Position detection method for multi-code-channel absolute encoder

Abstract

The invention provides a method for detecting the position of a multi-code-channel absolute encoder. The multi-code-channel absolute encoder position detection method is characterized in that an incremental signal (1), a single-period subdivision position (2), an absolute position (3) and an absolute subdivision position (4) are included, wherein the absolute position (3) is composed of a credible interval (301) and an uncertain interval (302). Firstly, an incremental signal (1) is composed of periodic AB signals detected by an encoder, then a periodic incremental subdivision phase signal phi is calculated and subdivided from the AB periodic signals, a single-period subdivision position (2) is obtained through calculation, and meanwhile, the encoder calculates an absolute position (3) of a system at the moment from an absolute code channel; a trusted interval (301) of the absolute position (3) is determined from the incremental phase signal phi, and finally an absolute subdivision position (4) is obtained after fusion correction. The method can be used for high-precision absolute position measurement, and can be widely applied to the fields of industrial automation, robot technology, aerospace, precision measurement, positioning control and the like.

Description

(1) Technical field

[0001] The present invention relates to a multi-channel absolute encoder position detection method, which can be used in the fields of industrial automation, robotics, aerospace, precision measurement and positioning control, and belongs to the field of precision measurement technology. (2) Background technology

[0002] Absolute encoders achieve high-resolution measurement through the coordinated encoding of coarse and fine channels. The coarse channel, based on coding principles such as Gray code and pseudo-random sequences (such as m-sequences), allows absolute position measurement without the need for a zero return operation, eliminating cumulative errors and protecting data from power failures. The fine channel provides a periodic simple harmonic signal for precise relative displacement measurement. Therefore, absolute encoders offer advantages such as constant absolute position detection, robustness against power failures, zero cumulative errors, high precision, and high resolution.

[0003] Multi-channel absolute encoders use optical, magnetic or capacitive sensing technology to generate unique position codes through multiple independent channels (each channel has transparent / opaque areas or magnetic field / capacitance changes with different arrangements). The multi-channel design can achieve high resolution (such as micron-level accuracy for photoelectric types) and has better resistance to vibration interference than incremental encoders. However, the code disk of the multi-channel encoder needs to ensure strict synchronization between channels and has high requirements for line accuracy, resulting in lower yield and robustness than incremental encoders. Generally, anomalies in the fine code channel cause a decrease in accuracy performance, but will not affect the system function. However, when the coarse code is abnormal, the system function and performance will be seriously affected. In response to the shortcomings of the prior art, the present invention proposes a multi-channel absolute encoder position detection method, which adopts multi-channel grating encoding and decoding technology to realize absolute position identification, without cumulative error, and realizes high-resolution absolute position detection, effectively improving the reliability of absolute position detection. (3) Summary of the invention

[0004] The present invention aims to provide a multi-channel absolute encoder position detection method. The method is characterized in that: the multi-channel absolute encoder position detection method comprises an incremental signal (1), a single-cycle subdivision position (2), an absolute position (3), and an absolute subdivision position (4), wherein the absolute position (3) comprises a credible interval (301) and an uncertain interval (302);

[0005] The object of the present invention is achieved like this: Obtaining the periodic incremental signal generated by the encoder (1); A single-cycle subdivision position (2) is obtained by calculating and subdividing the incremental signal (1), wherein the single-cycle subdivision position (2) includes a periodic incremental phase signal Φ; Synchronously acquiring an absolute position (3) outputted by an absolute code channel of an encoder, wherein the absolute position (3) includes a credible interval (301) and an uncertainty interval (302); Determining the boundary range of the credible interval (301) in the absolute position (3) based on the dynamic change characteristics of the incremental subdivision phase signal Φ; The single-cycle subdivision position (2) is corrected for position matching by using a credible interval (301), and the absolute subdivision position (4) is generated by fusion. (Further details and explanations are given below, including other claims and their details)

[0006] The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code track.

