Incremental photoelectric encoder alignment detection and calibration system based on phase relation

Abstract

The invention provides an incremental photoelectric encoder alignment detection and calibration system based on a phase relation. The system is characterized in that the system is composed of a light source (1), a code disc (2), an incremental photoelectric encoder chip (3) and a signal processing and calibration system (4), wherein the incremental photoelectric encoder chip (3) is composed of a photoelectric signal acquisition module (31), an incremental signal generation module (32), a zero signal generation module (33), a phase analysis module (34), an alignment state determination module (35) and a feedback compensation module (36). By analyzing the phase relation between the zero signal and the increment signal, the alignment deviation and direction of the encoder and the code disc are judged, digital compensation is executed on the zero signal or the increment signal, automatic alignment detection and self-adaptive calibration are achieved, and therefore assembly errors and position errors caused by optical deviation are reduced, and the precision of the encoder is improved. And the precision, the stability and the reliability of the encoder system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of photoelectric encoder alignment detection and calibration technology, specifically to a kind of incremental photoelectric encoder alignment detection and calibration system based on phase relationship, suitable for rotary encoder or linear encoder, can be widely applied in servo control, motor drive, industrial automation and precision position detection etc. BACKGROUND

[0002] With the rapid development of industrial automation, servo control and high-precision motion control technology, photoelectric encoder as the key sensor to obtain position, speed and direction information is widely used in numerical control machine tool, industrial robot, motor control and precision measurement system. Among them, incremental photoelectric encoder is widely used due to its simple structure, high resolution and relatively low cost.

[0003] A typical incremental photoelectric encoder system usually includes a light source, a code disc and a photoelectric encoder chip. By periodic modulation of the light signal by the code disc, the encoder chip generates at least two phase-orthogonal incremental signals (such as A and B phases), and further generates a zero signal (Z phase) for absolute reference positioning. In an ideal state, the effective trigger edge of the zero signal should maintain a strict correspondence with a certain preset phase position of the incremental signal, thereby providing a stable and reliable zero reference for the system.

[0004] However, in actual application, due to the inevitable mechanical assembly error, thermal deformation or small offset caused by long-term operation of the encoder chip and the code disc during installation, packaging or operation, the phase relationship between the zero signal and the incremental signal often deviates. This alignment deviation will directly cause the zero trigger position to be inaccurate, thereby introducing position calculation error and affecting the repeatability and long-term stability of the system.

[0005] To solve the above problems, the existing technology usually adopts the following ways: First, rely on high-precision mechanical assembly and manual alignment adjustment to reduce the initial installation error between the chip and the code disc; second, through external calibration equipment or upper control system, manually calibrate the zero signal during system debugging; third, increase the complexity of the code disc structure or improve the manufacturing precision to reduce the influence of alignment error. The above schemes generally have strong dependence on mechanical precision and manual debugging, poor production consistency, high calibration cost and difficult to dynamically compensate during operation, etc., which is difficult to meet the application requirements of high reliability, high consistency and batch production.

[0006] In addition, the existing part of the photoelectric encoder chip only processes the incremental signal and the zero signal independently at the signal generation level, lacks systematic analysis and utilization of the phase relationship between the two, and cannot directly determine the alignment state of the chip and the code disc inside the chip, making it more difficult to determine the alignment offset direction and subsequent automatic compensation. This makes the encoder system still prone to problems such as zero drift accumulation and positioning accuracy decline under long-term operation or environmental changes.

[0007] Therefore, there is an urgent need for a technical solution that can detect the alignment state, determine the offset direction, and compensate for calibration based on the phase relationship between the incremental signal and the zero signal without relying on additional mechanical adjustment or external complex calibration equipment. This solution should be integrated into a photoelectric encoder chip under standard integrated circuit technology, support automatic alignment detection and calibration during system initialization or operation, and effectively reduce the position calculation error caused by the alignment deviation between the chip and the code disc, thereby improving the accuracy, stability, and reliability of the photoelectric encoder system.

