Displacement measurement system and displacement measurement method for a sensor device

Abstract

The present invention provides a displacement measurement system and a displacement measurement method for a sensor device. The sensor device includes a first displacement sensor. The displacement measurement system includes: a drive signal generation circuit for outputting a drive signal to the first displacement sensor; a first signal processing circuit for receiving a signal from the first displacement sensor and outputting a first ADSO signal; and a computing device including a first timer. Wherein, the first timer is used to receive a CLK512 signal and the first ADSO signal, and perform timing or counting according to the CLK512 signal and the first ADSO signal. Wherein, the CLK512 signal is a square wave signal related to the period and phase of the drive signal. The displacement measurement system and method provided by the present invention achieve performance improvement at a lower cost, and can obtain higher measurement resolution and measurement accuracy.

Description

Technical Field

[0001] The present invention relates to positioning and displacement measurement. Specifically, it relates to the positioning and displacement measurement technologies of angles and lengths. More specifically, it relates to a displacement measurement system and a displacement measurement method for a sensor device. Background Art

[0002] Displacement sensors are usually used as position measurement elements in measurement systems such as length measurement, angle measurement, speed measurement, precision positioning, and servo tracking. Displacement sensors include capacitive sensors, induction synchros, grating sensors, etc. Among them, the most widely used is the capacitive grating sensor in capacitive sensors. It forms a capacitive grating sensor displacement measurement system with a displacement measurement circuit, which is divided into a phase discrimination type and an amplitude discrimination type. Figure 1 An example diagram of a traditional phase discrimination type capacitive grating sensor displacement measurement system is shown. It uses the grating pitch as the measurement period, obtains the position quantity of the grating electrode of the capacitive grating sensor within one period through phase discrimination, and realizes displacement measurement exceeding one period through direction discrimination and counting. Figure 1 The shown traditional phase discrimination type capacitive grating sensor displacement measurement system includes a capacitive grating sensor 10 and a capacitive grating sensor ASIC chip 20 (hereinafter also simply referred to as the ASIC chip 20 or the chip 20). The capacitive grating sensor ASIC chip 20 integrates a crystal oscillator circuit 21, a clock frequency division circuit 22, a multi-channel (usually 8 channels) drive and analog switch signal generation circuit 23 (hereinafter also simply referred to as the drive signal generation circuit 23), a capacitive grating signal demodulation, amplification, filtering and comparison circuit 24 (hereinafter also simply referred to as the capacitive grating signal processing circuit 24, or the signal processing circuit 24), a phase discrimination and counting circuit 25, a displacement data processing circuit 26, an LCD display circuit 29, a voltage detection circuit 28, and a serial output port 27, etc.

[0003] The signal period (512CP) output by the above capacitive grating signal processing circuit 24 corresponds to the length of one grating pitch in the capacitive grating sensor in space. Assuming the length of one grating pitch is 5.08 mm, the minimum accuracy that the phase discrimination type capacitive grating sensor displacement measurement system can resolve is: 5.08 mm / 512 ≈ 0.01 mm ≈ 0.0004 inch. In this case, when the moving grating of the capacitive grating sensor moves one unit of the minimum accuracy, the phase of the CSI signal changes by 180 / 256 degrees. It can be seen that the resolution of the traditional phase discrimination type capacitive grating sensor displacement measurement system is not high. The reason for adopting this relatively low resolution is as follows: According to the measurement mechanism of the active discrimination capacitive grating technology, the phase difference obtained through the phase discrimination operation does not have a completely linear proportional relationship with the displacement change amount of the grating of the capacitive grating sensor, but has a deviation of about 0.1%. Therefore, a relatively low resolution needs to be adopted to ensure a certain output accuracy; in addition, the frequency of the 8-channel drive signal has a strong electrical correlation with the area of the grating in the capacitive grating sensor. In order to adapt to the impedance matching requirements of the capacitive grating sensor and the chip, and at the same time to take into account low power consumption and a certain resolution, the drive frequency of the capacitive grating sensor is usually set between 200 Hz and 500 Hz, and the operating frequency of the chip is set between 100 kHz and 300 kHz. This also makes the resolution of the measurement system relatively low.

[0004] As can be seen from the above description, the resolution of the traditional phase discrimination type capacitive grating sensor displacement measurement system has been fixed with the operating frequency of the chip. To improve the resolution, the common current practice is to reduce the grating pitch of the capacitive grating sensor. However, limited by manufacturing, assembly and other technologies, the reduction space of the grating pitch of the capacitive grating sensor is very limited, which makes it still difficult for the phase discrimination type capacitive grating sensor displacement measurement system to achieve high-resolution displacement measurement. Summary of the Invention

[0005] To solve the problems existing in the above-mentioned prior art, according to an embodiment of the present invention, there is provided a displacement measurement system for a sensor device, wherein the sensor device includes a first displacement sensor, and the displacement measurement system includes:

[0006] A drive signal generation circuit for outputting a drive signal to the first displacement sensor;

[0007] A first signal processing circuit for receiving a signal from the first displacement sensor and outputting a first ADSO signal; and

[0008] A computing device including a first timer;

[0009] Among them, the first timer is used to receive the CLK512 signal and the first ADSO signal, and perform timing or counting according to the CLK512 signal and the first ADSO signal; among them, the CLK512 signal is a square wave signal related to the period and phase of the drive signal.

[0010] In the above displacement measurement system, a clock frequency division circuit is further included, which is used to output a clock signal to the drive signal generation circuit and output the CLK512 signal.

[0011] In the above displacement measurement system, the computing device further includes a processor, which is used to convert the data obtained by the first timer through timing or counting into the absolute displacement value of the gate of the first displacement sensor within one pitch.

[0012] In the above displacement measurement system, a counting clock is further included, among which the first timer is used to perform timing or counting according to the CLK512 signal and the first ADSO signal at the clock frequency provided by the counting clock.

[0013] In the above displacement measurement system, the first timer is used to start timing or counting from zero at the clock frequency provided by the counting clock when detecting the rising edge of the CLK512 signal, and send the current time or current count to the processor when detecting the rising edge of the first ADSO signal.

[0014] In the above displacement measurement system, the first timer further includes a first buffer; among which, the first timer is used to start timing or counting from zero at the clock frequency provided by the counting clock when detecting the rising edge of the CLK512 signal, and write the current time or current count into the first buffer when detecting the rising edge of the first ADSO signal. The processor is used to read the data in the first buffer after receiving the interrupt flag signal triggered by the first ADSO signal or the CLK512 signal.

[0015] In the above displacement measurement system, the processor is used to obtain the position equivalent of the gate of the first displacement sensor within one pitch according to the data obtained by the first timer through timing and the clock frequency provided by the counting clock, and convert the position equivalent of the gate of the first displacement sensor within one pitch into the absolute displacement value of the gate of the first displacement sensor within one pitch. The processor is further used to perform digital filtering processing on the position equivalent of the gate of the first displacement sensor within one pitch, and perform deviation correction on the absolute displacement value of the gate of the first displacement sensor within one pitch.

[0016] In the above displacement measurement system, the counting clock may be included in the computing device.

[0017] In the above displacement measurement system, the computing device further includes a second timer, configured to receive the CLK512 signal and the first ADSO signal, and count the number of grating pitches of the gate movement of the first displacement sensor according to the CLK512 signal and the first ADSO signal. Wherein, the processor is further configured to obtain the total absolute displacement value of the gate of the first displacement sensor according to the data obtained by counting by the second timer and the data obtained by timing or counting by the first timer.

[0018] In the above displacement measurement system, the drive signal generation circuit and the first signal processing circuit are integrated in the same chip. The chip further includes: a phase discrimination and counting circuit, configured to receive the first ADSO signal; and a serial output port, configured to output a CLK signal and a DATA signal including the displacement information of the gate of the first displacement sensor. The computing device is further configured to receive the CLK signal and the DATA signal. The processor is further configured to obtain the number of grating pitches of the gate movement of the first displacement sensor according to the received CLK signal and DATA signal, and obtain the total absolute displacement value of the gate of the first displacement sensor according to the number of grating pitches of the gate movement of the first displacement sensor and the data obtained by timing or counting by the first timer.

