Motor speed measurement method and apparatus, electronic device, and storage medium

Abstract

A motor speed measurement method and apparatus, an electronic device, and a storage medium, wherein the method comprises: controlling a stroboscopic light source to project, according to a preset pulse period, a light source onto a motor to be measured, and controlling a camera to capture a motor image in the process of projecting the light source onto said motor (210); performing target detection on the motor image to determine a movement distance of a preset marker in the motor image (220); and determining the rotational speed of said motor on the basis of the movement distance and the preset pulse period (230). The stroboscopic light source is controlled, by means of a pulse signal, to strobe, an image captured by the camera in the strobing process is analyzed, and the pixel movement range of the preset marker in the image and the preset pulse period are used to measure a motor speed, avoiding the problem of inaccurate rotational speed measurement caused by inconsistent tooth pitches of a fluted disc.

Description

Motor speed measurement method, device, electronic device and storage medium Technical Field

[0001] The present invention relates to the technical field of online monitoring of generators, and in particular to a method, device, electronic equipment and storage medium for measuring the rotational speed of a motor. Background Art

[0002] During the operation of the generator set, it is necessary to detect the rotation speed of the motor in the generator set to determine the operating status of the generator set.

[0003] The existing method for measuring the speed of a generator set is mainly to measure the speed through a gear disc. By installing an annular toothed device at the end of the generator shaft and installing a gear disc speed sensor and a corresponding speed signal processor on the fixed component, when the unit rotates, a proximity or photoelectric sensor is used to generate a pulse signal that reflects the unit speed. The upper computer processes the pulse signal, measures the pulse width, and calculates the unit speed.

[0004] However, due to limitations in machining accuracy, the distance between teeth on the gear disc (i.e., the pitch) cannot be completely equal. High-sensitivity sensors calculate speed by scanning the time between teeth. This can cause the calculated speed to change due to variations in pitch, even if the unit's speed remains unchanged. This can generate interference signals and reduce the accuracy of the measurement results.

[0005] Summary of the Invention

[0006] Embodiments of the present invention provide a motor speed measurement method, device, electronic device, and storage medium to improve the accuracy of generator speed measurement.

[0007] In one aspect, an embodiment of the present invention provides a method for measuring motor speed, the method comprising:

[0008] Controlling a stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and controlling a camera to capture an image of the motor during the process of projecting the light onto the motor to be tested; a preset mark is provided on the surface of the rotating shaft of the motor to be tested;

[0009] performing target detection on the motor image to determine a movement distance of a preset mark in the motor image;

[0010] The rotation speed of the motor to be tested is determined based on the moving distance and the preset pulse period.

[0011] In another aspect, an embodiment of the present invention provides a motor speed measuring device, comprising:

[0012] An image acquisition module is used to control a stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and to control a camera to capture images of the motor during the process of projecting light onto the motor to be tested; a surface of the rotating shaft of the motor to be tested is provided with a preset mark;

[0013] a distance detection module, configured to perform target detection on the motor image and determine a moving distance of a preset mark in the motor image;

[0014] The rotation speed measurement module is used to determine the rotation speed of the motor to be measured based on the moving distance and the preset pulse period.

[0015] On the other hand, an embodiment of the present invention provides an electronic device, including a memory and a processor; the memory stores an application program, and the processor is used to run the application program in the memory to perform the operations in the above-mentioned motor speed measurement method.

[0016] On the other hand, an embodiment of the present invention provides a storage medium, wherein the storage medium stores a plurality of instructions, wherein the instructions are suitable for being loaded by a processor to execute the steps in the above-mentioned motor speed measurement method.

[0017] An embodiment of the present invention provides a motor speed measurement method, device, electronic device and storage medium, which relate to the technical field of online monitoring of generators. A stroboscopic light source is controlled to project a light source onto a motor to be tested according to a preset pulse period, and a camera is controlled to capture a motor image during the process of projecting the light source onto the motor to be tested. A preset mark is provided on the surface of a rotating shaft of the motor to be tested, and target detection is performed on the motor image to determine the moving distance of the preset mark in the motor image. Based on the moving distance and the preset pulse period, the speed of the motor to be tested is determined. The present invention controls the stroboscopic light source to strobe through a pulse signal, analyzes the imaging picture collected by the camera during the stroboscopic process, and uses the pixel moving range of the preset mark in the analysis picture and the preset pulse period to achieve the measurement of the generator speed, thereby avoiding the problem of inaccurate speed measurement caused by inconsistent tooth pitch of the gear disc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0019] 1 is a schematic structural diagram of a motor speed measurement system provided by an embodiment of the present invention;

[0020] 2 is a schematic flow chart of a method for measuring motor speed according to an embodiment of the present invention;

[0021] 3 is a schematic diagram of the shutter exposure time and the pulse period of the stroboscopic light source of a camera provided by an embodiment of the present invention;

[0022] 4 is a schematic flow chart of a method for detecting a moving distance of a preset mark provided in an embodiment of the present invention;

[0023] 5 is a schematic flow chart of another motor speed measurement method provided by an embodiment of the present invention;

[0024] 6 is a schematic structural diagram of a motor speed measuring device provided in an embodiment of the present invention;

[0025] FIG7 is a schematic structural diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0027] In addition, the described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present invention. However, it will be appreciated by those skilled in the art that the technical solutions of the present invention can be practiced without one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring various aspects of the present invention.

[0028] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0029] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0030] It should be noted that the term "plurality" used in this document refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. The character " / " generally indicates an "or" relationship between the associated objects.

