Belt slip detection device and method

Abstract

The application provides a belt slip detection device and method. By arranging the first sensor and the second sensor added at the kick-out mechanism along the conveying direction, the same material can be sensed successively passing through the positions of the two different sensors. The controller assigns the material serial number to the two sensing events respectively, and establishes the matching relationship between them, so as to accurately associate the two encoder count values corresponding to the same material passing through the first sensor and the second sensor. Through the two associated encoder count values, the controller can determine the displacement deviation of the material between the two sensors, and then judge whether the belt slips. Through the above scheme, the device can make a judgment before the kick-out operation, thereby effectively avoiding the problems of waste mixing, material damage and the like caused by kick-out errors.

Description

Technical Field

[0001] This application relates to the field of machine vision technology, and in particular to a belt slippage detection device and method. Background Technology

[0002] Material inspection machines are used for quality inspection and sorting of materials. Taking a printing inspection machine as an example, the current workflow is as follows: materials are transported via a belt; photoelectric sensors trigger image acquisition equipment to acquire and inspect the materials; and when an abnormality is detected, a scrap removal mechanism at a fixed position removes the abnormal material. The scrap removal of the printing inspection machine is controlled by a photoelectric encoder connected to the belt. For example, a preset encoder count difference from the trigger point to the scrap removal point is used; when the count value reaches this difference, the scrap removal operation is executed.

[0003] However, under actual high-speed operating conditions, relative slippage may occur between the belt and the drive shaft or between the belt and the material (i.e., belt slippage). Once belt slippage occurs, the fixed encoder count difference will not accurately reflect the true position of the material, causing deviations in the timing of scrap removal determined based on the fixed count difference, thus affecting the scrap removal results. Summary of the Invention

[0004] In view of this, this application provides a belt slippage detection method, apparatus and inspection machine to detect whether belt slippage has occurred.

[0005] The technical solution provided in this application is as follows: According to an embodiment of the first aspect of this application, a belt slippage detection device is provided. The device includes at least an encoder and a scrap removal mechanism. The encoder is used to monitor the rotation angle of the drive shaft of the belt. The device also includes a first sensor, a controller, and a second sensor disposed at the scrap removal mechanism. The first sensor and the second sensor are spaced apart along the belt conveying direction, and the first sensor detects the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder, respectively; the controller is configured to: When the first sensor detects the material being conveyed on the belt, the material is counted to obtain the first material sequence number ID, and the current first encoder count is recorded. When the second sensor detects the material being conveyed on the belt, a material count is performed to obtain the second material sequence number ID, and the current second encoder count is recorded. A first material serial number ID that matches the second material serial number ID is determined, and the slippage of the belt is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0006] Optionally, the device further includes a buffer; the buffer is used to cache the first material serial number ID and the first encoder count corresponding to the first material serial number ID; the controller is configured to determine the first material serial number ID that matches the second material serial number ID in the following manner: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

[0007] Optionally, the physical distance between the first sensor and the second sensor is fixed; the controller is configured to determine the belt slippage by: The controller determines the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

[0008] Optionally, the second sensor is integrated into the waste removal mechanism or set up independently of the waste removal mechanism.

[0009] Optionally, the belt includes a first sub-belt and a second sub-belt, and the material is conveyed from the first sub-belt to the second sub-belt; The first sensor is used to detect the material on the first sub-belt; the second sensor is used to detect the material on the second sub-belt; the first sub-belt and the second sub-belt operate at the same speed.

[0010] Optionally, the device further includes a line scan camera acquisition card; the controller is communicatively connected to the first sensor, the second sensor, and the encoder, and includes: The first sensor, the second sensor, and the encoder are connected to the line scan camera acquisition card; The line scan camera acquisition card is communicatively connected to the controller; the line scan camera acquisition card is used to provide the current encoder count to the controller when the first sensor or the second sensor detects material.