[0019] In the above displacement measurement system, the processor is configured to obtain the total absolute displacement equivalent of the gate of the first displacement sensor according to the number of grating pitches of the gate movement of the first displacement sensor and the data obtained by timing or counting by the first timer, and convert the total absolute displacement equivalent of the gate of the first displacement sensor into the total absolute displacement value of the gate of the first displacement sensor.

[0020] In the above displacement measurement system, the sensor device further includes a second displacement sensor, wherein the first displacement sensor has a plurality of grating pitches within one grating pitch of the second displacement sensor, and the drive signal generation circuit is further configured to output the drive signal to the second displacement sensor. The displacement measurement system further includes a second signal processing circuit for receiving the signal from the second displacement sensor and outputting a second ADSO signal. The computing device further includes a third timer for receiving the second ADSO signal and the CLK512 signal, and timing or counting according to the second ADSO signal and the CLK512 signal at the clock frequency provided by the counting clock. The processor is further configured to determine the number of grating pitches of the gate movement of the first displacement sensor according to the data obtained by the third timer through timing or counting, and obtain the total absolute displacement value of the gate of the first displacement sensor according to the number of grating pitches of the gate movement of the first displacement sensor and the data obtained by the first timer through timing or counting.

[0021] In the above displacement measurement system, the third timer is configured to start timing or counting from zero at the clock frequency provided by the counting clock when detecting the rising edge of the CLK512 signal, and send the current time or the current count to the processor or record the current time or the current count when detecting the rising edge of the second ADSO signal.

[0022] In the above displacement measurement system, the first displacement sensor and the second displacement sensor are capacitive grating sensors.

[0023] In the above displacement measurement system, the CLK512 signal is a square wave signal having the same period and the same phase as the drive signal.

[0024] In the above displacement measurement system, the computing device, the drive signal generation circuit, and the first signal processing circuit are integrated on the same chip.

[0025] According to another embodiment of the present invention, there is also provided a displacement measurement method for a sensor device, the sensor device including a first displacement sensor, and the displacement measurement method includes:

[0026] Outputting a drive signal to the first displacement sensor;

[0027] Receiving the signal from the first displacement sensor, processing the signal, and outputting a first ADSO signal; and

[0028] Receive the CLK512 signal and the first ADSO signal, and perform timing or counting according to the CLK512 signal and the first ADSO signal; wherein, the CLK512 signal is a square wave signal related to the period and phase of the drive signal.

[0029] In the above displacement measurement method, it further includes: converting the first data obtained through the timing or counting into the absolute displacement value of the gate of the first displacement sensor within one grating pitch.

[0030] In the above displacement measurement method, performing timing or counting according to the CLK512 signal and the first ADSO signal includes: starting timing or counting from zero at the rising edge of the CLK512 signal, and sending or recording the current time or current count at the rising edge of the first ADSO signal.

[0031] In the above displacement measurement method, converting the first data obtained through timing into the absolute displacement value of the gate of the first displacement sensor within one grating pitch includes:

[0032] Obtaining the position equivalent of the gate of the first displacement sensor within one grating pitch according to the first data obtained through timing and the clock frequency; and

[0033] Converting the position equivalent of the gate of the first displacement sensor within one grating pitch into the absolute displacement value of the gate of the first displacement sensor within one grating pitch.

[0034] In the above displacement measurement method, it further includes:

[0035] Performing digital filtering processing on the position equivalent of the gate of the first displacement sensor within one grating pitch; and

[0036] Performing deviation correction on the absolute displacement value of the gate of the first displacement sensor within one grating pitch.

[0037] In the above displacement measurement method, it further includes:

[0038] Receiving the CLK512 signal and the first ADSO signal, and counting the number of grating pitches of the gate movement of the first displacement sensor according to the CLK512 signal and the first ADSO signal; and

[0039] Obtaining the total absolute displacement value of the gate of the first displacement sensor according to the second data obtained by counting the number of grating pitches of the gate movement of the first displacement sensor and the first data.

[0040] In the above displacement measurement method, the sensor device further includes a second displacement sensor, wherein the first displacement sensor has a plurality of grating pitches within one grating pitch of the second displacement sensor, and the displacement measurement method further includes:

[0041] Output the drive signal to the second displacement sensor;

[0042] Receive the signal from the second displacement sensor, process the signal, and output a second ADSO signal;

[0043] Receive the second ADSO signal and the CLK512 signal, and perform timing or counting according to the second ADSO signal and the CLK512 signal at the clock frequency, wherein a third data is obtained by performing timing or counting according to the second ADSO signal and the CLK512 signal;

[0044] Determine the number of grating pitches by which the gate of the first displacement sensor moves according to the third data; and

[0045] Obtain the total absolute displacement value of the gate of the first displacement sensor according to the number of grating pitches by which the gate of the first displacement sensor moves and the first data.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] On the basis of inheriting the large-scale production technology of the traditional phase discrimination type displacement measurement system and without changing the size of the coupling structure of the displacement sensor, the displacement measurement system and method provided by the present invention achieve performance improvement at a lower cost, and obtain a relatively high (such as micron level and sub-micron level) measurement resolution and relatively high measurement accuracy.

[0048] In addition, the present invention has a wide range of applications. In addition to capacitive grating sensors, the present invention can also be used in combination with other types of capacitive sensors, induction synchros, grating sensors, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Exemplary embodiments will be described in detail below with reference to the accompanying drawings, which are intended to depict the exemplary embodiments and should not be construed as limiting the intended scope of the claims. Unless otherwise specified, the drawings are not considered to be drawn to scale.

[0050] Figure 1 is a block diagram of a traditional phase discrimination type capacitive grating sensor displacement measurement system;

[0051] Figure 2 is a schematic diagram of an equivalent pulse width modulation square wave modulated by an ADSO signal formed by mapping a CLK512 signal and an ADSO signal according to an embodiment of the present invention;

[0052] Figure 3 is a block diagram of a structure including a capacitive grating sensor and an ASIC chip in a displacement measurement system according to an embodiment of the present invention;

[0053] Figure 4 is a block diagram of a microcontroller in a displacement measurement system according to an embodiment of the present invention;

[0054] Figure 5 is a flowchart of the operation of a microcontroller according to an embodiment of the present invention;

[0055] Figure 6 is a block diagram of a microcontroller in a displacement measurement system according to another embodiment of the present invention;

[0056] Figure 7 is a flowchart of a data processing program performed by the CPU in a microcontroller according to another embodiment of the present invention;

[0057] Figure 8 is a block diagram of a structure including a capacitive grating sensor and an ASIC chip in a displacement measurement system according to yet another embodiment of the present invention;

[0058] Figure 9 is a block diagram of a microcontroller in a displacement measurement system according to yet another embodiment of the present invention;

[0059] Figure 10 is a block diagram of a structure including a coarse and fine capacitive grating sensor and an ASIC chip in a displacement measurement system according to yet another embodiment of the present invention;

[0060] Figure 11 is a block diagram of a microcontroller in a displacement measurement system according to yet another embodiment of the present invention. Detailed Embodiments

[0061] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below through specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0062] Before describing each embodiment of the present invention, it should be noted that for ease of understanding, the following embodiments of the present invention are all described around capacitive grating sensors, but displacement sensors such as other capacitive sensors are also applicable herein.

[0063] After studying the measurement principle of the traditional phase-detection type capacitive grating sensor displacement measurement system, the inventor found that the multi-channel driving signals used to drive the capacitive grating sensor are generated by the clock frequency division circuit in the chip through combinational logic. There is a strict phase matching relationship between this driving signal and the signal (referred to as the ADSO signal in this application) output by the capacitive grating sensor and obtained through demodulation, amplification, filtering, and comparison operations. If the ADSO signal is phase-compared with a square wave signal as shown in Figure 2 (this square wave signal has the same period as the multi-channel driving signals used to drive the capacitive grating sensor and the same phase as one of the driving signals), then an equivalent pulse-width modulation square wave modulated by the ADSO signal as shown in Figure 2 can be mapped. At the same time, further research found that the modulation pulse width of this equivalent pulse-width modulation square wave (such as A1, A2, A3, A4 shown in Figure 2 ) not only corresponds to the phase difference between the ADSO signal and the above square wave signal, but also corresponds to the position value of the grating of the capacitive grating sensor within one grating pitch in space. In addition, the inventor also found that compared with the prior art (as described above, the phase difference obtained after phase detection in the prior art does not have a completely linear proportional relationship with the displacement change amount of the grating of the capacitive grating sensor), according to the above corresponding relationship, it is possible to directly measure the modulation pulse width of the equivalent pulse-width modulation square wave to obtain a high-resolution position equivalent of the grating of the capacitive grating sensor within one grating pitch, and to obtain the position value of the grating of the capacitive grating sensor within one grating pitch, or the absolute displacement value, by converting this position equivalent.