[0031] As described in the background, due to limitations in machining accuracy, the distance between teeth on a geared disc (i.e., the pitch) cannot be completely equal. High-sensitivity sensors calculate speed by scanning the time between teeth. This can cause the unit's speed to remain unchanged, while the calculated speed changes due to changes in the pitch, generating interference signals that reduce the measurement results of the geared disc-based speed measurement method. Furthermore, because the geared disc speed sensor has a "sensing threshold," the generator may be at the sensor's "sensing critical point" when it is shut down. Due to vibrations in the generator set and plant, the speed sensor may sense the geared disc, resulting in false alarms, further reducing the accuracy of the speed measurement results. Furthermore, the geared disc-based speed measurement method requires the addition of geared disc equipment to the rotating component, increasing the complexity of the system and introducing certain safety risks. Furthermore, due to the sensor's temperature measurement range, the sensor, mounted on a fixed component, is typically only 1-2 mm away from the geared disc, making it easy for the moving and static components to collide and rub, leading to equipment damage and the need for replacement, increasing hardware costs. It can be seen that the existing toothed disc-based speed measurement method has the problems of inaccurate measurement results, complex measurement, high hardware cost, and potential safety hazards.

[0032] Based on this, in order to improve the accuracy of the generator speed measurement results, reduce the measurement hardware cost, and provide a speed measurement method that is convenient and safe, the embodiments of the present invention provide a motor speed measurement method, device, electronic device and storage medium, which controls the strobing of a stroboscopic light source through a pulse signal, analyzes the imaging picture collected by the camera during the strobing process, and uses the pixel movement range of the preset mark and the preset pulse period in the analysis picture to achieve the measurement of the generator speed, avoiding the problem of inaccurate speed measurement caused by inconsistent tooth pitch of the gear disc; and there is no need to add structural parts to the rotating parts of the generator, which reduces the complexity of the system and eliminates the safety risks brought by adding structural parts to the rotating parts. In addition, the camera and the rotating shaft can maintain a large distance, eliminating the risk of collision between moving and static parts in the measurement method.

[0033] To facilitate understanding of the technical solutions provided by the embodiments of the present invention, the motor speed measurement method, device, electronic device, and storage medium provided by the embodiments of the present invention will be introduced below in conjunction with specific application scenarios.

[0034] As shown in Figure 1, Figure 1 is a schematic diagram of the structure of a motor speed measurement system provided by an embodiment of the present invention. The motor speed measurement system shown includes a motor to be measured, a camera, a host computer, a pulse generator, and a dispersive light source. The camera can be an area array camera, such as an industrial camera.

[0035] Among them, the upper computer is connected to the camera and the pulse generator respectively, and is used to send instructions to the camera to enable the camera to collect the motor image of the motor to be tested, and to send instructions to the pulse generator to control the pulse generator to send pulses to the stroboscopic light source, and control the stroboscopic light source to project light to the motor to be tested according to a preset pulse period, and is used to receive the motor image collected by the camera, perform target detection on the motor image, determine the moving distance of the preset mark in the motor image, and determine the speed of the motor to be tested based on the moving distance and the preset pulse period.

[0036] In some embodiments, the surface of the motor shaft under test is provided with predetermined markings. For example, as shown in FIG1 , the surface of the motor shaft under test is provided with diagonal stripes. It should be noted that the predetermined markings shown in FIG1 are merely illustrative and do not constitute a limitation on the embodiments of the present invention. The predetermined markings may also be in the form of vertical stripes, circles, triangles, or other shapes.

[0037] Optionally, a preset mark may be set on the surface of the rotating shaft of the motor to be tested by spraying, printing, pasting, or other methods.

[0038] It can be understood that the pulse generator sends a pulse signal to the stroboscopic light source based on a preset pulse period, and the stroboscopic light source projects a light source onto the motor to be tested according to the pulse signal. Since the stroboscopic light source projects the light source onto the motor to be tested intermittently, during the time period when the stroboscopic light source does not project the light source onto the motor to be tested, there is no light source in the environment where the motor to be tested is located, and the camera cannot capture the preset mark on the surface of the rotating shaft. During the time period when the stroboscopic light source projects the light source onto the motor to be tested, the camera captures the preset mark on the surface of the rotating shaft. In this way, in the process of the stroboscopic light source projecting the light source onto the motor to be tested according to the pulse signal, the movement of the rotating shaft causes the preset mark on the surface of the rotating shaft to rotate. Since the camera has a shutter exposure time, when the RF flash source is projected onto the motor to be tested within the preset pulse period, the camera captures the moving distance of the preset mark on the surface of the rotating shaft within the preset pulse period, and then the rotational speed of the motor to be tested can be obtained based on the moving distance of the preset mark on the surface of the rotating shaft within the preset pulse period. For example, when a stroboscopic light source projects light twice onto the motor to be tested within a preset pulse period, there is a time difference between the projection times of the two light sources. During this time difference, the movement of the rotating shaft causes the preset mark on the surface of the rotating shaft to rotate. Therefore, in the motor image captured by the camera, there are two preset marks. By calculating the distance between the two preset marks, the movement distance of the preset mark in the motor image can be determined, and then the speed of the motor to be tested can be determined.

[0039] In some embodiments, as shown in Figure 1, the host computer includes a database, a shaft speed calculation unit, and a camera and light source control unit, wherein the shaft speed calculation unit is connected to the data, the shaft speed calculation unit is used to receive the motor image captured by the camera, perform target detection on the motor image, determine the moving distance of the preset mark in the motor image, determine the speed of the motor to be tested based on the moving distance and the preset pulse period, and write the speed of the motor to be tested into the database; the camera and light source control unit is used to send control instructions to the area array camera and send control instructions to the pulse generator.

[0040] The motor speed measurement system provided by the embodiment of the present invention controls the strobing of a stroboscopic light source through a pulse signal, analyzes the imaging picture collected by the camera during the strobing process, and uses the pixel movement range of preset marks and the preset pulse period in the analysis picture to measure the generator speed, thereby avoiding the problem of inaccurate speed measurement caused by inconsistent tooth pitch of the gear disc; and does not require adding structural parts to the rotating parts of the generator, thereby reducing the complexity of the system and eliminating the safety risks brought by adding structural parts to the rotating parts. In addition, the camera and the rotating shaft can maintain a large distance, eliminating the risk of friction between the moving and static parts in the measurement method.

