An optical displacement detection system and its displacement detection method

Abstract

This invention discloses an optical displacement detection system and method, comprising a first fixed grating, a second fixed grating, a movable grating, and a signal processor. The first and second fixed gratings are sequentially arranged on the same side of the movable grating along the measurement direction. A first light source is located on the side of the first fixed grating away from the movable grating, and a second light source is located on the side of the second fixed grating away from the movable grating. A first optical signal receiver and a second optical signal receiver are respectively provided on the other side of the movable grating for receiving light emitted from the first and second light sources. The first and second optical signal receivers are respectively connected to the signal processor. This invention uses two light sources for displacement detection, resulting in low energy consumption, small space occupation, and greatly increased flexibility in structural design. In use, compared to the motor end connected to a coaxial encoder and magnetic encoder, it can better avoid measurement errors and improve measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of displacement detection technology, specifically to an optical displacement detection system and its displacement detection method. Background Technology

[0002] Currently, displacement detection of moving parts is mainly achieved using coaxial encoders or magnetic encoders. However, in practical applications, both coaxial encoders and magnetic encoders have specific installation requirements, occupy a large amount of space, and have fixed design patterns, making them unsuitable for use in products with limited structural space. Furthermore, ordinary coaxial encoders and magnetic encoders have limited accuracy, posing significant drawbacks for short-distance, high-precision displacement detection. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing an optical displacement detection system and its detection method, which increases the flexibility of the displacement detection system's structural design, improves detection accuracy, and better avoids measurement errors.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] In a first aspect, an optical displacement detection system is proposed, comprising a first fixed grating, a second fixed grating, a movable grating, and a signal processor. The first fixed grating and the second fixed grating are sequentially arranged on the same side of the movable grating along the measurement direction. A first light source is provided on the side of the first fixed grating away from the movable grating, and a second light source is provided on the side of the second fixed grating away from the movable grating. A first optical signal receiver and a second optical signal receiver are respectively provided on the other side of the movable grating for receiving light emitted by the first light source and the second light source. The first optical signal receiver and the second optical signal receiver are respectively connected to the signal processor.

[0006] As a preferred technical solution, the first fixed grating is provided with a plurality of identical first light-transmitting slots distributed along the measurement direction, the second fixed grating is provided with a plurality of identical second light-transmitting slots distributed along the measurement direction, and the movable grating is provided with a plurality of identical third light-transmitting slots distributed along the measurement direction, wherein the spacing between the first light-transmitting slots, the second light-transmitting slots and the third light-transmitting slots is the same.

[0007] As a preferred technical solution, the number of the first light-transmitting groove and the second light-transmitting groove is the same, and the number of the third light-transmitting groove is greater than the number of the first light-transmitting groove and the second light-transmitting groove.

[0008] As a preferred technical solution, the widths of the first light-transmitting groove, the second light-transmitting groove, and the third light-transmitting groove are all the same.

[0009] As a preferred technical solution, the intensity of the optical signal received by the first optical signal receiver is 90 degrees out of phase with the intensity of the optical signal received by the second optical signal receiver.

[0010] As a preferred technical solution, the distances between the first fixed grating, the second fixed grating, and the movable grating are the same.

[0011] As a preferred technical solution, the first fixed grating and the second fixed grating are integrally connected.

[0012] As a preferred technical solution, the first light source and the second light source have the same light intensity and do not interfere with each other.

[0013] Secondly, a displacement detection method is proposed, including the following steps:

[0014] (1) Make the first light source and the second light source emit light of constant intensity, make the movable grating move relative to the first fixed grating and the second fixed grating along the measurement direction, the first light signal receiver receives the light from the first light source passing through the first fixed grating and the movable grating, and the second light signal receiver receives the light from the second light source passing through the second fixed grating and the movable grating.

[0015] (2) The light intensity signals of the light received by the first optical signal receiver and the second optical signal receiver are converted into periodically changing electrical signals y1(x) and y2(x) respectively, and the phase difference between the electrical signals y1(x) and y2(x) is 90 degrees.

