Signal processing method of time grating displacement sensor

Abstract

The invention discloses a signal processing method of a time grating displacement sensor. The signal processing method comprises a position signal modulation method, wherein a first excitation signal with the angular frequency of w is input into the time grating displacement sensor to modulate a position signal; the position signal demodulation method comprises the following steps: demodulating a signal output by the time grating displacement sensor to convert a position signal into a detectable electric signal; a high-frequency signal re-modulation method: performing frequency mixing and re-modulation processing on the demodulated electric signal by adopting a second excitation signal with the angular frequency of nw; and the high-resolution displacement value demodulation method comprises the step of carrying out demodulation processing on the signals subjected to frequency mixing and modulation processing. According to the method, the problems that the displacement data is good in stability but slow in response under low-frequency excitation and the displacement data is high in updating rate and fast in response but poor in stability under high-frequency excitation can be solved at the same time; displacement data processing of the time grating displacement sensor with good stability, high updating rate and high resolution can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of displacement sensors, and in particular to a signal processing method for a time-grating displacement sensor. Background Art

[0002] The time-grating displacement sensor is a high-precision displacement measurement device that uses the principle of measuring space with time to achieve accurate displacement measurement through a time reference. The innovation of the time-grating technology is that it abandons the traditional spatial line measurement method and uses time pulses as the measurement reference. This method gives the time-grating displacement sensor significant advantages in terms of resolution, ability to adapt to harsh environments, cost-effectiveness, and intelligent effects. Compared with traditional grating sensors, time-grating sensors have higher accuracy, lower cost, and stronger anti-interference ability to harsh environments such as vibration, impact, oil, dust, and water vapor.

[0003] The application field of time-grating displacement sensor is very wide, including precision machine tools, measuring instruments, semiconductor industry measurement and production equipment, as well as machine tool rotary table, servo motor, automation equipment, industrial robots, etc. Its appearance fills the gap in the field of domestic high-end precision displacement measurement and provides strong support for the development of domestic high-end equipment manufacturing industry.

[0004] The time-grating displacement sensor includes a moving measuring head and a fixed measuring head. The function of the fixed measuring head is to apply an excitation signal to the moving measuring head as an excitation source, and the function of the dynamic measuring head is to sense the signal of the fixed measuring head. When in use, the fixed measuring head is installed above the fixed measuring head. Because the fixed measuring head and the moving measuring head both exist in the state of metal conductors, the signal of the fixed measuring head will transmit the excitation signal source to the moving measuring head through space in the form of an electric field signal. When the existing time-grating displacement sensor processes the displacement signal, under low-frequency excitation signals, the displacement data has good stability but a slow response problem, while under high-frequency excitation signals, the displacement data has a high update rate but a poor data stability problem. Therefore, it is necessary to design a signal processing method for a time-grating displacement sensor that can ensure both the stability of the displacement data and the response speed. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide a signal processing method for a time-grating displacement sensor that can ensure both the stability of displacement data and the response speed.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A signal processing method for a time-grating displacement sensor, comprising:

[0008] Position signal modulation method: using a first excitation signal with an angular frequency of w to input into the time-grating displacement sensor to modulate the position signal;

[0009] Position signal demodulation method: demodulate the signal output by the time-grating displacement sensor to convert the position signal into an electrical signal that can be detected;

[0010] High-frequency signal remodulation method: using a second excitation signal with an angular frequency of nw to perform mixing and remodulation processing on the demodulated electrical signal;

[0011] High-resolution displacement value demodulation method: a high-resolution displacement value signal is obtained by demodulating the signal after mixing and remodulation.

[0012] Preferably, the position signal modulation method is as follows: a signal generator generates a first excitation signal with an angular frequency of w, a signal amplifier amplifies the first excitation signal and inputs it into a time-grating displacement sensor, when the position change is x, the position signals generated by the time-grating sensor are sin(x), cos(x), -sin(x), -cos(x), respectively, and the first excitation signal after amplification input into the time-grating sensor is modulated with the position signal and then output.

