Ceramic piston rod absolute stroke measuring method based on pulse differential decoding

Abstract

The invention provides a ceramic piston rod absolute stroke measuring method based on pulse differential decoding, and the method comprises the steps: arranging binary coded grooves in a piston rod, enabling each groove to correspond to a binary number, and enabling a plurality of binary numbers to form a code; a sensor array is arranged at the position close to the piston rod and comprises a first single-row sensor and a second single-row sensor which are arranged in a front-back staggered mode. Signals are read through the sensor array, a circulation direction period is formed by voltage wave crests and wave troughs of the signals, and the moving direction of the piston rod is obtained; and in combination with codes and pulse counts obtained by the sensor array, a decoding mapping relation is established, and the absolute stroke value of the piston rod is obtained. According to the method, through binary coding, a sensor array and pulse difference, the sensor is prevented from being interfered by an external magnetic field, the accuracy of a measurement signal is ensured, and high-precision displacement measurement and direction identification can also be achieved on an oil cylinder with a piston rod with a small diameter.

Description

Technical Field

[0001] The present invention relates to the technical field of piston rod stroke measurement, and in particular to an absolute stroke measurement method for a ceramic piston rod based on pulse difference decoding. Background Art

[0002] The piston rod is a key component of actuators such as hydraulic cylinders and pneumatic cylinders, and its stroke directly reflects the motion state and control accuracy of the actuator. Accurately measuring the piston rod stroke is crucial for achieving precise control, improving equipment performance, and ensuring safe operation. Ceramic materials have excellent properties such as high hardness, wear resistance, corrosion resistance, and high temperature resistance, and are used as piston rod materials under special working conditions such as high temperature and corrosive environments. Therefore, by using the excellent properties of ceramic materials to manufacture the piston rod, the displacement of the piston rod is output as a corresponding signal through sensor technology and converted into displacement data of the piston rod, thereby realizing the stroke measurement of the ceramic piston rod.

[0003] Early traditional stroke measurement methods such as mechanical, pneumatic or hydraulic methods have many problems such as low accuracy, susceptibility to environmental influence, high maintenance cost or limited application. With the continuous development of electronic technology, the stroke of the piston rod is measured by using the change of electrical signals of components such as resistors, inductors, and capacitors. This method further improves the measurement accuracy and has strong anti-interference ability. However, since it works based on the electromagnetic field principle, it will inevitably be affected by the external electromagnetic field, thereby interfering with the measurement accuracy. Further, optoelectronic technology is applied in stroke measurement, such as using optical devices such as grating rulers or laser interferometers for measurement. Such methods can achieve high-precision measurements at the micron or even nanometer level, and have good measurement stability, but have high requirements for the use environment and relatively high equipment prices, which to a certain extent limit their wide application. In recent years, magnetic encoders have gradually been applied to piston rod stroke measurement, such as Hall effect encoders, magnetoresistive encoders, etc., which use the change of magnetic signals to determine the position of the piston rod. Such methods have no wear during the measurement process, have a long service life, and can achieve high-precision measurements, but are susceptible to magnetic field interference.

[0004] Chinese Patent CN1O128O796B, an absolute stroke detection method and device used in combination with a ceramic piston rod, encodes by setting area markers and area number markers on the detection section of the piston rod. The area number markers are encoded in binary order and are achieved through a specific arrangement of grooves and convex rings. However, when using multiple multi-mounted sensors, the adaptability to oil cylinders with a relatively small piston rod diameter is relatively poor. Chinese Patent CN11243182OA, a system and method for measuring the absolute position displacement of a ceramic piston rod with grooves, discloses setting an upper groove group and a lower groove group on the piston rod, and the structures of the upper groove group and the lower groove group are different. The upper magnetic Hall sensor and the lower magnetic Hall sensor respectively measure the upper groove group and the lower groove group to obtain the absolute position of the piston rod. However, two groups of grooves with different structures need to be machined on the piston rod, that is, the equally spaced first grooves of the upper groove group and the non-equally spaced grooved sections and non-grooved sections of the lower groove group. The overall process is relatively complex, and it does not involve how to specifically convert the signal into the displacement of the piston rod. Summary of the Invention

