and encoder based on an eddy current encoder. By placing the determination of the main frequency and the generation of a second orthogonal signal group used as a reference signal in the startup phase before the operating phase where the reference signal is required, the time difference between the construction and use of the reference signal is reduced, and the influencing factors and the degree of influence of the phase error during the construction and use of the reference signal are basically consistent, so that the phase compensation effect achieved by the reference signal is better, and a more accurate physical quantity measurement value is obtained.

[0016] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will appreciate that many technical details are provided in each embodiment of the present application to help readers better understand the present application. However, even without these technical details and various variations and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0017] The following embodiments are divided for the convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined with each other and referenced to each other without contradiction.

[0018] The present application provides, on one hand, a measurement method based on an eddy current encoder, applicable to an eddy current encoder, or a module (or circuit, chip, etc.) involved in signal processing within an eddy current encoder, or a host computer of an eddy current encoder. This method will be described below in conjunction with various embodiments.

[0019] In some embodiments, as Figure 1 As shown in FIG, the process of the measurement method based on the eddy current encoder includes the following steps: Step 101: During the startup phase of the eddy current encoder, a main frequency and an amplitude and an initial phase value corresponding to the main frequency are determined from a first orthogonal signal group output by the eddy current encoder, and a second orthogonal signal group is generated based on the main frequency and the amplitude and initial phase value corresponding to the main frequency.

[0020] Step 102 : When the eddy current encoder is in operation, the second orthogonal signal group is used as a reference signal for the third orthogonal signal group output by the eddy current encoder, and digital signal processing is performed to obtain a physical quantity measurement value.

[0021] exist Figure 1 In the illustrated embodiment, in the startup phase of the eddy current encoder, the main frequency and the amplitude and initial phase value main frequency corresponding to the main frequency of the encoder are determined from the first orthogonal signal group output by the encoder eddy current encoder to generate a second orthogonal signal group as a reference signal for the startup phase, rather than pre-extracting the main frequency and then constructing the reference signal when needed. This allows the main frequency and the reference signal to be acquired in a consistent eddy current encoder state, especially when the reference signal is acquired in the startup phase before the start of the operating phase. This can accurately describe the state of the eddy current encoder in the operating phase, thereby providing a better phase error compensation effect for the operating phase, and can more accurately and reliably provide a reference for digital signal processing based on the third orthogonal signal group, thereby obtaining a more accurate physical quantity measurement value.

[0022] For easier understanding Figure 1 The embodiment shown is described below and its steps are explained.

[0023] In step 101, during the startup phase of the eddy current encoder, a main frequency, an amplitude corresponding to the main frequency, and an initial phase value are determined from a first quadrature signal group output by the eddy current encoder, and a second quadrature signal group is generated based on the main frequency, an amplitude corresponding to the main frequency, and an initial phase value. The first quadrature signal group is the original signal output by the eddy current encoder. For example, in some embodiments, the first quadrature signal group is obtained by sampling the electrical signal output by the receiving coil in the eddy current encoder differently.

[0024] It should be noted that the embodiments of the present application do not limit the number of signal paths included in the first orthogonal signal group. This number is related to the output of the receiving coil of the eddy current encoder and may be 2, 3, 6, etc., which are not listed here. For ease of understanding, the following description mainly uses the example of the first orthogonal signal group including 2 orthogonal signals.

[0025] It should also be noted that the embodiment of the present application does not limit the determination of the main frequency and the amplitude and initial phase value corresponding to the main frequency, and the generation of the second orthogonal signal group.

[0026] In some embodiments, determining the main frequency and the amplitude and initial phase value corresponding to the main frequency from the first orthogonal signal group output by the eddy current encoder can be achieved as follows: determining the main frequency from the first orthogonal signal group; converting the first orthogonal signal group to the frequency domain to obtain a complex spectrum; in the complex spectrum, determining the amplitude and initial phase value of the spectral component corresponding to the main frequency as the amplitude and initial phase value corresponding to the main frequency.

