Carton packaging unstacking and restacking system and method

Abstract

The application discloses a carton package unstacking and restacking system and method, and belongs to the technical field of industrial robots. The system comprises an industrial robot, a visual detection unit, a control unit and an end grabbing device. The end grabbing device has a grabbing structure and an adaptive vacuum adjusting device. The grabbing structure enables the suction cup to adapt to the surface topography of the carton. The adaptive vacuum adjusting device dynamically adjusts the suction flow according to the surface state of the carton and the real-time vacuum degree. The system also has a multi-stage abnormality processing mechanism and a unstacking / restacking dual-mode switching capability. The application solves the problems in the prior art, such as the difficulty of the suction cup to adapt to the deformed carton, the inability to dynamically adjust the vacuum degree and the lag of abnormality processing, and significantly improves the grabbing success rate and the system adaptability. The application can be widely applied to the automatic unstacking and restacking of carton materials.

Description

Technical Field

[0001] This invention belongs to the field of automated palletizing technology for industrial robots, specifically relating to a system and method for depalletizing and repalletizing cardboard boxes, which is suitable for depalletizing, posture correction and repalletizing messy cardboard boxes with irregular surface conditions. Background Technology

[0002] In industries such as logistics warehousing, food and beverage, and home appliance manufacturing, depalletizing and palletizing cardboard packaging products are typical repetitive and high-intensity tasks. With the popularization of industrial robot technology, using robots to replace manual labor for depalletizing and palletizing has become an industry trend. However, in actual production, cardboard boxes are prone to compression and moisture during transportation and storage, resulting in irregular deformations such as wrinkles, dents, and damage on the surface, posing a significant challenge to automated handling.

[0003] In the prior art, various industrial robot depalletizing or palletizing systems have been disclosed. For example, patent CN119349238A discloses a system for palletizing items by vacuum adsorption. This system reduces physical pressure on the items through vacuum adsorption, preventing damage to external items, while a lifting platform allows the robotic arm to flexibly adjust its working height. However, this system uses a constant vacuum adsorption method and cannot dynamically adjust the adsorption parameters according to the surface condition of the carton (such as flatness, wrinkles, damage, etc.), resulting in poor adaptability to deformed or uneven cartons.

[0004] Patent CN120397741A discloses a paper box handling and palletizing robot that prevents paper boxes from falling. It adds limiting and anti-fall components to physically limit and lift the top and bottom of the paper box after the suction cup picks it up, preventing it from falling. While this mechanical anti-fall structure provides additional safety, it increases the complexity and weight of the end-effector. Furthermore, the size of the limiting components needs to be designed for specific paper box specifications, resulting in poor versatility for different sizes of cartons. It also fails to address the problem of poor suction cup adhesion caused by surface deformation of the carton.

[0005] Patent CN121186087B discloses a machine vision-based method and system for detecting stacking defects in corrugated cardboard. It uses an industrial CCD camera to acquire images of reflected light, transmitted light, and visible light channels, and fuses these image features to generate a defect response map for detecting stacking defects in corrugated cardboard. However, this solution focuses on offline detection of cardboard defects and does not provide real-time feedback of the detection results to a vacuum adsorption system for dynamic adjustment of adsorption parameters, nor does it address adaptive control during the robot's grasping process.

[0006] Patent CN107945192B discloses a real-time detection method for palletized cardboard boxes, which provides real-time data for robotic arms to automatically destacking by measuring the top layer distribution of stacked cardboard boxes. However, this method only detects the positional distribution information of the cardboard boxes and does not involve the fine classification of the surface condition of the cardboard boxes, making it difficult to meet the gripping requirements when the cardboard box surface is deformed such as wrinkles, dents, or damage.

[0007] Patent CN223385429U discloses a visual positioning gripper for automatic depalletizing, which uses a buffer system and a negative pressure bonding mechanism to attach a vacuum suction cup module to the outer surface of flexible packaging to form a stable negative pressure. Although this solution uses a buffer system, its buffer mechanism only achieves a simple bonding function and lacks precise design for the extension stroke and linkage control with vacuum adjustment.

[0008] Patent CN120987022A discloses a suction cup carton destacking and interference prevention method and system based on dynamic position offset. This solution uses dynamic adjustment of the suction cup's gripping position to avoid accidentally gripping adjacent cartons, primarily addressing the interference problem between adjacent cartons in multi-sized carton stacking scenarios. However, this solution focuses on the physical interference between the suction cup and adjacent cartons, without addressing the adhesion and sealing issue between the suction cup and the target carton surface.

[0009] In addition, existing depalletizing and palletizing systems often control the two stages independently, lacking coordinated scheduling, and often require intermediate buffer devices, which increases system complexity and floor space.

