An absolute grating sensor

Abstract

This application discloses an absolute grating sensor, including a light source module for generating partially coherent light; a grating module including a grating ruler disposed in the light output path of the light source module to modulate the partially coherent light into a characteristic fringe pattern; a plurality of light-transmitting units and light-blocking units are alternately disposed on the grating ruler, each light-transmitting unit forming a gap with its adjacent light-blocking unit on one side, and the partially coherent light covering at least two adjacent light-transmitting units of the grating ruler; a receiving module correspondingly disposed to the light source module for receiving the characteristic fringe pattern and converting it into an electrical signal; a processing module for performing cross-correlation calculation on the electrical signal to determine the positional offset of the target object; wherein, the grating ruler is movably disposed between the light source module and the receiving module along its length direction; this application can realize absolute displacement detection, avoid the influence of cumulative errors, and ensure the accuracy and reliability of the detection results.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sensors, and particularly relates to an absolute grating sensor. BACKGROUND

[0002] In the industrial production fields such as printing, textile and lithium battery manufacturing, real-time position correction of moving objects such as paper, cloth and pole pieces needs to be performed by a deviation correction sensor to guarantee product quality and production efficiency. The position deviation information of the objects needs to be accurately captured in the production process to adapt to the high-speed running scene of the production line.

[0003] At present, the commonly used deviation correction sensors generally have the problems of large size and insufficient integration, and are difficult to adapt to compact production line layouts. The measurement results of some schemes depend on continuous accumulation, which is easy to be affected by accumulation errors and cannot realize absolute detection of the target objects, thereby limiting the application of the sensors in high-precision deviation correction scenes to some extent. SUMMARY

[0004] The application provides an absolute grating sensor, which can realize absolute displacement detection, avoid the influence of accumulation errors and ensure the accuracy and reliability of the detection results.

[0005] To solve the above technical problems, the application provides an absolute grating sensor, which comprises:

[0006] A light source module for generating partially coherent light;

[0007] A grating module comprising a grating ruler arranged in the light path of the light source module to modulate the partially coherent light into a characteristic fringe pattern; a plurality of light-transmitting units and light-blocking units are alternately arranged on the grating ruler, a gap interval is formed between each light-transmitting unit and its single-side adjacent light-blocking unit, the widths of the gap intervals are different from each other, and the partially coherent light covers at least two adjacent light-transmitting units of the grating ruler.

[0008] A receiving module arranged correspondingly to the light source module and configured to receive the characteristic fringe pattern and convert it into an electrical signal;

[0009] A processing module configured to perform cross-correlation calculation on the electrical signal to determine the position deviation of a target object.

[0010] The grating ruler is movably arranged between the light source module and the receiving module along the length direction of the grating ruler, the light-transmitting unit comprises one or more continuous light-transmitting fringes, the light-blocking unit comprises one or more continuous light-blocking fringes, and the plurality of light-transmitting fringes and the plurality of light-blocking fringes are continuously arranged in a pseudo-random sequence.

[0011] As a further improvement of the present application, the light source module comprises a light emitting element and a spatial filter arranged between the light emitting element and the grating ruler.

[0012] The spatial filter is configured to convert the light signal emitted by the light emitting element into the partially coherent light, and the light emitting element comprises a wide-spectrum LED or a low-coherence laser.

[0013] As a further improvement of the present application, the wavelength range of the partially coherent light is 400 nm to 800 nm, and the coherence length is 5 μm to 50 μm.

[0014] As a further improvement of the present application, two adjacent light-transmitting units and a light-blocking unit arranged between the two light-transmitting units form a double-slit structure, and the partially coherent light is split into interference fringes after passing through the double-slit structure.

[0015] When the grating ruler moves along a preset direction, the interference fringes are modulated by the pseudo-random sequence arrangement of the light-transmitting fringes and the light-blocking fringes on the grating ruler to form the characteristic fringe pattern.

[0016] As a further improvement of the present application, the pseudo-random sequence is a Gold sequence or an M sequence, the light-transmitting fringes correspond to a coded number in the pseudo-random sequence, and the light-blocking fringes correspond to a coded number different from the light-transmitting fringes in the pseudo-random sequence.

[0017] The number of consecutive coded numbers in the pseudo-random sequence is the same as the number of consecutive fringes of the corresponding type.

