Ultra-long distance linear measurement system

Abstract

The invention provides an ultra-long distance linear measurement system. The system is characterized by comprising a reading head (1), a grating (2) and a signal processing module (3). Wherein a light source (100) and at least two detector modules (110) and (120) are arranged in the reading head (1); the grating (2) is provided with a code channel (210) on a grating substrate (200) for position measurement, and ultra-long distance test is realized by adopting multi-section splicing. The core of the invention lies in that through the collaborative design of the multi-detector module and the specific grating splicing layout, it is ensured that at least one detector can receive an effective position signal all the time in the whole measurement stroke. The signal processing module fuses and switches the signals, and finally outputs continuous and high-precision global position information. The high-precision grating ruler solves the technical bottleneck that a traditional high-precision grating ruler is difficult to realize long-distance measurement and splicing, and can be widely applied to various industrial and high-end equipment needing long-distance and high-precision speed closed loop and position measurement.

Description

(I) Technical Field

[0001] This invention relates to an ultra-long-distance linear measurement system, which can be used in instruments for long-distance, high-precision speed closed-loop control and accurate position measurement, and belongs to the field of photoelectric detection and precision measurement technology. (II) Background Technology

[0002] A grating ruler is a sensor based on grating measurement technology that detects and controls parameters such as position, displacement, velocity, and acceleration, playing a crucial role in high-precision measurement and motion control. With the rapid development of precision measurement and intelligent manufacturing, grating rulers are evolving towards higher precision, higher reliability, higher resolution, and higher adaptability.

[0003] The measurement reference of an optical encoder system is the encoder itself, with glass, ceramic, and metal being the mainstream substrates. Glass or ceramic encoders offer advantages such as high precision, low coefficient of thermal expansion, and good stability, but their inherent brittleness severely limits their length, making it difficult to manufacture them into lengths exceeding several meters. Therefore, they are mostly used in equipment requiring extremely high precision but with limited measuring range. While metal encoders offer high mechanical strength and easy installation, with lengths exceeding ten meters (though there is also a length limit), their precision and stability are generally lower than glass encoders, and they are more significantly affected by temperature changes, making it difficult to meet the dual requirements of ultra-long distances and high precision in high-end equipment.

[0004] Traditional splicing methods (especially for glass grid rulers) require experienced technicians to operate under a microscope in a standard laboratory, using hazardous chemicals such as hydrofluoric acid for welding. This method is complex, dangerous, and costly. Furthermore, the spliced ​​rulers are extremely vulnerable to damage during transportation and on-site installation, exhibiting very poor flexibility and failing to meet the needs for rapid deployment and adjustment at the equipment site.

[0005] Therefore, this invention proposes an ultra-long-distance linear measurement system. It overcomes length limitations by employing several high-precision gratings spliced ​​together on-site, and multiple detector modules within the read head achieve full-range coverage measurement to ensure accuracy. This invention enables ultra-long-distance measurement while guaranteeing high precision and reliability, and also possesses the capability for rapid and flexible on-site deployment. (III) Summary of the Invention

[0006] The purpose of this invention is to provide an ultra-long-distance linear measurement system. This system, through an innovative multi-detector readhead design, a flexible on-site grating splicing scheme, and intelligent signal processing, solves the technical challenges faced by traditional grating rulers in ultra-long-distance measurements, such as the trade-off between range and accuracy, splicing difficulties, complex absolute position identification, and easy signal interruption.

[0007] The objective of this invention is achieved as follows: A long-distance linear measurement system; characterized in that it includes a reader (1), a grating (2), and a signal processing module (3); The read head (1) includes a light source (100) and at least two detector modules (110, 120); The grating (2) is composed of code tracks (210) set on the grating substrate (200) and is used for position measurement. The system achieves ultra-long distance measurement by splicing several segments of the grating (2), and the splicing method is configured to ensure that at least one of the detector modules can receive an effective modulated light signal throughout the entire measurement range. The at least two detector modules (110, 120) are used to receive the optical signal modulated by the code channel (210), perform photoelectric conversion, and output position signals (111, 121) respectively. The signal processing module (3) is used to acquire and fuse the position signals (111, 121) to obtain and output continuous position information covering the entire measurement range. (The following is a further detailed explanation, including other claims and their details.)

[0008] The light source (100) is any one or a combination of collimated light source, divergent light source, point light source, surface light source, volume light source, multicolor light source or polycolor light source.