[0011] According to an embodiment of the second aspect of this application, a belt slippage detection method is provided. This method is applied to a belt slippage detection device, which includes an encoder, a waste removal mechanism, a first sensor, a controller, and a second sensor disposed at the waste removal mechanism. The encoder is used to monitor the rotation angle of the drive shaft of the belt. The first sensor and the second sensor are spaced apart along the belt conveying direction, with the first sensor detecting the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder. The method includes: When the first sensor detects the material being conveyed on the belt, the material is counted to obtain the first material sequence number ID, and the current first encoder count is recorded. When the second sensor detects the material being conveyed on the belt, a material count is performed to obtain the second material sequence number ID, and the current second encoder count is recorded. A first material serial number ID that matches the second material serial number ID is determined, and the slippage of the belt is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0012] Optionally, the belt slippage detection device further includes a buffer; after obtaining the first material serial number ID and recording the current first encoder count, the method further includes: The first material serial number ID and the first encoder count corresponding to the first material serial number ID are stored in the buffer; The step of determining the first material serial number ID that matches the second material serial number ID includes: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

[0013] Optionally, determining the belt slippage based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID includes: Based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID, the theoretical displacement of the belt between the first sensor and the second sensor is determined. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

[0014] Optionally, determining the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID includes: The encoder count change is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. The belt displacement corresponding to the change in encoder count value is determined based on the preset conversion relationship between encoder count value and belt displacement. The belt displacement corresponding to the change in the encoder count value is determined as the theoretical displacement of the belt between the first sensor and the second sensor.

[0015] As can be seen from the above technical solution, by arranging the first sensor and the second sensor added at the waste removal mechanism along the conveying direction, it is possible to sense the same material passing through the positions of two different sensors sequentially. The controller assigns a material sequence number to each of the two sensing events and establishes a matching relationship between them, thereby accurately associating the encoder count values ​​corresponding to the same material passing through the first and second sensors. Through these two associated encoder count values, the controller can determine the displacement deviation of the material between the two sensors, and thus determine whether the belt has slipped. This solution allows the equipment to make a judgment before performing the waste removal operation, effectively avoiding problems such as waste mixing and material damage caused by incorrect waste removal. Attached Figure Description

[0016] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this application and, together with the specification, serve to explain the principles of this application.

[0017] Figure 1 A schematic diagram of a printing inspection machine in a related art provided in this application embodiment; Figure 2 A belt slippage detection device provided in this application embodiment; Figure 3 Another belt slippage detection device provided in the embodiments of this application; Figure 4 A flowchart illustrating a belt slippage detection method provided in this application embodiment; Figure 5 This is a schematic diagram of the overall process of the belt slippage detection method provided in the embodiments of this application. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions provided in the embodiments of this application, and to make the above-mentioned objectives, features and advantages of the embodiments of this application more apparent and understandable, the technical solutions in the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0019] Current material inspection machines, such as printing inspection machines, typically transport materials via belts, use photoelectric sensors to trigger image acquisition devices to capture and detect images of the materials, and remove abnormal materials through a scrap removal mechanism when an abnormality is detected.

[0020] Taking a printing inspection machine as an example, a printing inspection machine is used to detect defects in various printed materials (such as packaging boxes, labels, publications, etc.) during the printing process. Its workflow is as follows: the stacked printed materials are separated into individual sheets by a vibrating feeding mechanism and sent out one by one. Further, the individual sheets are fed into the suction belt of the feeding section. This suction belt can use negative pressure to adsorb the materials, ensuring that the materials are transported flat and without slippage.

[0021] When the material moves to the beginning of the detection area, it triggers the photoelectric sensor, which signals the start of the detection. The material enters the camera imaging section conveyor belt, where multiple line scan cameras continuously scan and image the material. The image processing system can analyze these images in real time, identify various printing defects in the material (such as inaccurate printing, color difference, stains, etc.), and generate a final judgment result (qualified product or defective product).

[0022] When the material moves to the scrap removal mechanism, the printing inspection machine controls the scrap removal mechanism to remove the scrap from the production line based on the judgment result.

[0023] It should be noted that the current control method for achieving precise waste removal relies on a photoelectric encoder connected to the conveyor belt drive shaft. Since the physical distance between the trigger sensor and the waste removal mechanism is fixed, under ideal conditions with no relative slippage between the belt and the drive shaft, the encoder pulse count increment corresponding to the material traversing this distance is also a fixed value. Therefore, the control system can preset this fixed encoder count difference, and trigger the waste removal action when the count value reaches a preset threshold.

