A photoelectric information fusion reflective absolute angular displacement sensor and measurement method

Abstract

This invention discloses a photoelectric information fusion-based reflective absolute angular displacement sensor and measurement method, including a stator substrate and its excitation electrodes, and a rotor substrate and its sensing electrodes. A light-absorbing insulating layer is applied to the surface of the rotor substrate facing the stator substrate, and a ring of reflective patterns is arranged on the light-absorbing insulating layer, the number of which is coprime to the stator period. A photoelectric sensor is mounted on the surface of the stator substrate facing the rotor substrate. The light source of the photoelectric sensor sends a light beam to the reflective patterns, and the receiver of the photoelectric sensor collects the light intensity reflected by the reflective patterns and outputs the obtained photoelectric signal to a signal processing circuit. The measured value of the electric field portion is used as the fine measurement, and the measured value of the electric field portion is combined with the measured value of the light field portion as the coarse measurement to determine the period in which the fine measurement is performed, thus achieving absolute positioning. This invention can significantly reduce the radial size of the sensor, and the fine and coarse measurements do not interfere with each other, resulting in high measurement accuracy and ease of implementation.

Description

Technical Field

[0001] This invention relates to precision angular displacement measurement, specifically to a photoelectric information fusion reflective absolute angular displacement sensor and measurement method. This sensor obtains absolute position using different methods for fine and coarse measurements, and belongs to the field of precision measurement and sensing technology. Background Technology

[0002] High-precision and large-diameter angular displacement sensors are widely used in precision equipment, such as precision machine tools, military weapons, automobiles, medical devices, and high-precision worktables, serving as key functional units in these devices. Absolute sensors enable absolute displacement measurement, effectively solving the problem of data loss during power outages. They also allow for fully closed-loop control and feedback, reducing interference from external factors such as temperature, and improving sensor measurement accuracy, thus broadening their application range.

[0003] Currently, electric field-type angular displacement sensors mainly achieve absolute measurement by using differential pole or coprime methods. Although absolute measurement is achieved, there are also drawbacks.

[0004] 1) When using differential or coprime to achieve absolute positioning, two rings of sensors are required. This requires setting two rings of excitation electrodes and two rings of induction electrodes on the stator base and rotor base respectively, which increases the size of the sensor, especially the radial dimension of the sensor, which is not conducive to compactness and miniaturization.

[0005] 2) When using a differential pole structure, the difficulty of achieving absolute positioning around a large circle will increase significantly, mainly due to the positioning error. N and N-1 are the number of cycles for the two sensors, respectively. As the sensor diameter increases, the number of cycles required increases, the requirements for positioning accuracy become higher, and the more difficult it is to achieve.

[0006] 3) When absolute positioning is achieved by using differential polarity or coprime polarity, there is mutual interference between the two sensors, which will affect the measurement accuracy and is not conducive to high-precision large-size measurement. Summary of the Invention

[0007] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a photoelectric information fusion reflective absolute angular displacement sensor and measurement method. The present invention can significantly reduce the radial size of the sensor, and the fine and coarse measurements do not interfere with each other, resulting in high measurement accuracy, simple structure, and ease of implementation.

[0008] The technical solution of this invention is implemented as follows:

[0009] A photoelectric information fusion-based reflective absolute angular displacement sensor includes an incremental electric field angular displacement measurement section and an optical field measurement section. The measurement value of the incremental electric field angular displacement measurement section serves as the fine measurement, while the measurement value of the incremental electric field angular displacement measurement section is combined with the measurement value of the optical field measurement section as the coarse measurement to determine the period in which the fine measurement occurs. The combination of the fine measurement and the coarse measurement achieves absolute positioning. The incremental electric field angular displacement measurement section includes a rotor base and a stator base arranged in parallel with a gap. An excitation electrode is uniformly arranged around the circumference of the surface of the stator base facing the rotor base, and a sensing electrode is uniformly arranged around the circumference of the surface of the rotor base facing the stator base. The sensing electrode on the rotor base is directly opposite the excitation electrode on the stator base. The optical field measurement section includes a photoelectric sensor and a reflective pattern. The photoelectric sensor consists of a light source and a receiver. The reflective pattern is composed of several identical reflective patterns arranged end to end in a circle, and the number of reflective patterns is coprime to the number of cycles of the excitation electrodes. The area of ​​each reflective pattern along the circumference is a function of the corresponding angle. A ring-shaped light-absorbing insulating layer, concentric with the rotor substrate and covering all the sensing electrodes, is placed on the surface of the rotor substrate facing the stator substrate. The reflective pattern is disposed on the light-absorbing insulating layer and is concentric with the light-absorbing insulating layer. The photoelectric sensor is disposed on the surface of the stator substrate facing the rotor substrate, and the photoelectric sensor is directly opposite the reflective pattern. The light source of the photoelectric sensor is used to send a light beam to the reflective pattern, and the receiver of the photoelectric sensor is used to collect the light intensity reflected by the reflective pattern and output the obtained photoelectric signal to the signal processing circuit.