[0013] Preferably, the time-grating displacement sensor includes a fixed measuring head and a dynamic measuring head, the fixed measuring head is connected to the signal amplifier so as to apply an amplified first excitation signal to the dynamic measuring head through the fixed measuring head, the dynamic measuring head includes four pole pieces of a metal conductor, and the position signals corresponding to the four pole pieces are sin(x), cos(x), -sin(x), and -cos(x), respectively; and the dynamic measuring head modulates the four position signals respectively under the action of the excitation signal of the fixed measuring head and generates four amplitude detection signals whose amplitudes change with the displacement x.

[0014] Preferably, the first excitation signal generated by the signal generator is a sinusoidal signal sin(wt) with an angular frequency of w, and the signal amplifier adopts a differential amplifier. The sinusoidal signal sin(wt) is amplified by the differential amplifier into two differential signals A*sin(wt) and -A*sin(wt) with amplitudes A and then input into the fixed measuring head; the four amplitude detection signals generated by the dynamic measuring head are sin(x)*sin(wt), -sin(x)*sin(wt), cos(x)*sin(wt), and -cos(x)*sin(wt), respectively.

[0015] Preferably, a position signal demodulation module is used to demodulate the position signal, and the position signal demodulation module includes a first demodulation module and a second demodulation module. The sin(x)*sin(wt) and -sin(x)*sin(wt) amplitude detection signals are demodulated after passing through the first demodulation module to obtain a detectable electrical signal sin(x), and the cos(x)*sin(wt) and -cos(x)*sin(wt) amplitude detection signals are demodulated after passing through the second demodulation module to obtain a detectable electrical signal cos(x).

[0016] Preferably, the sin(x) and cos(x) signals obtained after demodulation are converted into digital signals by analog-to-digital conversion, and then the displacement value x is calculated by the inverse tangent formula, and x=arctan(sin(x) / cos(x)).

[0017] Preferably, the high-frequency signal remodulation module performs high-frequency signal remodulation, and the signal generator generates modulation signals sin(nwt) and cos(nwt) with an angular frequency of nw and inputs them into the high-frequency signal remodulation module, and the high-frequency signal remodulation module mixes the modulation signals sin(nwt) and cos(x), and mixes the modulation signals cos(nwt) and sin(x), and the two mixed signals are added together to obtain a sin(nwt+x) signal, and the sin(nwt+x) signal is passed through a zero-crossing comparator to obtain a square wave signal sin(nwt+x)', and then a high-resolution displacement value demodulation process is performed.

[0018] Preferably, a high-resolution displacement value calculation module is used to perform high-resolution displacement value demodulation, and the high-resolution displacement value calculation module uses high-frequency interpolation pulses to perform phase counting on sin(nwt)' and sin(nwt+x)', wherein sin(nwt)' is a square wave signal converted from the modulation signal sin(nwt), and sin(nwt+x)' is a square wave signal obtained after the sin(nwt+x) signal passes through a zero-crossing comparator. The pulse counter starts counting the high-frequency interpolation pulses at the rising edge of the sin(nwt)' signal and ends counting the high-frequency interpolation pulses at the rising edge corresponding to the sin(nwt+x)' signal. The pulse count change value obtained by the high-frequency interpolation pulse directly corresponds to the phase difference value x between the sin(nwt+x)' and sin(nwt)' signals, that is, the displacement change value x after demodulation.

[0019] Preferably, the sin(nwt+x) signal obtained by the mixing and addition is first filtered by a filter and then input into the zero-crossing comparator.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention only needs to generate a low-frequency signal with an angular frequency of w as the excitation signal of the time-grating displacement sensor, and the low-frequency signal helps to improve the stability of the displacement data of the time-grating displacement sensor. At the same time, the present invention uses a high-frequency signal with an angular frequency of nw to re-modulate the signal output by the time-grating displacement sensor, so that the subsequent displacement value can be solved at a high frequency, thereby effectively improving the displacement data response time and update rate. Since the high-frequency signal does not pass through the time-grating displacement sensor, when the frequency is doubled, it will not affect the characteristics of the time-grating displacement sensor, and therefore will not change the stability of the original data.