[0024] However, under actual high-speed operating conditions, the belt may slip during operation. Once the belt slips, the material position will be inaccurate when using a fixed photoelectric encoder to count, which will affect the scrap removal result.

[0025] The following description uses a printing inspection machine as an example to illustrate the belt slippage situation.

[0026] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a printing inspection machine in a related art, provided as an embodiment of this application.

[0027] like Figure 1 As shown, the belt in the inspection machine runs at a high speed of 300m / min. When the photoelectric sensor detects the passing of the printed material, it triggers the recording of the current encoder count value and controls the line scan cameras 1 to 3 to start scanning. If the printed material is determined to be a defective product based on the camera scanning results, the defective product rejection mechanism will reject the printed material when the difference between the encoder count value corresponding to the printed material and the encoder count value when the printed material passes the photoelectric sensor reaches a preset fixed difference.

[0028] The removal of waste material is controlled by a photoelectric encoder connected to the conveyor belt. Since the physical distance from the trigger photoelectric sensor to the waste removal position is fixed, the corresponding photoelectric encoder count difference is also fixed, and the control terminal can control the waste removal based on this difference.

[0029] However, if belt slippage occurs (such as relative slippage between the belt and the drive shaft, or relative slippage between the material and the belt), the material position will be inaccurate when using a fixed photoelectric encoder to count and calculate, which will affect the scrap removal result, potentially causing scrap to be mixed with qualified products, or even causing the material to be damaged by the scrap removal mechanism.

[0030] Based on this, this application proposes a belt slippage detection device to detect whether belt slippage occurs during material transport.

[0031] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the belt slippage detection device provided in an embodiment of this application.

[0032] like Figure 2As shown, the belt slippage detection device includes at least an encoder and a scrap removal mechanism; the encoder is used to monitor the rotation angle of the drive shaft of the belt; the device also includes: a first sensor, a controller, and a second sensor disposed at the scrap removal mechanism; The first sensor and the second sensor are spaced apart along the belt conveying direction, and the first sensor detects the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder, respectively.

[0033] In this embodiment, a new sensor is added to the reject mechanism of the inspection machine in the related art (to distinguish it from the existing sensor, the existing sensor located at the beginning of the detection area will be referred to as the first sensor in the following description). Figure 2 The photoelectric sensor 1 in the middle, and the newly added sensor at the waste removal mechanism is recorded as the second sensor (i.e., Figure 2 The photoelectric sensor 2) is connected to the controller for communication.

[0034] After the addition of this second sensor, the control logic of the controller was also adjusted.

[0035] Specifically, the controller is configured as follows: When the first sensor detects the material being conveyed on the belt, the material is counted to obtain the first material sequence number ID, and the current first encoder count is recorded. When the second sensor detects the material being conveyed on the belt, a material count is performed to obtain the second material sequence number ID, and the current second encoder count is recorded. A first material serial number ID that matches the second material serial number ID is determined, and the slippage of the belt is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0036] In this embodiment, when the first sensor detects the material being conveyed on the belt, the controller can count the material to obtain the first material serial number ID corresponding to the material.

[0037] As one embodiment, the first material serial number ID can be used to characterize which material is being transported on the belt. For example, when the first sensor first detects the material being transported on the belt, the first material serial number ID corresponding to that material is set to 1. This application does not impose any limitations on this.

[0038] Simultaneously, when the first sensor detects material being conveyed on the belt, it can also record the current first encoder count. Here, the encoder is connected to the belt's drive shaft, converting the continuous rotational motion of the drive shaft into discrete electrical pulse signals and outputting an encoder count value to characterize the rotation angle or number of rotations of the drive shaft.

[0039] It should be noted that, when the belt is not slipping, there is a definite geometric proportional relationship between the rotation angle of the drive shaft and the linear displacement of the belt. For example, if the drive shaft rotates by k degrees, the belt will travel by x meters. This relationship is determined by the radius of the drive shaft and is a fixed conversion relationship.