[0008] The present application is directed to the above technical problems, and proposes a phase relationship-based incremental photoelectric encoder alignment detection and calibration system. By introducing phase analysis, alignment state determination, and feedback compensation mechanisms inside the chip, the system can automatically detect and correct the alignment offset between the chip and the code disc, thereby overcoming the shortcomings of the prior art, such as reliance on mechanical adjustment for alignment accuracy, complex calibration process, and difficulty in dynamic compensation, and has good engineering practical value and promotion prospects. SUMMARY

[0009] The present application is directed to the above technical problems, and proposes a phase relationship-based incremental photoelectric encoder alignment detection and calibration system. By introducing phase analysis, alignment state determination, and feedback compensation mechanisms inside the chip, the system can automatically detect and correct the alignment offset between the chip and the code disc, thereby overcoming the shortcomings of the prior art, such as reliance on mechanical adjustment for alignment accuracy, complex calibration process, and difficulty in dynamic compensation, and has good engineering practical value and promotion prospects.

[0010] To achieve the above-mentioned purpose, the present application provides a phase relationship-based incremental photoelectric encoder alignment detection and calibration system, which comprises a light source (1), a code disc (2), an incremental photoelectric encoder chip (3), and a signal processing and calibration system (4). The incremental photoelectric encoder chip (3) comprises a photoelectric signal acquisition module (31), an incremental signal generation module (32), a zero signal generation module (33), a phase analysis module (34), an alignment state determination module (35), and a feedback compensation module (36).

[0011] The technical scheme of the present application is implemented as follows: the light signal emitted by the light source (1) irradiates to the code disc (2), the code disc (2) periodically modulates the light signal, and the modulated light signal is received by the incremental photoelectric encoder chip (3). The photoelectric signal acquisition module (31) receives the light signal modulated by the code disc (2) and converts it into a corresponding electrical signal output. The incremental signal generation module (32) generates at least two phase-quadrature incremental signals based on the electrical signal, preferably channel A (CHA) and channel B (CHB), the two signals have a fixed 90° phase difference in an ideal state, and are used to represent the relative displacement information of the encoder. The zero position signal generation module (33) generates a zero position signal with an effective trigger edge based on the electrical signal, which is used to provide zero position reference information of the encoder.

[0012] The phase analysis module (34) takes the CHA and CHB signals output by the incremental signal generation module (32) as input, extracts and analyzes the two quadrature incremental signals to obtain continuous incremental phase information or equivalent phase position information. The phase analysis module (34) can use any one or more of the inverse tangent operation, coordinate rotation digital computer algorithm (CORDIC), lookup table interpolation, zero-crossing interpolation or equivalent phase calculation methods to calculate the phase of CHA and CHB, forming the incremental phase φ(t) that changes with time.

[0013] In the incremental phase space, the phase analysis module (34) defines at least one preset reference phase point φREF, which can correspond to a specific edge of CHA, a specific phase combination of CHA and CHB, or a fixed phase position set by the system, and is used as a phase reference for the ideal trigger position of the zero position signal.

[0014] When the zero position signal generation module (33) outputs the zero position signal, the effective trigger edge thereof is synchronously sent to the alignment state determination module (35). The alignment state determination module (35) reads the incremental phase φZ corresponding to the time when the effective trigger edge of the zero position signal occurs, and compares it with the preset reference phase point φREF to obtain the phase deviation Δφ between the zero position signal and the incremental signal, where Δφ=φZ-φREF. Based on the sign and size of the phase deviation Δφ, the alignment state determination module (35) determines the alignment state between the chip and the code disc according to the following rules: (1) When Δφ>0, it indicates that the phase of the effective trigger edge of the zero position signal leads the reference phase point φREF, and the alignment state determination module determines that the incremental photoelectric encoder chip is in the left-biased alignment state relative to the code disc; (2) When Δφ<0, it indicates that the phase of the effective trigger edge of the zero position signal lags behind the reference phase point φREF, and the alignment state determination module determines that the incremental photoelectric encoder chip is in the right-biased alignment state relative to the code disc. (3) When |Δφ| is less than or equal to a preset phase tolerance threshold, it is determined that the chip and the code disc are in a normal alignment state.

[0015] Here, "left deviation" and "right deviation" refer to a physical position deviation state relative to a preset installation reference.

[0016] The above alignment state determination can be completed based on a single incremental signal period, or based on statistical analysis results of the zero position signal trigger phase in multiple consecutive incremental signal periods, to reduce the influence of jitter, noise and transient interference on the judgment results. After completing the alignment state determination, the alignment state determination module (35) outputs corresponding alignment state information. The alignment state information at least includes one or more of the following contents: (1) An alignment state flag signal for indicating that the chip is in a left deviation, right deviation or normal alignment state; (2) Alignment deviation direction information; (3) An equivalent phase deviation value corresponding to the alignment deviation.