[0041] Based on the motor speed measurement system shown in FIG1 , an embodiment of the present invention provides a motor speed measurement method, as shown in FIG2 , which is a flow chart of the motor speed measurement method provided by an embodiment of the present invention. The motor speed measurement method shown can be applied to the host computer in the motor speed measurement system shown in FIG1 , and can also be applied to computer equipment with data processing capabilities, such as industrial computers, servers, etc., which are not specifically limited in this embodiment of the present invention. Specifically, the motor speed measurement method shown includes at least steps 210 to 230, which are described in detail as follows:

[0042] Step 210 : Control the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and control the camera to capture images of the motor during the process of projecting the light onto the motor to be tested.

[0043] Wherein, the surface of the motor shaft to be detected is provided with a preset mark.

[0044] In some embodiments, the preset pulse period can be pre-set by a staff.

[0045] In some embodiments, the camera has a shutter exposure time. In order to ensure that the camera can capture the position information of the preset mark set on the surface of the motor shaft to be tested at different times within the shutter exposure time, it is necessary to ensure that the stroboscopic light source can project light to the motor to be tested at least twice within the shutter exposure time. Based on this, the preset pulse period can be determined according to the shutter exposure time of the camera.

[0046] Optionally, a shooting command is sent to the camera, and a preset pulse period is determined based on the shutter exposure time of the camera, a pulse signal is generated based on the preset pulse period, and the pulse signal is sent to a stroboscopic light source. The stroboscopic light source triggers the opening and closing of the light source based on the pulse signal, and projects the light source onto the motor to be tested. The camera responds to the shooting command to capture an image of the motor during the process of projecting the light source onto the motor to be tested.

[0047] In some embodiments, in order to ensure that the captured motor image can record the position information of the preset mark at different times, the camera can be controlled to continuously shoot according to a preset frame rate and shutter exposure time, and while controlling the camera to shoot continuously, the stroboscopic light source is controlled to project light to the motor to be tested according to a preset pulse period. In this way, it can be ensured that among the multiple motor images captured by the camera, there is at least one motor image that records the position information of the preset mark at different times.

[0048] Optionally, a shooting instruction can be sent to the camera at preset intervals, and a preset pulse period can be determined based on the shutter exposure time of the camera. A pulse signal is generated based on the preset pulse period, and the pulse signal is sent to a stroboscopic light source. The stroboscopic light source triggers the opening and closing of the light source based on the pulse signal, and projects the light source onto the motor to be tested. The camera responds to the shooting instruction, determines the camera frame rate, shutter exposure time and shooting duration of the camera, and the camera continuously shoots according to the camera frame rate and shutter exposure time within the shooting duration to obtain multiple motor images.

[0049] Step 220 : Perform target detection on the motor image to determine the movement distance of a preset mark in the motor image.

[0050] In some embodiments, target detection can be performed on the motor image using a preset detection model to obtain the movement distance of a preset marker in the motor image. The detection model can be a machine learning-based detection model, such as a dictionary learning-based detection model, or a neural network-based detection model, such as a CNN-based detection model, a Fast-RCNN-based detection model, a Faster-RCNN-based detection model, or a YOLO-based detection model.

[0051] In some embodiments, target detection can be performed on the motor image to identify preset markers at different locations in the motor image. The movement distance of the preset markers in the motor image can be determined based on the pixel distance between the preset markers. The pixel distance can be the distance between the preset markers in the image coordinate system of the motor image, or the number of pixels between the preset markers in the motor image.

[0052] Optionally, target detection can be performed on the motor image using a preset detection model; optionally, target detection can also be performed on the motor image using an edge detection operator.

[0053] In some embodiments, target detection can be performed on the motor image to determine whether there are at least two preset marks in the motor image. If there are at least two preset marks, the image area where each preset mark in the motor image is located is determined, and based on the position information of the image area where each preset mark is located, the movement distance of the preset mark in the motor image is obtained; if there are not at least two preset marks, the motor image is discarded, and target detection is performed on the next motor image, or the motor image is recaptured.

[0054] In some embodiments, a motor image can be differentiated from a pre-stored reference image to obtain a differential image between the motor image and the pre-stored reference image. Target detection is performed based on the differential image to determine the image region where a preset marker is located in the differential image. Based on the positional information of the image region where each preset marker is located, the movement distance of the preset marker in the motor image is obtained. The pre-stored reference image may be an image without the preset marker.

[0055] Step 230 : determining the rotation speed of the motor to be tested based on the moving distance and the preset pulse period.

[0056] In some embodiments, after the moving distance is determined, the rotational speed of the motor to be measured can be obtained according to the moving distance and the preset pulse period by dividing the moving distance by the preset pulse period.

[0057] In some embodiments, after determining the moving distance, the linear velocity of the motor to be tested can be obtained according to the moving distance and the preset pulse period by dividing the moving distance by the preset pulse period, and the rotational speed of the motor to be tested can be obtained according to the shaft radius and the linear velocity of the motor shaft to be tested by 120*π*shaft radius*linear velocity.

[0058] In some embodiments, after determining the moving distance, the linear velocity of the motor to be tested can be obtained based on the moving distance and a preset pulse period by dividing the moving distance by the preset pulse period, and the rotational speed of the motor to be tested can be obtained based on a preset mapping relationship between the linear velocity and the rotational speed of the motor to be tested. The preset mapping relationship between the linear velocity and the rotational speed of the motor to be tested indicates a mapping relationship between the linear velocity and the corresponding rotational speed of the motor to be tested.

[0059] In some embodiments, if there are multiple motor images, the initial rotational speed corresponding to each motor image can be obtained based on the moving distance of the preset mark in each motor image, and the initial rotational speed corresponding to each motor image can be averaged to obtain the rotational speed of the motor to be tested; if there is only one motor image, the initial rotational speed corresponding to the motor image is determined as the rotational speed of the motor to be tested.

