A motor speed monitoring system and method based on SPAD array

Abstract

The present invention relates to the technical field of motor speed monitoring, and in particular to a motor speed monitoring system and method based on a SPAD array, comprising: a mechanical rotation system, including a motor code disk, a rotating shaft and a motor housing; the motor code disk includes an outer ring and an inner ring, and the position of the inner ring close to the outer ring and the outer ring constitute a code disk coding area, the outer ring is fixedly connected to the motor housing, and the inner ring is fixedly connected to the rotating shaft and moves relative to the outer ring with the rotating shaft; a photoelectric conversion system is arranged below the code disk coding area, comprising an optical lens and an optical circuit board, a laser emitting light source and a SPAD array receiver are provided on the optical circuit board, the optical lens is arranged between the SPAD array receiver and the code disk coding area, the laser of the laser emitting light source shines on the code disk coding area, and the SPAD array receiver collects an image of the code disk coding area, thereby judging the running direction and running speed of the motor, solving the problem that the existing code disk detection accuracy is low and the code disk movement direction cannot be distinguished.

Description

Technical Field

[0001] The present invention relates to the technical field of motor speed monitoring, and in particular to a motor speed monitoring system and method based on a SPAD array. Background Art

[0002] Accurately estimating linear position and rotational angle is a critical task in industrial automation and similar applications, and rotary encoders are widely used in motor control. Rotary encoders (also known as encoders) are electromechanical devices that convert rotational position or rotational quantity into analog or digital signals. They are primarily used in scientific research, industrial control, robotics, and other fields requiring precise rotational position and speed feedback.

[0003] Currently, the mainstream motor speed monitoring encoding methods are divided into magnetic encoding and optical encoding. Chinese patent CN103852589A discloses a photoelectric positioning speed code disk for CNC motors. The code disk uses a pair of infrared positioning lamps, a positioning infrared receiver, and a dedicated positioning output pin on the signal pin to output a square wave signal, thereby determining the initial position of the CNC motor's spindle. The speed measuring infrared lamps, a positioning infrared transmitter and a speed measuring infrared receiver, also form a pair of working lamps. When the speed measuring hole passes between the two lamps, the dedicated speed measuring pin on the signal pin outputs multiple corresponding pulses, corresponding to the number of revolutions of the CNC motor's spindle, thereby determining the rotational speed of the CNC motor's spindle. This solution has the advantages of simple implementation and low cost, but the disadvantages are low detection accuracy and the inability to distinguish the direction of the code disk's movement. This low accuracy is primarily limited by the angles of light entering and exiting the transmitting and receiving components and the inherent refresh rate of the components. Consequently, the code disk's measuring holes cannot be effectively identified at smaller spacings.

[0004] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0005] One of the purposes of the present invention is to provide a motor speed monitoring system based on a SPAD array, which adopts a laser emitting light source and a SPAD array receiver, in conjunction with an array code disk, to form a motor speed monitoring system, and realizes high-precision monitoring of the motor speed and direction through a special array encoding and decoding algorithm.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A motor speed monitoring system based on a SPAD array, comprising:

[0008] A mechanical rotation system includes a motor code disk, a rotating shaft, and a motor housing; the motor code disk includes an outer ring and an inner ring, wherein a portion of the inner ring proximate to the outer ring and the outer ring form a code disk encoding area; the outer ring is fixedly connected to the motor housing, and the inner ring is fixedly connected to the rotating shaft and moves relative to the outer ring along with the rotating shaft;

[0009] The photoelectric conversion system is arranged below the code disk encoding area and includes an optical lens and an optical circuit board. A laser emitting light source and a SPAD array receiver are provided on the optical circuit board. The optical lens is arranged between the SPAD array receiver and the code disk encoding area. The laser of the laser emitting light source shines on the code disk encoding area, and the SPAD array receiver collects the image of the code disk encoding area to determine the running direction and speed of the motor.

[0010] Furthermore, the code disk coding area is composed of a feature array, a×b fixed feature bits are set on the outer ring, and c×b position coding bits are set on the inner ring near the outer ring. The fixed feature bits and the position coding bits constitute a code disk coding area with (a+c)×b features; wherein a, b, and c are all positive integers, and 4<(a+c)<128.