[0022] 2. The present invention can simultaneously solve the problems that the displacement data has good stability but slow response under low-frequency excitation, and the displacement data has a high update rate but poor data stability under high-frequency excitation. Combined with the high-resolution time measurement method of the time-grating displacement sensor, the displacement data processing of the time-grating displacement sensor with good stability, high update rate and high resolution can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 It is a flow chart of a signal processing method of a time-grid displacement sensor of the present invention;

[0024] Attached Figure 2 It is a schematic diagram of a fixed measuring head of a time-grid displacement sensor of the present invention;

[0025] Attached Figure 3 It is a schematic diagram of a dynamic measuring head of a time-grid displacement sensor of the present invention;

[0026] Attached Figure 4 Schematic diagram of the modulation process of sin(x) and sin(wt) in the signal processing method of the time-grating displacement sensor of the present invention;

[0027] Attached Figure 5 It is a schematic diagram of the process of obtaining sin(x) by demodulating in a switching manner in the signal processing method of the time-grid displacement sensor of the present invention;

[0028] Attached Figure 6 The present invention is a schematic diagram of a process of high-resolution displacement value demodulation performed by a high-resolution displacement value calculation module in a signal processing method for a time-grating displacement sensor. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0030] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] A signal processing method for a time-grating displacement sensor includes a position signal modulation method, a position signal demodulation method, a high-frequency signal remodulation method and a high-resolution displacement value demodulation method. Figure 1As shown, the method is implemented by a system consisting of a signal generator, a signal amplifier, a time-grating displacement sensor, a position signal demodulation module, a high-frequency signal remodulation module and a high-resolution displacement value calculation module that are sequentially connected in communication.

[0032] The position signal modulation method is: using a first excitation signal with an angular frequency of w to input into a time-grating displacement sensor to modulate the position signal; specifically, the signal generator, signal amplifier and time-grating displacement sensor in the system realize the modulation of the position signal: the signal generator generates a first excitation signal with an angular frequency of w, and the first excitation signal can be a sine signal or a square wave signal, etc. The use of a square wave signal can also achieve the effect of simplifying the circuit and reducing costs. In this specific embodiment, the first excitation signal is a sine signal for illustration, that is, the first excitation signal is sin(wt), and the first excitation signal is input to the signal amplifier. In this specific embodiment, the signal amplifier uses a double-ended differential amplifier. Of course, a single-ended amplifier can also be used in actual use. The single-ended amplifier can also realize the function. The disadvantage is that the amplitude of the final signal is reduced, which will reduce the resolution of the final calculation, and can be adapted to low-resolution scenes. After the first excitation signal passes through the double-ended differential amplifier, the output signals A*sin(wt) and -A*sin(wt) are output. The time-grating displacement sensor is a sensor that converts position changes into sinusoidal electrical signal changes. The time-grating displacement sensor includes a fixed measuring head and a dynamic measuring head. The fixed measuring head is used as an excitation source to apply an excitation signal to the dynamic measuring head. The fixed measuring head is connected to the signal amplifier to apply the amplified first excitation signal to the dynamic measuring head through the fixed measuring head. The fixed measuring head is as shown in the attached Figure 2 As shown, it is divided into two parts, upper and lower, by a sine-like dividing line. The upper and lower parts of the fixed measuring head are respectively used to connect two excitation signals A*sin(wt) and -A*sin(wt). The role of using differential excitation here is to enhance the excitation intensity, which is consistent with the single-ended 2A*sin(wt). The function of the dynamic measuring head is to sense the signal of the fixed measuring head. When in use, it is installed above the fixed measuring head. Because the fixed measuring head and the dynamic measuring head both exist in the state of metal conductors, the signal of the fixed measuring head will transmit the excitation signal source through space to the dynamic measuring head in the form of an electric field signal. The dynamic measuring head includes four metal conductor pole pieces. Assume that the position change is x, as shown in the attached figure. Figure 3 As shown, the position signals corresponding to the four pole pieces are sin(x), cos(x), -sin(x), and -cos(x) respectively; after receiving the excitation signal from the fixed probe, the dynamic probe modulates the four position signals respectively and generates four amplitude detection signals whose amplitudes change with the displacement x.