[0064] In view of this, in order to improve the measurement resolution on the basis of the existing capacitive grating sensor, according to an embodiment of the present invention, a displacement measurement system for a sensor device is provided, and the sensor device includes a capacitive grating sensor.

[0065] See Figure 3 and Figure 4 , the displacement measurement system according to an embodiment of the present invention includes: an ASIC chip 30 integrated with a crystal oscillator circuit 21, a clock frequency division circuit 22, a multi-channel driving and analog switch signal generation circuit 23 (hereinafter described by taking an 8-channel driving and analog switch signal generation circuit as an example) Figure 3 ); and a single-chip microcomputer 40 including a timer 41, a counting clock 42, a CPU 43, a RAM 44, a display unit 45, and a serial port 46 Figure 4 . Among them, the timer also includes a buffer Figure 4(not shown in the figure). Among them, the capacitive grid signal processing circuit 24 in the chip 30 sends the generated ADSO signal to the timer 41 of the single-chip microcomputer 40; in addition to sending the clock signal to the 8-channel driving and analog switch signal generation circuit 23, the clock frequency division circuit 22 also sends a square wave signal (referred to as the CLK512 signal in the present invention, whose period is the same as that of the 8-channel driving signals out1-out8, for example, 512T, where 1T represents the reciprocal of the chip operating frequency; and its phase is the same as that of one of the driving signals) to the timer 41 of the single-chip microcomputer 40. According to an embodiment of the present invention, the working process of the measurement system is as follows:

[0066] 1) In the ASIC chip 30, the crystal oscillator circuit 21 generates a clock signal and sends it to the clock frequency division circuit 22; the clock frequency division circuit 22 performs frequency division processing on the clock signal and sends the generated clock signal to the 8-channel driving and analog switch signal generation circuit 23. The clock frequency division circuit 22 also outputs a square wave signal (CLK512 signal) whose period is the same as that of the 8-channel driving signals and whose phase is the same as that of any one of the driving signals; the 8-channel driving and analog switch signal generation circuit 23 receives the signal from the clock frequency division circuit and generates and outputs 8-channel driving signals for driving the capacitive grid sensor 10.

[0067] After the 8-channel driving and analog switch signal generation circuit 23 outputs the 8-channel driving signals, the capacitive grid sensor 10 performs the following processing:

[0068] The 8 emitter plates of the capacitive grid sensor 10 respectively receive the 8-channel driving signals from the ASIC chip 30, and modulate the output voltage to generate periodic signals with different amplitudes (i.e., CSI signals) via the grid capacitance of the capacitive grid sensor 10. Then, the capacitive grid sensor 10 inputs the CSI signals into the inside of the ASIC chip 30.

[0069] 2) In the ASIC chip 30, the capacitive grid signal processing circuit 24 receives the CSI signals from the capacitive grid sensor 10, converts the CSI signals into ADSO signals related to the displacement of the grid of the capacitive grid sensor 10 through demodulation, amplification, filtering, and comparison operations, and outputs the ADSO signals. Those skilled in the art should understand that when the ADSO signal is phase-shifted by 360° electrical phase angle, it corresponds to one grid pitch in the capacitive grid sensor in space.

[0070] 3) In the microcontroller 40, the timer 41 of the microcontroller 40 receives the ADSO signal from the capacitive grating signal processing circuit 24 and the CLK512 signal from the clock frequency division circuit 22. In this embodiment, the timer 41 in the microcontroller 40 uses the clock frequency provided by the counting clock 42 as the counting frequency (i.e., counts the number of pulses of the counting clock 42), and performs counting according to the ADSO signal and the CLK512 signal. According to an embodiment of the present invention (see Figure 5 ), the working process of the microcontroller is as follows:

[0071] 31) The timer 41 of the microcontroller 40 receives the ADSO signal and the CLK512 signal. When the timer 41 detects the rising edge of the CLK512 signal, it clears the count; when the timer 41 detects the rising edge of the ADSO signal, it writes the current count into the buffer, generates an interrupt flag signal at the same time, and sends the interrupt flag signal to the CPU 43.

[0072] Refer to Figure 2 It can be seen that the count written by the timer 41 into the buffer corresponds to a modulation pulse width of an equivalent pulse width modulation square wave (such as Figure 2 A1, A2... shown), and this count represents the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch. In addition, since the timer 41 counts at the clock frequency provided by the counting clock 42, different position equivalents with different resolutions can be obtained by setting different clock frequencies for the counting clock 42. For example, assuming that the clock frequency of the microcontroller 40 is 6 MHz and the operating frequency of the ASIC chip 30 is 153.6 KHz, the duration of the 512T signal period corresponding to one grating pitch of the capacitive grating sensor 10 is 512x1 / 153.6x10 -3 seconds = 10 / 3x10 -3 seconds. During this duration, the maximum count value of the timer 41 of the microcontroller 40 is (10 / 3x10 -3 ) / (1 / 6x10 -6 ) = 20000. Therefore, the position equivalent subdivision is about 40 times higher than the original (i.e., 512). Assuming that one grating pitch of the capacitive grating sensor is 5.08 mm, the obtained position equivalent subdivision is 5.08 / 20000 = 0.000254 mm. Since the clock frequency in the microcontroller 40 can be set as needed, the position equivalent subdivision can be made several times to hundreds of times the original, so as to achieve the purpose of high resolution.

[0073] 32) After receiving the interrupt flag signal, the CPU 43 performs the following operations:

[0074] 321) Reads the data in the buffer, that is, the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch.

[0075] 322) Convert this data into the actual displacement value of the gate of the capacitive grating sensor 10 within one pitch (also known as the absolute displacement value of the gate of the capacitive grating sensor 10 within one pitch).

[0076] 323) Output the absolute displacement value of the gate of the capacitive grating sensor 10 within one pitch to the display unit 45 and the serial port 46 for output by the display unit 45 and the serial port 46.

[0077] The embodiments of the displacement measurement system described above are applicable to the case where the moving range of the gate of the capacitive grating sensor is within one pitch.

[0078] In the embodiments of the displacement measurement system described above, when the timer 41 generates an interrupt flag signal upon detecting the rising edge of the ADSO signal and sends the interrupt flag signal to the CPU 43. Those skilled in the art should understand that the timer 41 can also generate an interrupt flag signal and send it to the CPU 43 when detecting the falling edge of the ADSO signal or when detecting the rising edge or falling edge of the CLK512 signal. Therefore, in another embodiment, the CPU 43 reads the data in the buffer after receiving the interrupt flag signal triggered by the falling edge of the ADSO signal, the rising edge of the CLK512, or the falling edge of the CLK512 and converts it into the absolute displacement value of the gate of the capacitive grating sensor 10 within one pitch.

[0079] In the embodiments of the displacement measurement system described above, the timer 41 controls the counting based on the rising edges of the CLK512 signal and the ADSO signal, that is, when the timer 41 detects the rising edge of the CLK512 signal, the count is cleared; and when the timer 41 detects the rising edge of the ADSO signal, the current count of the timer 41 is written into the buffer. However, from Figure 2 It can be seen that in another embodiment, the timer 41 can also control the counting based on the falling edges of the CLK512 signal and the ADSO signal, that is, when detecting the falling edge of the CLK512 signal, the count is cleared; when the timer 41 detects the falling edge of the ADSO signal, the current count of the timer is written into the buffer, and this method can also obtain the position equivalent of the gate of the capacitive grating sensor 10 within one pitch. In the case of adopting this implementation method, the CPU 43 can read the data in the buffer according to the interrupt flag signal triggered by the rising edge / falling edge of the ADSO signal or the rising edge / falling edge of the CLK512 signal and convert it into the absolute displacement value of the gate of the capacitive grating sensor 10 within one pitch.