[0027] In some embodiments, generating the second orthogonal signal group according to the main frequency and the amplitude and initial phase value corresponding to the main frequency can be achieved by the following expression: ; ; in, and is the second orthogonal signal group, is the amplitude, is the main frequency, is the initial phase value.

[0028] It should be noted that the above is only an example of a first orthogonal signal group and a second orthogonal signal group comprising two signals. In some embodiments, the first orthogonal signal group and the second orthogonal signal group may also include three or six signals. Furthermore, the above is only an example of constructing orthogonal signals using cosine and sinine functions as examples. In some embodiments, other methods of constructing orthogonal signals may also be used. These will not be detailed here.

[0029] In some embodiments, in order to obtain more accurate amplitude and initial phase values, before frequency domain conversion, the first orthogonal signal group is first merged to obtain a complex signal, that is, the complex signal ,in, is the imaginary unit, 、 are two orthogonal signals included in the first orthogonal signal group. Further obtain the complex signal spectrum; obtain the main frequency on this spectrum The corresponding complex spectrum value ; and extract the amplitude from the spectral component according to the following expression and the initial phase value : ; ; in, represents the modulo operation, Indicates angle operation.

[0030] Of course, the above is only an example. The relevant technology has provided various methods for determining the amplitude and initial phase value of the signal component corresponding to the specified frequency in the signal, which are also applicable to the implementation of this step and will not be described here one by one.

[0031] In addition, the determination of the main frequency mentioned in the above embodiment will be described below through different embodiments.

[0032] In some embodiments, the primary frequency can be determined using zero-crossing detection, an algorithm that determines the frequency based on the time interval between the signal's zero-crossing points in the time domain (adjacent time-domain sign change points). This method has no requirement for the number of cycles contained in the signal and allows the signal duration to cover only a few waveform cycles (e.g., less than 5 cycles). Therefore, during the eddy current encoder's startup phase, when sampling time is short, the primary frequency can be accurately, reliably, and efficiently determined in real time.

[0033] In some embodiments, a zero-crossing detection method is used to determine the primary frequency from the first orthogonal signal group. This can be achieved by: selecting a signal from the first orthogonal signal group as the signal to be processed; determining the average time interval between adjacent time-domain symbol change points of the signal to be processed; determining the signal period of the signal to be processed based on the average time interval, and determining the frequency corresponding to the signal period as the primary frequency. Therefore, when multiple time-domain symbol change points (i.e., multiple groups of zero-crossing points) are involved, the time interval between the zero-crossing points is determined by taking the average value, and then the primary frequency is determined. This method is more accurate and reliable, can reduce the degree of interference from sudden factors and extreme values, and can obtain a more accurate primary frequency.

[0034] The first orthogonal signal group includes signals and signal For example, in some embodiments, there are: 1. Select or As a signal to be processed .

[0035] 2. Calculate the signal to be processed The sign change point of points, where Indicates the operation of taking the sign. Thus, we get the zero time series , Zero time series The total amount of data included.

[0036] 3. Calculate the zero time series The average time interval between adjacent time domain symbol change points , which can be realized by the following expression: .

[0037] 4. Calculate the main frequency , which can be realized by the following expression: .

[0038] It should be noted that the above example is only based on the arithmetic mean. In some embodiments, other averaging methods can be used, which are not listed here one by one. In addition, the above example is only based on the average time interval between any two adjacent time domain symbol change points. In some embodiments, it is also possible to take The average time interval between two adjacent time domain symbol change points and other methods are not listed here one by one.

[0039] Of course, the above is only an implementation example of the zero-crossing point detection method. In some embodiments, the main frequency can be determined by taking the median of the time intervals between adjacent time domain symbol change points, which will not be listed here one by one.

[0040] In some embodiments, the dominant frequency can be determined using frequency domain analysis, which involves converting a signal from the time domain to the frequency domain, thereby analyzing the signal's frequency components in the frequency domain. This method, while requiring a certain number of cycles in the signal, is more accurate and efficient, resulting in accurate, reliable, and timely determination of the dominant frequency.