[0011] Furthermore, each feature has the same included angle with the axis of the rotation axis.

[0012] Furthermore, an MCU single-chip computer is also provided on the optical circuit board, and the MCU single-chip computer is connected to and controls the laser emitting light source and the SPAD array receiver to realize scanning and refreshing of the feature array of the code disk encoding area.

[0013] Furthermore, the original array collected by the SPAD array sensor from the motor code disk can be decoded and processed by the MCU to obtain a total of m array combinations, where the m array combinations correspond to m coding states respectively, and the coding numbers are named in sequence.

[0014] Furthermore, during the rotation of the motor, the code number cycles in the order of 1→m or m→1.

[0015] Furthermore, the switching of two adjacent array combinations causes the motor to operate at a unit angle.

[0016] The second purpose of the present invention is to provide a monitoring method for a motor speed monitoring system based on a SPAD array, which determines the motor's running direction and speed by identifying the feature array on the motor code disk and cooperating with the MCU to control the scanning and refresh of the laser light source.

[0017] A monitoring method of a motor speed monitoring system based on a SPAD array comprises the following steps:

[0018] S1: The rotating shaft passes through the motor code disk to drive the motor code disk to rotate, and at the same time the laser emitting light source is powered on to emit laser;

[0019] S2: The laser is irradiated on the coding area of ​​the code disk, and is transmitted to the optical lens after reflection. The optical lens focuses the image formed on the coding area of ​​the code disk and transmits it to the SPAD array receiver;

[0020] S3: The MCU controls the laser light source to scan quickly, and causes the SPAD array sensor to refresh quickly, collecting the original dot matrix on the motor code disk;

[0021] S4: The MCU decodes the collected data to determine the running direction and speed of the motor.

[0022] Furthermore, when the ascending order of the code numbers is the forward rotation direction of the motor, the descending order of the code numbers is the reverse rotation direction of the motor;

[0023] Alternatively, when the descending order of the code numbers corresponds to the forward rotation direction of the motor, the ascending order of the code numbers corresponds to the reverse rotation direction of the motor.

[0024] Furthermore, in step S4, if the rotation speed exceeds the scanning and refreshing frequency, and code number 1 jumps directly to code number n,

[0025] like Then the rotation angle is judged to be 1→2→3→…→n;

[0026] like The rotation angle is judged to be 1→m→m-1→…→n.

[0027] The beneficial effects of the present invention are:

[0028] (1) The present invention comprises a motor speed monitoring system composed of a motor code disk, a laser emitting light source, a SPAD array sensor and an MCU single chip computer. The system recognizes the characteristic array on the motor code disk and realizes high-precision monitoring of the motor speed and direction through a special array encoding and decoding algorithm. The laser emitting light source emits a laser of a specific wavelength onto the test surface of the motor code disk, and a specific texture is set on the test surface of the motor code disk. When the laser of a specific wavelength is irradiated onto the test surface of the motor code disk, it will be reflected by the test surface to the SPAD array sensor. The MCU single chip computer determines the angle of rotation of the motor by comparing the changes in the encoding state, thereby judging the running direction and running speed of the motor.

[0029] (2) In the present invention, the laser light source can achieve an extremely high scanning frequency, and the SPAD array receiver can achieve an extremely high refresh frequency, ensuring that a sufficient number of pixels are collected, thereby laying the foundation for improving the resolution of motor speed monitoring and motion direction recognition. The optical lens mainly solves the problems of focusing and image distortion, so that the feature array can be effectively imaged on the SPAD array sensor. Compared with the existing technology, the size and form of the feature values ​​in this application are not restricted, and effective recognition can be achieved at a smaller spacing, greatly improving the accuracy while significantly reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Schematic cross-sectional view of a motor speed monitoring system based on a SPAD array according to an embodiment of the present invention;

[0032] Figure 2 for Figure 1 A partial enlarged view of point A in the middle;

[0033] Figure 3 This is a schematic diagram of the structure of the motor code disk in Example 1 of the present invention;

[0034] Figure 4 This is a diagram showing the encoding state of the encoding area of ​​the code disk in Example 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of the structure of the motor code disk in Example 2 of the present invention;

[0036] Figure 6 This is a diagram showing the encoding state of the encoding area of ​​the code disk in Example 2 of the present invention;

[0037] Figure 7 This is a principle framework diagram of a photoelectric conversion system according to an embodiment of the present invention;

[0038] Figure 8 Flowchart of the monitoring method in an embodiment of the present invention.