[0010] Furthermore, the number of photoelectric sensors is two, and they are located on the same circumference.

[0011] Furthermore, the reflective pattern is sinusoidal, and the angle formed by the lines connecting the two photoelectric sensors and the center of the stator substrate is equal to 1 / 4 of the circumference angle of a single reflective pattern; the functional relationship is a sine or cosine function relationship.

[0012] Furthermore, the reflective pattern is triangular, and let θ be the angle corresponding to one period of the triangle. x The angle occupied by the photoelectric sensor is θ y The angle formed by the lines connecting the two photoelectric sensors to the center of the stator base is θ. x -θ y The functional relationship is a linear functional relationship.

[0013] Furthermore, on the surface of the rotor base facing the stator base, two inner and outer rings of induction signal emitting rings are arranged around the outer ring of the induction electrodes. The two rings of induction signal emitting rings are respectively connected to the two induction phases formed by the induction electrodes to emit the induction signals generated by the corresponding induction phases. The light-absorbing insulating layer covers all the induction electrodes and the two rings of induction signal emitting rings. On the surface of the stator base facing the rotor base, two inner and outer rings of induction signal receiving rings are arranged around the outer ring of the excitation electrodes. The two rings of induction signal receiving rings correspond one-to-one with the two rings of induction signal emitting rings and are used to receive the induction signals emitted by the corresponding induction signal emitting rings.

[0014] Furthermore, the photoelectric sensor is located on one of the sensing signal receiving loops.

[0015] Furthermore, the excitation electrode is composed of 4m rectangular excitation electrodes of the same size with an electrode spacing of θ1, evenly arranged along the circumference; every four adjacent excitation electrodes form a group, and the 4m excitation electrodes form m groups; the excitation electrodes in the first position of each group are connected together to form excitation phase A, the excitation electrodes in the second position of each group are connected together to form excitation phase B, the excitation electrodes in the third position of each group are connected together to form excitation phase C, and the excitation electrodes in the fourth position of each group are connected together to form excitation phase D; the induction electrode is composed of 2m double sinusoidal electrodes of the same size with an electrode spacing of 2θ1, evenly arranged along the circumference; every two adjacent induction electrodes form a group, and the 2m induction electrodes form m groups; the induction electrodes in the first position of each group are connected together to form induction phase A, and the induction electrodes in the second position of each group are connected together to form induction phase B.

[0016] The measurement method of the above-mentioned photoelectric information fusion reflective absolute angular displacement sensor includes the following steps:

[0017] 1) Incremental electric field angular displacement measurement: An excitation signal is applied to the excitation electrode. Under the action of the excitation electrode, the induction electrode outputs a corresponding traveling wave signal. The signal processing circuit processes the induction traveling wave signal and the reference signal of the same frequency accordingly to obtain a square wave signal. Then, the angular displacement value θ is calculated. m And used as a precise measurement value;

[0018] 2) Light Field Measurement Section: The light source of the photoelectric sensor emits a beam of light and illuminates the reflective pattern. The receivers of the two photoelectric sensors respectively collect the corresponding reflected light and output photoelectric signals to the signal processing circuit. After processing by the signal processing circuit, the angular displacement value θ of the light field measurement section is obtained. n ;

