CN115597637A - Photoelectric encoder and absolute angle measurement method - Google Patents

Abstract

The embodiment of the application discloses a photoelectric encoder and an absolute angle measuring method, wherein the photoelectric encoder comprises an optical collimating device, an absolute grating code disc, an optical imaging device and a linear array CCD processing module; the optical collimating device is used for collimating the optical signals emitted by the light source so that the optical signals are uniformly irradiated on the absolute grating code disc to form a coding pattern with absolute angle information; the optical imaging device is used for amplifying the coding pattern; the linear array CCD processing module is used for collecting the amplified coding pattern, obtaining coding information through photoelectric conversion, and decoding the coding information to obtain an absolute angle value. According to the embodiment of the application, the single-code-channel absolute position coding based on the M sequence is adopted for the absolute grating code disc, so that the defects that the number of code channels is increased along with the improvement of the precision and the realization is difficult in process in the traditional position coding are overcome, the absolute angle measurement precision is improved, the size of a photoelectric encoder is reduced, and the production cost is saved.

Description

Photoelectric encoder and absolute angle measurement method

Technical Field

The application relates to the field of precise surveying and mapping instruments, in particular to a photoelectric encoder and an absolute angle measuring method.

Background

The photoelectric encoder uses a high-precision measuring circular grating as a core component, and converts the geometric displacement on an output shaft into a pulse or digital quantity through photoelectric conversion. The encoders of the present measuring devices are various in type, and can be classified into an incremental type and an absolute type according to the working principle of the encoders. The absolute angle measurement mode is different from the incremental angle measurement mode, and the current absolute angle position can be directly obtained by electrifying and starting. The absolute angle measuring device is convenient, reliable and quick to obtain the current angle value, and overcomes the difficulty that zero degree needs to be recalibrated after the equipment is powered off. All kinds of encoders have advantages and disadvantages, and generally, high precision, high resolution, high frequency response, miniaturization and intellectualization are development trends of the encoders, but the problems that the detection period is long, the efficiency is low, the error is large, the detection result can only reflect local characteristics of the encoders and the like still exist.

Disclosure of Invention

In a first aspect, the present invention provides a photoelectric encoder, which includes an optical collimating device, an absolute grating code disc, an optical imaging device and a linear array CCD processing module;

the optical collimating device is used for collimating optical signals emitted by a light source so that the optical signals are uniformly irradiated on the absolute grating code disc to form a coding pattern with absolute angle information;

the optical imaging device is used for amplifying the coding pattern;

the linear array CCD processing module is used for collecting the amplified coding pattern, obtaining coding information through photoelectric conversion, and decoding the coding information to obtain an absolute angle value.

In an optional embodiment, the absolute grating code disc is movably arranged on a fixed rod, and the fixed rod is used as a rotation center;

and the linear array CCD processing module is also used for calculating an eccentric error if the circle center of the absolute grating code disc is not on the same axis with the rotation center, and correcting the absolute angle value according to the eccentric error.

In an alternative embodiment, the calculating the eccentricity error comprises:

calculating the distance between the circle center and the rotation center as an eccentricity value;

and calculating the eccentricity error according to the eccentricity value, the radius of the absolute grating code disc and the theoretical rotation angle.

In an alternative embodiment, the correcting the absolute angle value according to the eccentricity error includes:

establishing an eccentric parameter measurement model;

calculating an eccentricity parameter fitting value based on the eccentricity parameter measurement model;

and correcting the eccentricity error according to the eccentricity parameter fitting value.

In an optional embodiment, the absolute grating code disc is provided with a zero-degree groove, and a pair of photoelectric detection devices are respectively arranged in the radial direction and used for reading a rotation angle;

the establishing of the eccentricity parameter measurement model comprises the following steps:

calculating actual rotation angles between the two photoelectric detection devices and the zero-degree reticle relative to the rotation center respectively to obtain a first rotation angle and a second rotation angle;

respectively reading the rotation angles, relative to the circle center, between the photoelectric detection devices and the zero-degree reticle detected by the two photoelectric detection devices to obtain a first reading angle and a second reading angle;

calculating a first included angle of the two photoelectric detection devices compared with the rotation center;

calculating a second included angle between the zero degree reticle and the circle center compared with the rotation center;

and establishing an eccentric parameter measurement model according to the first reading angle, the second reading angle, the first included angle and the second included angle.