[0039] Figure numerals: 10, motor code disk; 11, rotating shaft; 12, motor housing; 13, outer ring; 14, inner ring; 15, code disk encoding area; 16, optical lens; 17, optical circuit board; 18, laser emitting light source; 19, SPAD array receiver; 20, fixed feature bit; 21, position coding bit. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0041] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly attached to the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] Example 1

[0044] like Figures 1 to 8 A motor speed monitoring system based on a SPAD array is shown, comprising:

[0045] The mechanical rotation system includes a motor code disk 10, a rotating shaft 11, and a motor housing 12. The motor code disk 10 includes an outer ring 13 and an inner ring 14. The inner ring 14, located near the outer ring 13, and the outer ring 13 form a code disk encoding area 15. The outer ring 13 is fixedly connected to the motor housing 12, and the inner ring 14 is fixedly connected to the rotating shaft 11 and moves relative to the outer ring 13 with the rotating shaft 11.

[0046] The photoelectric conversion system is arranged below the code disk encoding area 15, and includes an optical lens 16 and an optical circuit board 17. A laser emitting light source 18 and a SPAD array receiver 19 are provided on the optical circuit board 17. The optical lens 16 is arranged between the SPAD array receiver 19 and the code disk encoding area 15. The laser of the laser emitting light source 18 shines on the code disk encoding area 15, and the SPAD array receiver 19 collects the image of the code disk encoding area 15, thereby judging the running direction and speed of the motor.

[0047] The present invention comprises a motor speed monitoring system composed of a motor code disk 10, a laser light source 18, a SPAD array sensor, and an MCU. This system identifies the characteristic array on the motor code disk 10 and uses a specialized array encoding and decoding algorithm to achieve high-precision monitoring of the motor speed and direction. The laser light source 18 emits a laser of a specific wavelength onto the surface to be measured of the motor code disk 10, which is provided with a specific texture. When the laser of a specific wavelength is irradiated onto the surface to be measured of the motor code disk 10, it is reflected by the surface to be measured onto the SPAD array sensor. The MCU determines the angle of motor rotation by comparing the changes in the encoding state, thereby determining the direction and speed of the motor.

[0048] In order to realize the feature identification of the code disk coding area 15, the code disk coding area 15 is composed of a feature array, a×b fixed feature bits 20 are set on the outer ring 13, and c×b position coding bits 21 are set on the inner ring 14 near the outer ring 13. The fixed feature bits 20 and the position coding bits 21 constitute a code disk coding area 15 with (a+c)×b features; wherein a, b, and c are all positive integers, 4<(a+c)<128.

[0049] like Figures 3-4 As shown, in this embodiment, the code disk coding area 15 is composed of a black and white grid array, a=2, b=1, c=3, so that 2×1 fixed feature bits 20 are set on the outer ring 13, and 3×1 position coding bits 21 are set on the inner ring 14 near the outer ring 13. The fixed feature bits 20 and the position coding bits 21 constitute a code disk coding area 15 with 5×1 features.

[0050] like Figure 4 As shown, the original array collected by the SPAD array sensor on the motor code disk 10 can be decoded by the MCU single-chip computer to obtain a total of 7 array combinations. The 7 array combinations correspond to 7 coding states, and the coding numbers are named in sequence. It should be noted here that the actual array combinations are not limited to 7. 7 is only a demonstration method of this embodiment. The 7 array combinations in this embodiment are obtained by binary calculation. The eigenvalue can also be set in other ways, such as identifying the color scale on the graph, etc., and those skilled in the art can set it according to the actual situation.