[0040] Similarly, when the controller detects material being conveyed on the belt by the second sensor, it can count the material to obtain the second material serial number ID corresponding to that material.

[0041] In this embodiment, the controller generates the first material sequence number ID and the second material sequence number ID in the same way, for example, they are both numbered according to the order of the materials transported on the belt. This application does not impose any restrictions on this.

[0042] Since the controller generates the first material serial number ID and the second material serial number ID in the same way, the generated first material serial number ID and second material serial number ID are also the same for the same material. Therefore, the controller can further determine the first material serial number ID that matches the second material serial number ID, and determine the belt slippage based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0043] As an example, considering that the controller needs to determine the first material sequence number ID that matches the second material sequence number ID, the generated first material sequence number ID needs to be stored. Therefore, the belt slippage detection device proposed in this application may also include a buffer (not shown in the figure), which is used to cache the first material sequence number ID and the first encoder count corresponding to the first material sequence number ID.

[0044] Specifically, the controller is configured to determine the first material sequence number ID that matches the second material sequence number ID in the following manner: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

[0045] In this embodiment, after obtaining each first material serial number ID and the first encoder count, the first material serial number ID and the corresponding first encoder count can be stored in a cache. When the controller obtains a second material serial number ID, it can search for a first material serial number ID that is the same as the current second material serial number ID from the cached first material serial number IDs, and determine the first material serial number ID that matches the second material serial number ID.

[0046] Meanwhile, since the buffer stores the first material serial number ID and the corresponding first encoder count, when the first material serial number ID that matches the second material serial number ID is determined, the first encoder count corresponding to the first material serial number ID can also be obtained.

[0047] The specific methods for determining belt slippage are described below: In this embodiment, the physical distance between the first sensor and the second sensor is fixed. The controller can determine the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

[0048] Specifically, the theoretical displacement of the belt without slippage can be determined based on the first encoder count and the second encoder count for the same material. Then, this theoretical displacement is compared with the physical distance between the first sensor and the second sensor (i.e., the actual running distance of the material).

[0049] If the deviation between the theoretical displacement and the physical distance between the first and second sensors is greater than an acceptable error threshold, such as the theoretical displacement being much greater than the physical distance between the first and second sensors, it indicates that the belt has slipped.

[0050] Conversely, if the deviation between the theoretical displacement and the physical distance between the first and second sensors is not greater than an acceptable error threshold, it indicates that the belt has not slipped.

[0051] Specifically, determining the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID can be achieved through the following method: The encoder count change is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. The belt displacement corresponding to the change in encoder count value is determined based on the preset conversion relationship between encoder count value and belt displacement. The belt displacement corresponding to the change in the encoder count value is determined as the theoretical displacement of the belt between the first sensor and the second sensor.

[0052] In this embodiment, the encoder count change can be determined first based on the second encoder count and the first encoder count for the same material. Then, based on a preset conversion relationship between encoder count values ​​and belt displacement (i.e., the defined geometric ratio between the rotation angle of the drive shaft and the linear displacement of the belt mentioned above), the encoder count change is converted into the theoretical belt displacement.

[0053] Furthermore, as an example, the second sensor can be integrated into the waste removal mechanism or set independently of the waste removal mechanism. This application does not limit this, as long as the second sensor can sense the material and generate the corresponding photoelectric signal before the waste removal mechanism is working.

[0054] In this embodiment, considering the long distances that materials need to be transported in practical applications, transporting materials via a single belt would make belt deployment difficult and costly. Therefore, the belt in this application can consist of one or more sub-belts. When there are multiple sub-belts, the first sensor is used to detect the material entering the first sub-belt, and the second sensor is used to detect the material being transported on the sub-belt where the waste removal mechanism is located. Here, all sub-belts operate at the same speed, so they can still be counted by a single encoder.

[0055] Taking two sub-belts as an example, the belt includes a first sub-belt and a second sub-belt, and the material is conveyed from the first sub-belt to the second sub-belt; wherein, the first sensor is used to detect the material on the first sub-belt; the second sensor is used to detect the material on the second sub-belt; the first sub-belt and the second sub-belt operate at the same speed.

[0056] This concludes the discussion on... Figure 2 Description of the belt slippage detection device.