[0060] In some embodiments, steps 210 to 230 may be executed at predetermined intervals over a period of time to obtain a rotational speed sequence of the motor under test. Based on the rotational speed sequence, the motor under test is subjected to rotational state detection to determine whether the rotational state of the motor under test is abnormal. If the rotational state of the motor under test is abnormal, an alarm message is issued to prompt personnel to perform maintenance on the motor under test. The rotational state may include abnormal rotation and normal rotation.

[0061] Exemplarily, when there are speeds continuously greater than a preset speed threshold in the speed sequence of the motor to be tested, it is determined that the motor to be tested is rotating abnormally; when the speeds in the speed sequence of the motor to be tested are all less than or equal to the preset speed threshold, it is determined that the motor to be tested is rotating normally.

[0062] The motor speed measurement method provided by the embodiment of the present invention controls the strobing of a stroboscopic light source through a pulse signal, analyzes the imaging picture collected by the camera during the strobing process, and uses the pixel movement range of preset marks and the preset pulse period in the analysis picture to measure the generator speed, thereby avoiding the problem of inaccurate speed measurement caused by inconsistent tooth pitch of the gear disc; and does not require adding structural parts to the rotating parts of the generator, thereby reducing the complexity of the system and eliminating the safety risks brought by adding structural parts to the rotating parts. In addition, the camera and the rotating shaft can maintain a large distance, eliminating the risk of collision between the moving and static parts in the measurement method.

[0063] Considering the camera's shutter exposure time, to ensure that the camera captures the positions of preset markers at different times within the same motor image, it is necessary to ensure that the stroboscopic light source projects light onto the motor at least twice within the shutter exposure time. Therefore, in some embodiments, a pulse period can be set based on the camera's shutter exposure time and the number of stroboscopic flashes of the stroboscopic light source. Specifically, the method for determining the pulse period includes steps a1 and a2:

[0064] Step a1: Obtain the shutter exposure time of the camera and the number of strobe times of the stroboscopic light source within the shutter exposure time.

[0065] Step a2: determining a preset pulse period of the stroboscopic light source according to the shutter exposure time and the number of stroboscopic times.

[0066] In some implementations, the shutter exposure time of the camera and the number of strobe flashes of the stroboscopic light source input by the staff based on the configuration page view may be obtained.

[0067] In some implementations, the shutter exposure time of the camera and the number of strobe times of the stroboscopic light source sent by the background server may be obtained.

[0068] In some implementations, the preset pulse period of the stroboscopic light source may be obtained by dividing the shutter exposure time and the stroboscopic number of times.

[0069] For example, the stroboscopic light source has a stroboscopic number of 2 times within the shutter exposure time, as shown in FIG3 . FIG3 is a schematic diagram of the shutter exposure time of the camera provided by an embodiment of the present invention and the pulse period of the stroboscopic light source. Two pulse signals are triggered within one shutter exposure time t, and the pulse period between the pulse signals is T=t / 2. Each pulse lasts for a moment T1, where K is the frame rate of the camera and 1 / K is the shooting frequency of the camera.

[0070] The embodiment of the present invention determines the preset pulse period of the stroboscopic light source through the shutter exposure time and the number of stroboscopic flashes, ensuring that the stroboscopic light source can project a light source of the required number of stroboscopic flashes onto the motor to be tested within the shutter exposure time. Since there is a time difference between each time the stroboscopic light source projects the light source onto the motor to be tested, and the motor to be tested operates sequentially, the motor can capture the position change of a preset mark set on the surface of the motor shaft to be tested within the time difference, thereby determining the movement distance of the preset mark in the motor image.

[0071] Given that the motor continues to rotate during the shutter exposure time, the motor image captured by the camera may contain multiple preset markers, each located at a different position in the motor image. The distances between the outlines of these multiple preset markers can be detected to determine the travel distances of these markers. Based on this, in some embodiments, edge detection can be performed on the motor image to determine the outlines of each preset marker in the motor image. The travel distances of these preset markers in the motor image can then be determined based on the distances between the outlines of each preset marker in the motor image.

[0072] Optionally, edge detection can be performed on the motor image using an edge detection operator to determine the contour of each preset marker in the motor image. The edge detection operator includes, but is not limited to, a gradient operator, a Sobel (discrete differential operator), a Roberts (gradient calculation method of oblique deviation points), a Prewitt (edge ​​detection operator of differential operators), a Canny (optimal step-type edge detection operator), and a Laplacian (second-order differential operator) edge recognition operator.

[0073] Among them, the distance between the contours of each preset mark in the motor image can be the distance between the outer edges of the contours of each preset mark in the motor image; it can also be the distance between the inner edges of the contours of each preset mark in the motor image; it can also be the distance between the center points of the contours of each preset mark in the motor image.

[0074] In some implementations, the distance between the outlines of each preset mark in the motor image may be determined as the movement distance of the preset mark in the motor image.

[0075] In some embodiments, the movement distance of the preset mark in the motor image can be obtained according to the distance between the contours of each preset mark in the motor image and the mapping relationship between the preset image distance and the actual distance.

[0076] The mapping relationship between the preset image distance and the actual distance is used to indicate the mapping relationship between the image distance and the actual distance in the corresponding real coordinate system. In some embodiments, the mapping relationship between the preset image distance and the actual distance can be a mapping function between the image distance and the actual distance, such as a conversion function between the image coordinate system and the world coordinate system.

[0077] Optionally, when there are two preset marks in the motor image, the movement distance of the preset marks in the motor image can be obtained according to the distance between the contours of the preset marks.

[0078] Optionally, when there are more than two preset marks in the motor image, the maximum distance between the contours of each preset mark in the motor image can be determined as the target contour distance, and the moving distance of the preset mark in the motor image can be obtained based on the target contour distance. For example, the target contour distance is determined as the moving distance of the preset mark in the motor image; for example, the moving distance of the preset mark in the motor image is obtained based on the target contour distance and the mapping relationship between the preset image distance and the actual distance.