[0009] The grating (2) is any one of a rectangular grating, a sinusoidal grating, a blazed grating, a step grating, or a volume grating; and / or, the grating (2) is any one of a transmission grating, a reflection grating, a diffraction grating, or an interference grating.

[0010] The material of the grating substrate (200) can be opaque materials such as steel alloy, aluminum alloy, or coated metal, or transparent or partially transparent materials such as glass or plastic; and / or, the shape of the grating (2) can be a straight grating ruler, a circular code disk, or the shape of any other motion trajectory.

[0011] The code channel (210) modulates light by means of absorption, reflection, transmission, scattering, interference or diffraction; and / or, the code channel (210) includes at least one of incremental code channel (211), reference code channel (212) and absolute code channel (213) or a mixture thereof.

[0012] The grating (2) can be spliced ​​in any one of the following ways: parallel splicing, serial splicing, or a combination of serial and parallel splicing.

[0013] The physical spacing between the at least two detector modules (110, 120) within the read head (1) is matched with the splicing layout of the grating (2) to achieve coverage of the measurement blind zone at the splicing point and seamless switching of position signals.

[0014] The gratings (2) may have the same template or type, and there is a preset or accidentally formed distance difference between two adjacent grating segments (2) at the splicing point. The signal processing module (3) is configured to determine the absolute position segment of the read head by identifying the unique feature of this distance difference. The feature of the distance difference includes, but is not limited to: the number of incremental cycles, subdivision displacement, and absolute code difference value between the reference code track (212) or the absolute code track (213).

[0015] The signal processing module (3) is configured to: determine the validity of the position signals output by each detector module in real time; when only one detector module outputs a valid signal, calculate the absolute position based on the valid signal and the current grating segment information; when at least two detector modules output valid signals at the same time, perform fusion calculation on the valid signals to improve the accuracy and reliability of the position information. Compared with the prior art, the present invention has the following significant advantages:

[0016] High-precision measurement over ultra-long distances was achieved: by using high-precision short gratings for on-site splicing, the high precision of the measurement benchmark was guaranteed from the source, overcoming the problem of insufficient precision of a single long metal grating ruler.

[0017] It solves the problems of on-site splicing and absolute position identification: it provides a flexible and safe on-site mechanical splicing solution, and innovatively uses the "distance difference" at the splicing point as a position segment identifier, realizing full-length absolute position identification without complicated alignment operations, which greatly simplifies installation and debugging.

[0018] The system ensures continuous measurement and high reliability: the combination of multi-detector modules and intelligent signal processing guarantees no measurement blind spots across the entire measurement range. The signal processing module can automatically select or fuse the optimal signal, effectively suppressing errors caused by local defects, contamination, or transient interference, resulting in extremely robust system performance.

[0019] The system is flexible in configuration and widely applicable: it offers a variety of options for key components such as light source, grating type, and substrate material, enabling the system to be customized according to different application scenarios (such as linear measurement, circular measurement, and different accuracy and range requirements), and has a wide range of applications. (iv) Description of the attached drawings

[0020] Figure 1This is a schematic diagram of a parallel splicing ultra-long-distance linear measurement system. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) in the system includes a light source (100) and at least two detector modules (110) and (120); the grating (2) has a code track (210) on a grating substrate (200) for position measurement. The light emitted by the light source (100) is modulated by the code track (210) on the grating, and after being received by the detector modules (110) and (120), it is converted by photoelectric conversion to output position signals (111) and (121) respectively. The system achieves ultra-long-distance measurement by splicing several segments of the grating (2), and the splicing method is configured to ensure that at least one of the detector modules can receive a valid modulated light signal throughout the entire measurement range. The signal processing module (3) collects the position signal (111) and the position signal (121) and performs fusion calculation to obtain the position information within the entire measurement range.

[0021] Figure 2 This is a schematic diagram of a serially spliced ​​ultra-long-distance linear measurement system. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) in the system includes a light source (100) and at least two detector modules (110) and (120); the grating (2) has a code track (210) on a grating substrate (200) for position measurement. The light emitted by the light source is modulated by the code track (210) on the grating, and after being received by the detector modules (110) and (120), it is converted by photoelectric conversion to output position signals (111) and (121) respectively. Several gratings (2) are serially spliced ​​to achieve long-distance testing, ensuring that at least one detector module receives a valid position signal throughout the entire measurement range. The signal processing module (3) is configured to: determine the validity of the position signals output by each detector module in real time; when only one detector module outputs a valid position signal (e.g., 111) at the splicing point of the grating (2), calculate the absolute position based on the valid position signal (111) and the current grating segment information; when at least two detector modules output valid position signals (111, 121) simultaneously, perform fusion calculation on the valid signals to improve the accuracy and reliability of the position information. The signal processing module (3) obtains the position information within the entire measurement range by collecting the position signals (111) and (121) along the entire splicing length and performing fusion calculation.