[0041] In some embodiments, frequency domain analysis is used to determine the dominant frequency from the first orthogonal signal group. This can be achieved by combining the first orthogonal signal group into a complex signal; and then, using the frequency domain analysis method, determining the frequency corresponding to the maximum amplitude in the complex signal as the dominant frequency. In this case, combining the first orthogonal signal group and then processing it allows for more comprehensive analysis, resulting in a more accurate and reliable dominant frequency.

[0042] For ease of understanding, the following description will be provided by taking the example that the first orthogonal signal group includes two signals, but this does not mean that the first orthogonal signal group can only include two signals.

[0043] The first orthogonal signal group includes signals and signal For example, in some embodiments, there are: 1. Combine the first orthogonal signal group to obtain a complex signal , which can be realized by the following expression: ,in, Is an imaginary unit.

[0044] 2. Complex signal Perform Discrete Fourier Transform (DFT) to obtain a sequence of spectrum points ,Right now: , where N is the number of sampling points contained in the signal.

[0045] 3. According to the spectrum point sequence , calculate the main frequency , which can be realized by the following expression: ; Where dt is the sampling time interval, for When the maximum value is reached The value of .

[0046] It should be noted that the above frequency domain analysis method is only provided by taking a complex signal as an example. In some embodiments, frequency domain analysis may be performed on each signal in the first orthogonal signal group respectively, which will not be listed here one by one.

[0047] Based on the above embodiments, and on the basis of frequency domain analysis, period truncation and a second frequency domain analysis can be further combined (i.e., determining the primary frequency using a frequency domain analysis method + period truncation + a second frequency domain analysis method). By using period truncation, the signal content of the first orthogonal signal group includes signals of an integer number of periods. Thus, the primary frequency is not affected by spectrum leakage that occurs when the first orthogonal signal group includes non-integer periods, thereby further improving the accuracy of the primary frequency and further optimizing the compensation effect of the reference signal constructed based on the primary frequency. Still taking the example of combining the first orthogonal signal group into a complex signal, in some embodiments, determining the primary frequency from the first orthogonal signal group using a frequency domain analysis method and a period stage can be achieved by: combining the first orthogonal signal group into a complex signal; determining the frequency corresponding to the maximum amplitude from the complex signal using a frequency domain analysis method as the initial primary frequency; performing period truncation on the complex signal based on the signal period corresponding to the initial primary frequency to obtain a truncated signal; and determining the frequency corresponding to the maximum amplitude from the truncated signal using a frequency domain analysis method as the primary frequency.

[0048] It should be noted that the embodiment of the present application does not limit the number of cycles of the truncated signal, which can be set according to the needs. In some embodiments, the complex signal is periodically truncated according to the signal period corresponding to the initial main frequency to obtain the truncated signal, which can be achieved by the following method: according to the signal period corresponding to the initial main frequency, the truncation position is determined. ; Keep the complex signal in the interval [0, ] on the signal part, and obtain the truncated signal. Among them, the truncation position It is obtained by the following expression: ; in, To cut off the signal, is the signal period corresponding to the initial main frequency, satisfying: , is the main frequency, To perform floor operation, is the signal length of the complex signal.

[0049] In other words, try to retain more signal fragments within the complete cycle to form a closed cycle window, so that the signal can be analyzed based on more comprehensive information, and the obtained main frequency will be more accurate.

[0050] Based on the above embodiment, simulation experiments were conducted on the reconstruction of the reference signal in the startup state and the running state, and the following results were obtained: Figures 2 to 6 The results shown.