[0016] (3) Divide the electrical signals y1(x) and y2(x) within a single cycle into four parts. If y1(x) is less than or equal to 0 and y2(x) is less than 0, record this as the first part. If y1(x) is less than or equal to 0 and y2(x) is greater than or equal to 0, record this as the second part. If y1(x) is greater than 0 and y2(x) is greater than or equal to 0, record this as the third part. If y1(x) is greater than 0 and y2(x) is less than 0, record this as the fourth part. Then perform different operations on each part:

[0017] Part 1: y = ((2*y2(x)min-y2(x)+y1(x))+y2(x)min);

[0018] Part Two: y = (y2(x) + y1(x) + y2(x)min);

[0019] Part 3: y = ((2*y1(x)max-y1(x)+y2(x))+y2(x)min);

[0020] Part 4: y = ((2*y1(x)max - y1(x) - y2(x)) + y2(x)min);

[0021] Here, y2(x)min refers to the minimum value of y2(x), which is equal to y1(x)min, and y1(x)max refers to the maximum value of y1(x), which is equal to y2(x)max. Combining these four parts, we obtain the offset value y of y1(x) and y2(x) that changes periodically with the movement of the moving grating, and the offset value y within the same period is directly proportional to the moving distance of the moving grating.

[0022] (4) The distance the active grating moves relative to the origin is calculated according to the formula L=nd+ykd, where n is the number of cycles of the offset value y, d is the distance the active grating moves for one cycle of the offset value y, y is the offset value of the current cycle calculated in step (3), and k is the proportional coefficient between the offset value y and d.

[0023] As a preferred technical solution, in step (4), the offset values ​​within the same period calculated in step (3) are divided into several segments and sorted by numbers. The moving direction of the active grating is determined according to the order of the change of the numbers.

[0024] Compared with existing technologies, this invention has significant advantages and beneficial effects. Specifically, displacement detection can be achieved by using two light sources, resulting in low energy consumption and small space occupation. The movable grating can be flexibly connected to the lens components, allowing for different connection methods to be designed according to different spaces. Furthermore, the length of the movable grating can be designed according to the movement range of the movable components, further saving space. Compared with the traditional fixed installation mode, it greatly increases the flexibility of structural design. By converting the two optical signals into electrical signals, and then converting the electrical signals of the two light sources into an offset value that is directly proportional to the displacement according to the atan2 function concept, the actual displacement can be obtained quickly and accurately. Since the sampling frequency is proportional to the accuracy, only the sampling frequency needs to be increased to achieve the purpose of high-precision displacement detection. In use, the movable grating can be directly connected to the displacement components, thereby directly detecting the displacement of the displacement components. Compared with the motor end connected to the coaxial encoder and magnetic encoder, it can better avoid measurement errors and improve measurement accuracy.

[0025] To more clearly illustrate the structural features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the detection principle of an embodiment of the present invention;

[0027] Figure 2 This is a signal curve diagram of an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the offset value segmentation sorting according to an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached diagram:

[0030] 10. First fixed grating; 11. First light-transmitting groove; 20. Second fixed grating

[0031] 21. Second light-transmitting groove 30. Movable grating 31. Third light-transmitting groove

[0032] 40, First light source; 50, Second light source; 60, First optical signal receiver

[0033] 70. Second optical signal receiver. Detailed Implementation

[0034] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] like Figure 1As shown, this invention proposes an optical displacement detection system, including a first fixed grating 10, a second fixed grating 20, a movable grating 30, and a signal processor (not shown). The first fixed grating 10 and the second fixed grating 20 are sequentially arranged on the same side of the movable grating 30 along the measurement direction. A first light source 40 is provided on the side of the first fixed grating 10 away from the movable grating 30, and a second light source 50 is provided on the side of the second fixed grating 20 away from the movable grating 30. A first optical signal receiver 60 and a second optical signal receiver 70 are provided on the other side of the movable grating 30 for receiving light emitted by the first light source 40 and the second light source 50, respectively. The first optical signal receiver 60 and the second optical signal receiver 70 are respectively connected to the signal processor. The phase difference between the light signal intensity received by the first optical signal receiver 60 and the light signal intensity received by the second optical signal receiver 70 is 90 degrees. In this invention, the signal processor is an MCU, and the first optical signal receiver 60 and the second optical signal receiver 70 are both photosensitive components. The light intensity signals received by the first optical signal receiver 60 and the second optical signal receiver 70 are processed by the signal processor using a certain algorithm to achieve the purpose of displacement detection.