[0080] In the embodiment of the displacement measurement system described above, the timer 41 in the single-chip microcomputer 40 continuously counts at the clock frequency provided by the counting clock 42. In another embodiment, a timer can be used which starts counting from zero at the clock frequency provided by the counting clock 42 when the rising edge of the CLK512 signal is detected, and ends counting and writes the current count into the buffer when the rising edge of the ADSO signal is detected (it should be understood that the counting can also be controlled according to the falling edges of the CLK512 signal and the ADSO signal). The CPU 43 can read the data in the buffer according to the interrupt flag signal triggered by the rising edge / falling edge of the ADSO signal or the rising edge / falling edge of the CLK512 signal and convert it into the absolute displacement value of the gate of the capacitive grating sensor 10 within one grating pitch. In yet another embodiment, a timer can be used which starts timing from zero when the rising edge of the CLK512 signal is detected and writes the current time into the buffer when the rising edge of the ADSO signal is detected (alternatively, starts timing from zero when the falling edge of the CLK512 signal is detected and writes the current time into the buffer when the falling edge of the ADSO signal is detected). After receiving the interrupt flag signal, the CPU 43 reads the data in the buffer, obtains the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch according to this data and the clock frequency (for example, multiplies the current time in the buffer by the clock frequency), and converts the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch into the absolute displacement value of the gate of the capacitive grating sensor 10 within one grating pitch. In yet another embodiment, a timer can also be used which writes the current count into the buffer when the rising edge of the CLK512 signal is detected, simultaneously generates an interrupt flag signal and sends the interrupt flag signal to the CPU 43, and the CPU 43 reads the data in the buffer after receiving the interrupt flag signal triggered by the rising edge of the CLK512 signal; when the rising edge of the ADSO signal is detected, writes the current count into the buffer, also generates an interrupt flag signal and sends this interrupt flag signal to the CPU 43, and the CPU 43 reads the data in the buffer after receiving the interrupt flag signal triggered by the rising edge of the ADSO signal, and subtracts these two data, thereby also being able to obtain the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch.

[0081] In the embodiment of the displacement measurement system described above, the timer 41 includes a buffer for temporarily storing the count, while in another embodiment, the timer 41 can not use a buffer. When the rising edge of the CLK512 signal is detected, the timer 41 clears the count; when the rising edge of the ADSO signal is detected, the timer 41 directly sends the current count to the CPU 43, and the CPU 43 converts this data into the absolute displacement value of the gate of the capacitive grating sensor 10 within one grating pitch.

[0082] Although not described in detail above, those skilled in the art should understand that the RAM 44 in the single-chip microcomputer 40 can be used to store the data used by the CPU 43 during the calculation process. For example, after receiving the interrupt flag signal, the CPU 43 stores the data in the buffer into the RAM 44; or stores the data directly sent by the timer 41 into the RAM 44, and then processes the data stored in the RAM 44 (for example, converts it into the absolute displacement value of the gate of the capacitance grating sensor 10 within one pitch). In the case of using an ARM single-chip microcomputer, the DMA path can directly store the data in the buffer into the RAM 44, and the CPU 43 can extract the most recently stored data from the RAM 44 according to the received interrupt flag signal for conversion processing.

[0083] When the clock frequency provided by the counting clock 42 is relatively high (that is, the resolution of the position equivalent of the gate of the capacitance grating sensor 10 obtained is relatively high), the position equivalent data obtained by timing or counting may be unstable and fluctuate. To reduce the influence of such fluctuations, in a further embodiment, the CPU 43 can perform digital filtering processing on the position equivalent before performing the conversion operation (for example, perform digital filtering by taking the average of 8 groups of data. For example, take the average of the 8 groups of position equivalents of the gate of the capacitance grating sensor 10 within one pitch that are most recently stored from the RAM 44), so as to obtain relatively stable data at a high resolution, and then convert the data after performing the digital filtering processing to obtain the absolute displacement value of the gate of the capacitance grating sensor 10 within one pitch.

[0084] In a further embodiment, after obtaining the absolute displacement value of the gate of the capacitance grating sensor 10 within one pitch, the CPU 43 also corrects the deviation of the absolute displacement value. For example, the influence of non-linear error and moving grating manufacturing error can be eliminated by performing sectional or point-by-point deviation correction through the method of position calibration using a standard measuring device to achieve high-precision measurement within one pitch. For example, when the resolution equivalent within one pitch (that is, the maximum count value of the timer within one pitch) is 20,000, for a 5.08 mm pitch, the resolution reaches 0.000254 mm, that is, 254 nm. After performing linear coefficient interpolation correction by equally dividing it into 8 segments (0.635 mm), and estimating according to 4 times the uncertainty error, the accuracy can be within the range of 1 um, which is 10 times that of the original. This deviation correction technology is applicable to a large number of micrometer measuring instruments.

[0085] Each of the embodiments of the displacement measurement system described above is applicable to measuring the absolute displacement value of the gate of the capacitance grating sensor within one pitch. The following will describe how to measure the total absolute displacement value of the movement exceeding one pitch.

[0086] According to another embodiment of the present invention, a displacement measurement system for a sensor device is further provided. The sensor device includes a capacitive grating sensor. This system adopts a method of combining a periodic position measurement technique with an incremental displacement measurement technique for continuously monitoring the change in the grating pitch, and is applicable to measuring the situation where the movement of the grating of the capacitive grating sensor exceeds one grating pitch (i.e., large-range measurement). The displacement measurement system includes an ASIC chip 30 as shown in Figure 3 and a single-chip microcomputer 60 as shown in Figure 6 .

[0087] Since the capacitive grating sensor 10, the ASIC chip 30 in Figure 3 and their working processes have been described above, they will not be elaborated here. The following will describe this embodiment in detail with reference to Figure 6 . As shown in Figure 6 , the single-chip microcomputer 60 includes: two timers 41, 61 (i.e., timer 1, timer 2), a counting clock 42, a CPU 43, a RAM 44, a display unit 45, and a serial port 46, and each timer 41, 61 also includes a buffer respectively. Briefly, the timer 41 receives the ADSO signal from the capacitive grating signal processing circuit 24 in the ASIC chip 30 and the CLK512 signal from the clock frequency division circuit 22 in the ASIC chip 30. The timer 41 uses the clock frequency provided by the counting clock 42 as the counting frequency, and counts according to the ADSO signal and the CLK512 signal to obtain the position equivalent of the grating of the capacitive grating sensor 10 within one grating pitch (this is the same as the counting method described above in combination with Figure 4 ); the timer 61 also receives the ADSO signal and the CLK512 signal, and the timer 61 performs an increment or decrement operation according to these two signals to obtain the number of grating pitches by which the grating of the capacitive grating sensor 10 moves. On this basis, the CPU 43 can calculate the total absolute displacement equivalent according to the position equivalent of the grating of the capacitive grating sensor 10 within one grating pitch and the number of grating pitches moved, and further obtain the total absolute displacement value. According to an embodiment of the present invention, the working process of the single-chip microcomputer 60 is as follows:

[0088] 1) The timer 41 in the single-chip microcomputer 60 uses the clock frequency provided by the counting clock 42 (for example, 6 MHz) as the counting frequency, and simultaneously receives the ADSO signal and the CLK512 signal. When the timer 41 detects the rising edge of the CLK512 signal, it clears the count; when the timer 41 detects the rising edge of the ADSO signal, it writes the current count into its buffer, and the timer 41 also sends an interrupt flag signal to the CPU 43.

[0089] Meanwhile, another timer 61 in the single-chip microcomputer 60 also receives the ADSO signal and the CLK512 signal. The timer 61 performs addition and subtraction counting operations based on whether there is a rising edge of the ADSO signal between two adjacent rising edges of the CLK512 signal and how many rising edges of the ADSO signal appear (wherein, if there is no rising edge of the ADSO signal between two adjacent rising edges of the CLK512 signal or the rising edge of the ADSO signal appears twice, it indicates that the gate pitch of the capacitive grating sensor has moved). Specifically, the timer 61 performs an increment operation when detecting a rising edge of the CLK512 signal; performs a decrement operation when detecting a rising edge of the ADSO signal, and writes the current count into its buffer, and this count represents the number of pitch values of the gate movement of the current capacitive grating sensor 10 (wherein, the initial value of the timer 61 is 0).