[0051] In the running state, the Figure 2 The waveform comparison diagram of the first orthogonal signal group and the second orthogonal signal group (i.e., reference signal) is shown in FIG. , wherein the horizontal axis represents time and the vertical axis represents amplitude. The blue solid line represents the signal in the first orthogonal signal group of the above embodiment. (After sampling, it will get ) waveform, the yellow solid line is the signal in the first orthogonal signal group of the above embodiment (After sampling, it will get ), the blue dotted line is the waveform of the second orthogonal signal group The yellow dotted line is the waveform of the second orthogonal signal group. waveform.

[0052] Depend on Figure 2 It can be seen that the second orthogonal signal group is modified in the amplitude dimension relative to the original waveform.

[0053] In the startup state, the amplitude spectrum and phase spectrum of the first spectrum analysis are as follows: Figure 3 、 Figure 4 As shown, the amplitude spectrum and phase spectrum of the second spectrum analysis are as follows: Figure 5 、 Figure 6 As shown. Among them, Figures 3 to 6 The horizontal axis represents the frequency of the corresponding signal. Figure 3 and Figure 5 The vertical axis represents the amplitude of the corresponding signal, Figure 4 and Figure 6 The vertical axis represents the phase of the corresponding signal.

[0054] Depend on Figures 3 to 6 It can be seen that the main frequency concentration in the amplitude spectrum of the second spectrum analysis is higher than that of the first spectrum analysis, which means that the accuracy of the main frequency estimation is improved after the second trimming.

[0055] It can be seen that the measurement method based on the eddy current encoder provided in the embodiment of the present application can have the following effects: 1. It can be applied to high-precision inductive sensor systems and can be widely used in I / Q output sensors such as eddy current encoders and resolvers. Combined with this algorithm for frequency estimation and reference waveform reconstruction, it can effectively improve the measurement accuracy of physical quantities such as angle and displacement and realize system self-calibration.

[0056] 2. The algorithm has a clear structure and strong adaptability. The core process includes DFT transformation, period truncation, window function weighting, and spectral line interpolation. It has a low computational load and a closed structure, making it suitable for deployment on low-power MCU (microcontroller unit), FPGA (field programmable gate array), or SoC (system on chip) platforms, facilitating software and hardware integration.

[0057] 3. A multi-strategy frequency extraction mechanism with controllable accuracy. Dynamic switching is performed based on the state of the eddy current encoder. When needed, the frequency estimation accuracy can reach one thousandth of the sampling frequency. (The current simulation experiment only illustrates the effect of the frequency domain analysis method, but it can also be combined with the zero-crossing detection method provided in the embodiments of this application.)

[0058] 4. No high sampling rate or complex hardware resources are required. Frequency and phase recovery can be completed by relying only on sampling data of a certain length (covering multiple cycles). No high-order filter or phase-locked loop is required, which reduces system cost and is suitable for low-cost integration in domestic sensor chips.

[0059] 5. It has clear industrial implementation scenarios and is oriented towards application scenarios such as industrial servo, motor control, rail transportation, and automation equipment. It can be deployed in coordination with inductive sensor chips and has a clear engineering direction and commercialization path.

[0060] Of course, the above is only an example. You can also retain the signal within one or a preset number of cycles as the truncation signal. Taking retaining one cycle as an example, at this time, you can start from any position (as long as the forward or backward signal length is greater than one cycle length) and find a signal of one cycle forward or backward as the truncation signal, etc., which will not be elaborated here.

[0061] In some embodiments, the determination of the main frequency can also be achieved by combining the DFT analysis method with other processing schemes. For example, the main frequency can be determined from the first orthogonal signal group by: merging the first orthogonal signal group into a complex signal; applying a Hanning window to the complex signal to obtain a windowed signal; according to the frequency domain analysis method, determining the frequency corresponding to the maximum amplitude from the windowed signal as the initial main frequency; interpolating the area where the initial main frequency is located on the spectrum point sequence of the windowed signal to obtain a sub-index offset; determining the main frequency based on the initial main frequency and the sub-index offset. At this time, after the main frequency is obtained by frequency domain analysis, the main frequency scheme under the target state is further introduced, and the main frequency search accuracy is further improved by windowing and interpolation (that is, the main frequency is determined by frequency domain analysis + windowing + interpolation), so that a higher-precision main frequency can be obtained, thereby generating a higher-precision reference signal and supporting a better compensation effect.