[0033] sin(x)*sin(wt),-sin(x)*sin(wt),cos(x)*sin(wt),-cos(x)*sin(wt), that is, the amplitude detection signals with a phase difference of 90° and the amplitude changing with the displacement are formed respectively. The signal diagram of sin(x)*sin(wt) is shown in the attached figure. Figure 4 As shown, the other three signals are similar, except that their phases differ by 90° relative to sin(x).

[0034] The position signal demodulation method is: demodulating the signal output by the time-grating displacement sensor to convert the position signal into a detectable electrical signal; specifically, according to the theory of communication, the induction signal is mixed with the excitation signal and filtered, and the electrical signals sin(x) and cos(x) that change with the position can be demodulated; therefore, this solution adopts a position signal demodulation module to demodulate the position signal, and adopts a position signal demodulation module to demodulate the position signal. The position signal demodulation module includes a first demodulation module and a second demodulation module. The amplitude detection signals of sin(x)*sin(wt) and -sin(x)*sin(wt) are demodulated by the first demodulation module to obtain a detectable electrical signal sin(x), as shown in the attached figure. Figure 5 As shown, the cos(x)*sin(wt) and -cos(x)*sin(wt) amplitude detection signals are demodulated through the second demodulation module to obtain a detectable electrical signal cos(x).

[0035] The sin(x) and cos(x) signals obtained after demodulation are converted into digital signals by analog-to-digital conversion, and then the displacement value x is calculated by the inverse tangent formula, and x = arctan(sin(x) / cos(x)). This is the position solution method of the amplitude detection scheme. At the same time, another processing method is also disclosed in this patent.

[0036] The high-frequency signal remodulation method is: using a second excitation signal with an angular frequency of nw to mix and remodulate the demodulated electrical signal; specifically, since the sin(x) and cos(x) signals obtained after demodulation are low-frequency signals, the signal residue introduced by the previous sin(wt) can be effectively filtered out by a low-pass filter, and the high-frequency interference introduced by the use environment can also be effectively filtered out, but it is sensitive to low-frequency interference. In order to solve the low-frequency interference problem, this solution will further use a higher frequency sin(nwt) and cos(nwt) to mix with cos(x) and sin(x) respectively. In this specific embodiment, a high-frequency signal remodulation module is used to remodulate the high-frequency signal. The signal generator generates modulation signals sin(nwt) and cos(nwt) with an angular frequency of nw and inputs them into the high-frequency signal remodulation module. The high-frequency signal remodulation module mixes the modulation signal sin(nwt) and the cos(x) signal, and mixes the modulation signal cos(nwt) and the sin(x) signal. The two mixed signals are then added to obtain the sin(nwt+x) signal. This process is equivalent to the following formula calculation:

[0037] sin(nwt)*cos(x)+cos(nwt)*sin(x)=sin(nwt+x)

[0038] This formula is the standard formula of the time-grating phase-detection technology. Here, since the high-frequency signals sin(nwt) and cos(nwt) do not pass through the time-grating displacement sensor, doubling the frequency will not affect the characteristics of the time-grating displacement sensor, and therefore will not change the stability of the original data. At the same time, doubling the frequency will mean that the response time will be doubled, and the resolution characteristics of the time-grating displacement sensor will also be maintained, thereby realizing a time-grating displacement sensor with high resolution, high stability and high response time.

[0039] The solution can directly sample the inverse tangent formula to calculate the angle value when the cost or volume is sensitive. If this solution is adopted, data stability and resolution will be sacrificed in exchange for a time-grating sensor solution with lower cost and volume.

[0040] The high-resolution displacement value demodulation method is: demodulate the signal after mixing and remodulation to obtain a high-resolution displacement value signal. Specifically, a high-resolution displacement value solution module is used for high-resolution displacement value demodulation. Before the high-frequency modulation signal sin(nwt+x) enters the high-resolution displacement value solution module, it is necessary to perform a bandpass filter on sin(nwt+x) again. Since the front pole cannot use a filter to filter out low-frequency interference (when the sensor moves, the low-frequency signal and the low-frequency interference overlap, and filtering the low frequency will affect the accuracy of the displacement signal), the low-frequency interference can be further filtered out by the filter to obtain a more stable signal. The input signal of the high-resolution displacement solution module is a square wave signal obtained after sin(nwt+x) passes through a zero-crossing comparator. The square wave signal retains the phase characteristics, which is represented by sin(nwt+x)'.