[0007] The method of calculating and subdividing to obtain a single-cycle subdivision position (2) specifically includes: performing interpolation processing on the AB orthogonal pulse signal to obtain a phase angle Φ by an inverse tangent operation; mapping the phase angle Φ to a continuous phase value in the range of 0 to 2π; and converting the phase value into a linear displacement according to a mechanical transmission ratio.

[0008] The single-cycle subdivision position (2) includes a periodic incremental phase signal Φ subdivision method including: hardware-level subdivision methods such as quadruple frequency technology utilizing the 90° phase difference characteristic of the A / B two-phase signal, phase-locked loop subdivision, resistor chain and space subdivision; digital signal processing subdivision methods such as sine / cosine signal interpolation, inverse tangent method, and subdivision using a high-precision time measurement chip after converting the moving signal into a time domain signal; and hybrid subdivision methods such as using an analog front end (differential amplification + bandpass filtering) to pre-process the signal and then implementing real-time orthogonal decoding and error correction through FPGA.

[0009] The method for determining the credible interval (301) of the absolute position (3) includes: Based on the threshold determination of the differential value of the incremental subdivision phase signal Φ, when the phase signal Φ is in a preset stable change range, it is determined that the current absolute position code channel signal is in a reliable state; When it is detected that the phase signal Φ has a jump or is not within the preset stable change range, a tolerance range set before and after the jump point is marked as an uncertain interval (302).

[0010] The credible interval (301) of the absolute position (3) covers the entire period: The absolute position (3) includes at least two groups of absolute position signal groups with phases staggered from each other, such as (310), (320), etc.; According to the value of the current incremental phase Φ, the absolute position signal with the highest credibility from the absolute position signal groups (310), (320), etc. is selected as a candidate signal (300); The respective credible intervals of the absolute position signal groups such as (310) and (320) are superimposed to cover the entire incremental subdivision phase signal Φ, ensuring that the candidate signal (300) has a credible interval (301) within the entire cycle range;

[0011] Optionally, the phase interval of the absolute position signal groups (310) and (320) is 1 / N of the encoder increment period, where N is the number of absolute position groups of the absolute code channel and N≥2, and the credible interval coverage range of each signal group is at least 2π / N phase angle.

[0012] The calculation of the candidate signal (300) is implemented by adopting a credibility judgment algorithm: according to the value of the current incremental phase Φ, the candidate signal is obtained after excluding the absolute position signal group in the uncertain interval, and the absolute position of the candidate signal (300) is selected and verified by adopting a credibility comparison algorithm, and the calculated output result is a credible signal (301).

[0013] The fusion generation of absolute subdivision positions (4) specifically includes: Establishing an absolute position reference point at an absolute position (3) within a credible interval (301); The absolute position reference is compensated for the differential amount by the continuous phase value of the single-cycle subdivision position (2); When entering the uncertainty interval (302), the inertial prediction algorithm is used to maintain position continuity until the next credible interval appears.

[0014] A dynamic calibration step is also included: In the overlapping area of the continuous credible intervals (301), the deviation between the absolute position measurement value and the incremental cycle count integral value is compared; When the deviation exceeds the preset threshold, a position calibration signal is triggered and the accumulated error is corrected. (IV) Description of the accompanying drawings

[0015] Figure 1The present invention is a schematic diagram of a multi-channel absolute encoder position detection method. The multi-channel absolute encoder position detection method is composed of an incremental signal (1), a single-cycle subdivision position (2), an absolute position (3), and an absolute subdivision position (4), wherein the absolute position (3) is composed of a credible interval (301) and an uncertain interval (302). First, the incremental signal (1) is composed of a periodic AB signal detected by the encoder. Second, a periodic incremental subdivision phase signal Φ is calculated and subdivided from the AB periodic signal to obtain the single-cycle subdivision position (2). At the same time, the encoder calculates the absolute position (3) of the system at this time from the absolute channel, and determines the credible interval (301) of the absolute position (3) from the incremental phase signal Φ. An absolute position reference point is established at the absolute position (3) within the credible interval (301), and the absolute position reference is compensated for by a differential amount through the single-cycle subdivision position (2); when entering the uncertain interval (302), an inertia prediction algorithm is used to maintain position continuity until the next credible interval appears. Finally, the absolute subdivision position (4) is obtained after fusion and correction.