[0057] In this embodiment, it can be done according to Figure 2 The method shown directly connects the signals from the first sensor, the second sensor, and the encoder to the controller, allowing the controller to directly read the sensor signals and count the encoder's pulse signals. However, the accuracy of this method largely depends on the performance of the controller itself. For scenarios requiring high precision, this application also proposes another belt slippage detection device.

[0058] Please refer to Figure 3 , Figure 3 Another belt slippage detection device provided in this application embodiment.

[0059] like Figure 3 As shown, in Figure 2 Based on the belt slippage detection device shown, Figure 3 The belt slippage device shown also includes a line scan camera acquisition card, and the controller communicates with the first sensor, the second sensor and the encoder through the line scan camera acquisition card.

[0060] The line scan camera acquisition card is used to provide the current encoder count to the controller when the first or second sensor detects material.

[0061] Specifically, in this embodiment, all sensor signals and encoder signals are first connected to a dedicated line scan camera acquisition card, and then the acquisition card sends the packaged and synchronized data to the controller via a bus. As dedicated signal acquisition and synchronization hardware, the line scan camera acquisition card, upon receiving any sensor trigger signal, can use its internal clock and circuitry to synchronously obtain the current encoder count value and send this data packet containing the sensor trigger event and the current encoder count value to the controller to achieve higher synchronization accuracy.

[0062] This concludes the discussion on... Figure 3 The description.

[0063] The belt slippage detection method proposed in this application is described below.

[0064] Please refer to Figure 4 , Figure 4 This is a flowchart of a belt slippage detection method provided in an embodiment of this application.

[0065] The method is applied to a belt slippage detection device, which includes an encoder, a waste removal mechanism, a first sensor, a controller, and a second sensor disposed at the waste removal mechanism. The encoder is used to monitor the rotation angle of the drive shaft of the belt. The first sensor and the second sensor are spaced apart along the belt conveying direction, and the first sensor detects the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder.

[0066] like Figure 4 As shown, the method may include the following steps: Step 401: When the first sensor detects the material being conveyed on the belt, perform material counting to obtain the first material serial number ID, and record the current first encoder count.

[0067] Specifically, when the first sensor is triggered, it indicates that material has entered the detection area. At this time, a first material sequence number (ID) can be generated for the material currently detected by the first sensor. The method for generating the first material sequence number (ID) can be to generate them sequentially from smallest to largest according to the order in which the materials are detected by the first sensor. For example, the first material detected by the first sensor has a first material sequence number (ID) of 1, and the second material detected by the first sensor has a first material sequence number (ID) of 2. This application does not limit the method for generating the first material sequence number (ID).

[0068] Furthermore, when the first sensor is triggered, the current first encoder count can also be obtained. In this embodiment, the encoder count can be continuously accumulated starting from 0. After obtaining the first encoder count when the first sensor is triggered, the count can be determined as the count value when the material enters the detection area (is sensed by the first sensor).

[0069] As one embodiment, the belt slippage device further includes a buffer. After obtaining the first material sequence number ID and recording the current first encoder count, the method may further include: The first material serial number ID and the first encoder count corresponding to the first material serial number ID are stored in the cache.

[0070] Specifically, after obtaining the first material serial number ID and the corresponding first encoder count, the first encoder count and the first material serial number ID can be cached in a cache. Here, the cache queue in the cache records each first material serial number ID and the corresponding first encoder count.

[0071] This concludes the description of step 401. We will now proceed to step 402.

[0072] Step 402: When the second sensor detects the material being conveyed on the belt, material counting is performed to obtain the second material serial number ID, and the current second encoder count is recorded.

[0073] In this embodiment, when the second sensor is triggered, it indicates that there is material arriving at the waste removal mechanism. At this time, the second material serial number ID can be determined for the material in the same way as in step 401, and the current second encoder count can be obtained.

[0074] As an example, the second material serial number ID is generated in the same way as the first material serial number ID, so as to match the second material serial number ID with the first material serial number ID. For example, both are generated in ascending order according to the order in which the materials pass through the sensor. This application does not limit this.

[0075] This concludes the description of step 402. We will now proceed to step 403.