[0022] Figure 3This is a schematic diagram of an absolute position identification technology using a grating ruler splicing system. The system's read head (1) includes at least two detector modules (110) and (120); the grating (2) has a code track (210) on a grating substrate (200) for position measurement. The code track (210) includes at least an incremental code track (211) and a reference code track (212). Light emitted from the light source is modulated by the incremental code track (211) and the reference code track (212) on the grating ruler, and after being received by the detector module (110), it is converted by photoelectric conversion to output position signals (111) and reference position signals (112), respectively; light emitted from the light source is modulated by the incremental code track (211) and the reference code track (212) on the grating ruler, and after being received by the detector module (120), it is converted by photoelectric conversion to output position signals (121) and reference position signals (122), respectively. When one of the detector modules (120) of the read head (1) passes through the splicing point of the grating (2), the position signal (121) output by the detector module (120) will be inaccurate. At the same time, the detector module (120) will record and output the accurate reference position signal (122) at the splicing point. At this time, at least another detector module (110) can output a valid position signal (111) even though it does not detect the reference position signal (112) at the splicing point. There is a preset or accidentally formed distance difference between the two adjacent grating segments (2) at the splicing point. The distance difference at the splicing point is characterized by the number of incremental cycles and the subdivision displacement of the valid position signal (111) when the reference position signal (122) is recorded. The signal processing module (3) is configured to determine the absolute position segment of the read head by identifying the unique feature of this distance difference.

[0023] Figure 4A schematic diagram of a parallel stitched absolute ultra-long distance linear measurement system. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) in the system includes a light source (100) and at least two detector modules (110) and (120); the grating (2) has code tracks (210) on a grating substrate (200) for position measurement. The light emitted by the light source (100) is modulated by the incremental code track (211) and the absolute code track (213) on the grating scale, and after being received by the detector module (110), it is converted by photoelectric conversion to output position signal (111) and absolute signal (113) respectively; the light emitted by the light source is modulated by the incremental code track (211) and the absolute code track (213) on the grating scale, and after being received by the detector module (120), it is converted by photoelectric conversion to output position signal (121) and absolute signal (123) respectively. The system achieves ultra-long-distance measurement by splicing several segments of the grating (2), and the splicing method is configured to ensure that at least one detector module can receive a valid modulated optical signal throughout the entire measurement range. When the read head (1) passes through the splicing point of the grating (2), the detector module (110) outputs a valid position signal (111) and an absolute signal (113), and at this time, at least another detector module (120) outputs a valid position signal (121) and an absolute signal (123). There is a preset or accidentally formed distance difference between two adjacent segments of the grating (2) at the splicing point. The distance difference at the splicing point is characterized by recording the number of incremental cycles and subdivision displacement of the position signal (111) and / or position signal (121) between two absolute codes in the absolute signal (113) and absolute signal (123). The signal processing module (3) is configured to determine the grating position segment where the read head is located by identifying the unique feature of this distance difference. The signal processing module (3) collects position signal (111), absolute signal (113) and position signal (121), absolute signal (123) and performs fusion calculation to obtain position information within the entire measurement range.