[0090] 2) After receiving the interrupt flag signal (i.e., the interrupt flag signal triggered by the rising edge of the ADSO signal), the CPU 43 performs the following operations:

[0091] 210) Read the data in the buffer of the timer 41, that is, the position equivalent A of the gate of the capacitive grating sensor 10 within one pitch n ; meanwhile, read the data in the buffer of the timer 61, that is, the number of pitch values N of the gate movement of the capacitive grating sensor 10 n .

[0092] 220) Perform the following calculations to obtain the total absolute displacement equivalent L exceeding one pitch n :

[0093] L n = A n + N n × M(1)

[0094] Wherein, M represents the resolution equivalent corresponding to each pitch (as described above, when the clock frequency provided by the counting clock 42 is 6 MHz, M = 20000).

[0095] 230) Convert the total absolute displacement equivalent L of the gate of the capacitive grating sensor 10 n into the total actual displacement value (or total absolute displacement value).

[0096] 240) Output the total absolute displacement value of the gate of the capacitive grating sensor 10 to the display unit 45 and the serial port 46 for output by the display unit 45 and the serial port 46. In this way, high-resolution, high-precision and large-range displacement measurement is realized.

[0097] As can be seen from the above solution, both Timer 41 and Timer 61 write the current count to their respective buffers at the rising edge of the ADSO signal. Subsequently, after receiving the interrupt flag signal triggered by the rising edge of the ADSO signal, CPU 43 reads the data from the two buffers respectively for subsequent processing, which ensures that the data read from the buffer of Timer 41 and the buffer of Timer 61 is synchronized. Those skilled in the art should understand that although not mentioned above, when Timer 61 detects the rising edge of the ADSO signal, in addition to performing the decrement operation and writing the current count to the buffer, it can also send an interrupt flag signal to CPU 43. Therefore, CPU 43 can read the data from the two buffers and perform subsequent processing after receiving the interrupt flag signal triggered by the rising edge of the ADSO signal from Timer 41 or Timer 61.

[0098] In another embodiment, the above process is executed using the falling edge of the signal. When Timer 41 detects the falling edge of the CLK512 signal, it clears the count; and when Timer 41 detects the falling edge of the ADSO signal, it writes the current count of the timer to its buffer. At the same time, when Timer 61 detects the falling edge of the CLK512 signal, it performs an increment operation; when it detects the falling edge of the ADSO signal, it performs a decrement operation and writes the current count to its buffer. Among them, when detecting the falling edge of the ADSO signal, Timer 41 or Timer 61 or both of them send an interrupt flag signal to CPU 43. After receiving the interrupt flag signal triggered by the falling edge of the ADSO signal, CPU43 reads the data from the two buffers for subsequent processing, which also ensures that the data read from the buffer of Timer 41 and the buffer of Timer 61 is synchronized.

[0099] In another embodiment, Timer 41 and 61 may not use buffers, and directly send the current count to CPU 43 respectively when detecting the rising edge of ADSO, and CPU 43 processes it. In yet another embodiment, after receiving the interrupt flag signal, CPU 43 stores the data in the buffers of Timer 41 and 61 into RAM 44, or stores the data directly sent by Timer 41 and 61 into RAM 44, and then processes the data stored in RAM 44 to calculate the total absolute displacement value of the gate of the capacitive grating sensor 10. In addition, in the case of using an ARM single-chip microcomputer, the DMA path can directly store the data in the buffers of Timer 41 and 61 into RAM 44, and CPU 43 can read the most recently stored data (i.e., the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch from Timer 41, and the number of grating pitches that the gate of the capacitive grating sensor 10 has moved from Timer 61) from RAM 44 according to the received interrupt flag signal for processing.

[0100] In a further embodiment, referring to Figure 7 , before step 230, that is, before the conversion operation, the CPU 43 also performs digital filtering on the total absolute displacement equivalent L n of the gate of the capacitive grating sensor 10 to obtain stable data (see step 221). After step 230, that is, after the conversion operation, the CPU 43 also performs deviation correction within the grating pitch on the total absolute displacement value of the gate of the capacitive grating sensor 10 (see step 231), and then performs deviation correction between grating pitches (see step 232). Among them, the deviation correction between grating pitches can adopt a calibration correction method with the grating pitch step as the calibration equivalent to correct the grating pitch error of the periodic signal at the same grating pitch position, so as to realize the correction of the manufacturing error of the gate of the capacitive grating sensor.

[0101] In the above embodiment of the displacement measurement system (for measuring the total absolute displacement value of the gate moving more than one grating pitch), the timer 61 is used to count the number of grating pitches of the gate movement. However, those skilled in the art should understand that some other counting methods are also applicable. For example, in another embodiment, two counters can be used to monitor the CLK512 signal and the ADSO signal respectively. One counter performs an increment operation and writes it into the corresponding buffer when detecting the rising edge of the CLK512 signal, and the other counter performs an increment operation and writes it into the corresponding buffer when detecting the rising edge of the ADSO signal. In addition, the rising edge of the ADSO signal also triggers the CPU 43 to read and compare the counts in the two buffers. If the count of the rising edge of the CLK512 signal is 1 more than the count of the rising edge of the ADSO signal, it means that there is no rising edge of the ADSO signal between two adjacent rising edges of the CLK512 signal (then the CPU 43 can perform an increment operation on the current number of grating pitches of the gate movement). If it is 1 less, it means that there are two rising edges of the ADSO signal between two adjacent rising edges of the CLK512 signal (then the CPU 43 can perform a decrement operation on the current number of grating pitches of the gate movement, where the initial value of the number of grating pitches of the gate movement is 0).

[0102] To achieve large-range, high-resolution, and high-precision measurement, according to another embodiment of the present invention, a displacement measurement system for a sensor device is further provided. The sensor device includes a capacitive grating sensor. The system utilizes the functions of a traditional ASIC chip and measures the total actual displacement value of the gate of the capacitive grating sensor according to the output of the traditional ASIC chip and the timing (counting) function of the single-chip microcomputer timer, and is particularly suitable for measuring the actual displacement of the capacitive grating sensor after it is stationary.

[0103] As Figure 8 shown, the ASIC chip 80 therein and Figure 1is similar to the traditional ASIC chip 20 in (except for the crystal oscillator circuit 21, etc., it also integrates a phase discrimination and counting circuit 25, a displacement data processing circuit 26, a serial output port 27, etc.). The difference is that, Figure 8 In the capacitive grating signal processing circuit 24 in, in addition to sending the ADSO signal to the phase discrimination and counting circuit 25 in the ASIC chip 80 for phase discrimination and counting processing, it also sends the ADSO signal to Figure 9 The single-chip microcomputer 90 shown in, and the clock frequency division circuit 22 also outputs a CLK512 signal to the single-chip microcomputer 90, which has the same period as the 8 driving signals and the same phase as any one of the driving signals. In addition, Figure 9 The single-chip microcomputer 90 in also receives the outputs from the serial output port 27 of the ASIC chip 80, including the DATA signal and the CLK signal. Among them, the DATA signal is a data signal, which contains the total absolute displacement value information (abbreviated as displacement information) of the gate of the capacitive grating sensor 10 generated by the ASIC chip 80 according to the traditional method (that is, through operations such as phase discrimination, counting, and data processing) of the ADSO signal; the CLK signal is a synchronous clock signal. The traditional data acquisition method is: sampling the DATA signal at the falling edge of the narrow pulse of the CLK signal.