[0019] 3) Coarse measurement to determine the period of fine measurement: Let the number of periods of the excitation electrode and the reflective pattern be m and n respectively. m and n are relatively prime and n > m. The total angle of the sensor is 2π. The angular displacement value θ measured by the incremental electric field angular displacement measurement part m changes periodically within [0 - 2π / m], and the angular displacement value θ measured by the optical field measurement part n changes periodically within [0 - 2π / n]. Let δ represent the angle difference between the two, δ = θ m - θ n ; Determine the number of periods N of the incremental electric field angular displacement measurement part through the δ value as the absolute positioning sequence value;

[0020] 4) Calculate the absolute angular displacement value: Combine the fine measurement value θ obtained in step 1) m and the number of periods N obtained in step 3) to obtain the final absolute angular displacement value θ a = Nθ + θ m ; θ is the period width of the incremental electric field angular displacement measurement part.

[0021] Furthermore, the light beam emitted by the light source of the photoelectric sensor is invisible light.

[0022] Furthermore, the angular displacement value θ of the optical field measurement part n is obtained as follows. Let the voltage converted by the first photoelectric sensor be U(θ), the reference voltage Vref be the middle level of U(θ), and the voltage converted by the second photoelectric sensor be U’(θ). Flip the voltage value of the second photoelectric sensor to Vref - U’(θ). When U(θ) < U’(θ), Uo = U(θ). When U’(θ) < U(θ), Uo = U’(θ). Uo is the voltage value output under different conditions; when U(θ) > Vref - U’(θ), Uo = , where is the maximum and minimum values of the output voltage of the photoelectric sensor; thus, the triangular wave signals collected by the two photoelectric sensors are integrated and converted into a linearly varying displacement signal, so as to obtain the displacement value measured by the optical field measurement part.

[0023] This invention generates four excitation signals with equal amplitude and 90° phase difference through an excitation module, which serve as inputs to an electric field-type grating angle sensor. The output signals from the electric field-type grating angle sensor and the photoelectric sensor are connected to a signal processing circuit. This circuit processes the traveling wave signal and reference signal generated by the grating angle sensor, and enhances the analog voltage signal converted from the amplitude sampling of the photoelectric sensor to improve the signal-to-noise ratio and ensure a clear signal. Finally, the processed signal is input to an embedded processor module. The embedded processor module receives the input signal from the signal processing circuit, performs phase measurement on the signal generated by the grating angle sensor to obtain a precise measurement value, demodulates the processed analog voltage signal from the photoelectric sensor to obtain the angular displacement value of the optical field measurement section, and then calculates the period in which the precise measurement occurs, which serves as a coarse measurement. Combining the precise and coarse measurements enables absolute measurement.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The coarse measurement signal of this invention is based on the amplitude sampling of the light field intensity by the photocell in the photoelectric sensor. The light field intensity collected by the photocell is proportional to the area integral of the reflected pattern and the photoelectric sensor. The output displacement signal is proportional to the area integral of the reflected pattern. The encoded pattern is simple and the output displacement is linear. The displacement value obtained by the photoelectric sensor is combined with the fine measurement value to calculate the period in which the fine measurement is performed. By combining the period data with the fine measurement data, the absolute position can be obtained through simple calculation. The encoding and decoding are simple.

[0026] 2. The coarse measurement method of this invention is used to achieve absolute angular periodic positioning. Coarse periodic positioning only requires locating the period value of the incremental angular displacement sensor; it does not require fine graphic printing to achieve periodic positioning. The positioning method is simple, and reflective graphic printing is easy to implement.

[0027] 3. This invention achieves absolute positioning without employing a double-ring structure, fully utilizing the sensor's thickness by using a two-layer structure for the reflective pattern and excitation electrode. The reflective pattern's thickness is only on the micrometer scale (only 20µm in this example), and its impact on the sensor's thickness is negligible. Compared to existing two-ring structures in the width direction, this invention effectively reduces the sensor's volume, facilitating compact and miniaturized design.

[0028] 4. The present invention employs two different positioning and signal transmission methods for optical field measurement and electric field measurement. There is no signal interference between the two methods, which ensures high measurement accuracy while achieving large-scale absolute positioning. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the sensor stator structure of the present invention.

[0030] Figure 2 This is a schematic diagram of the sensor rotor structure of the present invention.

[0031] Figure 3 This is a schematic diagram of the sensor installation according to the present invention.