[0016] Figure 2 The present invention is a schematic diagram of a multi-channel absolute encoder position detection method. The multi-channel absolute encoder position detection method comprises an incremental signal (1), a single-cycle subdivision position (2), an absolute position (3), and an absolute subdivision position (4). First, the incremental signal (1) is composed of a periodic AB signal detected by the encoder. Second, a periodic incremental subdivision phase signal Φ is calculated and subdivided from the AB periodic signal to obtain the single-cycle subdivision position (2). At the same time, the encoder calculates the absolute position (3) of the system at this time from the absolute channel, wherein the absolute position (3) includes at least two groups of absolute position signal groups with mutually staggered phases, such as (310) and (320). According to the value of the current incremental phase Φ, the absolute position signal with the highest credibility from the absolute position signal groups (310) and (320) is selected as the candidate signal (300); the credibility intervals of the absolute position signal groups (310) and (320) are superimposed to cover the entire incremental subdivision phase signal Φ, ensuring that the candidate signal (300) has a credibility interval (301) within the entire cycle range. Finally, the absolute subdivision position can be obtained after fusion correction in the entire measurement range (4).

[0017] Figure 3The present invention is a schematic diagram of an example of a dual-channel absolute encoder device and a position detection method. The dual-channel absolute encoder device (5) is composed of an incremental code channel (510) and an incremental detector (511), as well as an absolute code channel (520) and an absolute detector (521)(522). The incremental detector (511) acquires and generates an incremental signal (1) on the periodic incremental code channel (510). The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code channel. A periodic incremental subdivision phase signal Φ is calculated and subdivided from the AB periodic signal, and a single-cycle subdivision position (2) is calculated. At the same time, the absolute detector acquires and generates an absolute signal on the absolute code channel (520). The absolute signal generated by the absolute detector (521) is resolved and subdivided to obtain the absolute position signal Pa1. The absolute signal generated by the absolute detector (522) is resolved and subdivided to obtain the absolute position signal Pa2. By controlling the distance between the absolute detectors (521) and (522), two groups of absolute position signal groups (310) and (320) with mutually staggered phases can be obtained. According to the value of the current incremental phase Φ, the absolute position signal with the highest credibility among the absolute position signal groups (310) and (320) is used as the candidate signal (300); the credibility intervals of the absolute position signal groups (310) and (320) are superimposed to cover the entire incremental subdivision phase signal Φ, ensuring that the candidate signal (300) has a credibility interval (301) within the entire cycle range. Finally, the absolute subdivision position (4) can be obtained after fusion and correction within the entire measurement range.

