A conveying line tray posture self-adaptive shaping control method

Abstract

The embodiment of the application provides a kind of conveying line tray posture self-adapting shaping control method, it is related to automated logistics conveying equipment technical field, method includes at the entrance of shaping area along the direction of conveying interval arrangement three groups of sensors, the skew angle and skew direction are calculated by detecting the time difference of tray front end reaching each sensor;Skew angle is compared with threshold value, and divided into three grades of slight skew, moderate skew and serious skew;According to skew grade, corresponding shaping strategy is executed;In the shaping process, the displacement sensor and pressure sensor are used to monitor the push plate stroke and push force in real time, and when the push force exceeds the safety threshold and the displacement change is less than the set threshold, it is determined that the card is stuck and the machine is stopped for protection.The present application realizes the accurate detection of tray skew posture, on-demand hierarchical shaping and safety protection, and improves the shaping efficiency and reliability.

Description

Technical Field

[0001] This invention relates to the field of automated logistics conveying equipment technology, and in particular to a method for adaptive shaping control of pallet posture on a conveyor line. Background Technology

[0002] In automated warehousing and logistics systems, empty pallets are transported along the conveyor line after being collected from the sorting machine. Due to factors such as the inertial impact when the conveyor line starts and stops, and uneven friction between the pallet and the conveyor rollers, the pallets often become skewed on the conveyor line. When the skewed pallets enter the subsequent stacking station or automated storage and retrieval system, it will cause the pallets to fail to enter the warehouse normally, the stacker crane to alarm and stop, and even cause the conveyor line to be blocked and the equipment to be damaged.

[0003] Existing pallet shaping technologies have the following shortcomings: most devices can only detect whether a pallet has entered the shaping area, but cannot sense the specific tilt angle and direction of the pallet; they use fixed shaping force and methods, and cannot differentiate processing according to the degree of tilt, resulting in over-shaping and wasted cycle time when the tilt is slight, and under-shaping when the tilt is severe; the shaping process lacks closed-loop safety protection, and cannot stop the machine in time when the pallet is stuck, which can easily damage the equipment; the patent with publication number CN112298884B discloses a method of pushing goods straight by using limiters to block and clamping correction components, but does not involve the precise detection of tilt angle and graded shaping; the patent with publication number CN201810147855.X discloses adjusting the position of objects by detecting tilt with sensors and controlling the start and stop of the conveyor belt, but its adjustment method is to start and stop the conveyor belt rather than actively shaping; the patent with publication number CN202310919529 discloses a side-push component for shaping pallets, but the shaping method is singular.

[0004] To address the aforementioned issues, there is an urgent need for a control method that can accurately detect the skew angle, adaptively reshape according to the degree of skew, and provide closed-loop safety protection. Summary of the Invention

[0005] To address the aforementioned issues, this application provides an adaptive shaping control method for pallet posture on a conveyor line.