[0024] Figure 5This is a schematic diagram of a serially spliced ​​single-track ultra-long-distance linear measurement system. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) in the system includes a collimating light source (100) and at least two detector modules (110) and (120); the grating (2) has a code track (210) set on the grating substrate (200) for position measurement. To increase the installation tolerance, a reference code track (212) is embedded in the incremental code track (211) to form a single code track. The light emitted by the light source is modulated by the incremental code track (211) and the reference code track (212) on the grating ruler. After being received by the detector module (110), the light is converted by photoelectric conversion and output as position signal (111) and reference position signal (112) respectively. The light emitted by the light source is modulated by the incremental code track (211) and the reference code track (212) on the grating ruler. After being received by the detector module (120), the light is converted by photoelectric conversion and output as position signal (121) and reference position signal (122) respectively. When one of the detector modules (120) of the read head (1) passes through the splicing point of the grating (2), the position signal (121) output by the detector module (120) will be inaccurate. At the same time, the detector module (120) will record and output the accurate reference position signal (122) at the splicing point. At this time, at least another detector module (110) can output a valid position signal (111) even though it does not detect the reference position signal (112) at the splicing point. There is a preset or accidentally formed distance difference between two adjacent gratings (2) at the splicing point. The distance difference at the splicing point is characterized by the number of incremental cycles and subdivision displacement of the effective position signal (111) when the reference position signal (122) is recorded. The signal processing module (3) is configured to determine the absolute position segment of the read head by identifying the unique feature of the distance difference. Several gratings (2) are spliced ​​in series to achieve long-distance testing, ensuring that at least one detector module receives a valid position signal throughout the entire measurement range. The signal processing module (3) is configured to: determine the validity of the position signal output by each detector module in real time; when only one detector module outputs a valid position signal (such as 111) at the splicing point of the gratings (2), calculate the absolute position based on the valid position signal (111) and the current grating segment information; when at least two detector modules output valid position signals (111, 121) at the same time, perform fusion calculation on the valid signals to improve the accuracy and reliability of the position information. The signal processing module (3) acquires the position information within the entire measurement range by collecting and fusing the position signals (111) and (121) along the entire length. (V) Detailed Implementation The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly. In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention. Example 1: Figure 4An embodiment of a parallel stitched absolute ultra-long distance linear measurement system is given. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) in the system includes a light source (100) and at least two detector modules (110) and (120); the grating (2) has code tracks (210) on a grating substrate (200) for position measurement. The light emitted by the light source (100) is modulated by the incremental code track (211) and the absolute code track (213) on the grating scale, and after being received by the detector module (110), it is converted by photoelectric conversion to output position signal (111) and absolute signal (113) respectively; the light emitted by the light source is modulated by the incremental code track (211) and the absolute code track (213) on the grating scale, and after being received by the detector module (120), it is converted by photoelectric conversion to output position signal (121) and absolute signal (123) respectively. The system achieves ultra-long-distance measurement by splicing several segments of the grating (2), and the splicing method is configured to ensure that at least one detector module can receive a valid modulated optical signal throughout the entire measurement range. When the read head (1) passes through the splicing point of the grating (2), the detector module (110) outputs a valid position signal (111) and an absolute signal (113), and at this time, at least another detector module (120) outputs a valid position signal (121) and an absolute signal (123). There is a preset or accidentally formed distance difference between two adjacent segments of the grating (2) at the splicing point. The distance difference at the splicing point is characterized by recording the number of increment cycles, subdivision displacement, etc. of the position signal (111) and / or position signal (121) between two absolute codes of the absolute signal (113) and absolute signal (123). The signal processing module (3) is configured to determine the grating position segment where the read head is located by identifying the unique feature of this distance difference. The signal processing module (3) collects position signal (111), absolute signal (113) and position signal (121), absolute signal (123) and performs fusion calculation to obtain position information within the entire measurement range. Example 2: Figure 5An embodiment of a serially spliced ​​single-track ultra-long-distance linear measurement system is given. The system consists of a read head (1), a grating (2), and a signal processing module (3). The read head (1) includes a collimated light source (100) and at least two detector modules (110) and (120). The grating (2) has a code track (210) on a grating substrate (200) for position measurement. To increase the installation tolerance, a reference code track (212) is embedded in a periodic incremental code track (211), thereby forming a single composite code track. The light emitted by the light source is modulated by this single code track, simultaneously containing incremental information and reference point information. After being received and processed by the detector module (110), the position signal (111) and the reference position signal (112) can be separated and output; after being received and processed by the detector module (120), the position signal (121) and the reference position signal (122) can be separated and output. Several gratings (2) are serially spliced ​​to achieve long-distance testing. Their layout matches the spacing between the two detector modules in the read head to ensure that at least one detector module can receive a valid position signal throughout the entire measurement range. When the read head (1) moves such that one of the detector modules (e.g., 120) passes through the splicing point of the gratings (2), the incremental position signal (121) output by that module may be inaccurate due to being in a dead zone, but it can still accurately decode and output the reference position signal (122) at the splicing point. At the same time, at least another detector module (110) remains within the previous valid grating area and outputs a valid and accurate position signal (111). There is a preset or accidental distance difference between two adjacent grating segments (2) at the splicing point. The signal processing module (3) is configured to: upon receiving the reference position signal (122) output by the detector module (120), simultaneously record the precise incremental reading (such as the subdivision displacement within a specific period) corresponding to the effective position signal (111) output by the detector module (110) at this time. This pair of associated data (122, 111) uniquely characterizes the distance difference feature at the splicing point. By identifying this feature, the signal processing module (3) can accurately determine the absolute position segment that the read head is currently entering. In addition, the signal processing module (3) is also configured to: determine the validity of the position signals (111, 121) output by each detector module in real time. When only one detector module outputs a valid position signal (such as 111) at the grating splicing point, the absolute position is calculated based on the valid position signal (111) and the identified current grating segment information; when two detector modules are simultaneously in the valid measurement area and output valid position signals (111, 121), the two signals are fused to improve the accuracy and reliability of the position information. Through the effective acquisition and intelligent processing of all signals along the entire splicing length, the signal processing module (3) finally obtains continuous and high-precision position information throughout the entire measurement range.