[0017] The alignment state information can be directly output to the feedback compensation module (36) for automatic compensation, or can be simultaneously output to the signal processing and calibration system (4) for system-level calibration, state monitoring or external alignment adjustment indication. The feedback compensation module (36) performs phase compensation processing on the zero position signal and / or the incremental signal based on the phase deviation Δφ, to correct the zero position error caused by the alignment deviation of the chip and the code disc. The phase compensation processing includes one or more of the following ways: (1) When Δφ>0, a digital delay processing is performed on the effective trigger edge of the zero position signal, so that the trigger phase of the zero position signal moves towards the reference phase point φREF; (2) When Δφ<0, a digital advance processing is performed on the effective trigger edge of the zero position signal, so that the trigger phase of the zero position signal moves towards the reference phase point φREF; (3) The reference phase point φREF used in the phase analysis module (34) is corrected according to the phase deviation Δφ, so that the phase determination of the subsequent zero position signal is based on the corrected phase reference.

[0018] Through the above phase compensation processing, the phase deviation between the compensated zero position signal and the incremental signal satisfies |Δφ|≤preset phase tolerance threshold, so that the phase alignment between the zero position signal and the incremental signal is realized without changing the physical installation relationship between the chip and the code disc.

[0019] The signal processing and calibration system (4) is used for receiving the incremental signal, zero signal and alignment state and compensation related information output by the incremental optical encoder chip (3), and at least one of the following functions is completed: unified phase calibration and zero correction of the position signal output by the encoder; recording the alignment state of the chip and the code disc, for production test, installation calibration or operation monitoring; outputting alignment adjustment instruction signal to external system according to the alignment state information; triggering or managing the alignment detection and feedback compensation process in the system initialization stage or operation process. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a whole structure schematic diagram of an incremental optical encoder alignment detection and calibration system based on phase relationship according to the present application. The system comprises a light source (1), a code disc (2), an incremental optical encoder chip (3) and a signal processing and calibration system (4), wherein the incremental optical encoder chip (3) is internally integrated with a photoelectric signal acquisition module (31), an incremental signal generation module (32), a zero signal generation module (33), a phase analysis module (34), an alignment state determination module (35) and a feedback compensation module (36).

[0021] Figure 2 is a phase relationship schematic diagram of the incremental signal and the zero signal according to the present application. The diagram shows the orthogonal phase relationship between the incremental signals CHA and CHB, and the different trigger phase positions of the zero signal relative to CHA and CHB in the ideal alignment state, the left deviation alignment state and the right deviation alignment state.

[0022] Figure 3 is the alignment state determination and feedback compensation timing schematic diagram of embodiment one of the present application, which is used for explaining that when the effective trigger edge phase of the zero signal is positively deviated (Δφ>0) relative to the reference phase position φREF of the incremental signal CHA, the system determines that the chip is in the left deviation alignment state relative to the code disc, and the process of aligning the zero signal trigger edge with the reference phase position φREF through digital delay processing of the zero signal.

[0023] Figure 4 is the alignment state determination and feedback compensation timing schematic diagram of embodiment two of the present application, which is used for explaining that when the effective trigger edge phase of the zero signal is negatively deviated (Δφ<0) relative to the reference phase position φREF of the incremental signal CHA, the system determines that the chip is in the right deviation alignment state relative to the code disc, and the process of aligning the zero signal trigger edge with the reference phase position φREF through digital advance processing of the zero signal. DETAILED DESCRIPTION

[0025] The present invention will be further illustrated below with reference to specific embodiments. Example

[0026] Alignment determination and self-feedback calibration when the rising edge of the standard zero-position signal leads the CHA signal by 0° phase position. For example... Figure 1 , Figure 3 As shown in the figure, this embodiment illustrates the system operation process of the alignment state determination and feedback compensation based on phase relationship described in this invention.

[0027] The system includes a light source (1), a code disk (2), an incremental photoelectric encoder chip (3), and a signal processing and calibration system (4). The incremental photoelectric encoder chip (3) integrates a photoelectric signal acquisition module (31), an incremental signal generation module (32), a zero position signal generation module (33), a phase analysis module (34), an alignment state determination module (35), and a feedback compensation module (36). Each module is integrated on the same chip or achieves functional collaboration through on-chip interconnection.