[0006] The adaptive shaping control method for pallet posture on a conveyor line provided in this application adopts the following technical solution: An adaptive shaping control method for pallet posture on a conveyor line includes the following steps: S1. Accurate detection of the skewed posture of pallets: at least three sets of sensors are arranged at intervals along the conveying direction at the entrance of the shaping area on the conveyor line, each set of sensors comprises at least a first sensor and a second sensor along the width direction of the conveyor line, the spacing between two adjacent sets of sensors in the conveying direction is d, and the spacing between the first sensor and the second sensor in the width direction of the conveyor line is w. When the pallet enters the shaping area along the conveyor line at a speed v, a PLC records the time when each sensor detects the front end of the pallet. Since the pallet is skewed, there is a difference between the times when different positions of the front edge of the pallet reach different sensors in the same sensor set, and this time difference is recorded as Δt. The PLC calculates the skewing angle θ of the pallet in the horizontal plane according to the formula θ=arctan(d×Δt / w), and determines the skewing direction according to the side where the sensor with earlier detection time between the first sensor and the second sensor is located; S2. Graded determination of skewness degree: the PLC compares the absolute value of the skewing angle θ with a preset first threshold θ1 and a preset second threshold θ2, wherein 0<θ1<θ2, and the comparison results are divided into three cases: when |θ|≤θ1, it is determined as slight skewing; when θ1<|θ|≤θ2, it is determined as moderate skewing; when |θ|>θ2, it is determined as severe skewing. In this way, the continuous skewing angle is discretized into three grades, and each grade corresponds to a different processing strategy; S3. Adaptive execution of graded shaping strategies: the PLC calls and executes the corresponding shaping strategy from a pre-stored shaping strategy library according to the determined skewing grade; for slight skewing, since the skewing angle is small, the pallet can be righted only by applying a reverse light push to the pallet, so the PLC drives the unilateral push plate on the side opposite to the skewing direction to extend at a first speed v1, applies a first thrust F1 to the pallet for one-way straightening, and immediately retracts the push plate after straightening; for moderate skewing, the skewing angle is medium, and one-time strong straightening may cause the pallet to tip over or over-shaping, so the PLC drives the bilateral push plates to extend in an alternating manner, each push plate performs multiple progressive straightening at a second speed v2, and stays for t_wait after each advance, so that the pallet has enough time to respond, and then advances again until the skewing angle drops below θ1; for severe skewing, the skewing angle is large and the posture of the pallet is seriously deviated, so pre-positioning is required before strong shaping, therefore, the PLC first drives the positioning stopper arranged above the conveyor line to descend to a predetermined height to press the pallet, so as to prevent the pallet from warping or tipping over during shaping, and then drives the bilateral push plates to extend synchronously at a third speed v3 for two-way strong shaping. Among the three above strategies, the speed relationship satisfies v1<v2<v3, and F1 is smaller than the maximum thrust in the shaping strategies for moderate skewing and severe skewing, so as to ensure that excessive force is not applied to damage the pallet when the skewing is slight; S4. Closed-loop safety protection during the shaping process: During the shaping action of the shaping mechanism, the displacement sensor installed on the shaping mechanism detects the stroke S of the shaping push plate in real time, and the pressure sensor detects the thrust F applied by the shaping push plate to the side of the tray in real time. The PLC collects displacement data and pressure data at a sampling frequency f. The PLC compares the collected thrust F with the preset safety pressure threshold P_max, and at the same time compares the displacement change ΔS within the continuous time Δt_c with the preset displacement change threshold ΔS_min. When the thrust F exceeds P_max and the displacement change ΔS is less than ΔS_min, it indicates that the push plate has encountered a hard jam that cannot be pushed.

[0007] Optionally, each group of sensors in S1 also includes a third sensor along the width of the conveyor line. The first, second, and third sensors are distributed at equal intervals. The PLC combines the time difference Δt1 between the first and second sensors, the time difference Δt2 between the second and third sensors, and the time difference Δt3 between the first and third sensors, and takes the average of the three as the time difference Δt used to calculate the skew angle.

[0008] Optionally, in S3, for moderate skew, the PLC recalculates the current skew angle of the tray after each push plate advance. If the current skew angle has dropped below the first threshold θ1, the subsequent progressive push-correction action is terminated in advance.

[0009] Optionally, after the PLC in S4 determines that the pallet is stuck, it also sends a stop command to the conveyor control system to prevent subsequent pallets from entering the shaping station and avoid the jamming range from expanding.

[0010] Optionally, it also includes S5: quality verification and diversion after shaping. A verification sensor group is set at the exit of the shaping area, with the same layout as at the entrance. When the pallet passes through the exit, the PLC detects the tilt angle θ` of the shaped pallet. If |θ`| exceeds the preset qualified threshold θ_ok, the PLC diverts the pallet to the abnormal processing channel for secondary shaping; otherwise, the pallet is released.

[0011] Optionally, it also includes S6: recording of running data and adaptive optimization of parameters. The PLC records the skew angle θ, the shaping time T, the maximum thrust F_max, and the skew angle θ` after shaping for each shaping to the database. After every N runs, the PLC updates the first threshold θ1, the second threshold θ2, and the speed parameters in each shaping strategy based on the statistical results.