[0005] The main purpose of the present invention is to provide an absolute stroke measurement method for a ceramic piston rod based on pulse difference decoding, which solves the problem that a large number of sensors are arranged and is not suitable for oil cylinders with a relatively small piston rod diameter. On the basis of improving applicability, it avoids the problem of inaccurate measurement of the absolute stroke and direction identification of the piston rod.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is: an absolute stroke measurement method for a ceramic piston rod based on pulse difference decoding, the method includes: S1. Grooves encoded in binary are provided on the piston rod, each groove corresponds to a binary number, and multiple binary numbers form a code; S2. A sensor array is provided near the piston rod, and the sensor array includes a first single-row sensor and a second single-row sensor arranged in a staggered manner front and back; S3. Read signals through the sensor array, form a cycle direction period from the voltage peaks and valleys of the signals, and obtain the moving direction of the piston rod; S4. Combine the code and pulse count obtained by the sensor array, establish a decoding mapping relationship, and obtain the absolute stroke value of the piston rod.

[0007] In the preferred solution, the sensor array outputs signals according to the change of magnetic field strength, respectively obtains the voltage signals of the first single-row sensor and the second single-row sensor, and the voltage signals include the voltage valley value in the weak magnetic field area and the voltage peak value in the strong magnetic field area.

[0008] In a preferred embodiment, according to the positional relationship between the voltage valleys and peaks, a cycle direction period is formed by the wave peaks and valleys. Each cycle direction period includes four direction area arrays, and each direction area array is composed of the voltage values obtained by the first single-row sensor and the second single-row sensor at the same position; When the four direction area arrays are at the same position, the voltage values obtained by the first single-row sensor and the second single-row sensor are both voltage valleys, the voltage values obtained by the first single-row sensor and the second single-row sensor are both voltage peaks, the voltage value obtained by the first single-row sensor is a voltage peak and the voltage value obtained by the second single-row sensor is a voltage valley, and the voltage value obtained by the first single-row sensor is a voltage valley and the voltage value obtained by the second single-row sensor is a voltage peak.

[0009] In a preferred embodiment, the voltage valley value in the weak magnetic field region is denoted as X, and the voltage peak value in the strong magnetic field region is denoted as O. Then the four direction area arrays included in the cycle direction period are respectively denoted as XX, XO, OO, and OX; If the cycle direction period of the first single-row sensor and the second single-row sensor is XX, OX, OO, and XO, the piston rod moves from left to right; If the cycle direction period of the first single-row sensor and the second single-row sensor is XX, XO, OO, and OX, the piston rod moves from right to left.

[0010] In a preferred embodiment, the strong magnetic field region corresponds to the groove region of the piston rod, and the weak magnetic field region corresponds to the rack region between adjacent grooves.

[0011] In a preferred embodiment, one cycle direction period in the decoding mapping relationship corresponds to four continuously acquired codes. According to the number of cycles where the sensor array is located, the direction area array of the code in the current cycle is obtained, and the corresponding pulse count is obtained and converted into the absolute stroke value of the piston rod.

[0012] In a preferred embodiment, when the voltages of the first single-row sensor and the second single-row sensor are in the same state, that is, both are peaks or both are valleys, a low potential is generated; when the voltages of the first single-row sensor and the second single-row sensor are in different states, that is, one is at a peak and the other is at a valley, a high potential is generated; a pulse signal is formed by low potentials and high potentials with equal width and equal spacing; Whenever the pulse signal has a high potential jump to a low potential, or a low potential jump to a high potential, the pulse count is incremented by 1.

[0013] In a preferred embodiment, the first single-row sensor and the second single-row sensor each include a plurality of Hall sensors with the same quantity, and each Hall sensor is used to obtain a binary number corresponding to a groove; The code includes a column of code values obtained by the first single-row sensor and two columns of code values obtained by the second single-row sensor, and the column of code values and the two columns of code values are each composed of a plurality of binary numbers.

[0014] In a preferred embodiment, the grooves are distributed on the piston rod at the same interval distance. The grooves include shallow grooves and deep grooves. The depth of the shallow grooves is less than that of the deep grooves, and the shallow grooves and the deep grooves respectively correspond to different binary numbers.

[0015] In a preferred embodiment, the width of the grooves is 2 mm, the depth of the shallow grooves is 1 mm, and the depth of the deep grooves is 2 mm; the first single-row sensor and the second single-row sensor are arranged with a 1-mm offset front and back, and the second single-row sensor is located in the right-rear direction of the first single-row sensor.