[0079] To improve the accuracy of edge detection and, consequently, the precision of the movement distance of a preset marker in the motor image, thereby ensuring the credibility of the speed measurement results, in some embodiments, the motor image can be preprocessed, and edge detection can be performed based on the preprocessed motor image. This improves the image quality of the motor image, thereby improving the accuracy of edge detection and, consequently, the precision of the movement distance of the preset marker in the motor image, thereby ensuring the credibility of the speed measurement results. Preprocessing includes, but is not limited to, image sharpening, grayscale stretching, image noise reduction, and image edge enhancement.

[0080] Specifically, as shown in FIG4 , FIG4 is a flow chart of a method for detecting a moving distance of a preset mark provided in an embodiment of the present invention. The method for detecting a moving distance of a preset mark shown includes steps 221 to 223:

[0081] Step 221 , preprocessing the motor image to obtain a preprocessed motor image.

[0082] Step 222 : performing edge detection on the pre-processed motor image to determine the outline of each preset mark in the pre-processed motor image.

[0083] Step 223 : determining the pixel distance between each contour, and determining the moving distance of the preset mark in the pre-processed motor image based on the pixel distance between each contour.

[0084] In some embodiments, the image coordinates of the center point of each preset marker's outline in the image coordinate system of the motor image can be determined based on the outline of each preset marker. The pixel distance between the outlines can be calculated based on the distance between the image coordinates of the center points of the outlines of each preset marker. For example, the pixel distance between the outlines can be determined as the Euclidean distance or Mahalanobis distance between the image coordinates of the center points of the outlines of each preset marker based on the image coordinates of the center points of the outlines of each preset marker. The center point can be a geometric center point or a center of gravity point.

[0085] In some embodiments, the image coordinates of the edge of each preset marker's outline in the image coordinate system of the motor image can be determined based on the outline of each preset marker. Based on the image coordinates of the edge of each preset marker's outline in the image coordinate system of the motor image, the pixel distance between the outlines of each preset marker can be determined. The edge can be either an outer edge or an inner edge.

[0086] In some embodiments, the pixel distance between the contours of each preset marker can also be obtained based on the image coordinates of a preset key point in each contour in the image coordinate system of the motor image. The preset key point can be the center point of the contour, the center point of an edge of the contour, or any point in the contour.

[0087] In some embodiments, the pixel distance between the contours of each preset mark can also be determined based on the number of pixels between the preset key points in each contour. Specifically, the method for determining the pixel distance includes:

[0088] (1) According to the position information of the preset key points in each contour, the number of pixels between the preset key points in each contour is determined.

[0089] (2) The number of pixels between the preset key points in each contour is determined as the pixel distance between each contour.

[0090] Optionally, the position information of the preset key points in each contour can be compared in the motor image to obtain the image length between the preset key points in each contour, and the number of pixels between the preset key points in each contour can be obtained based on the image length between the preset key points in each contour and the resolution of the motor image.

[0091] Optionally, the number of pixels between the position information of the preset key points in each contour in the motor image and the position information of the preset key points in other contours in the motor image may be counted to obtain the number of pixels between the preset key points in each contour.

[0092] In some embodiments, after determining the pixel distance, the pixel distance can be mapped to the world coordinate system based on a mapping relationship between the image coordinate system and the world coordinate system to obtain the movement distance of the preset marker in the preprocessed motor image. The mapping relationship between the image coordinate system and the world coordinate system indicates the mapping relationship between the coordinate values ​​in the image coordinate system and the coordinate values ​​in the world coordinate system.

[0093] In some embodiments, after determining the pixel distance, to ensure the accuracy of the movement distance calculation, it is also necessary to consider the actual physical size represented by each pixel in the motor image, and then determine the movement distance of the preset mark in the preprocessed motor image. That is, the camera's preset pixel accuracy and pixel distance are required to determine the movement distance of the preset mark in the preprocessed motor image, wherein the camera's preset pixel accuracy is used to represent the actual physical size represented by each pixel in the image captured by the camera. Specifically, the method for determining the movement distance based on pixel distance includes:

[0094] (1) Based on the pixel distance between each contour and the preset pixel accuracy of the camera, the initial moving distance of the preset mark in the preprocessed motor image is obtained.

[0095] (2) A correction coefficient between the pixel length and the actual distance is obtained according to the image height of the preset mark in the preprocessed motor image and the preset actual height of the preset mark.

[0096] (3) The initial moving distance is corrected based on the correction coefficient to obtain the moving distance of the preset mark in the preprocessed motor image.

[0097] In some implementations, the initial movement distance of the preset mark in the preprocessed motor image can be obtained by multiplying the pixel distance by the preset pixel accuracy according to the pixel distance between the contours and the preset pixel accuracy of the camera.

[0098] In some embodiments, the physical distance between the contours can be obtained based on the pixel distance between the contours and the preset pixel accuracy of the camera by multiplying the pixel distance by the preset pixel accuracy, and the farthest distance among the physical distances between the contours is determined as the initial movement distance of the preset mark in the preprocessed motor image.

[0099] The correction factor indicates the mapping coefficient between the length in the image coordinate system and the length in the world coordinate system. In some embodiments, the correction factor can be calculated by dividing the image height of the preset marker in the preprocessed motor image by the preset actual height of the preset marker. The image height represents the height of the preset marker in the image coordinate system of the motor image.

[0100] In some implementations, the movement distance of the preset mark in the pre-processed motor image can be obtained based on the correction coefficient by multiplying the correction coefficient by the initial movement distance.

[0101] In some embodiments, after obtaining the movement distance of the preset mark in the preprocessed motor image, the rotation speed of the motor to be tested may be determined according to the method for determining the rotation speed of the motor to be tested in step 230 .