[0062] It should be noted that the embodiments of the present application do not limit the target state. It can be understood that the processing in the target state obtains a higher-precision main frequency. Therefore, the target state may have a state with high-precision requirements, for example, a state entered when the user indicates high-precision output, or a state entering a scene that requires high-precision detection, etc., which will not be listed one by one here.

[0063] In addition, the acquisition of complex signals has been described previously and will not be repeated here.

[0064] It should also be noted that the embodiments of the present application do not limit the parameters of the Hanning window, and can be set according to the application scenario, requirements, etc. In some embodiments, the window signal of the Hanning window It can be: ; Where N is the length of the window signal.

[0065] Of course, the above is only an example. In some embodiments, other Hanning windows may be used, which will not be listed here one by one.

[0066] Furthermore, the embodiments of the present application do not limit the interpolation method. For example, it can be parabolic interpolation or polynomial interpolation, etc., which will not be listed here one by one.

[0067] For ease of understanding, the following will use parabola three-point interpolation as an example to illustrate the processing under the above target state.

[0068] Assume that the signal after the window satisfy: , is the window function of the Hanning window, then the discrete Fourier transform will give a spectrum point sequence ,Right now, .

[0069] Thus, the position of the initial main frequency will be obtained satisfy: .

[0070] Therefore, based on the spectrum points at frequencies k-1, k, and k+1, parabolic interpolation can be performed on the interval [k-1, k+1] to obtain the sub-index offset of the frequency position. ,Right now, .

[0071] Then get the index of the main frequency , where, in some examples, the index of the dominant frequency satisfy: .

[0072] Finally, the main frequency is obtained satisfy: ; in, is the sampling time interval.

[0073] It should be noted that the main frequency obtained by the above method , determine its initial phase value. In addition to the examples provided above, it can also be obtained by the following expression: ; ; .

[0074] At this time, since the processing is performed based on the interpolated spectrum point sequence, the initial phase value will also have higher accuracy.

[0075] Through simulation experiments, it was found that the above method can improve the accuracy to 10 times the original one. It is suitable for the high-precision calibration logic built into the eddy current encoder chip, and can be used to determine the main frequency when high-precision measurement or high phase compensation effect is required.

[0076] Of course, the above is only an example of how to determine the main frequency. In some embodiments, other methods may be used, for example, Figure 7As shown, the above-mentioned zero-crossing point detection method, frequency domain analysis method + period truncation + second frequency domain analysis method, and frequency domain analysis method + windowing and other main frequency determination methods can be deployed in the eddy current encoder. When in use, one of the methods is flexibly selected to determine the main frequency according to the actual measurement scenario, and they are not listed one by one here.

[0077] In step 102, when the eddy current encoder is in operation, the second orthogonal signal group is used as a reference signal for the third orthogonal signal group output by the eddy current encoder, and digital signal processing is performed to obtain a physical quantity measurement value. Related art already provides solutions for performing digital signal processing based on the reference signal and the signal currently output by the eddy current encoder to obtain a physical quantity measurement value (such as a measurement value, a displacement measurement value, etc.). These solutions are also applicable to the implementation of step 102. The main difference is that the reference signal used in step 102 is obtained through step 101, and will not be further described here.

[0078] In some embodiments, as Figure 8 As shown in FIG, the process of the measurement method based on the eddy current encoder includes the following steps: Step 801: During the startup phase of the eddy current encoder, a main frequency and an amplitude and an initial phase value corresponding to the main frequency are determined from a first orthogonal signal group output by the eddy current encoder, and a second orthogonal signal group is generated based on the main frequency and the amplitude and initial phase value corresponding to the main frequency.

[0079] Step 802 , fitting the error between the first orthogonal signal group and the second orthogonal signal group to obtain an error fitting time series signal, wherein the fitting includes: piecewise linear fitting, polynomial fitting, or orthogonal basis projection fitting.