Claims

1. An ultra-long distance linear measuring system; characterized in that, The system comprises a reading head (1), a grating (2) and a signal processing module (3); The reading head (1) comprises a light source (100) and at least two detector modules (110, 120); The grating (2) is composed of code channels (210) arranged on a grating substrate (200) and is used for position measurement; the system realizes ultra-long distance measurement by splicing several segments of the grating (2), and the splicing mode is configured to ensure that at least one of the detector modules can receive an effective modulated light signal within the entire measurement range. The at least two detector modules (110, 120) are used for receiving light signals modulated by the code channels (210) and performing photoelectric conversion to respectively output position signals (111, 121). The signal processing module (3) is used for collecting and fusing the position signals (111, 121) to obtain and output continuous position information covering the entire measurement range.

2. An ultra long distance linear measuring system according to claim 1; characterized in that, The light source (100) is any one or a combination of a collimated light source, a divergent light source, a point light source, a surface light source, a volume light source, a multi-color light source or a complex light source.

3. The ultra-long distance linear measurement system according to claim 1, wherein the grating (2) is any one of a rectangular grating, a sinusoidal grating, a blazed grating, a step grating or a volume grating; and / or the grating (2) is any one of a transmissive grating, a reflective grating, a diffractive grating or an interference grating.

4. An ultra long distance linear measuring system according to claim 1; characterized in that, characterized in that, The material of the grating substrate (200) can be a light-proof process or material such as a steel alloy, an aluminum alloy or a plated metal, or a light-transmissive or partially light-transmissive process or material such as glass or plastic; and / or the shape of the grating (2) is a linear grating ruler, a circular code disc or any other shape of a motion track.

5. The ultra long distance linear measuring system according to claim 1, characterized in that The code channels (210) modulate light by absorption, reflection, transmission, scattering, interference or diffraction; and / or the code channels (210) include at least one of an incremental code channel (211), a reference code channel (212) and an absolute code channel (213), or a mixed code channel thereof.

6. An ultra long distance linear measuring system according to claim 1; characterized in that, The splicing mode of the grating (2) is any one of parallel splicing, serial splicing or mixed serial-parallel splicing.

7. The ultra-long distance linear measuring system according to claim 1 or 6, characterized in that The physical spacing of the at least two detector modules (110, 120) in the reading head (1) matches the splicing layout of the grating (2) to realize coverage of a measurement blind area at the splicing position and seamless switching of the position signals.

8. An ultra long distance linear measuring system according to claim 1, 5 or 7; characterized in that, The gratings (2) can have the same template or type, and the distance difference between the adjacent two segments of the gratings (2) at the splicing position is preset or accidentally formed. The signal processing module (3) is configured to determine the absolute position segment of the reading head by identifying the unique feature of the distance difference, wherein the feature of the distance difference includes but is not limited to the number of incremental periods, the amount of subdivided displacement and the absolute code difference value between the reference code channels (212) or the absolute code channels (213).

9. The ultra long distance linear measuring system according to claim 1, characterized in that The signal processing module (3) is configured to judge the validity of the position signals output by each detector module in real time; when only one detector module outputs a valid signal, the absolute position is calculated according to the valid signal and the current grating segment information; when at least two detector modules output valid signals at the same time, the valid signals are fused and calculated to improve the accuracy and reliability of the position information.

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