[0076] Step 403: Determine the first material serial number ID that matches the second material serial number ID, and determine the belt slippage status based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0077] In this embodiment, since the material passes through the first sensor first and then the second sensor, the first material serial number ID generated when it is sensed by the first sensor and the second material serial number ID generated when it is sensed by the second sensor can be matched to determine the same material sensed by the first sensor and the second sensor.

[0078] As an example, since the generation method of the first material identifier is the same as that of the second material identifier, the specific method for determining the first material serial number ID that matches the second material serial number ID may include: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

[0079] Since the buffer stores the first material serial number ID and the corresponding first encoder count, after determining the first material serial number ID that matches the second material serial number ID, the first encoder count corresponding to the first material serial number ID is also obtained.

[0080] Furthermore, the slippage of the belt can be determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

[0081] Specifically, based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID, the theoretical displacement of the belt between the first sensor and the second sensor is determined; If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

[0082] The specific method for determining the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID may include: The encoder count change is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. The belt displacement corresponding to the change in encoder count value is determined based on the preset conversion relationship between encoder count value and belt displacement. The belt displacement corresponding to the change in the encoder count value is determined as the theoretical displacement of the belt between the first sensor and the second sensor.

[0083] In this embodiment, according to the above method, the encoder count change can be determined based on the difference between the first encoder count and the second encoder count corresponding to the time when the same material is detected by the first sensor and the second sensor. Furthermore, based on the preset conversion relationship between encoder count and belt displacement, the theoretical displacement of the belt under non-slippage conditions can be determined.

[0084] Furthermore, the deviation between the theoretical displacement and the actual physical distance between the first sensor and the second sensor is determined. If the deviation is greater than the preset acceptable error threshold, it indicates that the deviation between the theoretical displacement of the belt and the actual displacement of the material is large, and at this time it can be determined that the belt is slipping.

[0085] In this embodiment, if it is determined that the belt is slipping, and the scrap removal mechanism is controlled to perform the scrap removal operation, it may result in an incorrect scrap removal result. Therefore, a shutdown alarm signal can be sent to alert the user that the belt is abnormal.

[0086] If the deviation between the theoretical displacement and the actual physical distance between the first sensor and the second sensor is not greater than the preset acceptable error threshold, it indicates that the deviation between the theoretical displacement of the belt and the actual displacement of the material is small, and it can be determined that the belt has not slipped.

[0087] In this embodiment, the belt slippage detection device further includes at least one line scan camera. The line scan camera is used to acquire images of the material being transported on the belt when the first sensor detects the material, and send the acquired images to the controller so that the controller can determine whether the material is abnormal or unqualified based on the acquired images.

[0088] If it is determined that the belt has not slipped, the scrap removal mechanism can be controlled to scrap abnormal or unqualified materials based on the judgment results of the images collected by the line scan camera.

[0089] This concludes the description of step 403.

[0090] As an example, the controller in this embodiment can communicate with the first sensor, the second sensor, and the encoder via a line scan camera acquisition card.

[0091] In this configuration, the line scan camera acquisition card is used to provide the current encoder count to the controller when the first or second sensor detects material.

[0092] Specifically, the line scan camera acquisition card can be pre-configured to call the application programming interface (API) provided by its Software Development Kit (SDK). Through this configuration, the line scan camera acquisition card can respond to callback events defined under the SDK framework. A callback event is a programming model that allows developers to pre-define a function (called a callback function) that is automatically invoked when a specific hardware event (such as sensor triggering) occurs, thereby achieving immediate and automatic response to hardware events.

[0093] For example, in this embodiment, callback events can be configured for the two photoelectric sensors respectively. That is, if either sensor is triggered by the material, the callback event will be triggered, and the acquisition card can immediately and automatically execute the callback function that the developer has pre-associated with the sensor through the SDK mechanism.

[0094] Specifically, when any sensor is triggered, the hardware circuit of the acquisition card immediately latches the instantaneous value of the encoder at that moment, and automatically triggers a callback event through the SDK, sending a data packet containing "which sensor triggered" and "the encoder value at the moment of triggering" to the controller.