[0080] Step 803: Update the second orthogonal signal group according to the error fitting signal.

[0081] Step 804 : When the eddy current encoder is in operation, the second orthogonal signal group is used as a reference signal for the third orthogonal signal group output by the eddy current encoder, and digital signal processing is performed to obtain a physical quantity measurement value.

[0082] exist Figure 8 In the illustrated embodiment, on the basis of the aforementioned embodiment, fitting of the error between the first orthogonal signal group and the second orthogonal signal group is further introduced, so that the phase error is further compensated by the error fitting signal obtained by the fitting process, thereby further improving the accuracy of the reference signal, achieving further improvement of the compensation effect, and obtaining a more accurate measurement effect.

[0083] For easier understanding Figure 8 The following is an explanation of the steps of the embodiment shown. Figure 1 Step 101 and step 102 in the illustrated embodiment are substantially the same and will not be described in detail here.

[0084] In step 802, the error between the first orthogonal signal group and the second orthogonal signal group is fitted to obtain an error fitting time series signal, wherein the fitting includes: piecewise linear fitting, polynomial fitting, or orthogonal basis projection fitting. The embodiment of the present application does not limit the fitting method.

[0085] In some embodiments, the first orthogonal signal group includes signals and signal For example, the error signal between the reference signal and the measured reference signal is: ; ; in, and is the error signal, and is the measured reference signal.

[0086] This error usually includes characteristics such as system gain offset, phase drift, nonlinear response, DC bias, and amplitude-frequency distortion.

[0087] Therefore, the above error signal can be fitted using the corresponding fitting method: If piecewise linear fitting is used, the error signal is divided into several segments according to equal time intervals or signal amplitude distribution, and the following linear model is used for fitting within each segment: ; in, is the fitting result, 、 are the parameters of the linear fit, is the fitting interval.

[0088] This approach can capture slowly changing phenomena such as gain drift, time drift, and integral bias. Its low number of model parameters facilitates real-time estimation and online deployment. The fitting residuals can be used to determine the degree of error anomalies or offset accumulation.

[0089] If polynomial fitting (also known as high-order term modeling) is used, it is suitable for situations where the error signal exhibits periodic drift or high-order nonlinear response (such as harmonic distortion). In this case, the following linear model can be used for fitting: ; in, are polynomial fitting parameters, The fitting order can be selected according to the requirements. For example, based on the need to capture acceleration drift, N=2; or based on the need to model asymmetric jitter and response offset caused by device aging, N=3, 4, or 5.

[0090] It should be noted that some variations of polynomial fitting, such as least squares method, sliding window fitting, recursive least squares, etc., can be used to dynamically estimate coefficients.

[0091] Orthogonal basis projection (also known as frequency domain compensation modeling) is used to fit the error signal by projecting it onto several orthogonal bases (such as Fourier bases or discrete cosine bases). This approach is suitable for modeling periodic errors (such as power frequency interference and systemic noise) and can identify the main interference frequency components. The following error models can be used for fitting: ; in, is the error signal, 、 、 are the orthogonal basis projection fitting parameters.

[0092] In some examples, the fitting parameters can be adjusted using a digital front-end dynamic filter, and the algorithm can be integrated into a PLL (Phase-Locked Loop) or synchronous shaping network for dynamic update.

[0093] In step 803, the second orthogonal signal group is updated according to the error fitting signal. In the embodiment of the present application, the second orthogonal signal group is updated by adding the error fitting signal to the second orthogonal signal group.

[0094] The step division of the above various methods is only for the purpose of clear description. During implementation, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this application; adding insignificant modifications or introducing insignificant designs to the algorithm or process without changing the core design of the algorithm and process are all within the scope of protection of this application.

[0095] The second aspect of the embodiment of the present application further provides a measuring device based on an eddy current encoder, such as Figure 9 As shown, it includes: a first processing module and a second processing module.