[0016] The present invention provides an absolute stroke measurement method for a ceramic piston rod based on pulse difference decoding. The method includes providing binary-encoded grooves on the piston rod, each groove corresponding to a binary number, and a plurality of binary numbers forming a code; a sensor array is provided near the piston rod, and the sensor array includes a first single-row sensor and a second single-row sensor arranged with a front-back offset; signals are read by the sensor array, and a cycle direction period is formed by the voltage peaks and valleys of the signals to obtain the moving direction of the piston rod; a decoding mapping relationship is established by combining the code obtained by the sensor array and pulse counting to obtain the absolute stroke value of the piston rod. This method uses binary encoding, a sensor array, and pulse difference technology to enable high-precision displacement measurement and direction recognition on an oil cylinder with a relatively small piston rod diameter. The sensor array is set as two rows of parallel sensors, making its volume smaller and improving application universality; the stroke information of the piston rod is converted into corresponding signals, and the signals are processed using pulse difference to effectively overcome the problem that the sensor is easily interfered by external magnetic fields, ensuring the accuracy of the measurement signal, and thus accurately extracting the information related to the absolute stroke of the piston rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the drawings and embodiments: Figure 1 is the flowchart of the method of the present invention; Figure 2 is a schematic diagram of the sensor array of the present invention; Figure 3 is a schematic diagram of the first single-row sensor reading when the piston rod of the present invention moves; Figure 4 is a schematic diagram of the grooves in Embodiment 2 of the present invention; Figure 5 is a schematic diagram of the output signal of the sensor array in Embodiment 2 of the present invention; In the figure: sensor array 1; first single-row sensor 2; second single-row sensor 3; Hall sensor 4; groove 5; shallow groove 6; deep groove 7; rack 8. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Embodiment 1 As Figures 1 - 5As shown, a method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding, the method comprising: S1. a binary-coded groove 5 is provided on the piston rod, each groove 5 corresponds to a binary number, and a plurality of binary numbers form a code; S2. A sensor array 1 is provided near the piston rod, and the sensor array 1 includes a first single-row sensor 2 and a second single-row sensor 3 arranged in a front-to-back staggered manner; S3. Read the signal through the sensor array 1, and form a cyclic direction cycle by the voltage peaks and troughs of the signal to obtain the moving direction of the piston rod; S4. Combine the code and pulse count obtained by the sensor array 1 to establish a decoding mapping relationship to obtain the absolute stroke value of the piston rod.

[0019] According to this scheme, the piston rod in this embodiment is a ceramic piston rod, and a magnet or magnetic material is provided on the piston rod. By laser etching or mechanical processing, grooves 5 of equal width and spacing are formed on the surface of the piston rod, and each groove 5 corresponds to a binary number. The binary numbers of the continuous grooves 5 are obtained by the sensor array 1 to form the code. The first single-row sensor 2 is located below the second single-row sensor 3, and is arranged in a staggered manner along the axial direction of the piston rod, covering different phases of the same groove 5 to achieve phase difference measurement. Preferably, the staggered distance between the first single-row sensor 2 and the second single-row sensor 3 is half of the width of the groove 5, eliminating the error code caused by magnetic field interference or installation error of the single-row sensor. The voltage value of the output signal is obtained by using the first single-row sensor 2 and the second single-row sensor 3 to obtain a complete cycle direction cycle composed of peaks and troughs, thereby determining the moving direction of the piston rod. The code is obtained by the sensor array 1 to determine the number of cycles, and the absolute stroke value of the piston rod is obtained according to the decoding mapping relationship in combination with the moving direction of the piston rod and the pulse count. This method uses binary coding, sensor array and pulse differential technology to achieve high-precision displacement measurement and direction identification on oil cylinders with smaller piston rod diameters. The sensor array 1 is set as two rows of parallel sensors to make it smaller; the stroke information of the piston rod is converted into a corresponding signal, and the signal is processed using pulse differential, which effectively overcomes the problem that the sensor is easily disturbed by the external magnetic field, ensures the accuracy of the measurement signal, and accurately extracts information related to the absolute stroke of the piston rod.