[0018] As a further improvement of the present application, the light-transmitting unit and the adjacent light-blocking unit on one side of the grating ruler along the length extension direction of the grating ruler form a gap interval, and a plurality of gap intervals are arranged continuously on the grating ruler.

[0019] As a further improvement of the present application, the receiving module is a linear array CCD image sensor or a linear array CMOS image sensor, and the receiving module is configured to sense the light intensity distribution of the characteristic fringe pattern to convert into an electrical signal.

[0020] As a further improvement of the present application, the processing module is configured to extract a real-time light intensity sequence from the received electrical signal, perform cross-correlation operation on the real-time light intensity sequence and a pre-stored reference template to obtain a cross-correlation result sequence.

[0021] And, the peak position of the cross-correlation result sequence is fitted by a Gaussian function to determine a correlation peak offset, and based on a preset correspondence relationship between the correlation peak offset and a displacement offset, the position offset of the target object is determined.

[0022] The reference template is a standard light intensity sequence corresponding to the pseudo-random sequence arrangement of the grating ruler.

[0023] As a further improvement of the present application, the formula of the cross-correlation operation is ;

[0024] Wherein, C (δ) is the cross-correlation result, I (n) is the real-time light intensity sequence, R (n) is the reference template, and δ is the correlation peak shift.

[0025] As a further improvement of the present application, the grating ruler comprises a quartz substrate, and a plurality of light-transmitting units and light-blocking units etched along the length extension direction of the quartz substrate.

[0026] The absolute grating sensor provided by the present application has the following beneficial effects:

[0027] The present application generates a partially coherent light by the light source module to irradiate the grating ruler, and the partially coherent light covers at least two adjacent light-transmitting units of the grating ruler. Since the light-transmitting stripes and the light-blocking stripes on the grating ruler are continuously arranged in a pseudo-random sequence, and the gap interval widths formed by each light-transmitting unit and its single-side adjacent light-blocking unit are different from each other, the partially coherent light will form a characteristic stripe pattern with a unique position identifier after passing through these uniquely arranged units and gaps. When the grating ruler moves along the length direction with the measured object, the position change of the grating ruler will synchronously drive the corresponding change of the characteristic stripe pattern. The receiving module is correspondingly arranged with the light source module, so as to capture the changed characteristic stripe pattern in real time and convert it into an electrical signal. The processing module determines the position shift of the target object by performing cross-correlation calculation on the electrical signal. The present application can realize absolute displacement detection without cumulative error, avoid the influence caused by cumulative error, and ensure the accuracy and reliability of the detection result. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only represent a part of the embodiments of the present application, and not all the embodiments. For those skilled in the art, other drawings obtained according to these drawings without creative labor belong to the scope of protection of the present application.

[0029] Figure 1 The functional module diagram of the absolute grating sensor provided by the present application.

[0030] Figure 2 The structural schematic diagram of the absolute grating sensor provided by the present application.

[0031] Figure 3This is a schematic diagram of the slit spacing in the absolute grating sensor provided in the embodiments of this application.

[0032] Figure 4 A specific embodiment of the absolute grating sensor provided in this application is shown in the figure.

[0033] Figure 5 A comparison diagram of the absolute grating sensor provided in the embodiments of this application and related technologies.

[0034] Figure 6 This is a schematic diagram of the structure of the first interference optical path in the absolute grating sensor provided in the embodiments of this application.

[0035] Figure 7 This is a schematic diagram of the structure of the second interference optical path in the absolute grating sensor provided in the embodiments of this application.

[0036] Figure 8 This is a schematic diagram of the third interference optical path in the absolute grating sensor provided in the embodiments of this application.

[0037] Figure 9 for Figures 6 to 8 A composite image of the characteristic stripe pattern shown.

[0038] Figure 10 The diagram shows the distribution of diffracted light intensity as a function of phase difference in the absolute grating sensor provided in this application embodiment. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0040] To make the description of this disclosure more detailed and complete, illustrative descriptions of the implementation methods and specific embodiments of this application are provided below; however, this is not the only form of implementing or utilizing the specific embodiments of this application. The implementation methods cover the features of multiple specific embodiments and the method steps and their order for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and in the above drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0042] In the description of the embodiments of the present application, unless otherwise specified, " / " represents the meaning of or, for example, A / B can represent A or B; "and / or" in the text only describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are three cases of A alone, A and B together, and B alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two, and other quantifiers similar thereto should be understood. The preferred embodiments described herein are only used to illustrate and explain the present application, and do not limit the present application, and in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0043] In the industrial production fields of printing, textile, lithium battery manufacturing, etc., it is necessary to correct the real-time position of the moving objects such as paper, cloth, pole piece, etc. by the deviation sensor to ensure product quality and production efficiency. The position deviation information of the object needs to be accurately captured in this production process to adapt to the high-speed running scene of the production line.