[0010] In summary, existing technologies generally suffer from the following shortcomings: First, the connection between the suction cup and the robot end effector is mostly rigid or a simple buffer connection, lacking precisely designed extension stroke, making it difficult to adaptively fit deformed or uneven cardboard boxes; second, vacuum adsorption systems generally operate in a constant vacuum mode, unable to dynamically adjust adsorption parameters according to the cardboard box surface condition, resulting in decreased adsorption reliability when the cardboard box is in poor condition, and wasted energy when the condition is good; third, anomaly handling mechanisms rely on post-event detection (such as servo overload or limit switch triggering), lacking the ability to predict and actively intervene before adsorption failure; fourth, there is a lack of coordination between the depalletizing and palletizing stages, resulting in low system integration. Therefore, developing an industrial robot system that can adapt to the cardboard box surface condition, has extension margin and dynamic vacuum adjustment functions, and can achieve coordinated depalletizing and palletizing operations has significant engineering application value. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide a depalletizing and repalletizing system and method for cardboard packaging. This invention achieves adaptive bonding with the surface of the cardboard box through the gripping structure of the end gripping device, and adapts to cardboard boxes with different surface conditions through the vacuum degree dynamic adjustment function, thereby improving the reliability of operation. At the same time, it realizes the coordinated scheduling of depalletizing and palletizing to meet the requirements of high-efficiency and highly adaptable automated operation.

[0012] To achieve the above objectives, the present invention adopts the following technical solution: a depalletizing and repalletizing system for cardboard box packaging, comprising an industrial robot, an end-effector gripping device, a vision inspection unit, and a control unit;

[0013] The end effector, mounted on the end of an industrial robot, includes a gripping structure and an adaptive vacuum adjustment device. The gripping structure comprises a connecting flange, a buffer telescopic mechanism, and a suction cup assembly. The gripping structure is connected to the end effector of the industrial robot via the connecting flange, and the connecting flange is connected to the suction cup assembly via the buffer telescopic mechanism to drive the suction cups to adaptively conform to changes in the surface shape of the cardboard box. The suction cup assembly includes a mounting plate, multiple suction cups mounted in the center of the mounting plate, suction cup lips located at the edge of the mounting plate, and several tactile sensors mounted on the suction cup lips. The tactile sensors are used to detect the uniformity of contact between the suction cup assembly and the cardboard box surface. The adaptive vacuum adjustment device is connected to the mounting plate and communicates with each suction cup through the mounting plate, used to detect the vacuum level of the suction cups and adjust the gripping suction force.

[0014] The visual inspection unit is fixedly installed on the top of the depalletizing station by a mounting bracket, and is used to collect two-dimensional image data and three-dimensional point cloud data of the stacked cartons on the depalletizing station.

[0015] The control unit is communicatively connected to the industrial robot, the end effector, and the vision inspection unit. It is used to acquire the three-dimensional pose information of the carton to be grasped based on the two-dimensional image data and three-dimensional point cloud data collected by the vision inspection unit, and to extract the degree of wrinkles and edge integrity features of the carton surface. This allows for the classification of the carton surface state into multiple state levels, thereby obtaining the carton surface state information. It is also used to control the industrial robot's movements based on the three-dimensional pose information, ensuring the end effector faces the surface of the carton to be grasped, and then grasps the carton. During the grasping process, the suction force is dynamically adjusted based on the carton surface state level and the real-time detected suction cup vacuum. Furthermore, it is used to control the industrial robot to fine-tune its grasping posture when the tactile sensor detects uneven contact.

[0016] The system uses industrial robots and end-effectors to pick up and transport messy cardboard boxes to the palletizing station, and then re-palletize them into neat stacks.

[0017] Furthermore, the buffer telescopic mechanism is disposed between the connecting flange and the suction cup assembly, so that the suction cup assembly has a preset telescopic stroke in the vertical direction relative to the connecting flange, so as to adaptively conform to the shape changes of the carton surface when the suction cup assembly contacts the carton surface; the buffer telescopic mechanism includes a guide rod, a linear bearing and a compression spring, the linear bearing is fixedly connected to the connecting flange externally, the linear bearing is slidably connected to the guide rod internally, the lower end of the guide rod is connected to the mounting plate, and the compression spring is sleeved on the outside of the guide rod and abuts against the connecting flange and the mounting plate to provide preload force for the suction cup assembly.

[0018] Furthermore, the adaptive vacuum adjustment device includes a vacuum generator, a vacuum pressure sensor, and a signal conditioning circuit; the guide rod of the buffer telescopic mechanism has a hollow structure, and the air inlet pipe of the vacuum generator is connected to each suction cup through the hollow channel of the guide rod and the mounting plate, for adjusting the vacuum level inside the suction cup cavity; the vacuum pressure sensor is connected to the mounting plate and communicates with each suction cup through the mounting plate, for detecting the vacuum level inside the suction cup cavity; the vacuum pressure sensor is communicatively connected to the control unit through the signal conditioning circuit to convert the vacuum level signal into an electrical signal and transmit it to the control unit;

[0019] The control unit dynamically adjusts the suction flow rate of the vacuum generator based on the vacuum degree signal detected by the vacuum pressure sensor and the surface condition information of the carton obtained by the vision detection unit, so as to adapt to the suction needs of cartons with different surface conditions.

[0020] Furthermore, the surface condition level of the carton includes at least several condition levels, such as flat, slightly wrinkled, severely deformed, and damaged. The control unit performs adaptive adjustment of the vacuum level based on the vacuum signal and the surface condition level of the carton, including at least:

[0021] When the vacuum level detected by the vacuum pressure sensor reaches the first threshold and the surface of the carton is flat, the vacuum generator is controlled to operate at the first suction flow rate.