[0095] After receiving a data packet from the data acquisition card, if the controller finds that the data packet carries data from the first sensor, it performs material counting to obtain the first material sequence number ID and records the current first encoder count. If the data packet carries data from the second sensor, it performs material counting to obtain the second material sequence number ID and records the current second encoder count. It then determines the first material sequence number ID that matches the second material sequence number ID, and based on the second encoder count corresponding to the second material sequence number ID and the first encoder count corresponding to the matched first material sequence number ID, it determines the belt slippage condition.

[0096] This concludes the discussion on... Figure 4 Description of the method.

[0097] The following is based on Figure 3 Taking the belt slippage detection device shown as an example, the overall belt slippage detection method flow is described.

[0098] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the overall process of the belt slippage detection method provided in the embodiments of this application.

[0099] First, pre-configure the system by installing a photoelectric sensor at the reject mechanism of the printing inspection machine. Figure 3 The photoelectric sensor 2 is used to ensure accurate detection of material passing through. The signal output lines of photoelectric sensor 2 and photoelectric sensor 1 are connected to the acquisition card of the line scan camera.

[0100] The acquisition card is further configured to respond to SDK callback events. When the photoelectric sensor for taking pictures and the photoelectric sensor at the waste removal mechanism are triggered, the corresponding callback events are triggered respectively.

[0101] like Figure 5 As shown, the method may include the following steps: When photoelectric sensor 1 is triggered, the line scan camera acquisition card obtains the current first encoder count and sends it to the controller. The controller generates the first material serial number ID and records the first encoder count and the first material serial number ID into the cache queue.

[0102] When the photoelectric sensor 2 at the waste removal mechanism is triggered, the acquisition card obtains the current second encoder count and sends it to the controller. The controller generates a second material sequence number ID and at the same time obtains a first material sequence number ID that matches the second material sequence number ID from the cache queue and obtains the corresponding first encoder count.

[0103] Calculate the difference between the first encoder count and the second encoder count to obtain the encoder count change, and convert the encoder count change into the theoretical displacement based on the conversion relationship between encoder count and material distance.

[0104] A judgment threshold (e.g., 10 cm) is preset. When the calculated theoretical displacement is greater than the actual material distance from the first sensor to the second sensor plus the judgment threshold, an alarm shutdown signal is issued.

[0105] During the normal operation of the printing inspection machine, monitor the belt for slippage in real time according to the above detection method. Once belt slippage is detected, an alarm stop signal can be issued immediately, and the operator can adjust or repair the belt in a timely manner to ensure the normal operation of the printing inspection machine.

[0106] This concludes the discussion on... Figure 5 The description.

[0107] This application utilizes a first sensor and a second sensor, added at the waste removal mechanism, arranged at intervals along the conveying direction to detect the same material passing through the positions of two different sensors sequentially. The controller assigns a material sequence number to each of the two sensing events and establishes a matching relationship between them, thereby accurately associating the encoder count values ​​corresponding to the same material passing through the first and second sensors. Using these two associated encoder count values, the controller can determine the displacement deviation of the material between the two sensors, and thus determine whether the belt has slipped. This scheme allows the equipment to make a judgment before the waste removal operation, effectively avoiding problems such as waste mixing and material damage caused by incorrect waste removal.

[0108] In addition, this application adopts a non-contact detection method. By converting the actual material distance to the encoder difference, the actual encoder difference is compared with the theoretical encoder difference to obtain an accurate result of whether the material is slipping. This method can determine whether slipping exists very efficiently.

[0109] Meanwhile, the cost required to implement this application is low. Only one photoelectric sensor needs to be added to the physical material, and the rest of the equipment is already present on the original equipment. By utilizing the existing encoder and data acquisition card and other hardware, it is possible to detect material slippage at low cost. Regardless of the fluctuation of the conveyor belt speed, it can accurately identify slipping materials.