[0041] As attached Figure 6 As shown, the high-resolution displacement value solution module uses high-frequency interpolation pulses to count the phases of sin(nwt)' and sin(nwt+x)', wherein sin(nwt)' is the square wave signal converted from the modulation signal sin(nwt), and sin(nwt+x)' is the square wave signal obtained after the sin(nwt+x) signal passes through the zero-crossing comparator. The high-frequency interpolation pulse starts counting the high-frequency interpolation pulses at the rising edge of the sin(nwt)' signal and ends counting the high-frequency interpolation pulses at the rising edge corresponding to the sin(nwt+x)' signal. This can reflect the relative phase change between the excitation signal and the induced signal. The actual displacement value change will be directly mapped to the change in the number of pulses here, that is, the pulse count change value obtained by the high-frequency interpolation pulse directly corresponds to the phase difference x between the sin(nwt+x)' and sin(nwt)' signals, that is, the demodulated displacement change value x. Therefore, the pulse count change value here corresponds to the displacement change value after demodulation, thereby realizing the high-resolution position solution of this method. At the same time, the sin(nwt) here can increase the frequency several times, so the sampling rate will also be increased several times, and the response time will also be increased several times.

[0042] Specifically, the higher the frequency of the high-frequency interpolation pulse, the higher the measured phase resolution. For example: if the length of a periodic pattern of the time-grating displacement sensor is 4mm, then the frequency of sin(wt) is 4Khz. Then when the time-grating displacement sensor moves a period of 4mm, the induction signal sin(wt+x) corresponds to a phase change period of 250us. Therefore, the lower the frequency of sin(wt), the larger the corresponding phase change period value, and the tighter the measured displacement value of the time-grating displacement sensor. At the same time, the higher the time resolution of the phase change period, the higher the measurement resolution of the distance moved by the corresponding time-grating displacement sensor. As for the problem of low update rate caused by low frequency, when the secondary modulation of the scheme is sin(nwt+x), the frequency is amplified n times, that is, the update rate is increased n times. For example, if the frequency of sin(wt) is 4Khz, if n is 100, the update rate is increased from 250us to 2.5us, solving the problem of low update rate.

[0043] The present invention only needs to generate a low-frequency signal with an angular frequency of w as an excitation signal of the time-grating displacement sensor, and the low-frequency signal helps to improve the stability of the displacement data of the time-grating displacement sensor. At the same time, the present invention uses a high-frequency signal with an angular frequency of nw to re-modulate the signal output by the time-grating displacement sensor, so that the subsequent displacement value can be solved at a high frequency, thereby effectively improving the response time and update rate of the displacement data.

[0044] The present invention can simultaneously solve the problems that displacement data has good stability but slow response under low-frequency excitation, and has high update rate but poor data stability under high-frequency excitation. Combined with the high-resolution time measurement method of the time-grating displacement sensor, the displacement data processing of the time-grating displacement sensor with good stability, high update rate and high resolution can be realized.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A signal processing method for a time-grating displacement sensor, characterized in that: include: Position signal modulation method: using a first excitation signal with an angular frequency of w to input into the time-grating displacement sensor to modulate the position signal; Position signal demodulation method: demodulate the signal output by the time-grating displacement sensor to convert the position signal into an electrical signal that can be detected; High-frequency signal remodulation method: using a second excitation signal with an angular frequency of nw to perform mixing and remodulation processing on the demodulated electrical signal; High-resolution displacement value demodulation method: a high-resolution displacement value signal is obtained by demodulating the signal after mixing and remodulation.

2. The signal processing method of the time-grating displacement sensor according to claim 1, characterized in that: The position signal modulation method is specifically as follows: the signal generator generates a first excitation signal with an angular frequency of w, the signal amplifier amplifies the first excitation signal and inputs it into the time-grating displacement sensor, when the position change is x, the position signals generated by the time-grating sensor are sin(x), cos(x), -sin(x), -cos(x), respectively, the first excitation signal after amplification input into the time-grating sensor is modulated with the position signal and then output.