[0044] At present, the commonly used deviation sensor generally has the problems of large volume and insufficient integration, which is difficult to adapt to the compact production line layout. The measurement result of the sensor of some schemes depends on continuous accumulation, which is easy to be affected by accumulation error to cause deviation accuracy, and cannot realize absolute detection of the target object, which limits its application in high-precision deviation scene to some extent.

[0045] Please refer to Figures 1-10 The present application provides an absolute grating sensor which can realize absolute displacement detection, avoid the influence caused by accumulation error, and ensure the accuracy and reliability of the detection result. Please refer to Figure 1 The functional module diagram of the absolute grating sensor provided by the embodiments of the present application is provided, which includes a light source module, a grating module, a receiving module and a processing module.

[0046] In the embodiments of the present application, the light source module is used to generate partially coherent light. Compared with ordinary light sources, partially coherent light can effectively suppress speckle noise and improve the adaptability of the sensor in complex industrial environments.

[0047] Further, please refer to Figure 2The absolute grating sensor provided by the embodiment of the present application has a structure diagram as shown in FIG. 1. The grating module includes a grating ruler arranged in the light path of the light source module. The present application alternately arranges a plurality of light-transmitting units and light-blocking units on the grating ruler (not shown in the figure). A gap interval is formed between each light-transmitting unit and the light-blocking unit adjacent to one side of the light-transmitting unit. The present application sets the widths of the gap intervals to be different from each other. The partially coherent light should cover at least two light-transmitting units adjacent to each other on the grating ruler.

[0048] Specifically, please refer to Figure 3 The absolute grating sensor provided by the embodiment of the present application has a structure diagram of the gap interval as shown in FIG. 2. The present application movably arranges the grating ruler along the length direction between the light source module and the receiving module. Each light-transmitting unit includes one or more continuous light-transmitting stripes. Similarly, each light-blocking unit includes one or more continuous light-blocking stripes. The present application continuously arranges the plurality of light-transmitting stripes and the plurality of light-blocking stripes in a pseudo-random sequence. In this way, each region on the grating ruler has a unique feature code, which fundamentally avoids the error accumulation problem caused by the continuous accumulation in the traditional detection scheme.

[0049] In the embodiment of the present application, the light-transmitting stripes and the light-blocking stripes on the grating ruler are arranged in a pseudo-random sequence, so that the gap intervals between each light-transmitting unit and the light-blocking unit adjacent to one side of the light-transmitting unit are different from each other. Please further refer to Figure 3 , Figure 3 is the corresponding grating ruler structure when the code segment is 【10101010】. “1” is the light-transmitting stripe, and “0” is the light-blocking stripe. In this way, a gap interval is formed between each light-transmitting unit and the light-blocking unit adjacent to one side of the light-transmitting unit, which corresponds to the gap intervals d1, d2 and d3 in the figure respectively.

[0050] On this basis, the widths of the gap intervals are limited to be different from each other, i.e. d1≠d2≠d3≠(......).

[0051] It should be noted that Figure 3 only shows the corresponding grating ruler structure when the code segment is 【1010101010】. Each light-transmitting unit in the grating ruler includes only one light-transmitting stripe, and each light-blocking unit includes only one light-blocking stripe. However, in actual application, each light-transmitting unit can include one or more continuous light-transmitting stripes, and similarly, each light-blocking unit can include one or more continuous light-blocking stripes. In this case, the gap intervals should also be different from each other to ensure that each local region of the grating ruler has a unique coding feature, so as to realize the absolute displacement detection without cumulative error.

[0052] Further, since the partially coherent light covers at least two adjacent light-transmitting units of the grating ruler, when the partially coherent light transmits through the two adjacent light-transmitting units, the two adjacent light-transmitting units and the light-blocking unit arranged therein jointly form a double-slit structure.