[0102] Taking into account the fact that the motor shaft may move at a low speed due to factory vibration or inertial movement after the motor is shut down, or when the motor is running at a low speed, it may be difficult to capture the position change of the preset mark within the shutter exposure time of the camera, or the position change of the preset mark is small. Therefore, if the camera uses the same shutter exposure time for image acquisition, there may be a problem of low accuracy in calculating the moving distance, thereby reducing the accuracy of the speed measurement result. Based on this, in order to ensure the accuracy of the speed measurement result, in some embodiments, after obtaining the moving distance, the moving distance is compared with the preset distance threshold. When the moving distance is less than or equal to the preset distance threshold, the shutter exposure time of the camera is adjusted to ensure that the position change of the preset mark can be captured within the shutter exposure time of the camera. Specifically, as shown in Figure 5, Figure 5 is a flow chart of another motor speed measurement method provided in an embodiment of the present invention. The motor speed measurement method shown includes at least steps 510 to 580:

[0103] Step 510 : Control the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and control the camera to capture images of the motor during the process of projecting the light onto the motor to be tested.

[0104] In some embodiments, referring to step 210 in the motor speed measurement method provided in FIG2 , the stroboscopic light source can be controlled to project light onto the motor to be tested according to a preset pulse period, and the camera can be controlled to capture the motor image during the process of projecting the light onto the motor to be tested. The embodiments of the present invention are not described in detail here.

[0105] In some embodiments, the preset pulse period can be determined according to the pulse period determination method provided in steps a1 to a2. Referring to step 210 in the motor speed measurement method provided in FIG2 , the stroboscopic light source is controlled to project light onto the motor to be tested according to the preset pulse period, and the camera is controlled to capture the motor image during the process of projecting the light onto the motor to be tested. The embodiments of the present invention are not described in detail here.

[0106] Step 520 : Perform target detection on the motor image to determine the movement distance of the preset mark in the motor image.

[0107] In some implementations, the moving distance of the preset mark in the motor image may be determined by referring to the detection method of the moving distance of the preset mark provided in FIG. 4 , which will not be described in detail in this embodiment of the present invention.

[0108] Step 530 : If the moving distance is greater than the preset distance threshold, the rotation speed of the motor to be tested is determined based on the moving distance and the preset pulse period.

[0109] In some embodiments, the moving distance can be compared with a preset distance threshold. If the moving distance is greater than the preset distance threshold, the speed of the motor to be measured is determined according to step 230 of the motor speed measurement method provided in Figure 2. The embodiment of the present invention is not described in detail here.

[0110] Step 540: If the moving distance is less than or equal to the preset distance threshold, adjust the shutter exposure time of the camera and adjust the pulse period.

[0111] In some embodiments, if the movement distance is less than or equal to a preset distance threshold, an adjustment coefficient is obtained, and the shutter exposure time of the camera is adjusted based on the adjustment coefficient. Based on the adjusted shutter exposure time and the number of strobe flashes of the stroboscopic light source, an adjusted pulse period is obtained by dividing the adjusted shutter exposure time by the number of strobe flashes of the stroboscopic light source. The adjustment coefficient is an integer greater than 1.

[0112] Optionally, the adjusted shutter exposure time can be obtained by multiplying the adjustment coefficient by the shutter exposure time of the camera.

[0113] Optionally, the adjusted shutter exposure time can be obtained by multiplying the camera's shutter exposure time by 2^(adjustment coefficient).

[0114] Optionally, the adjustment coefficient can be obtained from a preset adjustment coefficient sequence; optionally, the adjustment coefficient input by the staff can be obtained; optionally, the number of adjustments of the shutter exposure time can be obtained and the number of adjustments can be determined as the adjustment coefficient, or 2^(number of adjustments) can be determined as the adjustment coefficient.

[0115] Step 550 : Projecting light onto the motor to be tested based on the adjusted pulse period, and controlling the camera to capture a new motor image during the process of projecting light onto the motor to be tested according to the adjusted shutter exposure time.

[0116] In some embodiments, step 210 of the motor speed measurement method provided in Figure 2 can be used to project a light source to the motor to be tested based on the adjusted pulse period, and the camera is controlled to capture a new motor image during the process of projecting the light source to the motor to be tested according to the adjusted shutter exposure time. The embodiments of the present invention are not described in detail here.

[0117] Step 560 : Perform target detection on the new motor image to determine a new moving distance of the preset mark in the motor image.

[0118] In some implementations, the new moving distance of the preset mark in the motor image may be determined by referring to the detection method of the moving distance of the preset mark provided in FIG. 4 , which will not be described in detail in this embodiment of the present invention.

[0119] Step 570: If the new moving distance is less than or equal to the preset distance threshold, the preset rotational speed is determined as the rotational speed of the motor to be tested.

[0120] In some embodiments, if the new movement distance is less than or equal to a preset distance threshold, steps 540 to 560 are repeated to obtain a new movement distance. If the new movement distance is less than or equal to the preset distance threshold, it indicates that the shaft of the motor under test has no rotational speed or the rotational speed is too low, and the set rotational speed is determined to be the rotational speed of the motor under test. The preset rotational speed may be 0 / s.

[0121] In some embodiments, if the new moving distance is less than or equal to a preset distance threshold, the number of shutter exposure time adjustments is greater than the preset number threshold, and the speed is determined to be the speed of the motor to be tested; if the number of shutter exposure time adjustments is less than or equal to the preset number threshold, steps 540 to 560 are repeated to obtain a new moving distance.

[0122] Step 580 , after step 560 , if the new moving distance is greater than the preset distance threshold, the rotation speed of the motor to be tested is determined based on the new moving distance and the adjusted pulse period.

[0123] In some implementations, if the new moving distance is greater than a preset distance threshold, the speed of the motor to be measured is determined according to step 230 of the motor speed measurement method provided in FIG. 2 , which is not described in detail in this embodiment of the present invention.

[0124] The motor speed measurement method provided in an embodiment of the present invention adds the detection of the moving distance. When the speed is too low or there is no speed, resulting in insufficient pixel accuracy and inability to accurately obtain the moving distance, the camera shutter exposure time is automatically controlled. By increasing the shutter exposure time, the effective moving distance is obtained, so that the parameters of equipment such as the camera and the pulse generator are matched with the current speed of the motor to be measured, so as to perform more accurate measurements and avoid the problem of inaccurate speed measurement results caused by too low speed or factory vibration.