[0020] Example 2 Further illustrate with reference to Example 1, Figures 2 - 5As shown, in the preferred embodiment, the sensor array 1 outputs signals according to the change of magnetic field strength, and obtains the voltage signals of the first single-row sensor 2 and the second single-row sensor 3 respectively. The voltage signals include the voltage valley value in the weak magnetic field region and the voltage peak value in the strong magnetic field region, which are used to obtain the moving direction and position of the piston rod. With this solution, when the groove 5 on the piston rod passes through the sensor array 1, the voltage signal output by the sensor array 1 changes with the change of magnetic field strength. When the sensor array 1 is in the weak magnetic field region, the magnetic field strength is low and the output voltage is low, forming a voltage valley value; when the sensor array 1 is in the strong magnetic field region, the magnetic field strength is high and the output voltage is high, forming a voltage peak value.

[0021] In the preferred embodiment, as Figure 4 and 5 shown, according to the position relationship between the voltage valley value and the peak value, a cycle direction period is formed by the wave peak and the wave valley. Each cycle direction period includes four direction area arrays, and each direction area array is composed of the voltage values obtained by the first single-row sensor 2 and the second single-row sensor 3 at the same position; The four direction area arrays include that when at the same position, both the voltage values obtained by the first single-row sensor 2 and the second single-row sensor 3 are voltage valley values, both the voltage values obtained by the first single-row sensor 2 and the second single-row sensor 3 are voltage peak values, the voltage value obtained by the first single-row sensor 2 is a voltage peak value and the voltage value obtained by the second single-row sensor 3 is a voltage valley value, and the voltage value obtained by the first single-row sensor 2 is a voltage valley value and the voltage value obtained by the second single-row sensor 3 is a voltage peak value.

[0022] With this solution, the signal processing unit filters, amplifies and shapes the signals output by the sensor array 1 so as to clearly reflect the wave peaks and wave valleys. The voltage values of the first single-row sensor 2 and the second single-row sensor 3 at different positions are collected, and the corresponding relationship between the voltage valley value, the peak value and the position of the piston rod is established. Four consecutive positions correspond to four direction area arrays, and the four direction area arrays change cyclically to form a cycle direction period. Since the two single-row sensors are arranged in a staggered manner front and back, there is a phase difference in the voltage values obtained at the same position. By using the sorting of the four direction area arrays within the cycle direction period, the moving direction of the piston rod is judged. Preferably, the distances between the four direction area arrays are the same and depend on the staggered distance between the first single-row sensor 2 and the second single-row sensor 3.

[0023] In the preferred embodiment, as Figure 5 shown, the voltage valley value in the weak magnetic field region is denoted as X, and the voltage peak value in the strong magnetic field region is denoted as O. Then the four direction area arrays included in the cycle direction period are respectively denoted as XX, XO, OO and OX; If the cycle direction period of the first single-row sensor 2 and the second single-row sensor 3 is XX, OX, OO and XO, then the piston rod moves from left to right; If the cycle direction periods of the first single-row sensor 2 and the second single-row sensor 3 are XX, XO, OO, and OX, the piston rod moves from right to left.

[0024] In this solution, when in a strong magnetic field region, when the read voltage peak value is about 3V or 5V, it is all recorded as O; when in a weak magnetic field region, when the read voltage valley value is about 1V, it is recorded as X. The cycle direction period includes that when the first single-row sensor 2 and the second single-row sensor 3 are at the same position and both are voltage valley values X, the direction area array is recorded as XX; when the first single-row sensor 2 and the second single-row sensor 3 are at the same position and both are voltage peak values O, the direction area array is recorded as OO; when at the same position, the first single-row sensor 2 is a voltage peak value O and the second single-row sensor 3 is a voltage valley value X, the direction area array is recorded as OX; and when at the same position, the first single-row sensor 2 is a voltage valley value X and the second single-row sensor 3 is a voltage peak value O, the direction area array is recorded as X0.