[0012] In summary, this application includes at least one of the following beneficial technical effects: First, by using a specific layout of multiple sensors and a formula for calculating the tilt angle, the precise detection and direction determination of the tray tilt angle were achieved, providing a reliable data foundation for differentiated shaping. Second, by setting two threshold levels and three corresponding shaping strategies, on-demand shaping is achieved. When there is slight deviation, quick one-way push-to-correction saves time. When there is moderate deviation, alternating and gradual approach avoids overshoot. When there is severe deviation, pre-positioning and bi-directional strong force ensure the shaping effect. The three strategies work together to significantly improve the overall shaping efficiency compared to a single fixed method. Third, the dual-judgment logic of thrust and displacement is more reliable than single-sensor detection and can effectively prevent equipment damage. Attached Figure Description

[0013] Figure 1 This is the overall flowchart of this method; Figure 2 This is a schematic diagram of an empty pallet shaping machine.

[0014] Explanation of reference numerals in the attached drawings: 1. Frame; 2. Conveyor line; 3. Shaping pusher assembly; 4. Detection sensor; 5. Attitude detection sensor; 6. Verification sensor. Detailed Implementation

[0015] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of this application, “at least one” and “one or more” refer to one, two, or more than two. The term “and / or” is used to describe the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can indicate: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0016] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0017] The following is in conjunction with the appendix Figure 1and attached Figure 2 The present invention will be described in further detail below. Example 1

[0018] This embodiment is implemented on an empty pallet shaping machine, which includes a frame 1 and a conveyor line 2 on the frame 1. The conveyor line 2 is a roller conveyor. The shaping station is installed in the middle section of the conveyor line 2. A shaping push plate assembly 3 is installed on each of the left and right sides of the shaping station. The left and right push plate assemblies are identical in structure and symmetrically arranged. Each assembly includes a push plate, a push rod, a ball screw pair, a servo motor, a displacement sensor, and a pressure sensor. The side of the push plate facing the center of the conveyor line 2 is provided with a rubber buffer layer. The back of the push plate is connected to the push rod. The other end of the push rod is connected to the nut seat of the ball screw pair. The screw of the ball screw pair is connected to the output shaft of the servo motor. A displacement sensor is installed on the ball screw pair to detect the extension and retraction of the push plate. A pressure sensor is provided at the connection between the push rod and the push plate to detect the thrust applied to the push plate.

[0019] A positioning block assembly is installed above the conveyor line 2 at the center of the shaping station. The positioning block assembly includes a cylinder, which is vertically mounted on a crossbeam fixed above the frame of the conveyor line 2. The cylinder output end is equipped with a pressure plate, and the surface of the pressure plate is equipped with a rubber pad. When the shaping is severely skewed, the cylinder drives the pressure plate to descend to a height of 50 mm from the upper surface of the conveyor roller, pressing the pallet down from above.

[0020] At the entrance of the shaping station, three sets of detection sensors 4 are arranged at intervals along the conveying direction. The distance d between two adjacent sets in the conveying direction is 100 mm. Each set of detection sensors 4 has three photoelectric sensors arranged at equal intervals along the width direction of the conveyor line 2, namely the first sensor, the second sensor, and the third sensor. The first sensor is located on the left side of the conveyor line 2, the second sensor is located in the middle, and the third sensor is located on the right side. The distance w between adjacent sensors in the width direction is 200 mm. The signal output terminals of all sensors are connected to the digital input port of the PLC. The PLC reads the running speed of the roller conveyor every 10 milliseconds. Similarly, three sets of attitude detection sensors 5 are set directly above the shaping station. Three sets of verification sensors 6 are set at the exit of the shaping station, and their arrangement is exactly the same as the three sets of detection sensors 4.