3. The signal processing method of the time-grating displacement sensor according to claim 2, characterized in that: The time-grating displacement sensor includes a fixed measuring head and a dynamic measuring head. The fixed measuring head is connected to the signal amplifier so as to apply an amplified first excitation signal to the dynamic measuring head through the fixed measuring head. The dynamic measuring head includes four pole pieces of a metal conductor. The position signals corresponding to the four pole pieces are sin(x), cos(x), -sin(x), and -cos(x), respectively. Under the action of the excitation signal of the fixed measuring head, the dynamic measuring head modulates the four position signals respectively and generates four amplitude detection signals whose amplitudes change with the displacement x.

4. The signal processing method of the time-grating displacement sensor according to claim 3, characterized in that: The first excitation signal generated by the signal generator is a sinusoidal signal sin(wt) with an angular frequency of w. The signal amplifier adopts a differential amplifier. The sinusoidal signal sin(wt) is amplified by the differential amplifier into two differential signals A*sin(wt) and -A*sin(wt) with amplitudes A and then input into the fixed measuring head. The four amplitude detection signals generated by the dynamic measuring head are sin(x)*sin(wt), -sin(x)*sin(wt), cos(x)*sin(wt), and -cos(x)*sin(wt).

5. The signal processing method of the time-grating displacement sensor according to claim 4, characterized in that: A position signal demodulation module is used to demodulate the position signal. The position signal demodulation module includes a first demodulation module and a second demodulation module. The sin(x)*sin(wt) and -sin(x)*sin(wt) amplitude detection signals are demodulated by the first demodulation module to obtain a detectable electrical signal sin(x). The cos(x)*sin(wt) and -cos(x)*sin(wt) amplitude detection signals are demodulated by the second demodulation module to obtain a detectable electrical signal cos(x).

6. The signal processing method of the time-grating displacement sensor according to claim 5, characterized in that: The sin(x) and cos(x) signals obtained after demodulation are converted into digital signals by analog-to-digital conversion, and then the displacement value x is calculated by the inverse tangent formula, and x=arctan(sin(x) / cos(x)).

7. The signal processing method of the time-grating displacement sensor according to claim 5, characterized in that: The high-frequency signal remodulation module performs high-frequency signal remodulation. The signal generator generates modulation signals sin(nwt) and cos(nwt) with an angular frequency of nw and inputs them into the high-frequency signal remodulation module. The high-frequency signal remodulation module mixes the modulation signal sin(nwt) and the cos(x) signal, and mixes the modulation signal cos(nwt) and the sin(x) signal. The two mixed signals are then added to obtain a sin(nwt+x) signal. The sin(nwt+x) signal passes through a zero-crossing comparator to obtain a square wave signal sin(nwt+x)', and then a high-resolution displacement value demodulation process is performed.

8. The signal processing method of the time-grating displacement sensor according to claim 7, characterized in that: A high-resolution displacement value calculation module is used to perform high-resolution displacement value demodulation. The high-resolution displacement value calculation module uses high-frequency interpolation pulses to perform phase counting on sin(nwt)' and sin(nwt+x)', wherein sin(nwt)' is a square wave signal converted from the modulation signal sin(nwt), and sin(nwt+x)' is a square wave signal obtained after the sin(nwt+x) signal passes through a zero-crossing comparator. The pulse counter starts counting the high-frequency interpolation pulses at the rising edge of the sin(nwt)' signal and ends counting the high-frequency interpolation pulses at the rising edge corresponding to the sin(nwt+x)' signal. The pulse count change value obtained by the high-frequency interpolation pulse directly corresponds to the phase difference value x between the sin(nwt+x)' and sin(nwt)' signals, that is, the displacement change value x after demodulation.

9. The signal processing method of the time-grating displacement sensor according to claim 7, characterized in that: The sin(nwt+x) signal obtained by adding the mixed signals is first filtered by a filter and then input into the zero-crossing comparator.

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