[0051] Specifically, each feature has the same angle with the axis of the rotating shaft 11. This allows the motor to rotate at an angle of one unit when two adjacent array combinations are switched. Specifically, the value of each angle is related to the size of the black and white grid. The larger the size of the black and white grid, the larger the angle at which the motor rotates at one unit, and the smaller the angle of the black and white grid, the smaller the angle at which the motor rotates at one unit. Since the SPAD array sensor is a chip structure with 1536 detection points, each point is 5.5 microns apart, the 1536 feature points in each frame can be compared to determine the displacement between the two frames. Therefore, even if the spacing between the black and white grids is smaller, high-precision monitoring can be achieved.

[0052] like Figure 7 As shown, an MCU single-chip computer is also provided on the optical circuit board 17, and the MCU single-chip computer is connected to and controls the laser emitting light source 18 and the SPAD array receiver 19 to realize the scanning and refreshing of the feature array of the code disk encoding area 15. In the present invention, the laser emitting light source 18 can achieve an extremely high scanning frequency, and the SPAD array receiver 19 can achieve an extremely high refresh frequency, ensuring that a sufficient number of pixels are collected, thereby laying the foundation for improving the resolution of motor speed monitoring and motion direction recognition. The optical lens 16 mainly solves the problems of focusing and image distortion, so that the feature array can be effectively imaged on the SPAD array sensor. Compared with the prior art, the size and form of the characteristic values ​​in this application are not restricted, and effective recognition can be achieved at a smaller spacing, which greatly improves the accuracy while significantly reducing the cost.

[0053] Specifically, as the motor rotates, the code numbers cycle in the order of 1→7 or 7→1. When the ascending code numbers correspond to the motor's forward rotation direction, the descending code numbers correspond to the motor's reverse rotation direction; alternatively, when the descending code numbers correspond to the motor's forward rotation direction, the ascending code numbers correspond to the motor's reverse rotation direction. This solution utilizes a black and white code disk, a laser light source 18, a SPAD array sensor, and an MCU to form an array encoding and decoding system. By identifying the black and white grid array on the motor code disk 10 and coordinating the MCU's control of light source scanning and refresh, the motor's rotation direction and speed can be determined.

[0054] like Figure 8 A monitoring method of a motor speed monitoring system based on a SPAD array is shown, comprising the following steps:

[0055] S1: The rotating shaft 11 passes through the motor code disk 10 to drive the motor code disk 10 to rotate, and at the same time the laser emitting light source 18 is powered on to emit laser light;

[0056] S2: The laser is irradiated on the code disk encoding area 15, and is transmitted to the optical lens 16 after reflection. After being focused by the optical lens 16, the image formed on the code disk encoding area 15 is transmitted to the SPAD array receiver 19;

[0057] S3: The MCU controls the laser light source 18 to scan quickly and causes the SPAD array sensor to refresh quickly to collect the original dot matrix on the motor code disk 10;

[0058] S4: The MCU decodes and processes the collected data to determine the direction and speed of the motor.

[0059] Furthermore, in step S4, if the rotation speed exceeds the scanning and refreshing frequency, and code number 1 jumps directly to code number n,

[0060] like Then the rotation angle is judged to be 1→2→3→…→n;

[0061] like The rotation angle is judged to be 1→m→m-1→…→n.

[0062] Among them, when n=3, it is judged to be a rotation angle of 1→2→3,

[0063] When n=4, the rotation angle is judged to be 1→2→3→4.

[0064] When n=5, the rotation angle is judged to be 1→7→6→5.

[0065] When n=6, the rotation angle is judged to be 1→7→6.

[0066] When n=7, it is determined to be a rotation angle of 1→7.

[0067] Example 2

[0068] like Figures 5-6 As shown, in this embodiment, the motor speed monitoring system based on the SPAD array is similar to that in Example 1 and will not be described again here.

[0069] In this embodiment, the code disk coding area 15 is composed of a black and white grid array, a=1, b=4, c=3, so that 1×4 fixed feature bits 20 are set on the outer ring 13, and 3×4 position coding bits 21 are set on the inner ring 14 near the outer ring 13. The fixed feature bits 20 and the position coding bits 21 constitute a code disk coding area 15 with 4×4 features.