[0125] In order to better implement the motor speed measurement method provided by the embodiment of the present invention, based on the embodiment of the motor speed measurement method, the embodiment of the present invention provides a motor speed measurement device, as shown in FIG6 , which is a structural schematic diagram of the motor speed measurement device provided by the embodiment of the present invention. The motor speed measurement device shown includes:

[0126] The image acquisition module 601 is used to control the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and to control the camera to capture the motor image during the process of projecting light onto the motor to be tested; the surface of the motor shaft to be tested is provided with a preset mark;

[0127] The distance detection module 602 is used to perform target detection on the motor image and determine the movement distance of the preset mark in the motor image;

[0128] The speed measurement module 603 is used to determine the speed of the motor to be measured based on the moving distance and the preset pulse period.

[0129] In some implementations, the distance detection module 602 includes:

[0130] An image preprocessing unit, configured to preprocess the motor image to obtain a preprocessed motor image;

[0131] an edge detection unit, configured to perform edge detection on the preprocessed motor image and determine the contour of each preset mark in the preprocessed motor image;

[0132] The distance detection unit is used to determine the pixel distance between each contour, and based on the pixel distance between each contour, determine the movement distance of the preset mark in the preprocessed motor image.

[0133] In some embodiments, the distance detection unit is configured to:

[0134] Based on the pixel distance between each contour and the preset pixel accuracy of the camera, the initial movement distance of the preset mark in the pre-processed motor image is obtained;

[0135] Obtaining a correction coefficient between the pixel length and the actual distance based on the pixel height of the preset mark in the preprocessed motor image and the preset actual height of the preset mark;

[0136] The initial moving distance is corrected based on the correction coefficient to obtain the moving distance of the preset mark in the preprocessed motor image.

[0137] In some embodiments, the distance detection unit is configured to:

[0138] Determining the number of pixels between the preset key points in each contour according to the position information of the preset key points in each contour;

[0139] The number of pixels between the preset key points in each contour is determined as the pixel distance between each contour.

[0140] In some implementations, the rotation speed measurement module 603 is configured to:

[0141] According to the moving distance and the preset pulse period, the linear speed of the motor to be tested is obtained;

[0142] Obtain the shaft radius of the motor to be tested;

[0143] The speed of the motor to be tested is obtained based on the shaft radius and linear speed.

[0144] In some embodiments, the motor speed measurement device further includes:

[0145] A feedback adjustment module 604 is configured to adjust the camera's shutter exposure time and the pulse period if the moving distance is less than or equal to a preset distance threshold;

[0146] An image acquisition module 601 is configured to project a light source onto the motor under test based on the adjusted pulse period, and to control a camera to capture a new motor image during the process of projecting the light source onto the motor under test according to the adjusted shutter exposure time;

[0147] The distance detection module 602 is used to perform target detection on the new motor image and determine the new moving distance of the preset mark in the motor image;

[0148] The speed measurement module 603 is used to determine the preset speed as the speed of the motor to be tested if the new moving distance is less than or equal to the preset distance threshold; if the new moving distance is greater than the preset distance threshold, determine the speed of the motor to be tested based on the new moving distance and the adjusted pulse period.

[0149] In some embodiments, the motor speed measurement device further includes:

[0150] The control module 605 is used to obtain the shutter exposure time of the camera and the number of strobes of the stroboscopic light source within the shutter exposure time; and determine a preset pulse period of the stroboscopic light source according to the shutter exposure time and the number of strobes.

[0151] The motor speed measurement device provided by the embodiment of the present invention controls the strobing of a stroboscopic light source through a pulse signal, analyzes the imaging picture collected by the camera during the strobing process, and uses the pixel movement range of preset marks and the preset pulse period in the analysis picture to measure the generator speed, thereby avoiding the problem of inaccurate speed measurement caused by inconsistent tooth pitch of the gear disc; and does not require adding structural parts to the rotating parts of the generator, thereby reducing the complexity of the system and eliminating the safety risks brought by adding structural parts to the rotating parts. In addition, the camera and the rotating shaft can maintain a large distance, eliminating the risk of collision between the moving and static parts in the measurement method.

[0152] An embodiment of the present invention further provides an electronic device, as shown in FIG7 , which shows a schematic structural diagram of the electronic device involved in an embodiment of the present invention. Specifically:

[0153] The electronic device may include components such as a processor 701 with one or more processing cores, a memory 702 with one or more computer-readable storage media, a power supply 703, and an input unit 704. Those skilled in the art will appreciate that the electronic device structure shown in FIG7 does not limit the electronic device and may include more or fewer components than shown, or combine certain components, or arrange the components differently.

[0154] Processor 701 is the control center of the electronic device. It connects the various parts of the entire electronic device using various interfaces and lines. By running or executing software programs and / or modules stored in memory 702 and accessing data stored in memory 702, it performs various functions of the electronic device and processes data, thereby monitoring the electronic device as a whole. Optionally, processor 701 may include one or more processing cores; preferably, processor 701 may integrate an application processor and a modem processor, wherein the application processor primarily processes the operating system, user interface, and application programs, and the modem processor primarily handles wireless communications. It is understood that the modem processor may not be integrated into processor 701.

[0155] The memory 702 can be used to store software programs and modules. The processor 701 executes various functional applications and data processing by running the software programs and modules stored in the memory 702. The memory 702 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device, etc. In addition, the memory 702 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other volatile solid-state storage device. Accordingly, the memory 702 may also include a memory controller to provide the processor 701 with access to the memory 702.

[0156] The electronic device also includes a power supply 703 for supplying power to various components. Preferably, the power supply 703 can be logically connected to the processor 701 via a power management system, thereby enabling the power management system to manage charging, discharging, and power consumption. The power supply 703 can also include one or more DC or AC power supplies, a recharging system, a power failure detection circuit, a power converter or inverter, a power status indicator, and other arbitrary components.

[0157] The electronic device may further include an input unit 704, which may be configured to receive input digital or character information and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function control.