[0053] In this way, the partially coherent light is diffracted at the double-slit structure to form interference fringes, and the light-transmitting fringes and the light-blocking fringes arranged in a pseudo-random sequence on the grating ruler spatially modulate the interference fringes, thereby forming a characteristic fringe pattern with unique coding and non-periodicity, that is, the position information of the grating ruler corresponding to the characteristic fringe pattern is unique, and the current position can be identified at any starting point of movement without relying on initial position calibration, thereby realizing absolute displacement measurement without cumulative error.

[0054] In an optional embodiment, the application corresponds to the light source module and the receiving module, and the grating ruler is movably arranged between the light source module and the receiving module along the length direction, the modulated characteristic fringe pattern is obtained through the receiving module, and the light intensity distribution of the characteristic fringe pattern is converted into an electrical signal through sensing.

[0055] On this basis, the processing module is connected to the receiving module in a wired or wireless manner, and the electrical signal output by the receiving module is subjected to cross-correlation calculation and processing to obtain the position offset of the target object.

[0056] Specifically, when the grating ruler moves along the length direction with the target object, the characteristic fringe pattern is translated synchronously with the grating ruler, and the corresponding light intensity distribution and electrical signal also change accordingly, and the processing module can capture the correlation peak offset corresponding to the change through cross-correlation operation, and then convert the position offset of the target object, thereby realizing absolute displacement detection without cumulative error, high precision and anti-interference.

[0057] As an optional implementation, please refer to Figure 4 The specific embodiment of the absolute grating sensor provided by the embodiment of the application is shown in the figure, the length direction of the grating ruler is the preset direction, the light source module and the receiving module are oppositely arranged, and the grating module is arranged between the light source module and the receiving module, and the grating ruler is controlled to move bidirectionally along the preset direction through a certain driving structure (not shown in the figure).

[0058] In the embodiment of the application, the light source module, the grating module and the receiving module are integrated in the absolute grating sensor, specifically, the light source module and the receiving module are fixedly arranged in the absolute grating sensor, and the grating ruler of the grating module is movably arranged in the absolute grating sensor through a certain driving structure, and the grating ruler is directly abutted with the measured object for displacement detection.

[0059] Specifically, the light source module emits partially coherent light to the grating ruler in abutment with the measured object, the grating ruler moves synchronously with the measured object, and the pseudo-random arrangement of the light-transmitting units and the light-blocking units on the grating ruler modulates the partially coherent light to form a characteristic fringe pattern with unique coding information. Then, the receiving module receives the pattern and converts it into an electrical signal, and the processing module performs cross-correlation calculation on the electrical signal to determine the position offset of the target object in combination with the coding characteristics of the grating ruler and the preset conversion relationship.

[0060] During the entire detection process, only the grating ruler is in abutment with the measured object and moves synchronously, and the light source module, the receiving module, and the processing module are fixed in the sensor and remain stationary, thereby ensuring the stability of the light signal transmission and reception path, accurately capturing the change in light intensity when the grating ruler moves, and realizing high-precision displacement detection.

[0061] It should be noted that the above-mentioned driving structure can be selected according to the use requirements, such as a motor driving structure, a screw transmission structure, a transmission belt driving structure, etc. Other driving structures that can ensure the accurate synchronous movement of the grating ruler with the displacement of the measured object and guarantee the stability and reliability of displacement transmission are also feasible, and the present application does not make specific limitations thereto.

[0062] Further, please refer to Figure 5 The absolute grating sensor provided by the embodiment of the present application and the related art are compared in the figure. Since the partially coherent light covers at least two adjacent light-transmitting units of the grating ruler, the two adjacent light-transmitting units and the light-blocking unit arranged between the two light-transmitting units form a double-slit structure, so that the partially coherent light is split into interference fringes after passing through the double-slit structure. When the grating ruler moves along the preset direction, the interference fringes are modulated by the pseudo-random sequence arrangement of the light-transmitting fringes and the light-blocking fringes on the grating ruler to form a characteristic fringe pattern.

[0063] In Figure 5 It can be observed that L12 < L22, which is because the lens is usually used to realize light signal regulation in the related art, and the thickness of the lens is usually large, which leads to a large overall volume of the sensor and a bulky structure, making it difficult to adapt to some space-limited precision detection scenes. The grating ruler used in the present application is thinner, so that the overall structure of the sensor is more compact and lightweight while realizing the core function of light signal modulation, flexibly adapting to more detection requirements in narrow spaces and improving the scene applicability of the sensor.