[0021] The pallet enters the shaping station from conveyor line 2. During transport, the pallet tilts due to inertial impact, specifically to the right, with the left edge in front and the right edge behind. When the front of the pallet reaches the first set of detection sensors 4, the first sensor is triggered first, and the PLC records the trigger time as 0.000 seconds. 0.030 seconds later, the second sensor is triggered, and the time is recorded as 0.030 seconds. Another 0.030 seconds later, the third sensor is triggered, and the time is recorded as 0.060 seconds. Therefore, the time difference Δt1 between the first and second sensors is 0.030 seconds, the time difference Δt2 between the second and third sensors is 0.030 seconds, and the time difference Δt3 between the first and third sensors is 0.060 seconds. The PLC takes the average of the three values, Δt = (0.030 + ... 0.030 + 0.060) / 3 = 0.040 seconds. Substituting this into the deflection angle calculation formula: θ = arctan(d × Δt / w) = arctan(100 mm × 0.040 seconds / 200 mm) = arctan(0.020) ≈ 1.15°. Since the first sensor is triggered before the third sensor, it indicates that the left side of the tray arrives first, so the tray deflects to the right. To verify the accuracy of the detection, the PLC simultaneously performs the same calculation on the detection data of the second group of detection sensors 4 and the third group of detection sensors 4, obtaining 1.10° and 1.18° respectively. Taking the average of the three groups, 1.14°, as the final deflection angle θ, the accurate deflection angle and direction are obtained.

[0022] The PLC internally presets a first threshold θ1 of 2° and a second threshold θ2 of 8°. Comparing |θ| = 1.14° with these two thresholds: 1.14° ≤ 2°, satisfying the condition |θ| ≤ θ1, the PLC determines the tray is slightly tilted. Based on this determination, the PLC retrieves the corresponding first shaping strategy from the shaping strategy library. Since the tray is tilted to the right, it needs to be straightened from the left. Therefore, the PLC instructs the servo motor of the left pusher to operate in speed control mode, setting the first speed v1 to 20 mm / s. The target stroke is determined theoretically, and the theoretically required pushing stroke is the longitudinal length of the tray multiplied by the tangent of the tilt angle, i.e., 1200 mm × tan1.14° ≈ 1200 mm × 0. 0199≈23.9 mm. Considering the factor of the push plate compressing the rubber buffer layer, the PLC sets the target stroke to 25 mm and the upper limit of thrust F1 to 200 N. This value is monitored by the pressure sensor and used as the limit value in the program. After the PLC issues the start command, the left push plate extends at a speed of 20 mm per second. During this process, the PLC reads the values ​​of the displacement sensor and the pressure sensor in real time. When the push plate reaches the 25 mm stroke, the peak thrust is about 210 N, which is slightly higher than the set value but still within the safe range. After the PLC detects that the displacement has reached the target value, it immediately stops pushing and instructs the push plate to return to the initial position at a speed of 40 mm per second. The whole process from the push plate starting to extend to its complete retraction takes about 1.9 seconds.

[0023] During the extension of the shaping pusher, the jamming detection program runs continuously. The PLC sets the safety pressure threshold P_max to 800 Newtons, the displacement change threshold ΔS_min to 1 millimeter, and the continuous time Δt_c to 0.2 seconds. In each sampling cycle, the PLC reads the current thrust F and displacement S, and calculates the displacement change ΔS in the past 0.2 seconds. In this embodiment, the peak thrust is only 210 Newtons, which is far lower than 800 Newtons. Therefore, the first condition for jamming detection is not met, and the PLC will not misjudge jamming. The shaping pusher advances smoothly until completion, and no alarm is triggered in the jamming detection step in step four.

[0024] After the shaping is completed, the pallet continues to move forward along conveyor line 2. When the pallet passes through the exit, the PLC detects the skew angle θ` after shaping in the same way as in step one. The detection result is θ`≈0.3°, which is less than the preset qualified threshold θ_ok=1.5°. Therefore, the PLC determines that the shaping is qualified and does not perform the diversion action. The pallet continues to move forward along the main conveyor line 2. If θ` is greater than 1.5°, the PLC will send a command to the pneumatic flap located downstream of the exit to guide the pallet to the bypass abnormal handling channel.