In an alternative embodiment, the correcting the eccentricity error according to the eccentricity parameter fit value includes:

calculating to obtain a corrected absolute angle value according to a preset eccentric error compensation model and the eccentric parameter fitting value;

the eccentricity error compensation model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

In an alternative embodiment, if the first rotation angle is within a range (0 °,180 °), the second rotation angle is within a range (180 °,360 °); the eccentricity parameter measurement model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

In an alternative embodiment, if the first rotation angle is within the interval (180 °,360 °), the second rotation angle is within the interval (0 °,180 °); the eccentricity parameter measurement model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

In an optional embodiment, the photoelectric encoder further comprises a light source, wherein the light source is a light emitting diode array composed of at least four LED light sources;

the optical collimating device selects a collimating focusing lens;

the absolute grating code disc adopts M-sequence coding;

the optical imaging device adopts an imaging lens.

In a second aspect, the present invention provides an absolute angle measurement method applied to the photoelectric encoder as described above, the method including:

collimating an optical signal emitted by a light source to enable the optical signal to uniformly irradiate an absolute grating code disc so as to form a coding pattern with absolute angle information;

magnifying the coding pattern;

and acquiring the amplified coding pattern, performing photoelectric conversion to obtain coding information, and decoding the coding information to obtain an absolute angle value.

The embodiment of the application has the following beneficial effects:

according to the embodiment of the application, the light source is irradiated on the absolute grating code disc, the corresponding code pattern is read through the linear array CCD processing module, and the measured absolute angle value is obtained after the code pattern is decoded. In the process, an optical collimating device is also adopted to collimate the light emitted by the light source, so that the light irradiated on the grating code disc is uniform, and the reliability of absolute angle measurement is facilitated; and the absolute grating code disc overcomes the defects that the code channels are increased along with the improvement of the precision and the realization is difficult in the process of the traditional position coding through the single-code-channel absolute position coding based on the M sequence, not only improves the absolute angle measurement precision, but also reduces the size of the photoelectric encoder and saves the production cost.

Drawings

To more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope of the present application. Like components are numbered similarly in the various figures.

FIG. 1 is a schematic diagram illustrating a first structure of an optical encoder according to an embodiment of the present application;

FIG. 2a is a schematic diagram illustrating a second structure of an optical encoder according to an embodiment of the present application;

FIG. 2b is a schematic diagram illustrating a third structure of the optical-electrical encoder according to the embodiment of the present application;

FIG. 3 is a diagram illustrating a fourth exemplary structure of an optical encoder according to an embodiment of the present application;

FIG. 4 shows a schematic structural diagram of an absolute grating code wheel according to an embodiment of the present application;

fig. 5 shows a schematic structural diagram of a linear array CCD processing module according to an embodiment of the present application;

fig. 6 is a schematic display screen diagram of an upper computer according to an embodiment of the present application;

FIG. 7 is a first schematic diagram of an eccentric error theoretical model according to an embodiment of the present application;

FIG. 8 is a second schematic diagram of an eccentric error theoretical model according to an embodiment of the present application;

FIG. 9 is a third schematic diagram of an eccentric error theoretical model according to an embodiment of the present application;

fig. 10 shows a schematic diagram of an implementation of the absolute angle measurement method according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments.

The components of the embodiments of the present application, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.

Hereinafter, the terms "including", "having", and their derivatives, which may be used in various embodiments of the present application, are intended to indicate only specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be construed as first excluding the existence of, or adding to, one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.

Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present application belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments.

A CCD (Charge coupled Device), a Charge coupled Device, which may be referred to as a CCD image sensor; a CCD is a semiconductor device having a plurality of capacitors arranged in order to sense light and convert an optical image into an electrical signal.

Examples

The present embodiment provides a photoelectric encoder, which will be described in detail below.

Referring to fig. 1, fig. 2a and fig. 2b, the present application provides a photoelectric encoder, which includes an optical collimating device 10, an absolute grating code wheel 20, an optical imaging device 30 and a linear array CCD processing module 40.