[0064] In an optional embodiment, the pseudo-random sequence is set as a Gold sequence or an M sequence, the light-transmitting stripes correspond to one coded number in the pseudo-random sequence, the light-blocking stripes correspond to a coded number different from the light-transmitting stripes in the pseudo-random sequence, and the number of continuous coded numbers in the pseudo-random sequence is limited to be the same as the number of continuous stripes of the corresponding type, so as to establish the correspondence between the light-blocking stripes, the light-transmitting stripes and the coded numbers.

[0065] It should be noted that the M sequence is a binary sequence with the longest period generated by a linear feedback shift register, which has good pseudo-randomness, the number of "0" and "1" in the sequence is approximately equal, and only when the sequence is completely matched, the peak value is presented, and when the sequence is misaligned, the correlation value decreases rapidly. This feature can quickly identify the encoding area of the grating ruler.

[0066] The Gold sequence is a binary sequence obtained by exclusive OR operation of two M sequences with the same period and different code types, and the period is the same as the M sequence. Compared with the M sequence, the Gold sequence can generate a larger number of sequence sets, and the mutual correlation characteristics between the sequences are excellent, and also has good pseudo-randomness and identification ability, which is suitable for scenes requiring multiple encoding schemes.

[0067] The pseudo-random sequence is set as a Gold sequence or an M sequence in the application is a preferred embodiment, but is not limited thereto. In other optional embodiments, as long as the sequence used meets the requirements of aperiodicity, good autocorrelation characteristics and local uniqueness, for example, other sequences generated by LFSR, Barker code, etc., can be used to construct the arrangement form of the light-blocking stripes and the light-transmitting stripes in the grating ruler, and the application does not limit this.

[0068] The mapping relationship between the pseudo-random sequence and the light-blocking stripes and the light-transmitting stripes will be explained in the following specific embodiments.

[0069] For example, when the encoding segment is 【10 1 1 0 0 1】, since the light-transmitting stripes correspond to one coded number in the pseudo-random sequence, and the light-blocking stripes correspond to a coded number different from the light-transmitting stripes in the pseudo-random sequence, "1" is set as the light-transmitting stripe and "0" is set as the light-blocking stripe.

[0070] At this time, the arrangement of the light-blocking stripes and the light-transmitting stripes on the grating ruler corresponding to the example code segment 【1 0 1 1 0 0 1】 is: “the first light-transmitting stripe, the first light-blocking stripe, the second light-transmitting stripe, the third light-transmitting stripe, the second light-blocking stripe, the third light-blocking stripe, and the fourth light-transmitting stripe”. Since each light-transmitting unit includes one or more continuous light-transmitting stripes, and each light-blocking unit includes one or more continuous light-blocking stripes, the arrangement of the light-transmitting units and the light-blocking units on the grating ruler corresponding to the example code segment 【1 0 1 1 0 0 1】 is: “the first light-transmitting unit, the first light-blocking unit, the second light-transmitting unit, the second light-blocking unit, and the third light-transmitting unit”.

[0071] Specifically, the first light-transmitting unit includes the first light-blocking stripe, the first light-blocking unit includes the first light-blocking stripe, the second light-transmitting unit includes the second light-transmitting stripe and the third light-transmitting stripe, the second light-blocking unit includes the second light-blocking stripe and the third light-blocking stripe, and the third light-blocking unit includes the fourth light-transmitting stripe.

[0072] In another embodiment, the example code segment is set to 【1 1 1 0 0 1 1】, and the arrangement of the light-blocking stripes and the light-transmitting stripes on the grating ruler corresponding to the example code segment is: “the first light-transmitting stripe, the second light-transmitting stripe, the third light-transmitting stripe, the first light-blocking stripe, the second light-blocking stripe, the fourth light-transmitting stripe, and the fifth light-transmitting stripe”. Since each light-transmitting unit includes one or more continuous light-transmitting stripes, and each light-blocking unit includes one or more continuous light-blocking stripes, the arrangement of the light-transmitting units and the light-blocking units on the grating ruler corresponding to the example code segment 【1 1 1 0 0 1 1】 is: “the first light-transmitting unit, the first light-blocking unit, and the second light-transmitting unit”.