[0096] The first processing module is configured to determine the main frequency and the amplitude and initial phase value corresponding to the main frequency from the first orthogonal signal group output by the eddy current encoder during the startup phase of the eddy current encoder, and generate a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; The second processing module is used to use the second orthogonal signal group as a reference signal of the third orthogonal signal group output by the eddy current encoder during the operation phase of the eddy current encoder, and perform digital signal processing to obtain a physical quantity measurement value.

[0097] It is not difficult to find that this embodiment is an apparatus embodiment corresponding to the method embodiment, and this embodiment can be implemented in conjunction with the method embodiment. The relevant technical details mentioned in the method embodiment are still valid in this embodiment, and to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the method embodiment.

[0098] It is worth mentioning that all modules involved in this embodiment are logical modules. In actual applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, to highlight the innovation of this application, this embodiment does not include units that are not closely related to solving the technical problem proposed by this application. However, this does not mean that other units do not exist in this embodiment.

[0099] The third aspect of the embodiment of the present application further provides an integrated circuit, such as Figure 10 As shown, it includes: a receiving module, an analog signal processing module and a digital signal processing module connected in sequence; The receiving module is configured to obtain the signal generated by the receiving coil in the eddy current encoder and output it to the analog signal processing module; The analog signal processing module is configured to sample the received signal to obtain a first orthogonal signal group or a third orthogonal signal group, and output the sampled signal to the digital signal processing module, wherein the first orthogonal signal group is a sampling result of the startup phase, and the third orthogonal signal group is a sampling result of the operation phase; The digital signal processing module is configured to determine the main frequency and the amplitude and initial phase value corresponding to the main frequency from the received first orthogonal signal group, and generate a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; use the second orthogonal signal group as a reference signal for the received third orthogonal signal group, and perform digital signal processing to obtain physical quantity measurement values.

[0100] It is not difficult to find that this embodiment is a circuit embodiment corresponding to the method embodiment, and this embodiment can be implemented in conjunction with the method embodiment. The relevant technical details mentioned in the method embodiment are still valid in this embodiment, and to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the method embodiment.

[0101] It is worth mentioning that, in actual application, each module involved in this embodiment can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, in order to highlight the innovative part of this application, this embodiment does not introduce units that are not closely related to solving the technical problem proposed by this application, but this does not mean that other modules or units do not exist in this embodiment.

[0102] A fourth aspect of the embodiments of the present application further provides an eddy current encoder, comprising: carrier; The excitation coil and the receiving coil are arranged on the carrier; The integrated circuit is arranged on the carrier and connected to the output end of the receiving coil, wherein the integrated circuit is the integrated circuit as described above.

[0103] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and that in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A measurement method based on an eddy current encoder, characterized in that: include: During the startup phase of the eddy current encoder, a main frequency and an amplitude and an initial phase value corresponding to the main frequency are determined from a first orthogonal signal group output by the eddy current encoder, and a second orthogonal signal group is generated based on the main frequency and the amplitude and the initial phase value corresponding to the main frequency; In the operation phase of the eddy current encoder, the second orthogonal signal group is used as a reference signal of the third orthogonal signal group output by the eddy current encoder, and digital signal processing is performed to obtain a physical quantity measurement value.

2. The measurement method based on eddy current encoder according to claim 1, characterized in that: Determining a main frequency and an amplitude and an initial phase value corresponding to the main frequency from the first orthogonal signal group output by the eddy current encoder includes: Determining the main frequency from the first orthogonal signal group; Converting the first orthogonal signal group into the frequency domain to obtain a complex spectrum; In the complex spectrum, the amplitude and initial phase value of the spectrum component corresponding to the main frequency are determined as the amplitude and initial phase value corresponding to the main frequency.