Exemplarily, the optical collimating device 10 is configured to collimate an optical signal emitted by a light source, so that the optical signal is uniformly irradiated on an absolute grating code disc 20 (hereinafter, may be referred to as a code disc), thereby forming a code pattern with absolute angle information; the optical imaging device 30 is used to magnify the coding pattern; the linear array CCD processing module 40 is used for collecting the amplified coded pattern, and obtaining coded information existing in the form of an electrical signal through photoelectric conversion, and decoding the coded information to obtain an absolute angle value.

In one embodiment, the light source adopts a light emitting diode array consisting of at least four LED light sources, so that the problem that the forming of a coding pattern and the measurement accuracy of absolute angle values are influenced due to the fact that the light spot area and the luminous intensity are limited and are caused by a single LED light source is avoided.

Specifically, light emitted by the light source is collimated by the optical collimating device 10 to form parallel light, and when the parallel light passes through the absolute code channels based on M-sequence encoding arranged on the absolute grating code disk 20, light-transmitting and light-non-transmitting portions are arranged on each code channel according to a certain rule, so that light-transmitting and light-non-transmitting light and dark stripe patterns, i.e., encoding patterns, are formed. The optical imaging device 30 images and amplifies the coding pattern, and the linear array CCD processing module 40 decodes the amplified coding pattern to obtain the absolute angle position corresponding to the absolute grating code disc 20.

Further, after the optical collimating device 10 collimates the light emitted from the light source, the light uniformly irradiates the absolute grating code disc 20, so as to form a code pattern capable of accurately reflecting the absolute angle information, thereby improving the energy utilization rate of the light source and the reliability of the absolute angle measurement. For example, the optical collimating device 10 may be a collimating and focusing lens.

As shown in fig. 3, the absolute grating code disc 20 is movably disposed on a fixed rod, for example, the absolute grating code disc 20 is mounted on a metal rod by a bolt. And the fixed rod is used as a rotation center, the absolute grating code wheel 20 can rotate around the rotation center, and the rotation center is generally set to be on the same axis with the center of the absolute grating code wheel 20. The absolute grating code disc 20 adopts M sequence coding which is absolute angle coding and has a pseudo-random characteristic, and adopts an absolute coding mode, so that no accumulated error exists, the photoelectric encoder does not lose position information after power failure, the resolution ratio is high, the design of the absolute coding depends on a linear feedback shift register in the photoelectric encoder, the size of the photoelectric encoder is reduced, and the measurement precision is ensured to be unchanged while the size of the encoder is reduced; and the single-code-channel absolute position coding based on the M sequence overcomes the defects that the traditional position coding increases the number of code channels along with the improvement of the precision and is difficult to realize in the process, so that the single-code-channel photoelectric encoder is more miniaturized.

Further, as shown in fig. 4, the absolute track is engraved on the glass surface of the absolute grating code disc 20, and is irradiated by a light source to form a code pattern with absolute angle information and alternate light and dark. Then, the encoding pattern is collected by the linear array CCD processing module 40.

As shown in fig. 5, the line CCD processing module 40 includes a line CCD sensor 41, an analog-to-digital conversion unit 42, and a signal processing unit 43; the linear array CCD sensor 41 is used for receiving the coding pattern and converting the coding pattern into a corresponding voltage signal (analog signal); the analog-to-digital conversion unit 42 is configured to convert the voltage signal corresponding to the encoding pattern into a digital signal carrying encoded information; the signal processing unit 43 is configured to decode the encoded information to obtain an absolute angle value. The analog-to-digital conversion unit 42 inputs the digital signal carrying the encoded information to the signal processing unit 43 for decoding, so as to obtain an absolute angle value. In addition, as shown in fig. 6, the line CCD processing module 40 also visually displays the waveform diagram of the code pattern and the absolute angle value obtained after decoding on the connected upper computer. Therefore, after the light source irradiates the code disc, the code disc is received by the photoelectric element behind the code disc, the absolute angle value can be directly displayed after processing, and the absolute angle value is output in a digital form, so that the angle position information can be directly read out.

Specifically, when the photoelectric encoder works, light is projected on the absolute grating code wheel 20, the code wheel rotates along with the metal rod, the light passing through the light-transmitting part of the code wheel passes through the optical imaging device 30 and is received by the linear array CCD processing module 40, the signals output by the photosensitive elements corresponding to the light-transmitting part and the light-tight part of the code wheel are "1" and "0" respectively, when the code wheel rotates at different positions, the combination of the signals output by the photosensitive elements reflects a certain regular digital quantity representing the angular displacement of the axis of the code wheel, i.e. the analog signal output by the photosensitive elements is converted into a digital signal by the analog-to-digital conversion unit 42, and then the encoded information in the digital signal can be decoded by the signal processing unit 43 to obtain the corresponding absolute angle value.