[0032] Figure 4 This is a schematic diagram of the rotor of the present invention (without a light-absorbing insulating layer).

[0033] Figure 5 This is a schematic diagram of the encoding of the present invention.

[0034] Figure 6 This is a schematic diagram of the photoelectric periodic signal conversion process of the present invention.

[0035] Figure 7 A schematic diagram showing how the measurement cycle is determined by the combined measurement values ​​and precision values ​​from the photoelectric sensor.

[0036] Figure 8 This is a flowchart of the signal generation and data processing of the present invention. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0038] See Figures 1-5 This invention discloses a reflective absolute angular displacement sensor, comprising a rotor base 2 and a stator base 1 arranged parallel to each other with a gap (d). A ring of excitation electrodes 1-1 is uniformly arranged along the circumference of the upper surface of the stator base 1, and a ring of sensing electrodes 2-1 is uniformly arranged along the circumference of the lower surface of the rotor base 2. The sensing electrodes on the rotor base are directly opposite the excitation electrodes on the stator base. A concentric annular light-absorbing insulating layer 2-3, covering all the sensing electrodes 2-1, is placed on the lower surface of the rotor base 2. A ring of reflective patterns 2-4 is uniformly arranged along the circumference of the light-absorbing insulating layer 2-3. The reflective patterns 2-4 consist of several identical, end-to-end reflective patterns, and the number of reflective patterns is coprime to the number of excitation electrode cycles. The area change of each reflective pattern along the circumference is a function of the corresponding angle change. Two photoelectric sensors 1-4 are disposed on the upper surface of the stator base 1, directly opposite the reflective patterns. Each photoelectric sensor consists of a light source and a receiver. The light source of the photoelectric sensor is used to send a light beam (which can be invisible or visible light) to the two rings of reflective patterns. The receiver of the photoelectric sensor is used to collect the light intensity reflected by the reflective patterns and output the obtained photoelectric signal to the signal processing circuit. Since the area change of each reflective pattern along the circumference is a function of the corresponding angle change, correspondingly, during the rotation of the rotor base along the stator base, the area (overlapping area) of the photoelectric sensor and the reflective patterns changes in a corresponding function of the angular displacement.

[0039] In this invention, the rotor base 2 and stator base 1 are positioned relative to each other. Alternatively, the rotor base 2 can be below and the stator base 1 above, which is equivalent to flipping the entire sensor 180° without changing its structure. This depends on the actual installation configuration.

[0040] The inventive concept of this invention lies in setting up an incremental electric field angular displacement measurement section and an optical field measurement section. The measurement value of the incremental electric field angular displacement measurement section is used as a fine measurement, measuring a precise angle within a small period. Simultaneously, the measurement value of the incremental electric field angular displacement measurement section is combined with the measurement value of the optical field measurement section to determine the period of the fine measurement, which is then used as a coarse measurement. The combination of fine and coarse measurements achieves absolute precision measurement by the angular displacement sensor. Therefore, the measurement value of the incremental electric field angular displacement measurement section is used twice: firstly, directly as the fine measurement value, and secondly, combined with the measurement value of the optical field measurement section to determine the period of the fine measurement value. The rotor base, stator base, and their excitation and induction electrodes constitute the main body of the incremental electric field angular displacement measurement section, while the reflective pattern and photoelectric sensor constitute the main body of the optical field measurement section. The measurements of these two parts are independent of each other; they are only combined in the algorithm.

[0041] See Figure 1 The excitation electrode 1-1 is composed of 4m rectangular excitation electrodes of the same size and with a spacing of θ1, evenly arranged along the circumference. Every four adjacent excitation electrodes form a group, and the 4m excitation electrodes form m groups; m represents the stator cycle number. The excitation electrodes in the first position of each group are connected together to form excitation phase A, the excitation electrodes in the second position of each group are connected together to form excitation phase B, the excitation electrodes in the third position of each group are connected together to form excitation phase C, and the excitation electrodes in the fourth position of each group are connected together to form excitation phase D. See also... Figure 4 The induction electrode 2-1 consists of 2m identical double sinusoidal electrode plates evenly arranged along the circumference. Each pair of adjacent induction electrodes forms a group, and the 2m induction electrodes form m groups, where m represents the rotor cycle number (i.e., the stator cycle number is the same as the rotor cycle number). The induction electrodes in the first position of each group are connected together to form induction phase A, and the induction electrodes in the second position of each group are connected together to form induction phase B. The excitation module inputs four excitation signals to the four excitation phases of the stator base. These four excitation signals are represented as follows: , , , The mutual movement between the rotor and stator generates an induced traveling wave signal on the induction electrodes on the rotor base. The signal processing circuit amplifies and filters the induced traveling wave signal and the reference signal of the same frequency. After the traveling wave signal and the reference signal are shaped into a square wave by the zero-crossing comparator, the data is output to the embedded processor for high-frequency clock interpolation calculation to obtain the precise measurement value.