[0025] The PLC records the complete data of this shaping process to the built-in SD card database, including: timestamp, tray number, original skew angle, skew direction, execution strategy number, shaping duration, maximum thrust of the left pusher, maximum thrust of the right pusher, skew angle after shaping, and whether to divert traffic. This data will be used for parameter optimization analysis after every 500 runs.

[0026] After the system runs 500 times consecutively, the PLC automatically performs parameter optimization analysis. The PLC reads the records of the most recent 500 shaping operations from the database and statistically analyzes the distribution of the original skew angle θ_in. The results show that the mean skew angle μ = 3.2°, the standard deviation σ = 2.1°, and only 3.2% of the trays exceed the second threshold of 8°, while 68% exceed the first threshold of 2°. This means that most trays have skew angles concentrated between 1.1° and 5.3°. The original first threshold θ1 = 2° caused a large number of trays with skew angles between 2° and 5.3° to be classified as moderately skewed, resulting in the execution of time-consuming alternating progressive shaping. However, in reality, these... The tray can potentially be shaped quickly in one direction with a slight skew. Therefore, the PLC calculates and suggests a new first threshold of μ + 0.5σ = 3.2° + 1.05° = 4.25°. However, to prevent the threshold from being too high and causing shaping failure, an upper limit of 4° is set, and the final suggestion is θ1 = 4°. At the same time, the PLC statistics show that the average duration of the moderate skew shaping strategy is 3.5 seconds, which is much higher than the theoretical expectation of 2.0 seconds. The analysis suggests that the dwell time t_wait = 0.3 seconds is too long and it is recommended to shorten it to 0.2 seconds. These optimization suggestions are displayed to the operator through the human-machine interface. After the operator confirms, the PLC updates the parameters, and the system enters the optimized operating mode. Example 2

[0027] This embodiment uses the same equipment and parameter settings as Embodiment 1, the difference being the initial tilt angle of the pallet. In this embodiment, the pallet tilts to the left, and the tilt angle θ calculated by attitude detection is 5.2°. Comparing |θ|=5.2° with the first threshold of 2° and the second threshold of 8°: 2°<5.2°≤8°, this satisfies the condition... The condition θ1 < |θ| ≤ θ2 is met, therefore the PLC determines it to be a moderate skew.

[0028] Based on the determination of moderate skew, the PLC retrieves the second shaping strategy. The second shaping strategy adopts a method of alternating and progressively pushing the tray to the right. Since the tray is skewed to the left, it needs to be pushed to the right first. Therefore, the PLC first drives the left pusher to extend, setting the second speed v2 to 40 mm / s. The single push stroke is allocated according to the total skew amount. The theoretically required total stroke is L×tanθ=1200 mm×tan5.2°≈1200 mm×0.0910≈109 mm. The PLC divides the total stroke into 4 left pushes and 4 right pushes, alternating. The stroke of each push gradually decreases: the first push is 20 mm, the second push is 18 mm, the third push is 16 mm, and the fourth push is 14 mm, totaling 108 mm. The dwell time t_wait after each push is set to 0.3 seconds to allow the tray enough time to respond to the attitude change.

[0029] The specific execution sequence is as follows: At time 0 seconds, the left pusher extends 20 millimeters at a speed of 40 millimeters per second, stops upon reaching the target, pauses for 0.3 seconds, and then retracts; at time 0.8 seconds, the right pusher extends 20 millimeters, pauses for 0.3 seconds, and then retracts; at time 1.6 seconds, the left pusher extends 18 millimeters, pauses for 0.3 seconds, and then retracts; at time 2.4 seconds, the right pusher extends 18 millimeters, pauses for 0.3 seconds, and then retracts; at time 3.2 seconds, the left pusher extends 16 millimeters, pauses for 0.3 seconds, and then retracts; at time 4.0 seconds, the right pusher extends 16 millimeters, pauses for 0.3 seconds, and then retracts. After completing the third left-side push and the third right-side push, that is, after the left-side push is completed at 3.2 seconds, the PLC uses the attitude detection sensor 5 to re-detect the current tilt angle of the pallet. The detection result is 1.8°, which is already below the first threshold of 2°. Therefore, the PLC determines that the shaping is complete and terminates the subsequent fourth push action in advance. The planned fourth left-side and right-side pushes are no longer executed. After all the pushers return to their initial positions, the pallet is released. From the first pusher extension to the final release, the total time is about 3.5 seconds, which saves about 1.5 seconds compared to executing all 8 pushes.