The photoelectric encoder provided by the embodiment has the advantages that the sensing detection element (such as an absolute grating code disc) and the photosensitive element output signal circuit (such as a linear array CCD processing module) are packaged together on the circuit structure, the anti-interference capability is strong during angle and position measurement, the capability of reliably and stably outputting pulse signals is realized, and the absolute angle measurement precision is further improved.

In one embodiment, if the absolute grating code wheel 20 is fixed on the metal rod 50 by a bolt, the metal rod 50 and the center of the code wheel are not located on the same axis, that is, the center of the metal rod and the center of rotation are not located on the same axis, and when the code wheel rotates along with the metal rod 50, a certain eccentricity error exists according to the absolute angle value decoded by the rotated code pattern. If the deviation degree between the circle center and the rotation center is larger, the eccentric error of the circle center and the rotation center is larger, and the accuracy of absolute angle value measurement is further reduced, so that the eccentric error which may exist needs to be compensated.

In this embodiment, the linear array CCD processing module 40 is further configured to calculate an eccentricity error if the center of the absolute grating code wheel 20 is not on the same axis as the rotation center, and correct the absolute angle value according to the eccentricity error. Specifically, an eccentricity value may be calculated according to the positions of the center of the circle and the rotation center, and an eccentricity error may be calculated according to the eccentricity value, the radius of the absolute grating code disk 20, and a preset theoretical rotation angle, so that the absolute angle value may be corrected according to the eccentricity error.

In one embodiment, the eccentricity error is corrected by establishing an eccentricity parameter measurement model to calculate an eccentricity parameter fit value according to the eccentricity parameter measurement model and correcting the eccentricity error according to the eccentricity parameter fit value. The absolute grating code disc 20 is provided with a zero-degree groove, and a pair of radial directions are respectively provided with a photoelectric detection device, and the photoelectric detection device is used for reading the rotation angle of the code disc, namely reading the coded information. Furthermore, an eccentricity parameter measurement model can be established according to the position of the circle center and the rotation center, the read rotation angle, the radius of the absolute grating code disc 20 and other information. Specifically, actual reading angles between the photoelectric detection devices detected by the two photoelectric detection devices and the zero-degree reticle relative to the circle center are respectively read to obtain a first reading angle and a second reading angle; calculating a first included angle between the two photoelectric detection devices and the rotation center; calculating a second included angle between the zero degree reticle and the circle center and compared with the rotation center; and establishing an eccentric parameter measurement model according to the first reading angle, the second reading angle, the first included angle and the second included angle.

Further, referring to fig. 7, a circle center O is a circle center of the code wheel, i.e., a theoretical rotation center, O ' is an actual rotation center, d is an eccentricity value, θ is a theoretical rotation angle, and θ ' is an actually measured rotation angle, so that it can be known that an angle measurement error caused by eccentricity is Δ θ = θ ' - θ, and an actually measured rotation angle value can be obtained from the geometric relationship and the trigonometric function in fig. 8, so that an eccentricity error Δ θ can be obtained as follows:

calculating the eccentricity value (d) and the eccentricity direction (the direction of the rotating center deviating from the center of a circle, such as the horizontal deviation direction and the vertical deviation direction), establishing an eccentricity parameter measurement model by adopting an eccentricity adjustment method and a diameter reading method, and eliminating and compensating the eccentricity error.

Taking the horizontal deviation of the rotation center as an example, as shown in fig. 8 and 9, O' is the center of the circular grating code disk, and O is the actual rotation center, and the corresponding eccentric directions in both cases are the same and are both horizontal deviation directions. The point B is a zero degree scale line, and if the zero degree scale line is at different positions, the corresponding measured angle values are different. A1 and A2 are two photoelectric detectors respectively arranged in the radial direction of a circular grating code disc and used for reading absolute angle values; the angle A1OB and the angle A2OB (the angle A2OB is more than 180 degrees) are actual rotation angles and are respectively recorded as A1 and A2 (a first rotation angle and a second rotation angle); an angle A1O ' B and an angle A2O ' B (angle A2O ' B is more than 180 DEG) are actual reading angles (a first reading angle and a second reading angle), namely the angle values read by the photoelectric detection device and are respectively recorded as A1' and A2'; an included angle between the two photoelectric detection devices relative to a rotation center is marked as gamma (a first included angle), and an angle BO 'O is marked as delta (a second included angle), and for the convenience of calculation, the angle OBO', 'OA 1O' and 'OA 2O' are respectively marked as a, b and c. Dividing the actual rotation angles A1, A2 by 180 °, there are four cases:

1. 0 ° < A1<180 ° and 180 ° < A2<360 °;

2. 180 ° < A1<360 ° and 0 ° < A2<180 °;

3. 0 ° < A1<180 ° and 0 ° < A2<180 °;

4. 180 ° < A1<360 ° and 180 ° < A2<360 °.

Since both cases 3 and 4 are independent of the eccentricity direction, only both cases 1 and 2 need to be analyzed. And deducing to obtain an eccentric parameter measurement model according to the two conditions, fitting the eccentric parameters through a plurality of groups of values obtained by measuring the eccentric parameter measurement model to obtain eccentric parameter fitting values (d, delta), and substituting the eccentric parameter fitting values into a preset eccentric error compensation model to compensate the eccentric error.

Further, for the case of 0 ° < A1<180 ° and 180 ° < A2<360 ° as shown in fig. 8, the eccentricity parameter measurement model can be derived from sine theorem and triangle interior angles and formula as:

for the cases of 180 ° < A1<360 ° and 0 ° < A2<180 ° as shown in fig. 9, the same can be deduced for the eccentricity parameter measurement model as:

according to the eccentric parameter measurement models under different conditions, fitting can be performed for multiple times to obtain eccentric parameter fitting values (d, delta), the eccentric parameter fitting values (d, delta) are substituted into the following eccentric error compensation model, and the angle value obtained after eccentric error compensation is as follows:

by the eccentric error compensation, the eccentric error can be effectively reduced, and the measurement precision and the reliability of a measurement result are improved, so that the high-precision measurement of the absolute angle value is realized.

In the photoelectric encoder provided by this embodiment, a light source is irradiated onto a grating code disc, a linear array CCD processing module (photoelectric detection device) is used to read corresponding code information, i.e., a code pattern, and the code pattern is decoded to obtain a measured absolute angle value. On the first hand, the light emitted by the light source is collimated by the optical collimating device, so that the light irradiated on the grating code disc is uniform, and the reliability of absolute angle measurement is facilitated; in the second aspect, the defects that the number of code channels is increased along with the improvement of the precision and the realization is difficult in the process of the traditional position coding are overcome by the single-code-channel absolute position coding based on the M sequence, so that the absolute angle measurement precision is improved, the size of a photoelectric encoder is reduced, and the production cost is saved; and in the third aspect, an eccentricity error compensation model is constructed for the eccentricity error between the rotating center and the circle center of the code disc possibly caused in the actual installation process of the absolute grating code disc so as to compensate the measured absolute angle value, so that the accuracy and the reliability of the absolute angle value are improved.

Referring to fig. 10, the present embodiment provides an absolute angle measurement method applied to the above-mentioned optical encoder for absolute angle measurement, including:

s100, collimating the optical signal emitted by the light source to enable the optical signal to uniformly irradiate the absolute grating code disc, and further forming a coding pattern with absolute angle information.

S200, amplifying the coding pattern.

S300, collecting the amplified coding pattern, performing photoelectric conversion to obtain coding information, and decoding the coding information to obtain an absolute angle value.

By adopting the photoelectric encoder of the embodiment, the light emitted by the light source is collimated, so that the light irradiated on the grating code disc of the photoelectric encoder is uniform, and the reliability of the absolute angle value measured subsequently is facilitated.

The absolute code channel is engraved on the glass surface of the grating code disc, and forms a code pattern with absolute angle information and alternating light and dark through light source irradiation, and the code pattern is imaged after being amplified; and performing photoelectric conversion on the coding pattern to obtain coding information, and performing decoding processing on the coding information through the inside of a photoelectric encoder to obtain an absolute angle value corresponding to the coding pattern.