[0025] In the preferred solution, as Figure 4 and 5 shown, the strong magnetic field region corresponds to the groove 5 region of the piston rod, and the weak magnetic field region corresponds to the rack 8 region between adjacent grooves 5. In this solution, the groove 5 region of the piston rod is concave, and the rack 8 region of the piston rod is convex, so that the magnetic field intensities of the groove 5 and the rack 8 are different. By measuring the change in the magnetic field intensity with a sensor, it is converted into a corresponding signal output. The magnetic field intensity increases in the groove 5 region to form a strong magnetic field region for obtaining the voltage peak value; the magnetic field intensity is weak in the rack 8 region to form a weak magnetic field region for obtaining the voltage valley value. One groove 5 and one rack 8 form a cycle direction period, and the voltage peak value in the strong magnetic field region corresponds to the bottom position of the groove 5, and the voltage valley value in the weak magnetic field region corresponds to the top position of the rack 8.

[0026] Preferably, as Figure 4 and 5 shown, if the binary number corresponding to the groove 5 is 0011111010, the voltage peak value in the strong magnetic field region of the shallow groove 6 is about 3V, recorded as O, the voltage peak value in the strong magnetic field region of the deep groove 7 is about 5V, recorded as 1, and the voltage valley value in the weakest magnetic field region of the rack 8 is about 1V, recorded as X; for the convenience of calculation and program writing, both 0 and 1 are regarded as 0, that is, the voltage peak value of 3V or 5V is recorded as 0. Then the direction area array and position relationship of the above binary number 0011111010 are shown in Table 1; according to the cycle direction period, the moving direction of the piston rod can be judged. If the cycle direction period of the obtained direction area array is XX, OX, OO, and XO, the current piston rod moves to the right; if the cycle direction period of the obtained direction area array is XX, XO, OO, and OX, the current piston rod moves to the left.

[0027] Table 1 Position relationship table

[0028] Example 3 As further illustrated in combination with Embodiment 1 and Embodiment 2, as Figures 1 - 5 shown, in a preferred embodiment, one cycle direction period in the decoding mapping relationship corresponds to four continuously acquired encodings. According to the number of cycles where the sensor array 1 is located, the direction region array of the encoding within the current cycle is obtained, and the corresponding pulse count is obtained and converted into the absolute stroke value of the piston rod.

[0029] In a preferred embodiment, as Figure 5 shown, when the voltages of the first single-row sensor 2 and the second single-row sensor 3 are in the same state, that is, both are at the peak value or both are at the valley value, a low potential is generated; when the voltages of the first single-row sensor 2 and the second single-row sensor 3 are in different states, that is, one is at the peak value and the other is at the valley value, a high potential is generated; pulse signals are formed by low potentials and high potentials with equal width and equal spacing; whenever the pulse signal has a high potential jump to a low potential, or a low potential jump to a high potential, the pulse count is incremented by 1.

[0030] With this solution, the voltage signals of the first single-row sensor 2 and the second single-row sensor 3 are differentially processed to obtain pulse signals. Whenever a column of code values read by the first single-row sensor 2 changes, a new cycle direction period is entered. According to the preset encoding mapping relationship, the number of cycles where the sensor array 1 is located is determined. Within the current cycle, whenever the pulse signal of the piston rod has a high potential jump to a low potential, or a low potential jump to a high potential, the pulse count is incremented by 1. Preferably, the pulse counts corresponding to the direction region arrays XX, OX, OO, and XO are 1, 2, 3, and 4 in sequence.

[0031] Example 4 As further illustrated in combination with Embodiments 1 to 3, as Figure 2 and 3 shown, in a preferred embodiment, the first single-row sensor 2 and the second single-row sensor 3 each include a plurality of Hall sensors 4 with the same quantity, and each Hall sensor 4 is used to obtain the binary number corresponding to a groove 5; the encoding includes a column of code values obtained by the first single-row sensor 2 and two columns of code values obtained by the second single-row sensor 3, and the column of code values and the two columns of code values are each composed of a plurality of binary numbers.

[0032] With this solution, the sensor array 1 includes a plurality of Hall sensors 4. The Hall sensors 4 are small in size and light in weight, enabling a structurally compact measurement system. Only two rows of Hall sensors 4 are provided, making it suitable for an oil cylinder with a relatively small piston rod diameter. A gap is provided between the sensor array 1 and the piston rod. The first single-row sensor 2 and the second single-row sensor 3 are arranged with a 1-mm offset along the axial direction of the piston rod, covering the same groove 5 but with a phase shift, for forming a phase difference to identify the moving direction of the piston rod. A column code value and a second-column code value are composed of a plurality of consecutive binary numbers. A column code value and a second-column code value form a group of codes. The column code value and the second-column code value are respectively composed of 8-bit, 12-bit, or 16-bit binary numbers.