[0030] During the shaping process, the jamming detection continued to run. During the third leftward push, the pressure sensor detected that the thrust instantly rose to 620 Newtons, but the displacement sensor showed that the push plate was still moving forward at a normal speed. The displacement change within 0.2 seconds was 15.2 mm, which was much greater than 1 mm. Therefore, the jamming judgment condition was not met, and the PLC continued to execute. Example 3

[0031] This embodiment uses the same equipment and parameter settings as Embodiment 1. The difference is that the initial tilt angle of the tray is 12.8°, which is greater than the second threshold of 8°. Therefore, the PLC determines that it is a serious tilt. Based on the serious tilt determination result, the PLC retrieves the third shaping strategy, which is divided into two stages: pre-positioning and strong shaping.

[0032] Pre-positioning stage: The driving positioning block descends, with a descent stroke of 150 mm. After descending to its final position, the lower end of the block is approximately 50 mm from the surface of conveyor line 2, just touching the upper surface of the pallet. The block presses down on the pallet to prevent it from warping or tipping over during subsequent force-forming processes. The time for the positioning block to descend to its final position is approximately 0.5 seconds. Force-forming stage: The PLC drives the double-sided push plates to extend synchronously at a third speed v3 = 60 mm / s. The theoretically required total stroke is L × tanθ = 1200 mm × tan12.8° ≈ 1200 mm × 0.227 ≈ 272 mm. Considering severe skewness... The pallet may have been partially deformed. The PLC sets the target stroke to 290 mm. To reduce impact and ensure shaping accuracy, the PLC executes the 290 mm stroke in three stages. Stage 1: The double-sided pusher plates extend rapidly to a stroke of 200 mm at a speed of 60 mm / s, taking about 3.33 seconds. Stage 2: The double-sided pusher plates decelerate to 30 mm / s and continue to extend to a stroke of 270 mm, taking about 2.33 seconds. Stage 3: The double-sided pusher plates are finely adjusted to the target stroke of 290 mm at a minimum speed of 10 mm / s, taking 2.0 seconds. The entire high-pressure shaping stage takes about 7.66 seconds.

[0033] During the high-pressure shaping process, jamming detection was continuously running. When the second stage advanced to approximately 240 mm of travel, the thrust of the left pusher plate rose to 780 N, close to the safety threshold of 800 N, while the displacement change was only 0.8 mm within 0.2 seconds, slightly less than 1 mm. After detecting this situation, the PLC did not immediately determine it as jamming, but actively reduced the pushing speed of the left pusher plate from 30 mm / s to 15 mm / s, while continuing to monitor the thrust. After the speed was reduced, the thrust stabilized at around 750 N, and the displacement change returned to the normal range. The jamming judgment condition was removed. This adaptive adjustment mechanism effectively avoided shutdowns caused by misjudging jamming. Ultimately, both pushers successfully reached the target travel, with the maximum thrust peaks being 780 N on the left and 650 N on the right, neither exceeding 800 N.

[0034] After the shaping is completed, the PLC commands the positioning block to rise and reset. The verification sensor 6 detects that the skew angle after shaping is 2.4°, which is less than the preset qualified threshold θ_ok=3° under the severe skew shaping strategy. Therefore, the pallet is released. If the exit detects that the skew angle is greater than 3°, the PLC will start the diversion mechanism to send the pallet to the secondary shaping station. Example 4

[0035] This embodiment demonstrates the triggering and execution process of the jam detection function of the present invention. As a pallet enters the shaping station, a piece of wood on its left edge has broken and warped. The warped piece of wood gets stuck in the gap between the left push plate and the side baffle of the conveyor line 2.