[0042] In this invention, photoelectric sensors 1-4 are two sensors located on the same circumference. When the reflective pattern is sinusoidal, the angle formed by the lines connecting the two photoelectric sensors to the center of the stator substrate is equal to 1 / 4 of the circumferential angle of a single reflective pattern; in this case, the functional relationship is a sine or cosine function. When the reflective pattern is triangular, if the angle corresponding to one period of the triangle is θ... x The angle occupied by the photoelectric sensor is θ y The angle formed by the lines connecting the two photoelectric sensors to the center of the stator base is θ. x -θ y At this point, the functional relationship is a linear one. Therefore, the positional relationship, i.e., the distance between the two photoelectric sensors, can be determined.

[0043] Due to the motion properties of the rotor substrate, directly leading signal lines through the induction electrodes would increase design complexity. Therefore, this invention solves this problem by using wireless transmission via signal emission. Specifically, two induction signal transmitting rings 2-2 are arranged on the lower surface of the rotor substrate 2, surrounding the induction electrodes 2-1. Each ring is connected to one of the two induction phases to transmit the induction signals generated by the corresponding phases. The light-absorbing insulating layer 2-3 covers all the induction electrodes 2-1 and the two induction signal transmitting rings 2-2. Two induction signal receiving rings 1-2 are arranged on the upper surface of the stator substrate 1, surrounding the excitation electrodes 1-1. Each receiving ring corresponds to one of the induction signal transmitting rings 2-2, receiving the induction signals transmitted by the corresponding ring. The traveling wave signals received by the two receiving rings are 180° out of phase, forming a differential signal. In specific connection, the odd-numbered induction electrode plates are connected to the inner ring induction signal transmitting ring, and the even-numbered induction electrode plates are connected to the outer ring induction signal transmitting ring. The induction signal receiving ring couples and receives the differential traveling wave signal emitted by the induction signal transmitting ring, and then sends it to the signal processing circuit.

[0044] In the embodiments, such as Figure 1 As shown, the two photoelectric sensors 1-4 are located on the outer ring induction signal receiving ring 1-2.

[0045] The photoelectric sensing part of this invention is further described below, and can also be found in [reference 1]. Figure 2 and Figure 5, the light-absorbing insulating layer covering the rotor substrate induction electrode is a black covering film, the reflective pattern is white, and the area of the reflective pattern has a certain functional relationship with the angular displacement (which can be sinusoidal or triangular). Taking the illustrated triangle as an example, the embedded processor on the stator substrate controls the light source of the photoelectric sensor to emit invisible light with a constant light intensity. The invisible light is reflected back to the receiver of the photoelectric sensor through the rotor reflection pattern. The light intensity received by the receiver of the photoelectric sensor is linearly related to the facing area between the photoelectric sensor and the reflective pattern. There are two photoelectric sensors in the present invention. Through area integration, it can be known that the optical signals collected by the two photoelectric sensors are linearly related to the angle. The collected light intensity signal is converted into a current signal through the circuit processing module. After the current is converted into voltage, amplified, filtered, and ADC amplitude sampled, the collected voltage signal is sent to the embedded processor for processing. Since the collected voltage signal is a triangular wave with a rising section and a falling section, there is a problem that the same voltage signal value cannot be confirmed whether it is in the rising section or the falling section. For this reason, the embedded processor in the present invention reverses the triangular waveform output by one of the photoelectric sensors and makes a periodic judgment with the corresponding triangular waveform of the other photoelectric sensor, so as to convert the trigonometric function into a linearly varying linear displacement signal. This is also the reason for setting two photoelectric sensors. The specific principle can be seen in Figure 6 , the voltage converted by the first photoelectric sensor is U(θ), as shown in Figure 6 the red line in the first group of lines from top to bottom. The reference voltage Vref is the middle level of U(θ). The voltage converted by the second photoelectric sensor is U’(θ), as shown in Figure 6 the blue line in the first group of lines from top to bottom. The voltage value of the second photoelectric sensor is voltage-flipped to Vref-U’(θ), as shown in Figure 6 the second group of lines. Comparing the first group of lines and the second group of lines, it can be seen that the blue in the second group of lines is flipped up and down. When U(θ)<U’(θ), Uo = U(θ); when U’(θ)<U(θ), Uo = U’(θ). Uo is the voltage value output under different conditions; see Figure 6 the third group of lines. When U(θ)>Vref-U’(θ), Uo = , see Figure 6 the fourth group of lines (where is the maximum and minimum values of the output voltage of the photoelectric sensor). Through the above conversion, the triangular wave signal is finally converted into a linearly varying straight line, and the measurement value of the photoelectric sensor can be obtained.