[0028] In this embodiment, the system is pre-set to a standard alignment state where the effective rising edge of the zero-position signal Z is aligned with the 0° phase position of the incremental signal CHA. The CHA and CHB signals maintain a 90° electrical angle phase difference, used to represent the rotation direction and incremental displacement information of the code disk.

[0029] When the system is working, the code disk rotates with the object under test. The photoelectric sensing component collects the optical signal modulated by the code disk and generates a corresponding analog sine or cosine electrical signal. After processing by the signal conditioning module, the signal is converted into incremental signals CHA, CHB, and a zero-position signal Z. The zero-position signal Z generates only one valid trigger edge in each rotation cycle of the code disk.

[0030] The phase analysis module performs periodic phase division on the CHA and CHB signals, determines the 0° phase reference point of the CHA signal, and acquires the phase difference relationship between the rising edge of the zero-position signal Z and the 0° phase position of the CHA signal when the rising edge of the zero-position signal Z arrives. When the rising edge of the zero-position signal Z is detected to lead the 0° phase position of the CHA signal, the alignment state determination module determines the corresponding phase deviation Δφ > 0 according to a preset determination rule, and determines that the chip in the current system is in a left-leaning alignment state relative to the code disk, and generates a corresponding alignment state indication signal. The alignment state indication signal can be used as an external output of the system for assembly, testing, or operational status monitoring; on the other hand, it is sent to the feedback compensation module to initiate the self-feedback adjustment process.

[0031] The feedback compensation module performs digital delay processing on the trigger edge of the zero-position signal Z based on the detected phase lead, or performs equivalent correction on the phase reference point in the phase analysis module, so that the compensated zero-position signal trigger edge is closer to the 0° phase position of the CHA signal in logical timing. The zero-position signal and the incremental signals CHA and CHB after feedback compensation are re-inputted to the signal processing and calibration system. The signal processing and calibration system performs unified processing on the compensated signals, so that the system can calibrate the phase relationship between the zero-position signal and the incremental signal while keeping the original code disk installation state unchanged, thereby outputting an encoder signal that meets the standard alignment requirements.

[0032] Through the above method, this embodiment realizes automatic judgment and adaptive calibration when the chip and code disk have a leftward installation deviation, thereby improving the system's assembly tolerance and operational stability. Example

[0033] like Figure 1 , Figure 4 As shown, this embodiment uses the same system structure and hardware composition as Embodiment 1, the difference being the phase relationship between the zero-position signal and the incremental signal. In this embodiment, the system also sets the standard alignment state as follows: the effective rising edge of the zero-position signal Z is aligned with the 0° phase position of the incremental signal CHA. During system operation, the photoelectric sensing component acquires the code disk signal and generates the corresponding CHA, CHB, and zero-position signal Z, which are then input to the phase analysis module after passing through the signal conditioning module.

[0034] When the rising edge of the zero-position signal Z arrives, the phase analysis module samples and judges the current phase position of the CHA signal. When it detects that the rising edge of the zero-position signal Z lags behind the 0° phase position of the CHA signal, the alignment state determination module determines the corresponding phase deviation Δφ < 0 according to preset logic rules, and determines that the chip in the current system is in a rightward alignment state relative to the code disk, and generates a corresponding alignment state indication signal. The alignment state indication signal is output to the outside of the system to indicate the relative alignment relationship between the chip and the code disk, and is also sent to the feedback compensation module to trigger the self-feedback calibration process.

[0035] The feedback compensation module performs digital advance processing on the trigger edge of the zero-position signal Z based on the detected phase lag, or corrects the phase reference point used in the phase analysis module, so that the compensated zero-position signal trigger edge moves towards the 0° phase position of the CHA signal in time or phase.

[0036] The compensated zero signal and the incremental signals CHA and CHB are input to a signal processing and calibration system, which uniformly processes and outputs calibration of the signals, so that the encoder system realizes the standard phase alignment relationship between the zero signal and the incremental signals without changing the physical installation structure.

[0037] In the above manner, the embodiment realizes automatic identification and self-adaptive compensation when the chip and the code disc have a right installation deviation, and improves consistency and reliability of the system in actual application.

[0038] As can be seen from the embodiment one and the embodiment two, the real-time analysis of the phase relationship between the zero signal and the incremental signals is realized to automatically determine the alignment state of the chip and the code disc, and the self-adaptive calibration of the phase relationship is completed in combination with the feedback compensation module, so that the traditional mechanical precision or manual adjustment mode is avoided, and the application value is high.