[0036] When the left push plate extends according to the shaping command, the moment the front end of the push plate contacts the tray, the warped wooden board is squeezed and further jammed by the push plate. The displacement sensor shows that the push plate moves 0.5 mm in 0.1 seconds and then cannot move forward. The pressure sensor detects that the thrust rises sharply from 0 Newtons to 850 Newtons in 0.15 seconds. The PLC reads the data at a sampling frequency of 100 Hz. In the first sampling cycle, it detects that the thrust 850 Newtons > P_max = 800 Newtons. At the same time, it calculates the displacement change ΔS = 0.5 mm < ΔS_min = 1 mm in the past 0.2 seconds. When both conditions are met, the PLC immediately determines that the tray is jammed.

[0037] The PLC executes the jamming handling procedure as follows: First, it sends an emergency stop command to the servo driver of the left pusher, causing the pusher to immediately stop advancing. Second, it commands the left pusher to rotate in the opposite direction at a speed of 20 mm / s, returning the pusher to its initial position, a process that takes approximately 0.4 seconds. Third, it disconnects the contactor of the drive motor of conveyor line 2 via the digital output module, stopping conveyor line 2 and simultaneously sending a prohibition signal to the upstream accumulating conveyor, causing the stopper to rise and prevent subsequent pallets from sliding into the shaping station. Fourth, it displays fault code E-101 on the HMI and issues an audible and visual alarm, prompting "Left pusher jammed, please check the shaping station." After the operator resolves the jamming fault, they reset the PLC via the HMI. The PLC first closes the contactor of conveyor line 2 to restart conveyor line 2, and then sends a permission signal, restoring the system to normal operation. Example 5

[0038] In the detection process of Example 1, if only the first and second sensors are used, with a time difference Δt = 0.030 seconds, the calculated skew angle is arctan(100×0.030 / 200) = 0.86°. However, through manual measurement, the actual skew angle of the tray is approximately 1.20°. The reason for the error is that there is slight wear on the left front corner of the tray, causing the front edge of the tray to not be a perfect straight line. When the first sensor is triggered, the actual contact point is not the theoretically foremost point, while the second and third sensors detect a more rearward position. By taking the average value of these three sensors, Δt = (0.030 + 0.030 + 0.060) / 3 = 0.040 seconds, a value of 1.15° is calculated, which is very close to the actual value of 1.20°. The three-sensor layout and the average value algorithm effectively offset the measurement error caused by the local unevenness of the tray, improving the detection accuracy from ±0.4° to ±0.1°.