[0033] In a preferred solution, as Figures 2 - 4 shown, the grooves 5 are distributed on the piston rod at the same interval distance. The groove 5 includes a shallow groove 6 and a deep groove 7. The depth of the shallow groove 6 is less than that of the deep groove 7. The shallow groove 6 and the deep groove 7 respectively correspond to different binary numbers. With this solution, due to the greater depth of the deep groove 7, the change in magnetic field intensity generated is more significant, and an obvious voltage difference is formed when detected by the Hall sensor 4. The design of the shallow groove 6 and the deep groove 7 is used to enhance the magnetic field contrast and reduce the risk of signal confusion. The Hall sensor 4 outputs the corresponding binary number by detecting the magnetic field intensity of the groove 5. Preferably, a single shallow groove 6 is binary number 0, and a single deep groove 7 is binary number 1.

[0034] In a preferred solution, as Figures 2 - 4 shown, the width of the groove 5 is 2 mm, the depth of the shallow groove 6 is 1 mm, and the depth of the deep groove 7 is 2 mm. The first single-row sensor 2 and the second single-row sensor 3 are arranged with a 1-mm offset front and back. The second single-row sensor 3 is located in the right-rear direction of the first single-row sensor 2. With this solution, the width of the rack 8 is also 2 mm. The code composed of binary numbers and the grooves 5 with equal width and equal spacing are used to simplify the decoding logic. Each Hall sensor 4 corresponds to a groove 5 with a width of 2 mm. The two rows of Hall sensors 4 are arranged with an offset, making it suitable for an oil cylinder with a relatively small piston rod diameter and achieving a decoding accuracy of 1 mm.

[0035] Embodiment 5 Combined with Embodiments 1 to 4 for further illustration, as Figures 1 - 5 shown, preferably, the widths of the groove 5 and the rack 8 are both 2 mm, the depth of the shallow groove 6 is 1 mm, and the depth of the deep groove 7 is 2 mm. The sensor array 1 includes two single-row sensors arranged with a 1-mm offset. The first single-row sensor 2 and the second single-row sensor 3 respectively include eight Hall sensors 4 arranged side by side. There are 263 grooves 5 on the piston rod, and the binary number corresponding to each groove 5 is: 00000000111111110111111001111101011111000111101101111010011110010111100001110111011001110101011101000111001101110010011100010111000001101101011011000110101001101001011010000110011001010110010001100010011000010110000001010101000101001001010000010010000100010000000; The number of bits of the binary digital code values obtained by the first single-row sensor 2 and the second single-row sensor 3 is 8 bits, and some binary digital code values are shown in Table 2.

[0036] Table 2 Binary digital code values

[0037] The binary digital code value of the first single-row sensor 2 is a one-column code value, and the binary digital code value of the second single-row sensor 3 is a two-column code value. The one-column code value and the two-column code value form a group of codes; the moving direction of the piston rod is obtained by combining the voltage signal, the current cycle number is determined according to the obtained codes, the direction area array within the current cycle is obtained, and then the pulse count can be obtained. According to the decoding mapping relationship shown in Table 3, the absolute stroke value of the piston rod can be obtained.

[0038] For example, if the read code consists of a one-column code value of 00000000 and a two-column code value of 00000000, according to the decoding mapping relationship, the one-column code value is 00000000, the first single-row sensor 2 is in the 1st cycle, the current cycle number is 0, the direction area array obtained within the current cycle is OO, and the corresponding pulse count is 3, then the absolute stroke value of the piston rod is 3 mm; if the read code consists of a one-column code value of 00000011 and a two-column code value of 00000011, according to the decoding mapping relationship, the one-column code value is 00000011, the first single-row sensor 2 is in the 3rd cycle, the current cycle number is 2, the direction area array obtained within the current cycle is XO, and the corresponding pulse count is 4, then the absolute stroke value of the piston rod is 12 mm.