[0104] Figure 9 The single-chip microcomputer 90 shown in, in addition to including Figure 4 Those components in also have an I / O port 91 for receiving the DATA signal and the CLK signal from the serial output port 27 of the ASIC chip 80. Specifically, according to this embodiment, Figure 9 The working process of the single-chip microcomputer 90 in includes:

[0105] 1) The single-chip microcomputer 90 receives the CLK signal and the DATA signal from the serial output port 27 through its I / O port 91. At the same time, the timer 41 in the single-chip microcomputer 90 receives the ADSO signal and the CLK512 signal. The same as the method for calculating the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch in the above text, the timer 41 uses the clock frequency provided by the counting clock 42 (for example, 6 MHz) as the counting frequency and counts according to the ADSO signal and the CLK512 signal. For example, when the rising edge of the CLK512 signal is detected, the counting starts again, and when the rising edge of the ADSO signal is detected, the current count (that is, the position equivalent of the gate of the capacitive grating sensor 10 within one grating pitch) is written into the buffer ( Figure 9 The working principle of the timer 41 in is the same as that of Figure 4 and Figure 6 The timer 41 in).

[0106] 2) The CPU 43 obtains the number of pitch counts of the gate movement of the capacitive grating sensor 10 based on the DATA signal and the CLK signal received from the I / O port 91; and reads the data from the buffer of the timer 41 according to the interrupt flag signal sent by the timer 41 to obtain the position equivalent of the gate of the capacitive grating sensor 10 within one pitch. The CPU 43 then obtains the total absolute displacement value based on the number of pitch counts of the movement and the position equivalent within one pitch. Specifically, according to an embodiment of the present invention, it includes:

[0107] 21) According to the interrupt signal generated by the rising edge or falling edge of the CLK signal, read the high and low level states of the DATA signal to obtain the displacement information contained in the DATA signal (a multi-bit binary number represented by 0 and 1, where the low bit is in the front, and starting from the 12th bit is the number of pitch counts of the gate movement of the capacitive grating sensor 10), and separate the number of pitch counts of the gate movement of the capacitive grating sensor 10 therefrom. Also, read the data from the buffer of the timer 41 according to the interrupt flag signal sent by the timer 41 to obtain the position equivalent of the gate of the capacitive grating sensor 10 within one pitch.

[0108] 22) Obtain the total absolute displacement equivalent of the gate of the capacitive grating sensor 10 according to formula (1), that is, multiply the number of pitch counts obtained from the DATA signal by the resolution equivalent corresponding to each pitch (for example, 20000), and then add the position equivalent of the gate of the capacitive grating sensor 10 within one pitch obtained according to the count of the timer 41, so as to obtain the total absolute displacement equivalent of the gate of the capacitive grating sensor 10.

[0109] 23) Convert the total absolute displacement equivalent of the capacitive grating sensor gate into the total absolute displacement value.

[0110] 24) Output the total absolute displacement value of the gate of the capacitive grating sensor 10 to the display unit 45 and the serial port 46 for output by the display unit 45 and the serial port 46. In this way, high-resolution, high-precision large-range displacement measurement is achieved.

[0111] Similar to some of the above-given solutions, the buffer may not be used in the timer 41. Additionally, similar to some of the above-given solutions, the RAM 44 can be used to store the data in the buffer, as well as the data generated during the processing by the CPU 43, etc.

[0112] Similar to some of the above-given solutions, before the conversion operation (i.e., converting the total absolute displacement equivalent of the gate of the capacitive grating sensor 10 into the total absolute displacement value), the CPU 43 can perform digital filtering processing on the total absolute displacement equivalent of the gate of the capacitive grating sensor 10, and after the conversion operation, perform deviation correction within the pitch and deviation correction between pitches on the total absolute displacement value of the gate of the capacitive grating sensor 10.

[0113] For large-range, high-resolution, and high-precision angular displacement measurement, according to another embodiment of the present invention, a displacement measurement system for a sensor device is further provided. The sensor device includes two grid capacitance sensors, which will be described below with reference to Figure 10 and Figure 11 for description.

[0114] In this embodiment, two grid capacitance sensors are used, a coarse-resolution grid capacitance sensor 11 and a fine-resolution grid capacitance sensor 12 (for the description of using the combination of coarse-resolution and fine-resolution grid capacitance sensors to measure the absolute position in a large angular range, reference can be made to the Chinese patent application with the application number CN200710050658.3). Among them, the coarse-resolution sensor has one pitch on a circumference (that is, one pitch is equal to the full range of 360° of the circumference), and the fine-resolution sensor has multiple pitches on a circumference (for example, 20 pitches);

[0115] Figure 10 FIG. shows the ASIC chip 100 of this embodiment, which integrates a crystal oscillator circuit 21, a clock frequency division circuit 22, an 8-channel drive and analog switch signal generation circuit 23 (it should be noted that in this embodiment, the 8-channel drive signals are used to drive the coarse-resolution grid capacitance sensor 11 and the fine-resolution grid capacitance sensor 12), and two grid capacitance signal processing circuits 101 and 102; the two grid capacitance signal processing circuits 101 and 102 respectively receive the output signal CSI1 from the coarse-resolution sensor 11 and the output signal CSI2 from the fine-resolution sensor 12, and respectively output ADSO1 signal and ADSO2 signal to the Figure 11 single-chip microcomputer 110 in; in addition, the clock frequency division circuit 22 outputs a CLK512 signal to the Figure 11 single-chip microcomputer 110 in, which has the same period as the 8-channel drive signals and the same phase as any one of the drive signals.

[0116] Figure 11 The single-chip microcomputer 110 in includes two identical timers 111 and 112 (that is, timer 1 and timer 2); among them, timer 111 receives the ADSO1 signal from the grid capacitance signal processing circuit 101 and the CLK512 signal from the clock frequency division circuit 22, and timer 112 receives the ADSO2 signal from the grid capacitance signal processing circuit 102 and the CLK512 signal from the clock frequency division circuit 22. According to an embodiment of the present invention, the working process of the single-chip microcomputer 110 is as follows:

[0117] 1) Similar to the method described above for obtaining the position equivalent of the grating of the capacitive grating sensor within one pitch, Timer 111 uses the clock frequency provided by the counting clock 42 (e.g., 6 MHz) as the counting frequency, and counts according to the ADSO1 signal and the CLK512 signal to obtain the position equivalent of the grating of the coarse-resolution capacitive grating sensor 11 within one pitch; Timer 112 also uses the clock frequency provided by the counting clock 42 as the counting frequency, and counts according to the ADSO2 signal and the CLK512 signal to obtain the position equivalent of the grating of the fine-resolution capacitive grating sensor 12 within one pitch. According to an embodiment of the present invention, Timer 111 itself includes a buffer. Timer 111 starts counting from zero when detecting the rising edge of the CLK512 signal, and writes the current count into its buffer when detecting the rising edge of the ADSO1 signal. This count represents the position equivalent of the grating of the coarse-resolution capacitive grating sensor 11 within one pitch; Timer 112 also includes a buffer. Timer 112 starts counting from zero when detecting the rising edge of the CLK512 signal, and writes the current count into its buffer when detecting the rising edge of the ADSO2 signal. This count represents the position equivalent of the grating of the fine-resolution capacitive grating sensor 12 within one pitch. Timer 111 or Timer 112 can send an interrupt flag signal to the CPU 43 when detecting the rising edge of the CLK512 signal, so that the CPU 43 can read synchronized data from the buffers of Timer 111 and the timer.

[0118] 2) After the CPU 43 receives the interrupt flag signal triggered by the rising edge of the CLK 512 signal from Timer 111 or Timer 112, it performs the following operations:

[0119] 21) The CPU reads data from the buffer of Timer 111 and reads data from the timer of Timer 112. These two data are respectively the position equivalent of the grating of the coarse-resolution capacitive grating sensor 11 within one pitch and the position equivalent of the grating of the fine-resolution capacitive grating sensor 12 within one pitch.

[0120] 22) Determine the number of pitches that the grating of the fine-resolution capacitive grating sensor 12 moves according to the position equivalent of the grating of the coarse-resolution capacitive grating sensor 11 within one pitch.

[0121] For example, assume that the resolution equivalent corresponding to each pitch is 20000. Then, on a circumference, for the measurement data corresponding to the coarse-resolution capacitive grating sensor 11, 20000 / 20 = 1000; that is, 0 to 999 correspond to the 0th pitch position of the fine-resolution capacitive grating sensor 12 (the number of pitches moved is 0), and 1000 to 1999 correspond to the 1st pitch position of the fine-resolution capacitive grating sensor 12, and so on. Thus, the number of pitches that the grating of the fine-resolution capacitive grating sensor moves can be determined according to the position equivalent of the grating of the coarse-resolution capacitive grating sensor 11 within one pitch.