It is to be understood that the photoelectric encoder to which the method provided by the embodiment of the present application is applied is the photoelectric encoder described in the above embodiment, that is, any optional items in the photoelectric encoder provided by the above embodiment are also applicable to the method of the embodiment of the present application.

In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The apparatus embodiments described above are merely illustrative and, for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

In addition, each functional module or unit in each embodiment of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a smart phone, a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk, and various media capable of storing program codes.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application.

Claims (10)

1. A photoelectric encoder is characterized by comprising an optical collimating device, an absolute grating code disc, an optical imaging device and a linear array CCD processing module;

the optical collimating device is used for collimating optical signals emitted by a light source so that the optical signals are uniformly irradiated on the absolute grating code disc to form a coding pattern with absolute angle information;

the optical imaging device is used for amplifying the coding pattern;

the linear array CCD processing module is used for collecting the amplified coding pattern, obtaining coding information through photoelectric conversion, and decoding the coding information to obtain an absolute angle value.

2. The optical encoder as claimed in claim 1, wherein the absolute grating code disc is movably disposed on a fixed bar, the fixed bar being used as a rotation center;

and the linear array CCD processing module is also used for calculating an eccentric error if the circle center of the absolute grating code disc is not on the same axis with the rotation center, and correcting the absolute angle value according to the eccentric error.

3. The optoelectronic encoder of claim 2, wherein the calculating the eccentricity error comprises:

calculating the distance between the circle center and the rotation center as an eccentricity value;

and calculating the eccentricity error according to the eccentricity value, the radius of the absolute grating code disc and the theoretical rotation angle.

4. The optical-electrical encoder of claim 2, wherein the correcting the absolute angular value according to the eccentricity error comprises:

establishing an eccentric parameter measurement model;

calculating an eccentricity parameter fitting value based on the eccentricity parameter measurement model;

and correcting the eccentricity error according to the eccentricity parameter fitting value.

5. The optical encoder as claimed in claim 4, wherein the absolute grating code disc is provided with zero degree grooves and a pair of radial photo-detection devices are respectively provided with one photo-detection device for reading the rotation angle;

the establishing of the eccentricity parameter measurement model comprises the following steps:

calculating actual rotation angles between the two photoelectric detection devices and the zero-degree reticle relative to the rotation center respectively to obtain a first rotation angle and a second rotation angle;

respectively reading the rotation angles, relative to the circle center, between the photoelectric detection devices and the zero-degree reticle detected by the two photoelectric detection devices to obtain a first reading angle and a second reading angle;

calculating a first included angle of the two photoelectric detection devices compared with the rotation center;

calculating a second included angle between the zero degree reticle and the circle center compared with the rotation center;

and establishing an eccentric parameter measurement model according to the first reading angle, the second reading angle, the first included angle and the second included angle.

6. The optical encoder of claim 5, wherein the correcting the eccentricity error according to the eccentricity parameter fit value comprises:

calculating to obtain a corrected absolute angle value according to a preset eccentric error compensation model and the eccentric parameter fitting value;

the eccentricity error compensation model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

7. The optical encoder as claimed in claim 5, wherein if the first rotation angle is within a range (0 °,180 °), the second rotation angle is within a range (180 °,360 °); the eccentricity parameter measurement model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

8. The optical encoder according to claim 5, wherein if the first rotation angle is within a range (180 °,360 °), the second rotation angle is within a range (0 °,180 °); the eccentricity parameter measurement model is as follows:

wherein, A1 'is the first reading angle, A2' is the second reading angle, γ is the first included angle, d is a difference between the circle center and the rotation center, R is a radius of the absolute grating code disc, and δ is the second included angle.

9. The optical encoder according to claim 1, further comprising a light source, wherein the light source is a light emitting diode array of at least four LED light sources;

the optical collimating device is a collimating and focusing lens;

the absolute grating code disc adopts M-sequence coding;

the optical imaging device adopts an imaging lens.

10. An absolute angle measurement method applied to the photoelectric encoder according to any one of claims 1 to 9, the method comprising:

collimating an optical signal emitted by a light source to enable the optical signal to uniformly irradiate an absolute grating code disc so as to form a coding pattern with absolute angle information;

magnifying the coding pattern;

and acquiring the amplified coding pattern, performing photoelectric conversion to obtain coding information, and decoding the coding information to obtain an absolute angle value.

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