[0073] Specifically, the first light-transmitting unit includes the first light-transmitting stripe, the second light-transmitting stripe, and the third light-transmitting stripe, the first light-blocking unit includes the first light-blocking stripe and the second light-blocking stripe, and the second light-transmitting unit includes the fourth light-transmitting stripe and the fifth light-transmitting stripe.

[0074] As can be seen, the number and arrangement order of “1” and “0” in the example code segment determine the distribution form of the corresponding stripes. This unique arrangement enables each region of the grating ruler to be distinguished from other regions, ensures that each local region of the grating ruler forms a unique code feature, and realizes absolute displacement detection without cumulative error. The present application does not make too much enumeration and elaboration on how the light-transmitting stripes and the light-blocking stripes are continuously arranged according to the pseudo-random sequence.

[0075] As an optional implementation, the light source module provided in the application comprises a light emitting element and a spatial filter arranged between the light emitting element and the grating ruler, and the spatial filter is used to convert the light signal emitted by the light emitting element into partially coherent light.

[0076] Preferably, a wide-spectrum LED or a low-coherence laser is arranged as the light emitting element. The wide-spectrum LED has the advantages of controllable cost, strong light emitting stability and matching of the spectral range to most industrial detection scenes, and can effectively reduce the production and application cost of the sensor; the low-coherence laser has excellent light signal directivity, can reduce the divergence loss of light in the propagation process, and is particularly suitable for detection scenes with high requirements for light signal directivity.

[0077] In an optional embodiment, the wavelength range of the partially coherent light is 400 nm to 800 nm, and the coherence length is 5 μm to 50 μm.

[0078] Specifically, the wavelength range of 400 nm to 800 nm can cover the visible light to near-infrared band, and the coherence length of 5 μm to 50 μm can ensure that the light signal forms clear and high-contrast interference fringes between adjacent light transmission units of the grating ruler, avoiding the loss of encoding information of the characteristic fringe pattern due to the blurring of the interference fringes.

[0079] As an optional implementation, the application limits the gap interval between each light transmission fringe and the adjacent light shielding unit on one side along the length extension direction of the grating ruler, so that a plurality of gap intervals are arranged continuously on the grating ruler.

[0080] It should be noted that the length extension direction of the grating ruler can be understood as the arrangement direction of the pseudo-random code, which should be distinguished from the preset direction of the movement of the grating ruler, that is, the length extension direction of the grating ruler is unidirectional, while the preset direction of the movement is bidirectional.

[0081] Preferably, the receiving module is arranged as a linear array CCD image sensor or a linear array CMOS image sensor, which is used to sense the light intensity distribution of the characteristic fringe pattern and convert it into an electrical signal. The linear array CCD sensor has extremely low noise level and excellent light signal integration capability, can output light intensity signals with higher signal-to-noise ratio in scenes with strong environmental light interference, and reduce the interference of stray light on the encoding information; the linear array CMOS sensor has the advantages of high integration, fast response speed and low power consumption, and can realize fast conversion of the light signal to the electrical signal, meeting the real-time and high-precision detection requirements.

[0082] As an optional implementation, the processing module provided in the application can extract a real-time light intensity sequence from the received electrical signal, and perform cross-correlation calculation on the real-time light intensity sequence and a pre-stored reference template to obtain a cross-correlation result sequence.

[0083] And, by Gaussian fitting the peak position of the cross-correlation result sequence to determine a correlation peak offset, based on a preset correspondence relationship between the correlation peak offset and the displacement offset, determining the position offset of the target object; wherein the reference template is a standard light intensity sequence corresponding one-to-one with the pseudo-random sequence arrangement of the grating ruler.

[0084] Further, the formula of the above cross-correlation operation is ; wherein C (δ) is the cross-correlation result, I (n) is the real-time light intensity sequence, R (n) is the reference template, and δ is the correlation peak offset.

[0085] As an optional implementation, please refer to Figures 6-9 , wherein Figure 6 is the structural schematic diagram of the first interference light path in the absolute grating sensor provided by the embodiments of the present application, Figure 7 is the structural schematic diagram of the second interference light path in the absolute grating sensor provided by the embodiments of the present application, Figure 8 is the structural schematic diagram of the third interference light path in the absolute grating sensor provided by the embodiments of the present application, Figure 9 is Figures 6 to 8 the synthesized image of the feature stripe pattern shown in the figure.