[0018] Figure 4The present invention is a schematic diagram of an example of a dual-channel absolute encoder device and a position detection method. The dual-channel absolute encoder device (5) is composed of an incremental code channel (510) and an incremental detector (511), as well as an absolute code channel (520) and an absolute detector (521). The incremental detector (511) acquires and generates an incremental signal (1) on the periodic incremental code channel (510). The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code channel. A periodic incremental subdivision phase signal Φ is calculated and subdivided from the AB periodic signal, and a single-cycle subdivision position (2) is calculated. The absolute code is a single code channel with a special coding sequence. The absolute detector (521) acquires and generates an absolute position signal Pa on the absolute code channel (520). After decoding and solving, the absolute position (3) is obtained. The trust interval (301) of the absolute position (3) is determined from the incremental phase signal Φ. An absolute position reference point is established at the absolute position (3) within the credible interval (301), and differential compensation is performed on the absolute position reference through the single-cycle subdivision position (2). When entering the uncertain interval (302), an inertial prediction algorithm is used to maintain position continuity until the next credible interval appears, and finally, the absolute subdivision position (4) is obtained after fusion correction. The deviation between the absolute position measurement value and the incremental cycle count integral value is compared; when the deviation exceeds a preset threshold, a position calibration signal is triggered and the accumulated error is corrected. (V) Specific implementation methods The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention. It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances. In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention. Example 1: Figure 3 An example of a dual-channel absolute encoder device and position detection method is provided. The dual-channel absolute encoder device (5) is composed of an incremental code channel (510) and an incremental detector (511), as well as an absolute code channel (520) and absolute detectors (521) and (522). The incremental detector (511) acquires and generates an incremental signal (1) on the periodic incremental code channel (510). The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code channel. The AB orthogonal pulse signal is interpolated and the phase angle Φ is obtained by an inverse tangent operation; the phase angle Φ is mapped to a continuous phase value in the range of 0 to 2π; the phase value is converted into a linear displacement according to the mechanical transmission ratio, and the single-cycle subdivision position (2) is calculated. At the same time, the absolute detector acquires and generates an absolute signal on the absolute code channel (520). The absolute signal generated by the absolute detector (521) is resolved and subdivided to obtain the absolute position signal Pa1. The absolute signal generated by the absolute detector (522) is resolved and subdivided to obtain the absolute position signal Pa2. By controlling the distance between the absolute detectors (521) and (522), two groups of absolute position signal groups (310) and (320) with mutually staggered phases can be obtained. According to the value of the current incremental phase Φ, the absolute position signal with the highest credibility among the absolute position signal groups (310) and (320) is used as the candidate signal (300); the credibility intervals of the absolute position signal groups (310) and (320) are superimposed to cover the entire incremental subdivision phase signal Φ, ensuring that the candidate signal (300) has a credibility interval (301) within the entire cycle range. An absolute position reference point is established at the absolute position (3) within the credibility interval (301), and the absolute position reference is compensated for the differential amount by the single-cycle subdivision position (2). Finally, the absolute subdivision position (4) can be obtained after fusion and correction within the entire measurement range. Example 2: Figure 4An example of a dual-channel absolute encoder device and a position detection method is given. The dual-channel absolute encoder device (5) consists of an incremental code channel (510) and an incremental detector (511), as well as an absolute code channel (520) and an absolute detector (521). The incremental detector (511) acquires and generates an incremental signal (1) on the periodic incremental code channel (510). The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code channel. The AB orthogonal pulse signal is interpolated and the phase angle Φ is obtained by arc tangent operation; the phase angle Φ is mapped to a continuous phase value in the range of 0 to 2π; the phase value is converted into a linear displacement according to the mechanical transmission ratio, and the single-cycle subdivision position (2) is calculated. The absolute code is a single code channel with a special coding sequence. The absolute detector (521) acquires and generates an absolute position signal Pa on the absolute code channel (520), and the absolute position (3) is obtained after decoding and resolution. Based on the threshold judgment of the differential value of the incremental subdivision phase signal Φ, when the phase signal Φ is in a preset stable change range, the current absolute position code channel signal is determined to be in a credible state, and an absolute position reference point is established at the absolute position (3) within the credible range (301). The absolute position reference is compensated for the differential amount by the single-cycle subdivision position (2); when entering the uncertain range (302), the inertia prediction algorithm is used to maintain the position continuity until the next credible range appears, and finally the absolute subdivision position (4) is obtained after fusion correction. In the overlapping area of the continuous credible range (301), the deviation between the absolute position measurement value and the incremental cycle count integral value is compared; when the deviation exceeds the preset threshold, the position calibration signal is triggered and the accumulated error is corrected.

Claims

1. A multi-channel absolute encoder position detection method. Its characteristics are: The multi-channel absolute encoder position detection method comprises an incremental signal (1), a single-cycle subdivision position (2), an absolute position (3), and an absolute subdivision position (4), wherein the absolute position (3) comprises a credible interval (301) and an uncertain interval (302); and comprises the following steps: Obtaining the periodic incremental signal generated by the encoder (1); A single-cycle subdivision position (2) is obtained by calculating and subdividing the incremental signal (1), wherein the single-cycle subdivision position (2) includes a periodic incremental phase signal Φ; Synchronously acquiring an absolute position (3) outputted by an absolute code channel of an encoder, wherein the absolute position (3) includes a credible interval (301) and an uncertainty interval (302); Determining the boundary range of the credible interval (301) in the absolute position (3) based on the dynamic change characteristics of the incremental subdivision phase signal Φ; The single-cycle subdivision position (2) is corrected for position matching by using a credible interval (301), and the absolute subdivision position (4) is generated by fusion.