[0110] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A belt slippage detection device, the device comprising at least an encoder and a scrap removal mechanism; the encoder is used to monitor the rotation angle of the drive shaft of the belt; characterized in that, The device also includes: a first sensor, a controller, and a second sensor disposed at the waste removal mechanism; The first sensor and the second sensor are spaced apart along the belt conveying direction, and the first sensor detects the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder, respectively; the controller is configured to: When the first sensor detects the material being conveyed on the belt, the material is counted to obtain the first material sequence number ID, and the current first encoder count is recorded. When the second sensor detects the material being conveyed on the belt, a material count is performed to obtain the second material sequence number ID, and the current second encoder count is recorded. A first material serial number ID that matches the second material serial number ID is determined, and the slippage of the belt is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

2. The apparatus according to claim 1, characterized in that, The device further includes a buffer; the buffer is used to cache the first material serial number ID and the first encoder count corresponding to the first material serial number ID; the controller is configured to determine the first material serial number ID that matches the second material serial number ID in the following manner: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

3. The apparatus according to claim 1 or 2, characterized in that, The physical distance between the first sensor and the second sensor is fixed; the controller is configured to determine the belt slippage condition by: The controller determines the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

4. The apparatus according to claim 1, characterized in that, The second sensor is integrated into the waste removal mechanism or is set independently of the waste removal mechanism.

5. The apparatus according to claim 1, characterized in that, The belt includes a first sub-belt and a second sub-belt, and the material is conveyed from the first sub-belt to the second sub-belt; The first sensor is used to detect the material on the first sub-belt; the second sensor is used to detect the material on the second sub-belt; the first sub-belt and the second sub-belt operate at the same speed.

6. The apparatus according to claim 1, characterized in that, The device also includes a line scan camera acquisition card; the controller is communicatively connected to the first sensor, the second sensor, and the encoder, and includes: The first sensor, the second sensor, and the encoder are connected to the line scan camera acquisition card; The line scan camera acquisition card is communicatively connected to the controller; the line scan camera acquisition card is used to provide the current encoder count to the controller when the first sensor or the second sensor detects material.

7. A method for detecting belt slippage, characterized in that, This method is applied to a belt slippage detection device, which includes an encoder, a waste removal mechanism, a first sensor, a controller, and a second sensor disposed at the waste removal mechanism. The encoder is used to monitor the rotation angle of the drive shaft of the belt. The first sensor and the second sensor are spaced apart along the belt conveying direction, and the first sensor detects the material on the belt before the second sensor. The controller is communicatively connected to the first sensor, the second sensor, and the encoder, respectively; the method includes: When the first sensor detects the material being conveyed on the belt, the material is counted to obtain the first material sequence number ID, and the current first encoder count is recorded. When the second sensor detects the material being conveyed on the belt, a material count is performed to obtain the second material sequence number ID, and the current second encoder count is recorded. A first material serial number ID that matches the second material serial number ID is determined, and the slippage of the belt is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID.

8. The method according to claim 7, characterized in that, The belt slippage detection device further includes a buffer; after obtaining the first material sequence number ID and recording the current first encoder count, the method further includes: The first material serial number ID and the first encoder count corresponding to the first material serial number ID are stored in the buffer; The step of determining the first material serial number ID that matches the second material serial number ID includes: Obtain the current second material serial number ID; Search for the first material serial number ID that is the same as the current second material serial number ID from the first material serial number ID already cached in the cache; The first material serial number ID that is the same as the current second material serial number ID is determined as the first material serial number ID that matches the second material serial number ID.

9. The method according to claim 8, characterized in that, The step of determining the belt slippage based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID includes: Based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID, the theoretical displacement of the belt between the first sensor and the second sensor is determined. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is greater than a preset threshold, then it is determined that the belt has slipped. If the difference between the theoretical displacement and the physical distance between the first sensor and the second sensor is not greater than the preset threshold, then it is determined that the belt has not slipped.

10. The method according to claim 9, characterized in that, The determination of the theoretical displacement of the belt between the first sensor and the second sensor based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID includes: The encoder count change is determined based on the second encoder count corresponding to the second material serial number ID and the first encoder count corresponding to the matched first material serial number ID. The belt displacement corresponding to the change in encoder count value is determined based on the preset conversion relationship between encoder count value and belt displacement. The belt displacement corresponding to the change in the encoder count value is determined as the theoretical displacement of the belt between the first sensor and the second sensor.

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