Claims

1. A phase-relationship-based incremental photoelectric encoder alignment detection and calibration system, characterized in that: The system includes a light source (1), a code disk (2), an incremental photoelectric encoder chip (3), and a signal processing and calibration system (4). The incremental photoelectric encoder chip (3) includes a photoelectric signal acquisition module (31), an incremental signal generation module (32), a zero-position signal generation module (33), a phase analysis module (34), an alignment state determination module (35), and a feedback compensation module (36). The photoelectric signal acquisition module (31) receives the optical signal modulated by the code disk (2) and converts it into an electrical signal. The incremental signal generation module (32) generates at least two incremental signals with orthogonal phases based on the electrical signal. The zero-position signal generation module (33) generates at least two incremental signals with orthogonal phases based on the electrical signal. The incremental encoder chip (3) generates a zero-position signal with an effective trigger edge. The phase analysis module (34) is used to extract the phase of the incremental signal and determine the reference phase point corresponding to the preset phase position. The alignment state determination module (35) is used to compare the phase relationship between the effective trigger edge of the zero-position signal and the reference phase point, and determine the alignment offset state and offset direction between the incremental photoelectric encoder chip (3) and the code disk (2) according to the phase relationship. The feedback compensation module (36) compensates the trigger phase of the zero-position signal and / or the phase reference of the incremental signal according to the alignment offset state, or outputs alignment adjustment indication information, thereby reducing the position calculation error caused by the alignment deviation between the chip and the code disk.

2. The incremental photoelectric encoder alignment detection and calibration system based on phase relationship according to claim 1, characterized in that: The phase analysis module (34) extracts the phase of at least two orthogonal incremental signals output by the incremental signal generation module (32) to obtain continuous or equivalent incremental phase information, and defines at least one reference phase position φREF in the incremental phase space. When the zero position signal generation module (33) outputs a valid trigger edge of the zero position signal, the phase analysis module (34) obtains the actual phase position φZ corresponding to the valid trigger edge, and calculates the phase deviation Δφ between the actual phase position φZ and the reference phase position φREF, where: Δφ=φZ-φREF; the phase deviation Δφ is used to characterize the phase offset relationship between the zero position signal and the incremental signal, and serves as the basis for position state determination and feedback compensation.

3. The incremental photoelectric encoder alignment detection and calibration system based on phase relationship according to claim 2, characterized in that: The feedback compensation module (36) performs phase compensation processing on the zero-position signal and the incremental signal based on the phase deviation Δφ. The phase compensation processing includes one or more of the following methods: When Δφ>0, the effective trigger edge of the zero position signal is subjected to digital delay processing, causing the trigger phase of the zero position signal to move towards the reference phase position φREF. When Δφ < 0, the effective trigger edge of the zero-position signal is digitally advanced, causing the trigger phase of the zero-position signal to shift towards the reference phase position φREF. The reference phase position φREF is corrected according to the phase deviation Δφ, so that the phase determination of the subsequent zero-position signal is based on the corrected phase reference. Through the above phase compensation process, the compensated zero-position signal satisfies |Δφ|≤ preset phase tolerance threshold, thereby realizing phase alignment between the zero-position signal and the incremental signal.

4. The incremental photoelectric encoder alignment detection and calibration system based on phase relationship according to claim 1, characterized in that: The alignment state determination module (35) performs statistical analysis based on the phase relationship between the effective trigger edge of the zero position signal and the reference phase point within a single cycle or multiple consecutive cycles, so as to reduce the impact of transient jitter or noise on the alignment determination result.

5. The incremental photoelectric encoder alignment detection and calibration system based on phase relationship according to claim 1, characterized in that: The alignment detection and feedback compensation process can be performed in any of the following ways: during system power-on initialization, periodically during operation, triggered when a zero-position signal is detected, or when an external calibration command is received.

6. The incremental photoelectric encoder alignment detection and calibration system based on phase relationship according to claim 1, characterized in that: The incremental photoelectric encoder chip (3) is a chip manufactured based on standard integrated circuit technology. The phase analysis module (34), the alignment state determination module (35), and the feedback compensation module (36) are integrated inside the incremental photoelectric encoder chip (3) in the form of digital logic, circuit modules, or a combination of hardware and software.

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