[0037] Specifically, the first fixed grating 10 has multiple identical first light-transmitting slots 11 distributed along the measurement direction, the second fixed grating 20 has multiple identical second light-transmitting slots 21 distributed along the measurement direction, and the movable grating 30 has multiple identical third light-transmitting slots 31 distributed along the measurement direction. The spacing between the first light-transmitting slots 11, second light-transmitting slots 21, and third light-transmitting slots 31 is the same. The number of first light-transmitting slots 11 and second light-transmitting slots 21 is the same, and the number of third light-transmitting slots 31 is greater than the number of first light-transmitting slots 11 and second light-transmitting slots 21. The width of the first light-transmitting slots 11, second light-transmitting slots 21, and third light-transmitting slots 31 is the same. The distance between the first fixed grating 10, the second fixed grating 20, and the movable grating 30 is the same. In this embodiment, for ease of installation and use, the first fixed grating 10 and the second fixed grating 20 are integrally connected. It should be understood that in actual use, the first fixed grating 10 and the second fixed grating 20 can also be arranged separately. The widths of the first light-transmitting groove 11, the second light-transmitting groove 21, and the third light-transmitting groove 31 are all 0.08–0.12 mm, preferably 0.1 mm; the spacing between the first light-transmitting groove 11, the second light-transmitting groove 21, and the third light-transmitting groove 31 is all 0.08–0.12 mm, preferably 0.1 mm; the distance between the first fixed grating 10, the second fixed grating 20, and the movable grating 30 is 0.1–0.2 mm, preferably 0.15 mm; and the thicknesses of the first fixed grating 10, the second fixed grating 20, and the movable grating 30 are all 0.15–0.20 mm, preferably 0.175 mm.

[0038] To facilitate the conversion of optical signals and improve detection accuracy, the first light source 40 and the second light source 50 have the same light intensity and do not interfere with each other.

[0039] Secondly, the present invention also proposes a displacement detection method, comprising the following steps:

[0040] (1) Make the first light source 40 and the second light source 50 emit light of constant intensity, make the movable grating 30 move relative to the first fixed grating 10 and the second fixed grating 20 along the measurement direction, the first light signal receiver 60 receive the light from the first light source 40 through the first fixed grating 10 and the movable grating 30, and the second light signal receiver 70 receive the light from the second light source 50 through the second fixed grating 20 and the movable grating 30.

[0041] (2) The light intensity signals of the light received by the first optical signal receiver 60 and the second optical signal receiver 70 are converted into periodically changing electrical signals y1(x) and y2(x) respectively, and the phase difference between the electrical signals y1(x) and y2(x) is 90 degrees.

[0042] (3) Based on the atan2 function, the Triangle_atan2 function is written. This function first divides the electrical signal y1(x) and y2(x) in a single cycle into four parts. If y1(x) is less than or equal to 0 and y2(x) is less than 0, this is recorded as the first part. If y1(x) is less than or equal to 0 and y2(x) is greater than or equal to 0, this is recorded as the second part. If y1(x) is greater than 0 and y2(x) is greater than or equal to 0, this is recorded as the third part. If y1(x) is greater than 0 and y2(x) is less than 0, this is recorded as the fourth part. Then, different operations are performed on each part:

[0043] Part 1: y = ((2*y2(x)min-y2(x)+y1(x))+y2(x)min);

[0044] Part Two: y = (y2(x) + y1(x) + y2(x)min);

[0045] Part 3: y = ((2*y1(x)max-y1(x)+y2(x))+y2(x)min);

[0046] Part 4: y = ((2*y1(x)max - y1(x) - y2(x)) + y2(x)min);

[0047] Here, y2(x)min refers to the minimum value of y2(x), which is equal to y1(x)min, and y1(x)max refers to the maximum value of y1(x), which is equal to y2(x)max. Combining these four parts yields the offset value y of y1(x) and y2(x) that changes periodically as the active grating 30 moves, and the offset value y within the same period is directly proportional to the moving distance of the active grating 30.

[0048] (4) The distance that the active grating 30 moves relative to the origin is calculated according to the formula L=nd+ykd, where n is the number of cycles of the offset value y, d is the distance that the active grating 30 moves corresponding to one cycle of the offset value y, y is the offset value of the current cycle calculated in step (3), and k is the proportional coefficient between the offset value y and d.

[0049] like Figure 2 As shown, in this invention, the electrical signals y1(x) and y2(x) both have offset values ​​y that change with the same period. Specifically, y1(x) and y2(x) are triangular wave voltage signals with a phase difference of 90 degrees.

[0050] To facilitate the determination of the direction of movement of the active grating, in step (4), the offset values ​​within the same period calculated in step (3) are divided into several segments and sorted by numbers. The direction of movement of the active grating 30 is determined based on the order of the numbers. Figure 3 As shown, in this embodiment, the offset value within the same period is divided into three segments and marked with 1, 2, and 3 in sequence. During the detection process, as the active grating 30 moves, the offset value line will change from 1, 2, 3 or 3, 2, 1, thereby determining whether the active grating 30 is moving away from or closer to the origin.