[0046] The angular displacement value θ obtained through the light field measurement part n and the precise measurement value θ mSimilarly, the measurement is periodically changing, making it impossible to determine the exact period of the fine measurement. Therefore, this invention combines the measurements from the incremental electric field angular displacement measurement section with the measurements from the optical field measurement section as a coarse measure to determine the exact period of the fine measurement. The specific principle is as follows, and see also... Figure 7 Let m and n be the period of the incremental electric field angular displacement measurement section and the period of the reflected pattern, respectively, where m and n are coprime and n > m. The total angle of the sensor is 2π. The angular displacement value θ measured by the incremental electric field angular displacement measurement section is... m The angular displacement value θ collected by the photoelectric sensor varies periodically within the range of [0-2π / m]. n It varies periodically within the range [0-2π / n], and the angle difference θ between the two is represented by δ. m - θ n .pass Figure 7 It can be seen that there is no repeated δ value within the entire travel range of 2π, that is, each angle difference δ uniquely corresponds to a cycle number. Therefore, this unique δ value can be used as the absolute positioning sequence value and the cycle number N of the sensor's precise measurement can be determined by looking up a table.

[0047] Although the angular displacement value calculated by the two photoelectric sensors is a linear displacement value with relatively large error, it is only combined with the measurement value of the incremental angular displacement sensor to determine the period of the incremental angular displacement sensor rotor. Therefore, even if the accuracy is not high, it does not affect the accuracy of the period value. The displacement value measured by the incremental electric field angular displacement sensor is a linearly periodically changing displacement value with high accuracy. Therefore, combining the two can yield a high-accuracy absolute angular displacement value.

[0048] The complete signal generation and processing flow of this invention is as follows: Figure 8 As shown, the excitation control module in the FPGA generates four excitation voltage signals U with a 90° phase difference. S+ U C+ U S- U C- (corresponding to the aforementioned U) a U b U c U d The excitation electrode on the stator base of the incremental angular displacement sensor is activated. Under the action of the excitation electrode, the induction electrode on the rotor base senses and outputs a corresponding traveling wave signal. This signal is then output to the signal processing circuit through the transmitting and receiving loops. The signal processing circuit performs corresponding processing on the sensed traveling wave signal and the reference signal of the same frequency, such as amplification, filtering, differential processing, and shaping, to obtain a square wave signal. This square wave signal is then input into the embedded processor for calculation, which yields the angle value θ. mThis is used as the precise measurement value. Simultaneously, the light-emitting control module in the embedded processor controls the light source of the photoelectric sensor to emit a beam of light, which illuminates the reflective pattern on the rotor substrate. The receiver of the photoelectric sensor on the stator substrate collects the reflected light and outputs a photoelectric signal to the signal processing circuit. The signal processing circuit performs corresponding processing, such as amplification, filtering, and analog-to-digital conversion, to obtain the amplitude displacement signal. This amplitude displacement signal is then input to the embedded processor. After demodulating the amplitude displacement value, the angular displacement value of the photoelectric sensor is obtained. This value is then combined with the precise measurement value to determine the period N of the rotor substrate's precise measurement. Finally, combining the precise measurement value with the period value achieves the absolute angle measurement, resulting in the final absolute angular displacement value θ. a = Nθ + θ m θ is the measurement period width, and here θ is 4θ1.