[0022] When the vacuum level is lower than the first threshold but not lower than the second threshold, and the surface of the carton is slightly wrinkled or locally dented, the vacuum generator is controlled to operate at a second suction flow rate greater than the first suction flow rate.

[0023] When the vacuum level is lower than the second threshold and remains below the preset time, it is determined to be an absorption abnormality, triggering automatic retry or an alarm.

[0024] Furthermore, the control unit has a built-in multi-level exception handling mechanism, which is configured as follows:

[0025] In the first stage, before the suction cup assembly contacts the cardboard box, the visual inspection unit determines whether there is serious deformation or damage to the surface of the cardboard box. If so, the current cardboard box is skipped or the gripping order is replanned.

[0026] In the second stage, if the vacuum level detected by the vacuum pressure sensor cannot reach the minimum working threshold within a predetermined time during the suction process, the system will automatically execute a retry strategy, that is, release the suction cup, fine-tune the gripping posture, and try again.

[0027] The third level involves retrying a set number of times without success. If the system fails, it will determine the type of abnormality based on the characteristics of the change in vacuum level and output a graded alarm signal. The types of abnormalities include suction cup leakage, carton displacement, and visual positioning deviation.

[0028] Furthermore, the end-effector gripping device has two operating modes: depalletizing mode and palletizing mode, which are automatically switched by the control unit according to the current operation stage.

[0029] In destacking mode, the gripping structure activates the large stroke setting, and the adaptive vacuum adjustment device adopts an adaptive adjustment strategy.

[0030] In palletizing mode, the gripping structure switches to the locking or short-stroke position, and the adaptive vacuum adjustment device operates at a constant high vacuum.

[0031] Furthermore, the extension stroke of the buffer telescopic mechanism is 5mm to 20mm, and the stiffness of the compression spring is designed such that when the suction cup assembly contacts the surface of the carton and compresses the spring, the resulting reaction force is not greater than the allowable overload threshold of the industrial robot.

[0032] Furthermore, the suction cups in the suction cup assembly can be controlled independently, each suction cup is connected to an independent vacuum line, the multiple air intake pipes of the vacuum generator are respectively connected to the vacuum lines of each suction cup, and the multiple vacuum pressure sensors of the adaptive vacuum adjustment device are respectively connected to the mounting plate and connected to the vacuum lines of each suction cup through the mounting plate; the control unit selectively activates all or some of the suction cups according to the size and posture of the carton, and performs vacuum detection and adjustment on the activated suction cups respectively.

[0033] The present invention also provides a method for destacking and restacking cardboard boxes based on the above system, comprising the following steps:

[0034] Step 1: The control unit uses a vision detection unit to detect the cardboard box to be grasped, and obtains the three-dimensional pose information and surface condition level of the cardboard box;

[0035] Step 2: The control unit presets the initial suction flow of the vacuum generator according to the surface condition level of the carton, and controls the industrial robot to move the end gripper to the gripping point;

[0036] Step 3: The suction cup assembly contacts the surface of the carton, the buffer telescopic mechanism adaptively compresses, and the vacuum generator starts suction according to the initial suction flow rate;

[0037] Step 4: The vacuum pressure sensor detects the vacuum level in real time. If the vacuum level rises to the target threshold within a preset time, the suction is considered successful and the industrial robot performs the handling action.

[0038] Step 5: If the vacuum level cannot reach the target threshold within the preset time, determine the type of abnormality based on the change in vacuum level and the surface condition of the carton, and execute the following sub-steps:

[0039] If the problem is determined to be a minor leak or poor contact, increase the suction flow rate and extend the holding time, and then check the vacuum level again.

[0040] If the damage is determined to be severe or the carton has shifted, the suction cup is released, the abnormal information is recorded, and an alarm is triggered or the current target is skipped.

[0041] Step 6: After the transfer is completed, control the vacuum generator to release the vacuum, so that the suction cup separates from the carton.

[0042] Furthermore, before step 1, a system self-test step is included: detecting the initial vacuum sealing of the end-effector and the flexibility of the buffer telescopic mechanism; if the self-test fails, a system fault alarm is output.

[0043] Furthermore, in step 4, when the suction is successful and the industrial robot is handling the material, the vacuum pressure sensor continuously monitors the vacuum level. If the vacuum level drops beyond the allowable fluctuation range during handling, vacuum compensation is immediately activated and an early warning signal is issued. At the same time, the industrial robot is controlled to decelerate and move to a safe position before further handling.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. This invention incorporates a buffer telescopic mechanism in the end gripping device, enabling the suction cup to adaptively compress according to the actual shape of the carton surface, ensuring that the suction cup lip is tightly attached to the carton surface, significantly improving the success rate of suction, and is especially suitable for cartons with uneven surfaces or slight deformation.

[0046] 2. Based on the surface condition level of the carton obtained by visual inspection and the real-time vacuum feedback, the present invention dynamically adjusts the suction flow of the vacuum generator, reducing energy consumption while ensuring reliable suction. At the same time, it can automatically increase the adsorption force for cartons with surface wrinkles or slight damage, thus enhancing the environmental adaptability of the system.