[0122] 23) Refer to Formula (1), multiply the number of grating pitches by the resolution equivalent corresponding to each grating pitch (such as 20000), and then add the position equivalent of the gate of the subdivided capacitance grating sensor 12 within one grating pitch to obtain the total absolute position equivalent of the gate of the subdivided capacitance grating sensor 12 within the circumferential range.

[0123] 24) Convert the total absolute position equivalent of the gate of the subdivided capacitance grating sensor 12 within the circumferential range (i.e., multiply by the equivalent coefficient 18 / 20000) to obtain the total absolute displacement value (i.e., the actual position angle value) of the gate of the subdivided capacitance grating sensor 12.

[0124] 25) Output the total absolute displacement value to the display unit 45 and the serial port 46 for output by the display unit 45 and the serial port 46.

[0125] The above-mentioned timers 111 and 112 have their own buffers. However, in other embodiments, the buffers may not be used. In the embodiments where the timers 111 and 112 do not have buffers, when the timer 111 detects the rising edge of the ADSO1 signal, the current count can be directly sent to the CPU 43 and stored in the RAM 44 by the CPU 43; when the timer 112 detects the rising edge of the ADSO2 signal, the current count can be directly sent to the CPU 43 and stored in the RAM 44 by the CPU 43. When the CPU 43 receives the interrupt flag signal triggered by the rising edge of the CLK512 signal from either the timer 111 or the timer 112, these two counts are retrieved from the RAM and subsequent processing is performed. In addition, in the embodiments using an ARM single-chip microcomputer, the DMA channel can directly store the data in the buffers of the timers 111 and 112 into the RAM 44, and the CPU 43 can extract the most recently stored data from the RAM 44 for processing according to the received interrupt flag signal.

[0126] Those skilled in the art should understand that in another embodiment, the timers 111 and 112 can also clear the count according to the falling edge of the CLK512 signal, write the current count into the buffer according to the falling edges of the ADSO1 signal and the ADSO2 signal respectively, and can send an interrupt flag signal to the CPU 43 when detecting the rising edge (or falling edge) of the CLK512 signal. In other embodiments, the timer 111 can send an interrupt flag signal to the CPU 43 when detecting the rising edge of the ADSO1 signal, and the timer 112 can send an interrupt flag signal to the CPU 43 when detecting the rising edge of the ADSO2 signal.

[0127] In addition, in a further embodiment, the CPU 43 also performs digital filtering on the total absolute position equivalent of the gates of the fine-divided capacitive grating sensor 12 within the circumferential range before the conversion operation, and corrects the deviation within and between pitch distances for the total absolute displacement value after the conversion operation.

[0128] Although the coarse-divided sensor is described above as having one pitch distance on a circumference and the fine-divided sensor is described as having multiple pitch distances on a circumference, that is, the displacement measurement system can achieve angular measurement over the entire circumference, it should be understood that the displacement measurement system is also applicable to the measurement of sector angles. In this case, it is required that the fine-divided sensor has N pitch distances (N is an integer and N≥2) within one pitch distance of the coarse-divided sensor. In addition to angles, Figure 10 and Figure 11 the displacement measurement system shown can also be used for absolute length measurement.

[0129] The above gives three displacement measurement systems for large measurement ranges, high resolutions, and high precisions. Among them, Figure 3 and Figure 6 the displacement measurement system shown occupies less space because it does not need to use traditional phase discrimination and counting circuits 25, displacement data processing circuits 26, etc., and this system is applicable to displacement measurement during movement and after stopping; Figure 8 and Figure 9 the displacement measurement system shown can be manufactured using existing ASIC chips and is relatively simple to implement compared with other displacement measurement systems, but it occupies a large space. This system is mainly applicable to displacement measurement after stopping; Figure 10 and Figure 11 the displacement measurement system shown is applicable to the measurement of angular displacement and linear displacement, and can be measured both during movement and after stopping. By using these displacement measurement systems for sensor devices provided by the present invention, on the basis of inheriting the large-scale production technology of traditional phase discrimination type capacitive grating sensors, the measurement technology of phase discrimination type capacitive grating sensors can be improved in terms of low-cost performance, and the resolution and precision of measurement are increased.

[0130] Those skilled in the art should understand that although the internal counting clock 42 of the single-chip microcomputer is used above to implement the timing and counting of the timer, in other embodiments, the external clock of the single-chip microcomputer can also be used to provide the clock frequency. In addition, although the ASIC chip and the single-chip microcomputer are described above as examples, that is, they are described separately as two components, however, in other embodiments, the single-chip microcomputer can also be integrated in the ASIC chip, or the ASIC chip can be integrated on the single-chip microcomputer, or the two can be integrated together, which can be integrated on the same chip or on multiple chips.

[0131] Those skilled in the art should also understand that in addition to the single-chip microcomputer, other digital processing devices with computing functions can also be used to implement the present invention.

[0132] Those skilled in the art should also understand that in addition to the capacitive grating sensor, the displacement measurement system provided by the present invention is also applicable to other displacement sensors. For example, other capacitive sensors, induction synchros, grating sensors, etc. in addition to the capacitive grating sensor. The working principles of these displacement sensors are similar to that of the capacitive grating sensor - the driving signal is a periodically changing voltage signal. After being coupled and modulated by the displacement sensor, the time change period corresponds to the spatial period of the change of the sensor grating pitch, and the output signal can obtain a square wave signal of the same period corresponding to the grating pitch position and having an electrical phase difference with the initial driving signal through the phase discrimination method.

[0133] In addition, although the present invention has been described above by taking the capacitive grating sensor that receives multiple (8-way) driving signals as an example, it should be noted that the displacement sensor that receives 1-way driving signal is also applicable to the present invention. In this case, the driving signal generation circuit 23 can only output one driving signal, and the CLK512 signal output by the clock frequency division circuit 22 has the same period and the same phase as the driving signal. In a further embodiment, the period or phase of the CLK512 signal may not be exactly the same as that of the driving signal. For example, the periods may be in a multiple relationship, the phases may be opposite or have other corresponding relationships.

[0134] It should be noted that some exemplary methods are depicted as flowcharts. Although the flowcharts depict the operations as being executed sequentially, it can be understood that many operations can be performed in parallel, simultaneously, or synchronously. Additionally, the order of the operations can be rearranged. The processing can terminate when the operations are completed, but it can also have additional steps that are not included in the figures or embodiments.

[0135] The above methods can be implemented by hardware, software, firmware, middleware, pseudocode, hardware description language, or any combination thereof. When implemented in software, firmware, middleware, or pseudocode, the program code or code segments used to perform the tasks can be stored in a computer-readable medium, such as a storage medium, and the processor can execute the tasks.

[0136] It should be understood that the exemplary embodiments implemented by software are generally encoded on some form of program storage medium or implemented on some type of transmission medium. The program storage medium can be any non-transitory storage medium, such as a disk (e.g., a floppy disk or a hard disk) or an optical disk (e.g., a compact disk read-only memory or "CD ROM"), and can be read-only or random access. Similarly, the transmission medium can be a twisted pair, a coaxial cable, an optical fiber, or some other suitable transmission medium known in the art.

[0137] Although the present invention has been described by way of preferred embodiments, the present invention is not limited to the embodiments described herein. Various changes and modifications may be made without departing from the scope of the present invention.