[0049] Compared with existing technologies, this invention employs a two-layer design structure to achieve precise measurement and absolute positioning, resulting in a more compact design and easier miniaturization. The lower layer uses an incremental grating angular displacement sensor to measure precise angle values ​​within a period, achieving high accuracy while maintaining miniaturization. In the upper layer, a photoelectric sensor acquires the pattern amplitude, and through light intensity sampling, circuit processing, and signal demodulation, obtains the angular displacement value of the light field measurement section. This value is then combined with the precise measurement value to obtain the period in which the precise measurement occurs. Combining the precise measurement value with the period (as a coarse measure) enables absolute measurement by the angular displacement sensor. This invention features simple reflective pattern printing, eliminating the need for finely printed patterns to achieve absolute period measurement. Displacement calculation is performed by using the facing area of ​​the reflective pattern and the photoelectric sensor, linearizing the pattern encoding and simplifying encoding and decoding. Furthermore, the two measurement methods do not interfere with each other, ensuring that the number of absolute position periods is obtained without affecting the precise measurement signal.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the applicant has described the present invention in detail with reference to preferred embodiments, those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A photoelectric information fusion reflective absolute angular displacement sensor, characterized in that: The system includes an incremental electric field angular displacement measurement section and an optical field measurement section. The measurement value from the incremental electric field angular displacement measurement section serves as the fine measurement, while the measurement value from the incremental electric field angular displacement measurement section is combined with the measurement value from the optical field measurement section as the coarse measurement to determine the period in which the fine measurement is performed. The combination of the fine measurement and the coarse measurement achieves absolute positioning. The incremental electric field angular displacement measurement section includes a rotor base and a stator base arranged in parallel with a gap. An excitation electrode is uniformly arranged around the circumference of the surface of the stator base facing the rotor base, and an induction electrode is uniformly arranged around the circumference of the surface of the rotor base facing the stator base. The induction electrode on the rotor base is directly opposite the excitation electrode on the stator base. The optical field measurement section includes a photoelectric sensor and a reflective pattern. The photoelectric sensor consists of a light source and a receiver. The device consists of: a ring of identical, interconnected reflective patterns, the number of which is coprime to the number of cycles of the excitation electrodes; the area of ​​each reflective pattern along the circumference is a function of the corresponding angle; a ring-shaped light-absorbing insulating layer, concentric with the rotor base and covering all sensing electrodes, is placed on the surface of the rotor base facing the stator base; the reflective pattern is disposed on and concentric with the light-absorbing insulating layer; a photoelectric sensor is disposed on the surface of the stator base facing the rotor base, facing the reflective pattern; the light source of the photoelectric sensor sends a light beam to the reflective pattern, and the receiver of the photoelectric sensor collects the light intensity reflected by the reflective pattern and outputs the resulting photoelectric signal to the signal processing circuit.

2. The photoelectric information fusion reflective absolute angular displacement sensor according to claim 1, characterized in that: The number of photoelectric sensors is two, and they are located on the same circumference.

3. The photoelectric information fusion reflective absolute angular displacement sensor according to claim 2, characterized in that: The reflective pattern is sinusoidal, and the angle formed by the lines connecting the two photoelectric sensors and the center of the stator substrate is equal to 1 / 4 of the circumference angle of a single reflective pattern; the functional relationship is a sine or cosine function relationship.

4. The photoelectric information fusion reflective absolute angular displacement sensor according to claim 2, characterized in that: The reflective pattern is triangular, and let θ be the angle corresponding to one period of the triangle. x The angle occupied by the photoelectric sensor is θ y The angle formed by the lines connecting the two photoelectric sensors to the center of the stator base is θ. x -θ y The functional relationship is a linear functional relationship.