[0047] 3. This invention establishes a multi-level anomaly handling strategy of "prediction-retry-tiered alarm", which can actively avoid anomalies before they occur, automatically retry and recover when anomalies occur, and accurately determine the anomaly type and output tiered alarms after retry failure, which greatly reduces system downtime and improves the reliability of unmanned operation.

[0048] 4. This invention uses a dual-mode switching design to ensure gripping reliability during the depalletizing stage and positioning accuracy during the palletizing stage. The two stages of operation can be completed without replacing the end effector, simplifying the system structure.

[0049] 5. This invention combines visual detection and control strategies to achieve dynamic planning of destacking sequence and optimization of handling path, thereby improving overall operation efficiency. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall structure of the depalletizing and repalletizing system for cardboard packaging provided in an embodiment of the present invention.

[0051] Figure 2 This is a schematic diagram of the end-effector gripping device in an embodiment of the present invention.

[0052] Figure 3 This is a schematic diagram of the grasping structure in an embodiment of the present invention.

[0053] Figure 4 This is a schematic diagram of the suction cup assembly in an embodiment of the present invention.

[0054] Figure 5 This is a flowchart illustrating the adaptive vacuum regulation process in an embodiment of the present invention.

[0055] Figure 6 This is a flowchart illustrating the multi-level exception handling mechanism in an embodiment of the present invention.

[0056] In the diagram: 1-Industrial robot; 2-End gripper; 3-Vision inspection unit; 4-Control unit; 5-Carton; 6-Depalletizing station; 7-Palletizing station; 21-Connecting flange; 22-Buffer telescopic mechanism; 23-Suction cup assembly; 24-Vacuum generator; 25-Vacuum pressure sensor; 26-Signal conditioning circuit; 221-Guide rod; 222-Linear bearing; 223-Compression spring; 231-Suction cup lip; 232-Mounting plate; 233-Tactile sensor. Detailed Implementation

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0059] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0060] like Figure 1-4 As shown, the cardboard box depalletizing and repalletizing system provided in this embodiment includes a six-degree-of-freedom industrial robot 1, an end effector 2, a vision inspection unit 3, and a control unit 4. In this embodiment, cardboard boxes 5 are stacked on the depalletizing station 6, with 5 boxes per layer and a total of 4 layers to be depalletized; the target stacking station 7 repalletizes the boxes according to the target stacking pattern of 4 boxes per layer and a total of 5 layers.

[0061] An end-effector 2 is mounted on the end of an industrial robot 1 and includes a gripping structure and an adaptive vacuum adjustment device. The gripping structure includes a connecting flange 21, a buffer telescopic mechanism 22, and a suction cup assembly 23. The gripping structure is connected to the end of the industrial robot 1 via the connecting flange 21, and the connecting flange 21 is connected to the suction cup assembly 23 via the buffer telescopic mechanism 22 to drive the suction cups to adaptively conform to the shape changes of the carton surface. The suction cup assembly 23 includes a mounting plate 232, multiple suction cups mounted in the middle of the mounting plate 232, suction cup lips 231 set on the edge of the mounting plate 232, and several tactile sensors 233 mounted on the suction cup lips 231. The tactile sensors 233 are used to detect the uniformity of contact between the suction cup assembly 23 and the carton surface. The adaptive vacuum adjustment device is connected to the mounting plate 232 and communicates with each suction cup through the mounting plate 232 to detect the suction cup vacuum level and adjust the gripping suction force.

[0062] The visual inspection unit 3 is fixedly mounted on the top of the depalletizing station 6 via a mounting bracket, and is used to collect two-dimensional image data and three-dimensional point cloud data of the stacked cartons 5 on the depalletizing station 6. In this embodiment, the visual inspection unit 3 includes a 3D camera and a laser ranging module, which are used to photograph and measure the distance of the cartons to be grasped before each depalletizing.

[0063] The control unit 4 is communicatively connected to the industrial robot 1, the end effector 2, and the vision inspection unit 3. It is used to acquire the three-dimensional pose information of the carton to be grasped based on the two-dimensional image data and three-dimensional point cloud data collected by the vision inspection unit 3, and to extract the degree of wrinkles and edge integrity features of the carton surface. This allows for the classification of the carton surface state into multiple state levels, thereby obtaining the carton surface state information. It is also used to control the movement of the industrial robot 1 based on the three-dimensional pose information, ensuring that the end effector 2 faces the surface of the carton to be grasped. The end effector 2 then grasps the carton, and during the grasping process, it dynamically adjusts the suction force based on the carton surface state level and the real-time detected suction cup vacuum. Furthermore, it is used to control the industrial robot 1 to fine-tune its grasping posture when the tactile sensor 233 detects uneven contact.

[0064] The system uses an industrial robot 1 and an end-effector 2 to pick up and transport messy cardboard boxes 5 to the palletizing station 7, and then re-palletize them into neat stacks.