[0039] Table 3 Partial decoding mapping relationship table

[0040] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding, characterized in that: The method comprises: S1. a binary-coded groove (5) is provided on the piston rod, each groove (5) corresponds to a binary number, and a plurality of binary numbers form a code; S2. A sensor array (1) is provided near the piston rod, the sensor array (1) comprising a first single-row sensor (2) and a second single-row sensor (3) arranged in a front-to-back staggered manner; S3. Reading the signal through the sensor array (1), forming a cyclic direction cycle by the voltage peaks and troughs of the signal, and obtaining the movement direction of the piston rod; S4. Combine the code and pulse count obtained by the sensor array (1), establish a decoding mapping relationship, and obtain the absolute stroke value of the piston rod.

2. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 1 is characterized in that: The sensor array (1) outputs a signal according to changes in the strength of the magnetic field, and respectively obtains voltage signals of the first single-row sensor (2) and the second single-row sensor (3), wherein the voltage signals include a voltage valley value in a weak magnetic field region and a voltage peak value in a strong magnetic field region.

3. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 2 is characterized in that: According to the positional relationship between the voltage valley value and the peak value, a cyclic direction period is formed by the wave crest and the wave valley, each cyclic direction period includes four directional area arrays, each directional area array is composed of voltage values ​​obtained by the first single-row sensor (2) and the second single-row sensor (3) at the same position; The four directional area arrays include that when at the same position, the first single-row sensor (2) and the second single-row sensor (3) both obtain voltage valley values, the first single-row sensor (2) and the second single-row sensor (3) both obtain voltage peak values, the first single-row sensor (2) obtains a voltage peak value and the second single-row sensor (3) obtains a voltage valley value, and the first single-row sensor (2) obtains a voltage valley value and the second single-row sensor (3) obtains a voltage peak value.

4. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 3 is characterized in that: The voltage valley value in the weak magnetic field region is recorded as X, and the voltage peak value in the strong magnetic field region is recorded as O. Then the four direction region arrays included in the cyclic direction period are recorded as XX, XO, OO and OX respectively; If the cycle direction periods of the first single-row sensor (2) and the second single-row sensor (3) are XX, OX, OO and XO, the piston rod moves from left to right; If the cycle direction periods of the first single-row sensor (2) and the second single-row sensor (3) are XX, XO, OO and OX, the piston rod moves from right to left.

5. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to any one of claims 2 to 4, characterized in that: The strong magnetic field region corresponds to the groove (5) region of the piston rod, and the weak magnetic field region corresponds to the rack (8) region between adjacent grooves (5).

6. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 1 is characterized in that: In the decoding mapping relationship, one cyclic direction period corresponds to four continuously acquired codes. According to the period number of the sensor array (1), the direction area array of the code in the current period is obtained, and the corresponding pulse count is obtained and converted into the absolute stroke value of the piston rod.

7. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 6 is characterized in that: The voltages of the first single-row sensor (2) and the second single-row sensor (3) are in the same state, that is, they are both peak values ​​or both valley values, thus generating a low potential; the voltages of the first single-row sensor (2) and the second single-row sensor (3) are in different states, that is, one is at a peak value and the other is at a valley value, thus generating a high potential; a pulse signal is formed by low potentials and high potentials of equal width and spacing; Whenever the pulse signal changes from a high potential to a low potential, or from a low potential to a high potential, the pulse count increases by 1.

8. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 1 is characterized in that: The first single-row sensor (2) and the second single-row sensor (3) respectively include a plurality of Hall sensors (4) of the same number, each Hall sensor (4) being used to obtain a binary number corresponding to a groove (5); The encoding comprises a column of code values ​​acquired by the first single-row sensor (2) and two columns of code values ​​acquired by the second single-row sensor (3), wherein the column of code values ​​and the two columns of code values ​​are respectively composed of a plurality of binary numbers.

9. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 8 is characterized in that: The grooves (5) are distributed on the piston rod at the same interval. The grooves (5) include shallow grooves (6) and deep grooves (7). The depth of the shallow grooves (6) is less than the depth of the deep grooves (7). The shallow grooves (6) and the deep grooves (7) correspond to different binary numbers.

10. The method for measuring the absolute stroke of a ceramic piston rod based on pulse differential decoding according to claim 9 is characterized in that: The width of the groove (5) is 2 mm, the depth of the shallow groove (6) is 1 mm, and the depth of the deep groove (7) is 2 mm; the first single-row sensor (2) and the second single-row sensor (3) are arranged with a front-to-back offset of 1 mm, and the second single-row sensor (3) is located in the right rear direction of the first single-row sensor (2).

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