5. A photoelectric information fusion reflective absolute angular displacement sensor according to claim 1, characterized in that: Two rings of induction signal emitting rings are arranged on the outer ring of the induction electrodes on the surface of the rotor base facing the stator base. The two rings of induction signal emitting rings are respectively connected to the two induction phases formed by the induction electrodes to emit the induction signals generated by the corresponding induction phases. The light-absorbing insulating layer covers all induction electrodes and the two rings of induction signal emitting rings. Two rings of induction signal receiving rings are arranged on the outer ring of the excitation electrodes on the surface of the stator base facing the rotor base. The two rings of induction signal receiving rings correspond one-to-one with the two rings of induction signal emitting rings and are used to receive the induction signals emitted by the corresponding induction signal emitting rings.

6. A photoelectric information fusion reflective absolute angular displacement sensor according to claim 5, characterized in that: The photoelectric sensor is located on one of the sensing signal receiving loops.

7. A photoelectric information fusion reflective absolute angular displacement sensor according to claim 1, characterized in that: The excitation electrode consists of 4m rectangular excitation electrodes of the same size with an electrode spacing of θ1, evenly arranged along the circumference. Each group consists of four adjacent excitation electrodes, and the 4m excitation electrodes form m groups. The excitation electrodes in the first position of each group are connected together to form excitation phase A, the excitation electrodes in the second position of each group are connected together to form excitation phase B, the excitation electrodes in the third position of each group are connected together to form excitation phase C, and the excitation electrodes in the fourth position of each group are connected together to form excitation phase D. The induction electrode consists of 2m double sinusoidal electrodes of the same size with an electrode spacing of 2θ1, evenly arranged along the circumference. Each group consists of two adjacent induction electrodes, and the 2m induction electrodes form m groups. The induction electrodes in the first position of each group are connected together to form induction phase A, and the induction electrodes in the second position of each group are connected together to form induction phase B.

8. The measurement method of a photoelectric information fusion reflective absolute angular displacement sensor as described in claim 2, characterized in that: The steps are as follows: 1) Incremental electric field angular displacement measurement: An excitation signal is applied to the excitation electrode. Under the action of the excitation electrode, the induction electrode outputs a corresponding traveling wave signal. The signal processing circuit processes the induction traveling wave signal and the reference signal of the same frequency accordingly to obtain a square wave signal. Then, the angular displacement value θ is calculated. m And used as a precise measurement value; 2) Light Field Measurement Section: The light source of the photoelectric sensor emits a beam of light and illuminates the reflective pattern. The receivers of the two photoelectric sensors respectively collect the corresponding reflected light and output photoelectric signals to the signal processing circuit. After processing by the signal processing circuit, the angular displacement value θ of the light field measurement section is obtained. n ; 3) Coarse measurement to determine the period of fine measurement: Assume the period numbers of the excitation electrode and the reflective pattern are m and n, respectively, m and n are coprime and n > m, the total angle of the sensor is 2π, and the angular displacement value θ measured by the incremental electric field angular displacement measurement section is... m The angular displacement θ, which varies periodically within the range of [0-2π / m], is measured by the optical field measurement section. n It varies periodically within the range [0-2π / n], and the angle difference between the two is represented by δ, where δ = θ. m - θ n The number of cycles N in the incremental electric field angular displacement measurement section is determined by using the δ value as the absolute positioning sequence value. 4) Calculate the absolute angular displacement value: Calculate the precise measurement value θ obtained in step 1). m Combining the number of periods N obtained in step 3) yields the final absolute angular displacement value θ. a = Nθ + θ m θ represents the period width of the incremental electric field angular displacement measurement section.

9. The measurement method according to claim 8, characterized in that: The light source of the photoelectric sensor emits invisible light.

10. The measurement method according to claim 8, characterized in that: The angular displacement value θ of the light field measurement part n is obtained by the following method. Let the voltage after conversion by the first photoelectric sensor be U(θ), the reference voltage Vref be the middle level of U(θ), and the voltage after conversion by the second photoelectric sensor be U’(θ). The voltage value of the second photoelectric sensor is voltage-inverted to Vref - U’(θ). When U(θ) < U’(θ), Uo = U(θ); when U’(θ) < U(θ), Uo = U’(θ). Uo is the voltage value output under different conditions; When U(θ)>Vref-U'(θ), Uo= ,in These are the maximum and minimum values ​​of the output voltage of the photoelectric sensor; This integrates the triangular wave signals collected by the two photoelectric sensors and converts them into a linearly changing displacement signal, thereby obtaining the displacement value measured by the optical field measurement section.

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