[0158] Although not shown, the electronic device may further include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor 701 in the electronic device will load the executable files corresponding to the processes of one or more application programs into the memory 702 according to the following instructions, and the processor 701 will run the application programs stored in the memory 702 to implement various functions as follows:

[0159] Controlling the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and controlling the camera to capture images of the motor during the process of projecting the light onto the motor to be tested; a preset mark is provided on the surface of the rotating shaft of the motor to be tested;

[0160] Performing target detection on the motor image to determine the movement distance of a preset marker in the motor image;

[0161] The speed of the motor to be tested is determined based on the moving distance and the preset pulse period.

[0162] Those skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be accomplished by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0163] To this end, an embodiment of the present invention provides a storage medium storing a plurality of instructions that can be loaded by a processor to execute the steps of any motor speed measurement method provided in an embodiment of the present invention. For example, the instructions can execute the following steps:

[0164] Controlling the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and controlling the camera to capture images of the motor during the process of projecting the light onto the motor to be tested; a preset mark is provided on the surface of the rotating shaft of the motor to be tested;

[0165] Performing target detection on the motor image to determine the movement distance of a preset marker in the motor image;

[0166] The speed of the motor to be tested is determined based on the moving distance and the preset pulse period.

[0167] The specific implementation of the above operations can be found in the previous embodiments and will not be repeated here.

[0168] The storage medium may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0169] Since the instructions stored in the storage medium can execute the steps in any motor speed measurement method provided in the embodiments of the present invention, the beneficial effects that can be achieved by any motor speed measurement method provided in the embodiments of the present invention can be achieved. Please refer to the previous embodiments for details and will not be repeated here.

[0170] The above is a detailed introduction to a motor speed measurement method, device, electronic device and storage medium provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for measuring motor speed, characterized in that: The method comprises: Controlling the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and controlling the camera to collect the motor image during the process of projecting the light onto the motor to be tested; the surface of the rotating shaft of the motor to be tested is provided with a preset mark; Performing target detection on the motor image to determine the moving distance of a preset mark in the motor image; Based on the moving distance and the preset pulse period, the rotation speed of the motor to be tested is determined.

2. The motor speed measurement method according to claim 1, characterized in that: The performing target detection on the motor image to determine the moving distance of a preset mark in the motor image includes: Preprocessing the motor image to obtain a preprocessed motor image; Performing edge detection on the preprocessed motor image to determine the contour of each preset mark in the preprocessed motor image; The pixel distance between each of the contours is determined, and based on the pixel distance between each of the contours, the moving distance of the preset mark in the preprocessed motor image is determined.

3. The motor speed measurement method according to claim 2, characterized in that: The step of determining the moving distance of the preset mark in the preprocessed motor image based on the pixel distance between the contours comprises: Based on the pixel distance between each of the contours and the preset pixel accuracy of the camera, obtaining an initial moving distance of a preset mark in the preprocessed motor image; Obtaining a correction coefficient between a pixel length and an actual distance according to a pixel height of a preset mark in the preprocessed motor image and a preset actual height of the preset mark; The initial moving distance is corrected based on the correction coefficient to obtain the pre-processed electric The moving distance of the preset mark in the machine image.

4. The motor speed measurement method according to claim 2, characterized in that: Determining the pixel distance between the contours comprises: Determining the number of pixels between the preset key points in each of the contours according to the position information of the preset key points in each of the contours; The number of pixels between the preset key points in each of the contours is determined as the pixel distance between the contours.

5. The motor speed measurement method according to claim 1, characterized in that: The step of determining the rotation speed of the motor to be tested based on the moving distance and the preset pulse period includes: According to the moving distance and the preset pulse period, the linear speed of the motor to be tested is obtained; Obtaining the shaft radius of the motor shaft to be detected; The rotation speed of the motor to be tested is obtained according to the shaft radius and the linear speed.

6. The motor speed measurement method according to claim 1, characterized in that: After performing target detection on the motor image and determining the moving distance of a preset mark in the motor image, the method further includes: If the moving distance is less than or equal to a preset distance threshold, adjusting the shutter exposure time of the camera and adjusting the pulse period; Projecting a light source to the motor to be tested based on the adjusted pulse period, controlling the camera to collect a new motor image during the process of projecting the light source to the motor to be tested according to the adjusted shutter exposure time; Performing target detection on the new motor image to determine a new moving distance of a preset mark in the motor image; If the new moving distance is less than or equal to the preset distance threshold, the preset rotation speed is determined as the rotation speed of the motor to be tested; If the new moving distance is greater than the preset distance threshold, the rotation speed of the motor to be tested is determined based on the new moving distance and the adjusted pulse period.

7. The motor speed measurement method according to any one of claims 1 to 6, characterized in that: Before controlling the stroboscopic light source to project a light source onto the motor to be tested according to a preset pulse period and controlling the camera to collect the motor image during the process of projecting the light source onto the motor to be tested, the method includes: Obtaining the shutter exposure time of the camera and the number of stroboscopic times of the stroboscopic light source within the shutter exposure time; A preset pulse period of the stroboscopic light source is determined according to the shutter exposure time and the stroboscopic number of times.

8. A motor speed measuring device, characterized in that: The device comprises: An image acquisition module is used to control the stroboscopic light source to project light onto the motor to be tested according to a preset pulse period, and to control the camera to capture the motor image during the process of projecting the light onto the motor to be tested; the surface of the rotating shaft of the motor to be tested is provided with a preset mark; A distance detection module, used to perform target detection on the motor image and determine the moving distance of a preset mark in the motor image; The rotation speed measurement module is used to determine the rotation speed of the motor to be tested based on the moving distance and the preset pulse period.

9. An electronic device, characterized in that: It comprises a memory and a processor; the memory stores an application program, and the processor is used to run the application program in the memory to execute the operations in the motor speed measurement method according to any one of claims 1 to 7.

10. A storage medium, characterized in that: The storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor to execute the steps in the motor speed measurement method according to any one of claims 1 to 7.

Images