[0070] like Figure 6 As shown, the original array captured by the SPAD array sensor on the motor code disk 10 is decoded and processed by the MCU to obtain a total of 7 array combinations. The 7 array combinations correspond to 7 encoding states and are named in sequence. Specifically, the 7 array combinations are obtained through binary calculation.

[0071] Those skilled in the art will appreciate that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A motor speed monitoring system based on a SPAD array, characterized in that: include: A mechanical rotation system includes a motor code disk, a rotating shaft, and a motor housing; the motor code disk includes an outer ring and an inner ring, wherein a portion of the inner ring proximate to the outer ring and the outer ring form a code disk encoding area; the outer ring is fixedly connected to the motor housing, and the inner ring is fixedly connected to the rotating shaft and moves relative to the outer ring along with the rotating shaft; A photoelectric conversion system is provided below the code disk encoding area and includes an optical lens and an optical circuit board. A laser emitting light source and a SPAD array receiver are provided on the optical circuit board. The optical lens is provided between the SPAD array receiver and the code disk encoding area. The laser emitting light source illuminates the code disk encoding area, and the SPAD array receiver collects an image of the code disk encoding area to determine the running direction and speed of the motor. The code disk encoding area is composed of a feature array, a×b fixed feature bits are set on the outer ring, and c×b position coding bits are set on the inner ring near the outer ring. The fixed feature bits and the position coding bits constitute a code disk encoding area with (a+c)×b features; wherein a, b, and c are all positive integers, and 4<(a+c)<128.

2. A motor speed monitoring system based on a SPAD array according to claim 1, characterized in that: Each feature has the same included angle with the axis of the rotation axis.

3. The motor speed monitoring system based on the SPAD array according to claim 1, characterized in that: The optical circuit board is also provided with an MCU single chip computer, which is connected to and controls the laser emitting light source and the SPAD array receiver to realize scanning and refreshing of the feature array of the code disk encoding area.

4. The motor speed monitoring system based on the SPAD array according to claim 3, characterized in that: The original array collected by the SPAD array sensor from the motor code disk can be decoded and processed by the MCU to obtain m array combinations. The m array combinations correspond to m coding states respectively, and the coding numbers are named in sequence.

5. The motor speed monitoring system based on the SPAD array according to claim 4, characterized in that: When the motor is rotating, the code number cycles in the order of 1→m or m→1.

6. The motor speed monitoring system based on the SPAD array according to claim 5, characterized in that: The switching of the two adjacent array combinations causes the motor to operate by a unit angle.

7. The monitoring method of a motor speed monitoring system based on a SPAD array according to claim 1, characterized in that: The following steps are involved: S1: The rotating shaft passes through the motor code disk to drive the motor code disk to rotate, and at the same time the laser emitting light source is powered on to emit laser; S2: The laser is irradiated on the coding area of ​​the code disk, and is transmitted to the optical lens after reflection. The optical lens focuses the image formed on the coding area of ​​the code disk and transmits it to the SPAD array receiver; S3: The MCU controls the laser light source to scan quickly, and causes the SPAD array sensor to refresh quickly, collecting the original dot matrix on the motor code disk; S4: The MCU decodes the collected data to determine the running direction and speed of the motor.

8. The monitoring method of a motor speed monitoring system based on a SPAD array according to claim 7, characterized in that: When the ascending order of the code numbers is the forward rotation direction of the motor, the descending order of the code numbers is the reverse rotation direction of the motor; Alternatively, when the descending order of the code numbers corresponds to the forward rotation direction of the motor, the ascending order of the code numbers corresponds to the reverse rotation direction of the motor.

9. The monitoring method of a motor speed monitoring system based on a SPAD array according to claim 7, characterized in that: In step S4, if the rotation speed exceeds the scanning and refreshing frequency, and code number 1 jumps directly to code number n, like , then it is judged to be The rotation angle; like , then it is judged to be The rotation angle.

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