3. The measurement method based on eddy current encoder according to claim 2, characterized in that: The determining the main frequency from the first orthogonal signal group includes: Combining the first orthogonal signal groups into a complex signal; Determine, from the complex signal, a frequency corresponding to a maximum amplitude according to a frequency domain analysis method, as an initial main frequency; performing periodic truncation on the complex signal according to the signal period corresponding to the initial main frequency to obtain a truncated signal; According to the frequency domain analysis method, the frequency corresponding to the maximum amplitude is determined from the truncated signal to serve as the main frequency.

4. The measurement method based on eddy current encoder according to claim 2, characterized in that: The determining the main frequency from the first orthogonal signal group includes: Selecting a signal from the first orthogonal signal group as a signal to be processed; Determining an average time interval between adjacent time-domain symbol change points of the signal to be processed; The signal period of the signal to be processed is determined according to the average time interval, and the frequency corresponding to the signal period is determined as the main frequency.

5. The measurement method based on eddy current encoder according to claim 2, characterized in that: The determining the main frequency from the first orthogonal signal group includes: Combining the first orthogonal signal groups into a complex signal; Applying a Hanning window to the complex signal to obtain a windowed signal; According to the frequency domain analysis method, determining the frequency corresponding to the maximum amplitude from the windowed signal as the initial main frequency; Interpolating the area where the initial main frequency is located on the spectrum point sequence of the windowed signal to obtain a sub-index offset; The main frequency is determined according to the initial main frequency and the sub-index offset.

6. The measurement method based on an eddy current encoder according to any one of claims 1 to 5, characterized in that: After generating the second orthogonal signal group according to the main frequency and the amplitude and initial phase value corresponding to the main frequency, the method further includes: Fitting the error between the first orthogonal signal group and the second orthogonal signal group to obtain an error fitting time series signal, wherein the fitting includes: piecewise linear fitting, polynomial fitting, or orthogonal basis projection fitting; The second orthogonal signal group is updated according to the error fitting signal.

7. The measurement method based on an eddy current encoder according to any one of claims 1 to 5, characterized in that: The second orthogonal signal group is generated according to the main frequency and the amplitude and initial phase value corresponding to the main frequency, which is achieved by the following expression: ； ； in, and are different signals in the second orthogonal signal group, is the amplitude corresponding to the main frequency, is the main frequency, is the initial phase value corresponding to the main frequency.

8. A measuring device based on an eddy current encoder, characterized in that: include: a first processing module, configured to determine, during a startup phase of the eddy current encoder, a main frequency and an amplitude and an initial phase value corresponding to the main frequency from a first quadrature signal group output by the eddy current encoder, and generate a second quadrature signal group based on the main frequency and the amplitude and the initial phase value corresponding to the main frequency; The second processing module is used to use the second orthogonal signal group as a reference signal of the third orthogonal signal group output by the eddy current encoder when the eddy current encoder is in the operation stage, and perform digital signal processing to obtain a physical quantity measurement value.

9. An integrated circuit, characterized in that: include: A receiving module, an analog signal processing module and a digital signal processing module connected in sequence; Wherein, the receiving module is configured to obtain the signal generated by the receiving coil in the eddy current encoder and output it to the analog signal processing module; The analog signal processing module is configured to sample the received signal to obtain a first orthogonal signal group or a third orthogonal signal group, and output the sampled signal to the digital signal processing module, wherein the first orthogonal signal group is a sampling result of the startup phase, and the third orthogonal signal group is a sampling result of the operation phase; The digital signal processing module is configured to determine the main frequency and the amplitude and initial phase value corresponding to the main frequency from the first orthogonal signal group received, and generate a second orthogonal signal group based on the main frequency and the amplitude and initial phase value corresponding to the main frequency; use the second orthogonal signal group as a reference signal for the third orthogonal signal group received, and perform digital signal processing to obtain a physical quantity measurement value.

10. An eddy current encoder, characterized in that: include: carrier; The excitation coil and the receiving coil are arranged on the carrier; An integrated circuit is arranged on the carrier and connected to the output end of the receiving coil, wherein the integrated circuit is the integrated circuit according to claim 9.

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