[0065] like Figure 3 As shown, the buffer telescopic mechanism 22 is disposed between the connecting flange 21 and the suction cup assembly 23, so that the suction cup assembly 23 has a preset telescopic stroke in the vertical direction relative to the connecting flange 21, which is used to adaptively conform to the shape changes of the carton surface when the suction cup assembly 23 contacts the carton surface. The buffer telescopic mechanism 22 includes a guide rod 221, a linear bearing 222 and a compression spring 223. The linear bearing 222 is fixedly connected to the connecting flange 21 on the outside and slidably connected to the guide rod 221 on the inside. The lower end of the guide rod 221 is connected to the mounting plate 232. The compression spring 223 is sleeved on the outside of the guide rod 221 and abuts against the connecting flange 21 and the mounting plate 232, providing preload force for the suction cup assembly 23. When the suction cup assembly 23 contacts the carton surface, the mounting plate 232 can overcome the spring force and slide upward to achieve a maximum telescopic stroke of 15mm, so that the suction cup lip 231 is evenly conformed to the carton surface.

[0066] In this embodiment, the extension stroke of the buffer telescopic mechanism 22 is 5mm to 20mm, and the stiffness of the compression spring 223 is designed such that when the suction cup assembly 23 contacts the surface of the carton and compresses the spring, the resulting reaction force is not greater than the allowable overload threshold of the industrial robot 1.

[0067] like Figure 2As shown, the adaptive vacuum adjustment device includes a vacuum generator 24, a vacuum pressure sensor 25, and a signal conditioning circuit 26. The guide rod 221 of the buffer telescopic mechanism 22 has a hollow structure. The air inlet pipe of the vacuum generator 24 is connected to each suction cup through the hollow channel of the guide rod 221 and the mounting plate 232, and is used to adjust the vacuum degree in the suction cup cavity. The vacuum pressure sensor 25 is connected to the mounting plate 232 and communicates with each suction cup through the mounting plate 232, and is used to detect the vacuum degree in the suction cup cavity. The vacuum pressure sensor 25 is communicatively connected to the control unit 4 through the signal conditioning circuit 26 to convert the vacuum degree signal into an electrical signal and transmit it to the control unit 4. The control unit 4 dynamically adjusts the suction flow rate of the vacuum generator 24 according to the vacuum degree signal detected by the vacuum pressure sensor 25 and the cardboard box surface state information obtained by the vision detection unit 3, so as to adapt to the suction needs of cardboard boxes with different surface states.

[0068] Preferably, the multiple suction cups in the suction cup assembly 23 can be controlled independently, each suction cup is connected to an independent vacuum line, the multiple air intake pipes of the vacuum generator 24 are respectively connected to the vacuum lines of each suction cup, the multiple vacuum pressure sensors 25 of the adaptive vacuum adjustment device are respectively connected to the mounting plate 232 and connected to the vacuum lines of each suction cup through the mounting plate 232; the control unit 4 selectively activates all or some of the suction cups according to the size and posture of the carton, and performs vacuum detection and adjustment on the activated suction cups respectively.

[0069] In this embodiment, the suction cup assembly 23 has a rectangular frame structure with six independently controlled suction cups arranged in a 2×3 matrix at the bottom. Figure 4 As shown, the control unit 4 can automatically select and activate four suction cups and deactivate two suction cups based on the carton size obtained through visual detection to avoid ineffective suction. When gripping small-sized cartons, only the two central suction cups can be activated. Each suction cup unit independently detects the vacuum level. If a suction cup leaks air due to partial damage to the carton, the system can temporarily deactivate that suction cup and increase the vacuum level of the other suction cups as compensation to ensure sufficient overall suction force.

[0070] When the suction cup contacts the surface of the cardboard box, the tactile sensor 233 detects the contact pressure distribution at each point. If the pressure distribution is uneven (e.g., the pressure on one side is significantly greater than on the other), the control unit 4 determines that the suction cup is tilted and then fine-tunes the robot's end effector posture (by modifying the rotation amount in the tool coordinate system) until the pressure distribution is uniform before vacuum suction is performed. This design further improves the success rate of gripping tilted cardboard boxes.

[0071] In this embodiment, the vacuum generator 24 is a Venturi vacuum generator, and the compressed air flow rate is adjusted by the PWM signal output by the control unit 4, thereby changing the vacuum level. The control unit 4 is an industrial PLC or an embedded industrial computer.

[0072] In this embodiment, the system operates as follows:

[0073] (a) System self-test: After startup, the control unit 4 controls the vacuum generator 24 to operate at a medium flow rate, detects the vacuum change rate of each suction cup unit, and judges the pipeline sealing performance; at the same time, it controls the robot end effector to make small-range movements to check whether the buffer telescopic mechanism 22 is flexible. Only after the self-test is passed can the operation cycle begin.

[0074] (II) Destacking Stage:

[0075] 1. The visual inspection unit 3 takes pictures and measures the distance of the top layer of cardboard boxes at the depalletizing station 6. The 3D camera obtains the distance between the cardboard box surface and the camera. The control unit automatically adjusts the camera focal length and acquires images. The image processing algorithm extracts the outline, center coordinates, deflection angle, and surface flatness features of each cardboard box, and classifies the surface condition into four levels: "flat", "slightly wrinkled", "severely deformed", and "damaged".

[0076] 2. The control unit 4 sets the initial suction flow rate parameter for each carton according to the surface condition level: a lower flow rate (corresponding to a vacuum degree of about -40 kPa) for flat cartons, a medium flow rate (about -60 kPa) for slightly wrinkled cartons, and a high flow rate (about -80 kPa) for severely deformed cartons, and indicates the risk of possible failure.