[0086] It can be observed that the partially coherent light emitted by the light-emitting element covers at least two adjacent light-transmitting units of the grating ruler, i.e. covers the double-slit structure marked at the grating ruler, and the light-emitting area of the light-emitting element in the figure is substantially the light-emitting area corresponding to the entire line segment, and the circular ring only represents the current light-emitting point and does not limit the light-emitting element to emit light only at a single point.

[0087] On this basis, Figures 6-8 respectively represent the interference light paths and the corresponding feature stripe patterns when the light-emitting point is located in the middle, the top and the bottom of the line segment, which means that when passing through the grating ruler, the original sinusoidal light signal waveform is modulated by the grating ruler into a feature stripe pattern.

[0088] Specifically, when the height position of the light-emitting point is different, the propagation path of the light signal incident to the grating ruler (i.e. the interference light path) will be different, which is reflected in the feature stripe pattern. Although the details of the light and dark distribution of the stripes of each figure are slightly different, the core coding features that the stripes of each figure maintain one-to-one correspondence with the pseudo-random sequence of the grating ruler, i.e. the alternating law of light transmission and light shielding of the stripes, the consistent interval and width of the key stripes, are not missed or distorted due to the change of the position of the light-emitting point.

[0089] Figure 9 is Figures 6-8The schematic diagram of the superimposed feature stripe pattern of the absolute grating sensor, further visually presents the feature stripe pattern under different light emitting positions, and after superposition, no stripe confusion or encoding failure occurs, but the overlap and reinforcement of the core encoding area in each pattern can be clearly seen, which does not affect the identification of the overall encoding information, further verifying the reliability of the scheme, and ensuring that it can also achieve stable detection in complex industrial scenes.

[0090] Further, the electrical signal output by the receiving module is essentially the light intensity distribution of the feature stripe pattern, and the stripe arrangement of each local area on the grating ruler is unique, and the corresponding light intensity sequence also has uniqueness. The reference template is a standard light intensity sequence corresponding one-to-one with the pseudo-random sequence of the grating ruler, and when the grating ruler moves along the preset direction, the real-time light intensity sequence will be synchronized with the standard light intensity sequence.

[0091] When performing cross-correlation calculation, the processing module compares the real-time light intensity sequence and the reference template along the displacement dimension, and calculates the similarity under different offsets through the formula When the real-time light intensity sequence and a certain standard light intensity sequence in the reference template are aligned and matched, the cross-correlation result (δ) will have a significant peak value at the alignment position, and then the displacement of the grating ruler is determined according to the correlation peak offset δ corresponding to the peak value.

[0092] In the embodiment of the present application, please refer to Figure 10 The distribution graph of the diffraction light intensity in the absolute grating sensor provided by the embodiment of the present application with respect to the phase difference, in which the horizontal coordinate is "phase difference fai", i.e. phase difference, in radian, reflecting the phase difference of the light signal caused by different gap widths of the grating ruler, and the vertical coordinate is "relative intensity I", which is a dimensionless relative light intensity value, used to represent the light intensity under different phase differences, further verifying the rationality of the processing module in determining the current displacement of the grating ruler by comparing the light intensity sequences through the cross-correlation algorithm.

[0093] However, since the pixel sampling of the receiving module is discrete, the accuracy of the directly read peak position is limited, and it cannot meet the nanoscale detection requirement, therefore, the Gaussian fitting technology is introduced in the present application to continuously fit the peak value area of the cross-correlation result sequence with a curve, and based on the preset corresponding relationship between the correlation peak offset and the displacement offset, the accurate calculation of the displacement of the target object is realized.

[0094] It should be noted that the preset correspondence between the correlation peak offset and the displacement offset refers to the quantitative conversion relationship between the correlation peak offset and the actual displacement offset of the target object. For example, the corresponding correlation peak offset δ and the actual displacement offset of the target object after each movement are collected in advance to determine the quantitative conversion relationship therebetween. The above conventional technology is well known to those skilled in the art in the research and development of high-precision displacement detection devices, and the determination of the preset relationship will not be described in detail herein.

[0095] In an optional embodiment, the grating ruler provided by the application comprises a quartz substrate and a plurality of light-transmitting units and light-blocking units etched along the length extension direction of the quartz substrate, and is preferably prepared by using an electron beam lithography process.