Claims

1. A displacement measurement system for a sensor device, the sensor device including a first displacement sensor, the displacement measurement system comprises: a drive signal generation circuit for outputting a drive signal to the first displacement sensor; a first signal processing circuit for receiving a signal from the first displacement sensor and outputting a first ADSO signal; and a computing device including a first timer; wherein, the computing device further comprises: a processor for converting data obtained by timing or counting by the first timer into an absolute displacement value of the gate of the first displacement sensor within one pitch; wherein, the computing device further comprises: a second timer for receiving a CLK512 signal and the first ADSO signal, and counting the number of pitches of the gate movement of the first displacement sensor according to the CLK512 signal and the first ADSO signal; wherein, the processor is further configured to obtain a total absolute displacement value of the gate of the first displacement sensor according to the data obtained by counting by the second timer and the data obtained by timing or counting by the first timer; wherein, the processor is configured to calculate the following formula to obtain a total absolute displacement equivalent Ln of the gate of the first displacement sensor: Ln = An + Nn × M wherein, An represents the data obtained by counting by the first timer, Nn represents the data obtained by counting by the second timer, and M represents the resolution equivalent corresponding to each pitch of the first displacement sensor; and converting the total absolute displacement equivalent Ln of the gate of the first displacement sensor into a total absolute displacement value of the gate of the first displacement sensor; wherein, the first timer is configured to receive the CLK512 signal and the first ADSO signal, and perform timing or counting according to the CLK512 signal and the first ADSO signal; wherein, the CLK512 signal is a square wave signal having the same period and phase as the drive signal.

2. The displacement measurement system according to claim 1, further comprises: a clock frequency division circuit for outputting a clock signal to the drive signal generation circuit and outputting the CLK512 signal.

3. The displacement measurement system according to claim 1, further comprises: a counting clock; wherein, the first timer is configured to perform timing or counting according to the CLK512 signal and the first ADSO signal at the clock frequency provided by the counting clock.

4. The displacement measurement system according to claim 3, wherein, the first timer is configured to start timing or counting from zero at the clock frequency provided by the counting clock when detecting a rising edge of the CLK512 signal, and send the current time or current count to the processor when detecting a rising edge of the first ADSO signal.

5. The displacement measurement system according to claim 3, the first timer further comprises: a first buffer; Wherein, the first timer is configured to start timing or counting from zero at the clock frequency provided by the counting clock when detecting the rising edge of the CLK512 signal, and write the current time or current count into the first buffer when detecting the rising edge of the first ADSO signal; The processor is configured to read the data in the first buffer after receiving an interrupt flag signal triggered by the first ADSO signal or the CLK512 signal.

6. The displacement measurement system according to claim 3, Wherein, The processor is configured to obtain the position equivalent of the gate of the first displacement sensor within one pitch based on the data obtained by timing by the first timer and the clock frequency provided by the counting clock, and convert the position equivalent of the gate of the first displacement sensor within one pitch into the absolute displacement value of the gate of the first displacement sensor within one pitch.

7. The displacement measurement system according to claim 6, Wherein, The processor is further configured to perform digital filtering on the position equivalent of the gate of the first displacement sensor within one pitch, and perform deviation correction on the absolute displacement value of the gate of the first displacement sensor within one pitch.

8. The displacement measurement system according to claim 3, Wherein, The counting clock is included in the computing device.

9. The displacement measurement system according to claim 1, Wherein, The drive signal generation circuit and the first signal processing circuit are integrated in the same chip, and the chip further includes: A phase discrimination and counting circuit for receiving the first ADSO signal; and A serial output port for outputting a CLK signal and a DATA signal including the displacement information of the gate of the first displacement sensor; The computing device is further configured to receive the CLK signal and the DATA signal; Wherein, the processor is further configured to obtain the number of pitches that the gate of the first displacement sensor has moved based on the received CLK signal and DATA signal, and obtain the total absolute displacement value of the gate of the first displacement sensor based on the number of pitches that the gate of the first displacement sensor has moved and the data obtained by the first timer through timing or counting.

10. The displacement measurement system according to claim 9, Wherein, The processor is configured to obtain the total absolute displacement equivalent of the gate of the first displacement sensor based on the number of pitches that the gate of the first displacement sensor has moved and the data obtained by the first timer through timing or counting, and convert the total absolute displacement equivalent of the gate of the first displacement sensor into the total absolute displacement value of the gate of the first displacement sensor.

11. For the displacement measurement system according to claim 3, the sensor device further includes a second displacement sensor, wherein the first displacement sensor has multiple pitches within one pitch of the second displacement sensor, the drive signal generation circuit is further configured to output the drive signal to the second displacement sensor, and the displacement measurement system further includes: A second signal processing circuit for receiving a signal from the second displacement sensor and outputting a second ADSO signal; The computing device further includes: A third timer for receiving the second ADSO signal and the CLK512 signal, and timing or counting according to the second ADSO signal and the CLK512 signal at the clock frequency provided by the counting clock; Wherein, the processor is further configured to determine the number of pitch numbers of the gate movement of the first displacement sensor according to the data obtained by the third timer through timing or counting, and obtain the total absolute displacement value of the gate of the first displacement sensor according to the number of pitch numbers of the gate movement of the first displacement sensor and the data obtained by the first timer through timing or counting.

12. The displacement measurement system according to claim 11, Wherein, The third timer is configured to start timing or counting from zero at the clock frequency provided by the counting clock when detecting the rising edge of the CLK512 signal, and send the current time or the current count to the processor or record the current time or the current count when detecting the rising edge of the second ADSO signal.

13. The displacement measurement system according to claim 11, Wherein, The first displacement sensor and the second displacement sensor are capacitance grating sensors.

14. The displacement measurement system according to claim 1, Wherein, The computing device, the drive signal generation circuit and the first signal processing circuit are integrated on the same chip.

15. A displacement measurement method for a sensor device, the sensor device including a first displacement sensor, the displacement measurement method comprises: Outputting a drive signal to the first displacement sensor; Receiving a signal from the first displacement sensor, processing the signal, and outputting a first ADSO signal; And Receiving the CLK512 signal and the first ADSO signal, and timing or counting according to the CLK512 signal and the first ADSO signal; wherein, the CLK512 signal is a square wave signal having the same period and the same phase as the drive signal; Converting the first data obtained by the timing or counting into an absolute displacement value of the gate of the first displacement sensor within one pitch; Receiving the CLK512 signal and the first ADSO signal, and counting the number of pitch numbers of the gate movement of the first displacement sensor according to the CLK512 signal and the first ADSO signal; and Obtaining the total absolute displacement value of the gate of the first displacement sensor according to the second data obtained by counting the number of pitch numbers of the gate movement of the first displacement sensor and the first data; Wherein, the total absolute displacement equivalent Ln of the gate of the first displacement sensor is calculated by the following formula: Ln = An + Nn × M Wherein, An represents the first data, Nn represents the second data, and M represents the resolution equivalent corresponding to each pitch of the first displacement sensor; and Convert the total absolute displacement equivalent Ln of the gate of the first displacement sensor into the total absolute displacement value of the gate of the first displacement sensor.

16. The displacement measurement method according to claim 15, wherein, Performing timing or counting according to the CLK512 signal and the first ADSO signal includes: Starting timing or counting from zero at the clock frequency when the rising edge of the CLK512 signal is detected, and Sending or recording the current time or current count when the rising edge of the first ADSO signal is detected.

17. The displacement measurement method according to claim 16, wherein, Converting the first data obtained through the timing into the absolute displacement value of the gate of the first displacement sensor within one pitch includes: Obtaining the position equivalent of the gate of the first displacement sensor within one pitch according to the first data obtained through the timing and the clock frequency; Converting the position equivalent of the gate of the first displacement sensor within one pitch into the absolute displacement value of the gate of the first displacement sensor within one pitch.

18. The displacement measurement method according to claim 17, further including: Performing digital filtering processing on the position equivalent of the gate of the first displacement sensor within one pitch; and Performing deviation correction on the absolute displacement value of the gate of the first displacement sensor within one pitch.

19. The displacement measurement method according to claim 16, the sensor device further includes a second displacement sensor, wherein the first displacement sensor has multiple pitches within one pitch of the second displacement sensor, and the displacement measurement method further includes: Outputting the drive signal to the second displacement sensor; Receiving the signal from the second displacement sensor, processing the signal, and outputting a second ADSO signal; Receiving the second ADSO signal and the CLK512 signal, and performing timing or counting according to the second ADSO signal and the CLK512 signal at the clock frequency, wherein third data is obtained by performing timing or counting according to the second ADSO signal and the CLK512 signal; Determining the number of pitches moved by the gate of the first displacement sensor according to the third data; and Obtaining the total absolute displacement value of the gate of the first displacement sensor according to the number of pitches moved by the gate of the first displacement sensor and the first data.

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