[0077] 3. The control unit 4 calculates the robot's grasping posture according to the preset grasping sequence (or the optimal sequence planned by intelligence), and drives the industrial robot 1 to move the end effector 2 above the first carton. The robot slowly descends, the suction cup lip 231 contacts the surface of the carton, and the buffer telescopic mechanism 22 adaptively compresses until the suction cup is fully attached.

[0078] 4. The vacuum generator 24 starts at the initial flow rate, and the vacuum pressure sensor 25 monitors the vacuum level in real time. If the vacuum level reaches more than 90% of the target threshold within 0.5 seconds, the suction is considered successful, and the robot lifts the carton and transports it to the palletizing station 7.

[0079] 5. If the vacuum level rises slowly or fails to reach the target threshold, the abnormality type is determined based on the vacuum level change rate: If the change rate is normal but the final value is low, it is judged as a slight leak (such as incomplete sealing due to wrinkles on the cardboard surface). In this case, the suction flow rate is automatically increased and the adsorption time is extended to 1 second. If the vacuum level hardly changes, it is judged as a serious damage or the suction cup is not in contact. The suction cup is released, the gripping height and posture are finely adjusted, and the attempt is repeated, with no more than 2 retries. If the retry still fails, an audible and visual alarm is output and the position of the cardboard box is recorded. The cardboard box is then skipped and other cardboard boxes are continued to be disassembled.

[0080] (III) Palletizing stage:

[0081] When the end gripper 2 picks up the carton and moves it above the palletizing station 7, the control unit 4 automatically switches to the palletizing mode: the virtual "locking" function of the buffer telescopic mechanism 22 (limiting spring compression through control logic or using an electromagnetic locking device; in this embodiment, the robot's descent speed is reduced during the palletizing stage and precise downward pressure is achieved using position control, resulting in minimal spring compression, equivalent to a short-stroke mode); the vacuum generator 24 operates at a constant high flow rate (approximately -70 kPa) to ensure the carton is firmly adsorbed before placement; the vision detection unit 3 simultaneously takes pictures to correct the target placement position, ensuring placement accuracy within ±2 mm.

[0082] When placing the cardboard box, the control unit 4 first releases the vacuum, then slightly lifts the suction cup, using the restoring force of the buffer spring to help separate the suction cup from the cardboard box, preventing the cardboard box from being lifted and moved.

[0083] (iv) Rhythm and Coordination:

[0084] The control unit 4 incorporates a collaborative scheduling algorithm that merges depalletizing and palletizing actions into a continuous process: each time the robot picks up a carton from the depalletizing station, it moves directly to the palletizing station and places it there, without passing through the buffer platform. By optimizing the motion trajectory (using an S-shaped speed curve and shortest path planning), the single pick-and-place cycle is approximately 24 seconds. The total time to complete all 20 cartons (4 layers of depalletizing × 5 cartons = 20 cartons, 5 layers of palletizing × 4 cartons = 20 cartons) is approximately 24 seconds × 20 = 480 seconds, or 8 minutes.

[0085] In this embodiment, the surface condition level of the carton includes at least four levels: flat, slightly wrinkled, severely deformed, and damaged. The control unit 4 performs adaptive adjustment of the vacuum level based on the vacuum signal and the surface condition level of the carton, including at least:

[0086] When the vacuum level detected by the vacuum pressure sensor 25 reaches the first threshold and the surface of the carton is flat, the vacuum generator 24 is controlled to operate at the first suction flow rate.

[0087] When the vacuum level is lower than the first threshold but not lower than the second threshold, and the surface of the carton is slightly wrinkled or locally dented, the vacuum generator 24 is controlled to operate at a second suction flow rate greater than the first suction flow rate.

[0088] When the vacuum level is lower than the second threshold and remains below the preset time, it is determined to be an absorption abnormality, triggering automatic retry or an alarm.

[0089] Figure 5 A flowchart illustrating the adaptive vacuum regulation process in this embodiment is shown.

[0090] This embodiment also provides a multi-level exception handling mechanism built into the control unit 4. For example... Figure 6As shown, the specific implementation process of this multi-level exception handling mechanism is as follows.

[0091] Level 1 (Pre-judgment): Before the suction cup contacts the cardboard box, the vision detection unit identifies a hole larger than 3 cm or a severe tilt exceeding 45° on the surface of the cardboard box. The control unit directly marks the cardboard box as "ungrabable", skips the box, records its position, and waits for manual processing.

[0092] Level 2 (Retry Level): If the vacuum level is not met during the suction process, the system will automatically perform the following retry: ① Readjust the gripping point (offset ±5 mm); ② Increase the suction flow to the maximum; ③ While maintaining the vacuum, slightly vibrate the suction cup (via micro-motion at the robot end) to promote better adhesion between the suction cup lip and the carton. A maximum of 3 retry attempts are allowed, each with a different strategy.