[0039] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or variations made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A method for adaptive shaping control of pallet posture on a conveyor line, characterized in that, Comprising the following steps: S1, Accurate detection of the skewed attitude of a pallet: at least three groups of sensors are arranged at intervals along the conveying direction at the entrance of the shaping area on the conveyor line, each group of sensors at least comprises a first sensor and a second sensor along the width direction of the conveyor line, the spacing between two adjacent groups of sensors in the conveying direction is d, and the spacing between the first sensor and the second sensor in the width direction of the conveyor line is w. When the pallet enters the shaping area along the conveyor line at a speed v, a PLC records the time when each sensor detects the front end of the pallet. Since the pallet is skewed, there is a difference in the time when different positions of the front end edge of the pallet reach different sensors in the same sensor group, and this time difference is recorded as Δt. The PLC calculates the skewing angle θ of the pallet in the horizontal plane according to the formula θ=arctan(d×Δt / w), and determines the skewing direction according to the side where the sensor with an earlier detection time between the first sensor and the second sensor is located; S2, Grading judgment of skewing degree: the PLC compares the absolute value of the skewing angle θ with a preset first threshold θ1 and a preset second threshold θ2, wherein 0<θ1<θ2, and the comparison results are divided into three cases: when |θ|≤θ1, it is judged as slight skewing; when θ1<|θ|≤θ2, it is judged as moderate skewing; when |θ|>θ2, it is judged as severe skewing. In this way, the continuous skewing angle is discretized into three grades, and each grade corresponds to a different processing strategy; S3, Adaptive execution of graded shaping strategies: the PLC retrieves and executes the corresponding shaping strategy from a pre-stored shaping strategy library according to the judged skewing grade; For slight skewing, since the skewing angle is small, the pallet can be righted only by applying a reverse gentle push to the pallet, therefore the PLC drives the single-side push plate on the side opposite to the skewing direction to extend at a first speed v1, applies a first thrust F1 to the pallet to perform one-way straightening, and the push plate is immediately retracted after straightening; for moderate skewing, the skewing angle is medium, and one-time strong straightening may cause the pallet to tip over or over-shaping, therefore the PLC drives double-side push plates to extend in an alternating manner, each push plate performs multiple progressive straightening at a second speed v2, and stays for t_wait after each pushing, so that the pallet has enough time to respond, and then pushes again until the skewing angle drops below θ1; for severe skewing, the skewing angle is large, and the attitude of the pallet is seriously deviated, so pre-positioning is required before strong shaping, therefore the PLC first drives the positioning stop block arranged above the conveyor line to descend to a predetermined height to press the pallet, so as to prevent the pallet from warping or tipping over during shaping, and then drives the double-side push plates to extend synchronously at a third speed v3 to perform two-way strong shaping. In the above three strategies, the speed relationship satisfies v1<v2<v3, and F1 is smaller than the maximum thrust in the shaping strategies for moderate skewing and severe skewing, so as to ensure that excessive force is not applied to damage the pallet when the skewing is slight; S4. Closed-loop safety protection during the shaping process: During the shaping action of the shaping mechanism, the displacement sensor installed on the shaping mechanism detects the stroke S of the shaping push plate in real time, and the pressure sensor detects the thrust F applied by the shaping push plate to the side of the tray in real time. The PLC collects displacement data and pressure data at a sampling frequency f. The PLC compares the collected thrust F with the preset safety pressure threshold P_max, and at the same time compares the displacement change ΔS within the continuous time Δt_c with the preset displacement change threshold ΔS_min. When the thrust F exceeds P_max and the displacement change ΔS is less than ΔS_min, it indicates that the push plate has encountered a hard jam that cannot be pushed.

2. The adaptive shaping control method for pallet posture on a conveyor line according to claim 1, characterized in that: Each group of sensors in S1 also includes a third sensor along the width of the conveyor line. The first, second, and third sensors are distributed at equal intervals. The PLC integrates the time difference Δt1 between the first and second sensors, the time difference Δt2 between the second and third sensors, and the time difference Δt3 between the first and third sensors, and takes the average of the three as the time difference Δt used to calculate the skew angle.

3. The adaptive shaping control method for pallet posture on a conveyor line according to claim 1, characterized in that: In S3, for moderate skew, the PLC recalculates the current skew angle of the tray after each push plate advance. If the current skew angle has dropped below the first threshold θ1, the subsequent gradual push-correction action is terminated in advance.

4. The adaptive shaping control method for pallet posture on a conveyor line according to claim 1, characterized in that: After the PLC in S4 determines that the pallet is stuck, it also sends a stop command to the conveyor control system to prevent subsequent pallets from entering the shaping station and avoid the jamming area from expanding.

5. The adaptive shaping control method for pallet posture on a conveyor line according to claim 1, characterized in that: It also includes S5: quality verification and diversion after shaping. A verification sensor group is set at the exit of the shaping area, with the same layout as at the entrance. When the pallet passes through the exit, the PLC detects the tilt angle θ` of the shaped pallet. If |θ`| exceeds the preset qualified threshold θ_ok, the PLC diverts the pallet to the abnormal processing channel for secondary shaping; otherwise, the pallet is released.

6. The adaptive shaping control method for pallet posture on a conveyor line according to claim 1, characterized in that: It also includes S6: recording of running data and adaptive optimization of parameters. The PLC records the skew angle θ, skew duration T, maximum thrust F_max and skew angle θ` after each shaping to the database. After every N runs, the PLC updates the first threshold θ1, the second threshold θ2 and the speed parameters in each shaping strategy according to the statistical results.

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