[0096] It can be understood that the quartz substrate itself is a highly transparent material. Along the length extension direction of the quartz substrate, the light-blocking units are etched in the region of the light-blocking units by using a lithography process to form the light-blocking units, and the region of the quartz substrate which is not etched forms the light-transmitting units by maintaining the original transparent properties. Finally, the grating ruler presents a structure in which the light-blocking units and the light-transmitting units are alternately arranged in a pseudo-random sequence.

[0097] In an optional embodiment, the processing module can be in the form of an FPGA (Field-Programmable Gate Array). In addition, according to actual application scenarios and performance requirements, the processing module can also be in the form of a common processor such as an MCU (Microcontroller Unit) or a SoC (Digital Signal Processor). As long as the processing module can realize the correlation calculation of the above-mentioned electric signals and the determination of the position offset, the form of the processing module is feasible, and the application does not make specific limitations thereto.

[0098] The absolute grating sensor provided by the application, part coherent light is generated by a light source module and irradiated to a grating ruler, the part coherent light covers at least two adjacent light transmission units of the grating ruler, due to the fact that the light transmission stripes and the light shielding stripes on the grating ruler are continuously arranged in a pseudo-random sequence, and the gap interval widths formed by each light transmission unit and its single-side adjacent light shielding unit are not equal to each other, the part coherent light will form a characteristic stripe pattern with unique position identification after passing through these uniquely arranged units and gaps; when the grating ruler moves along the length direction with a measured object, the position change of the grating ruler will synchronously drive the corresponding change of the characteristic stripe pattern, the receiving module is correspondingly arranged with the light source module, the changed characteristic stripe pattern can be captured in real time and converted into an electric signal, and the processing module determines the position offset of the target object by performing cross-correlation calculation on the electric signal, the application can realize absolute displacement detection without cumulative error, avoid the influence caused by cumulative error, and ensure the accuracy and reliability of the detection result.

[0099] It should be noted that, in specific implementation, each module / unit contained in each device / product described in the above embodiments can be a software module / unit, or a hardware module / unit, or part of a software module / unit and part of a hardware module / unit.

[0100] For example, for each device / product applied to or integrated in a chip, each module / unit contained therein can be implemented in the form of hardware such as a circuit, or at least part of the modules / units can be implemented in the form of a software program running on a processor integrated in the chip, and the remaining (if any) modules / units can be implemented in the form of hardware such as a circuit; for each device / product applied to or integrated in a chip module, each module / unit contained therein can be implemented in the form of hardware such as a circuit, and different modules / units can be located in the same component (for example, a chip, a circuit module, etc.) or different components of the chip module, or at least part of the modules / units can be implemented in the form of a software program running on a processor integrated in the chip module, and the remaining (if any) modules / units can be implemented in the form of hardware such as a circuit; for each device / product applied to or integrated in a terminal, each module / unit contained therein can be implemented in the form of hardware such as a circuit, and different modules / units can be located in the same component (for example, a chip, a circuit module, etc.) or different components of the terminal, or at least part of the modules / units can be implemented in the form of a software program running on a processor integrated in the terminal, and the remaining (if any) modules / units can be implemented in the form of hardware such as a circuit.

[0101] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

[0102] In summary, although the present application has been disclosed as above with preferred embodiments, the above-mentioned preferred embodiments are not used to limit the present application, and the description of the specification is only for clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. An absolute grating sensor, characterized by The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device.

2. The absolute encoder sensor of claim 1, wherein, The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device.

3. The absolute encoder sensor of claim 2, wherein, The application relates to a position displacement detection method and device.

4. The absolute encoder sensor of claim 1, wherein, The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device.

5. The absolute encoder sensor of claim 4, wherein, The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device.

6. The absolute optical encoder sensor of claim 1, wherein, The application relates to a position displacement detection method and device.

7. The absolute optical encoder sensor of claim 1, wherein, The application relates to a position displacement detection method and device.

8. The absolute encoder sensor of claim 1, wherein, The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection method and device. The application relates to a position displacement detection Wherein, C (δ) is the cross-correlation result, n is the serial number of the real-time light intensity sequence, I (n) is the real-time light intensity sequence, R (n) is the reference template, and δ is the correlation peak offset.

9. The absolute optical encoder sensor of claim 1, wherein, The grating ruler comprises a quartz substrate and a plurality of light-transmitting units and light-blocking units etched along the length extension direction of the quartz substrate.

Images