[0093] Level 3 (Alarm Level): If all three retries fail, the system outputs specific alarm information based on the vacuum level change characteristics: If the vacuum level drops rapidly to zero, it is determined that the suction cup is damaged or the pipeline is detached, and the system outputs "Level 1 Alarm - Equipment Failure, Repair Required"; if the vacuum level fluctuates slowly but remains below the threshold, it is determined that the carton is severely leaking, and the system outputs "Level 2 Alarm - Material Abnormality, Please Check the Carton"; if the vacuum level is normal but suddenly drops during handling, it is determined that the carton has fallen off, and the system outputs "Level 3 Alarm - Grab Failure, Stop Immediately". Different alarms correspond to different audible and visual modes and display prompts.

[0094] The depalletizing and repalletizing system for cardboard packaging provided by this invention has a reasonable structural design and advanced control method. It can adapt to the cardboard box gripping requirements of various surface conditions and has the advantages of high gripping success rate, low energy consumption and strong abnormal handling capability. It can be widely used in automated packaging production lines in the food, beverage, daily chemical and home appliance industries, and has high industrial practical value and market promotion prospects.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A depalletizing and repalletizing system for cardboard box packaging, characterized in that, It includes an industrial robot (1), an end effector (2), a vision inspection unit (3), and a control unit (4); The end-effector (2) is installed at the end of the industrial robot (1) and includes a gripping structure and an adaptive vacuum adjustment device. The gripping structure includes a connecting flange (21), a buffer telescopic mechanism (22), and a suction cup assembly (23). The gripping structure is connected to the end of the industrial robot (1) via the connecting flange (21), and the connecting flange (21) is connected to the suction cup assembly (23) via the buffer telescopic mechanism (22) to drive the suction cup to adaptively conform to the shape changes of the carton surface. The suction cup assembly (23) includes... The assembly includes a mounting plate (232), multiple suction cups mounted in the middle of the mounting plate (232), suction cup lips (231) set on the edge of the mounting plate (232), and several tactile sensors (233) mounted on the suction cup lips (231); the tactile sensors (233) are used to detect the uniformity of contact between the suction cup assembly (23) and the surface of the carton; the adaptive vacuum adjustment device is connected to the mounting plate (232) and communicates with each suction cup through the mounting plate (232) to detect the vacuum degree of the suction cup and adjust the gripping suction force; The visual inspection unit (3) is fixedly installed on the top of the destacking station (6) by a mounting bracket, and is used to collect two-dimensional image data and three-dimensional point cloud data of the cardboard boxes (5) stacked on the destacking station (6); The control unit (4) is connected to the industrial robot (1), the end gripping device (2), and the vision detection unit (3) respectively. It is used to obtain the three-dimensional pose information of the carton to be gripped based on the two-dimensional image data and three-dimensional point cloud data collected by the vision detection unit (3), and extract the wrinkle degree and edge integrity features of the carton surface. Then, the surface state of the carton is classified into multiple state levels to obtain the surface state information of the carton. It is also used to control the movement of the industrial robot (1) based on the three-dimensional pose information, so that the end gripping device (2) faces the surface of the carton to be gripped, and then grips the carton to be gripped through the end gripping device (2). During the gripping process, the suction force is dynamically adjusted according to the surface state level of the carton and the vacuum degree of the suction cup detected in real time. It is also used to control the industrial robot (1) to fine-tune the gripping posture when the tactile sensor (233) detects uneven contact. The system uses an industrial robot (1) and an end-effector (2) to grab and transport messy cardboard boxes (5) to the palletizing station (7) and re-palletize them into neat stacks.

2. The depalletizing and repalletizing system for cardboard packaging according to claim 1, characterized in that, The buffer telescopic mechanism (22) is disposed between the connecting flange (21) and the suction cup assembly (23), so that the suction cup assembly (23) has a preset telescopic stroke in the vertical direction relative to the connecting flange (21), so as to adaptively conform to the shape changes of the carton surface when the suction cup assembly (23) contacts the carton surface; the buffer telescopic mechanism (22) includes a guide rod (221), a linear bearing (222) and a compression spring (223). The linear bearing (222) is fixedly connected to the connecting flange (21) on the outside and slidably connected to the guide rod (221) on the inside. The lower end of the guide rod (221) is connected to the mounting plate (232). The compression spring (223) is sleeved on the outside of the guide rod (221) and abuts between the connecting flange (21) and the mounting plate (232) to provide preload force for the suction cup assembly (23).

3. The depalletizing and repalletizing system for cardboard packaging according to claim 2, characterized in that, The adaptive vacuum adjustment device includes a vacuum generator (24), a vacuum pressure sensor (25), and a signal conditioning circuit (26); the guide rod (221) of the buffer telescopic mechanism (22) has a hollow structure, and the air inlet pipe of the vacuum generator (24) is connected to each suction cup through the hollow channel of the guide rod (221) and the mounting plate (232) to adjust the vacuum degree in the suction cup cavity; the vacuum pressure sensor (25) is connected to the mounting plate (232) and communicates with each suction cup through the mounting plate (232) to detect the vacuum degree in the suction cup cavity; the vacuum pressure sensor (25) is communicatively connected to the control unit (4) through the signal conditioning circuit (26) to convert the vacuum degree signal into an electrical signal and transmit it to the control unit (4); The control unit (4) dynamically adjusts the suction flow of the vacuum generator (24) based on the vacuum degree signal detected by the vacuum pressure sensor (25) and the cardboard surface state information obtained by the vision detection unit (3) to adapt to the suction needs of cardboard boxes with different surface states.