[0051] In summary, this invention achieves displacement detection using two light sources, resulting in low energy consumption and a small footprint. The movable grating can be flexibly connected to the lens components, allowing for different connection methods to be designed according to different spaces. Furthermore, the length of the movable grating can be designed according to the movement range of the movable components, further saving space. Compared to traditional fixed installation methods, this significantly increases the flexibility of structural design. By converting the two optical signals into electrical signals, and then using the atan2 function concept to convert the electrical signals from the two light sources into an offset value proportional to the displacement, the actual displacement can be obtained quickly and accurately. Since sampling frequency and accuracy are proportional, simply increasing the sampling frequency achieves high-precision displacement detection. In use, the movable grating can be directly connected to the displacement components, allowing for direct detection of the displacement components' displacement. Compared to the motor end connected to coaxial encoders and magnetic encoders, this method better avoids measurement errors and improves measurement accuracy.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the actual technology of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A displacement detection method characterized by, The method comprises the following steps: (1) making the first light source and the second light source emit light with constant intensity, and moving the movable grating along the measuring direction relative to the first fixed grating and the second fixed grating, the first light signal receiver receiving light emitted by the first light source and passing through the first fixed grating and the movable grating, and the second light signal receiver receiving light emitted by the second light source and passing through the second fixed grating and the movable grating; (2) converting the light intensity signals of the light received by the first light signal receiver and the second light signal receiver into periodic electric signals y1(x) and y2(x) respectively, and the phases of the electric signals y1(x) and y2(x) being 90 degrees apart; (3) dividing the electric signals y1(x) and y2(x) in a single period into four parts, if y1(x) is less than or equal to 0 and y2(x) is less than 0, recording this as the first part, if y1(x) is less than or equal to 0 and y2(x) is greater than or equal to 0, recording this as the second part, if y1(x) is greater than 0 and y2(x) is greater than or equal to 0, recording this as the third part, and if y1(x) is greater than 0 and y2(x) is less than 0, recording this as the fourth part, and then performing different operations on each part: First part: y = ((2*y2(x)min-y2(x)+y1(x))+y2(x)min); Second part: y = (y2(x)+y1(x)+y2(x)min); Third part: y = ((2*y1(x)max-y1(x)+y2(x))+y2(x)min); Fourth part: y = ((2*y1(x)max-y1(x)-y2(x))+y2(x)min); Here, y2(x)min refers to the minimum value of y2(x), which is equal to y1(x)min, and y1(x)max refers to the maximum value of y1(x), which is equal to y2(x)max, and the four parts are combined to obtain the offset value y about the periodic change of y1(x) and y2(x) with the movement of the movable grating, and the offset value y in the same period is in a proportional relationship with the movement distance of the movable grating; (4) calculating the distance of the movable grating relative to the origin according to the formula L = nd + ykd, wherein n is the number of periods of the offset value y, d is the distance corresponding to the movement of the movable grating in one period of the offset value y, y is the offset value of the current period calculated in step (3), and k is the proportional coefficient between the offset value y and d.

2. The displacement detection method of claim 1, wherein In step (4), the offset value in the same period calculated in step (3) is equally divided into several segments, and the numbers are sorted, and the movement direction of the movable grating is determined according to the change order of the numbers.

3. The displacement detection method of claim 1, wherein The first fixed grating and the second fixed grating are arranged on the same side of the movable grating along the measuring direction, the side of the first fixed grating away from the movable grating is provided with the first light source, the side of the second fixed grating away from the movable grating is provided with the second light source, the other side of the movable grating is provided with the first light signal receiver and the second light signal receiver for receiving light emitted by the first light source and the second light source respectively, and the first light signal receiver and the second light signal receiver are connected with the signal processor respectively.

4. The displacement detection method of claim 3, wherein The first fixed grating is provided with a plurality of identical first light transmission grooves distributed along a measurement direction, the second fixed grating is provided with a plurality of identical second light transmission grooves distributed along the measurement direction, and the movable grating is provided with a plurality of identical third light transmission grooves distributed along the measurement direction, and the first light transmission grooves, the second light transmission grooves and the third light transmission grooves have the same distribution interval.

5. A displacement detection method according to claim 4, characterized in that, The first light transmission grooves and the second light transmission grooves have the same number, and the third light transmission grooves have a number greater than that of the first light transmission grooves and the second light transmission grooves.

6. The displacement detection method of claim 4, wherein The first light transmission grooves, the second light transmission grooves and the third light transmission grooves have the same width.

7. The displacement detection method of claim 4, wherein The phase difference between the light signal intensity received by the first light signal receiver and the light signal intensity received by the second light signal receiver is 90 degrees.

8. The displacement detection method of claim 4, wherein, The distance between the first fixed grating, the second fixed grating and the movable grating is the same.

9. A displacement detection method according to claim 8, wherein, The first fixed grating and the second fixed grating are integrally connected.

10. The displacement detection method of claim 4, wherein, The first light source and the second light source have the same light intensity and do not interfere with each other.

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