2. The multi-channel absolute encoder position detection method according to claim 1, characterized in that: The incremental signal (1) is an AB signal with a fixed phase difference, and its signal period is associated with the grating pitch of the encoder incremental code track.

3. The multi-channel absolute encoder position detection method according to claim 1, wherein: The method of calculating and subdividing to obtain a single-cycle subdivision position (2) specifically includes: performing interpolation processing on the AB orthogonal pulse signal to obtain a phase angle Φ by an inverse tangent operation; mapping the phase angle Φ to a continuous phase value in the range of 0 to 2π; and converting the phase value into a linear displacement according to a mechanical transmission ratio.

4. The multi-channel absolute encoder position detection method according to claim 1, wherein: The single-cycle subdivision position (2) includes a periodic incremental phase signal Φ subdivision method including: hardware-level subdivision methods such as quadruple frequency technology utilizing the 90° phase difference characteristic of the A / B two-phase signal, phase-locked loop subdivision, resistor chain and space subdivision; digital signal processing subdivision methods such as sine / cosine signal interpolation, inverse tangent method, and subdivision using a high-precision time measurement chip after converting the moving signal into a time domain signal; and hybrid subdivision methods such as using an analog front end (differential amplification + bandpass filtering) to pre-process the signal and then implementing real-time orthogonal decoding and error correction through FPGA.

5. The multi-channel absolute encoder position detection method according to claim 1, wherein: The method for determining the credible interval (301) of the absolute position (3) includes: Based on the threshold determination of the differential value of the incremental subdivision phase signal Φ, when the phase signal Φ is in a preset stable change range, it is determined that the current absolute position code channel signal is in a reliable state; When it is detected that the phase signal Φ has a jump or is not within the preset stable change range, a tolerance range set before and after the jump point is marked as an uncertain interval (302).

6. The multi-channel absolute encoder position detection method according to claim 1, wherein: The credible interval (301) of the absolute position (3) covers the entire period: The absolute position (3) includes at least two groups of absolute position signal groups with phases staggered from each other, such as (310), (320), etc.; According to the value of the current incremental phase Φ, the absolute position signal with the highest credibility from the absolute position signal groups (310), (320), etc. is selected as a candidate signal (300); The respective credible intervals of the absolute position signal groups such as (310) and (320) are superimposed to cover the entire incremental subdivision phase signal Φ, ensuring that the candidate signal (300) has a credible interval (301) within the entire cycle range.

7. The method according to claim 6, characterized in that Optionally, the phase interval of the absolute position signal groups (310) and (320) is 1 / N of the encoder increment period, where N is the number of absolute position groups of the absolute code channel and N≥2, and the credible interval coverage range of each signal group is at least 2π / N phase angle.

8. The method according to claim 6, characterized in that The calculation of the candidate signal (300) is implemented by adopting a credibility judgment algorithm: according to the value of the current incremental phase Φ, the candidate signal is obtained after excluding the absolute position signal group in the uncertain interval, and the absolute position of the candidate signal (300) is selected and verified by adopting a credibility comparison algorithm, and the calculated output result is a credible signal (301).

9. The multi-channel absolute encoder position detection method according to claim 1, wherein: The fusion generation of absolute subdivision positions (4) specifically includes: Establishing an absolute position reference point at an absolute position (3) within a credible interval (301); The absolute position reference is compensated for the differential amount by the continuous phase value of the single-cycle subdivision position (2); When entering the uncertainty interval (302), the inertial prediction algorithm is used to maintain position continuity until the next credible interval appears.

10. The multi-channel absolute encoder position detection method according to claim 1, wherein: The method according to claim 7, further comprising a dynamic calibration step: In the overlapping area of the continuous credible intervals (301), the deviation between the absolute position measurement value and the incremental cycle count integral value is compared; When the deviation exceeds the preset threshold, a position calibration signal is triggered and the accumulated error is corrected.

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