4. The depalletizing and repalletizing system for cardboard packaging according to claim 3, characterized in that, The surface condition levels of the carton include at least several levels, such as flat, slightly wrinkled, severely deformed, and damaged. The control unit (4) performs adaptive adjustment of the vacuum level based on the vacuum signal and the surface condition levels of the carton, including at least: When the vacuum level detected by the vacuum pressure sensor (25) reaches the first threshold and the surface of the carton is flat, the vacuum generator (24) is controlled to operate at the first suction flow rate. When the vacuum level is lower than the first threshold but not lower than the second threshold, and the surface of the carton is slightly wrinkled or locally dented, the vacuum generator (24) is controlled to operate at a second suction flow rate greater than the first suction flow rate. When the vacuum level is lower than the second threshold and remains below the preset time, it is determined to be an absorption abnormality, triggering automatic retry or an alarm.

5. The depalletizing and repalletizing system for cardboard packaging according to claim 3, characterized in that, The control unit (4) has a built-in multi-level exception handling mechanism, which is configured as follows: In the first stage, before the suction cup assembly (23) contacts the carton, the surface condition information of the carton obtained by the vision detection unit (3) is used to predict whether there is serious deformation or damage. If so, the current carton is skipped or the grabbing order is replanned. In the second stage, if the vacuum level detected by the vacuum pressure sensor (25) cannot reach the minimum working threshold within a predetermined time during the suction process, the system will automatically execute the retry strategy, that is, release the suction cup, fine-tune the gripping posture and try again. The third level involves retrying a set number of times without success. If the system fails, it will determine the type of abnormality based on the characteristics of the change in vacuum level and output a graded alarm signal. The types of abnormalities include suction cup leakage, carton displacement, and visual positioning deviation.

6. The depalletizing and repalletizing system for cardboard packaging according to claim 1, characterized in that, The end gripping device (2) has two working modes: depalletizing mode and palletizing mode, which are automatically switched by the control unit (4) according to the current operation stage. In destacking mode, the gripping structure activates the large stroke setting, and the adaptive vacuum adjustment device adopts an adaptive adjustment strategy. In palletizing mode, the gripping structure switches to the locking or short-stroke position, and the adaptive vacuum adjustment device operates at a constant high vacuum.

7. The depalletizing and repalletizing system for cardboard packaging according to claim 2, characterized in that, The extension stroke of the buffer telescopic mechanism (22) is 5mm to 20mm, and the stiffness of the compression spring (223) is designed such that when the suction cup assembly (23) contacts the surface of the carton and compresses the spring, the resulting reaction force is not greater than the allowable overload threshold of the industrial robot (1).

8. The depalletizing and repalletizing system for cardboard packaging according to claim 3, characterized in that, The suction cups in the suction cup assembly (23) can be controlled independently, and each suction cup is connected to an independent vacuum pipeline. The multiple air intake pipes of the vacuum generator (24) are connected to the vacuum pipelines of each suction cup. The multiple vacuum pressure sensors (25) of the adaptive vacuum adjustment device are connected to the mounting plate (232) and connected to the vacuum pipelines of each suction cup through the mounting plate (232). The control unit (4) selectively activates all or some of the suction cups according to the size and posture of the carton, and performs vacuum detection and adjustment on the activated suction cups respectively.

9. A method for destacking and restacking cardboard box packaging based on the system described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: The control unit (4) detects the carton to be grasped through the vision detection unit (3) to obtain the three-dimensional pose information and surface state level of the carton; Step 2: The control unit (4) presets the initial suction flow of the vacuum generator (24) according to the surface condition level of the carton, and controls the industrial robot (1) to move the end gripping device (2) to the gripping point; Step 3: The suction cup assembly (23) contacts the surface of the carton, the buffer telescopic mechanism (22) adaptively compresses, and the vacuum generator (24) starts adsorption according to the initial suction flow rate; Step 4: The vacuum pressure sensor (25) detects the vacuum level in real time. If the vacuum level rises to the target threshold within a preset time, the suction is determined to be successful and the industrial robot (1) performs the handling action. Step 5: If the vacuum level cannot reach the target threshold within the preset time, determine the type of abnormality based on the change in vacuum level and the surface condition of the carton, and execute the following sub-steps: If the problem is determined to be a minor leak or poor contact, increase the suction flow rate and extend the holding time, and then check the vacuum level again. If the damage is determined to be severe or the carton has shifted, the suction cup is released, the abnormal information is recorded, and an alarm is triggered or the current target is skipped. Step 6: After the transfer is completed, control the vacuum generator (24) to release the vacuum, so that the suction cup is separated from the carton.

10. The method for destacking and restacking cardboard box packaging materials according to claim 9, characterized in that, In step 4, when the suction is successful and the industrial robot (1) is handling the process, the vacuum pressure sensor (25) continuously detects the vacuum level. If the vacuum level drops beyond the allowable fluctuation range during the handling process, vacuum compensation is immediately activated and an early warning signal is issued. At the same time, the industrial robot (1) is controlled to decelerate and run to a safe position before being handled.

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