CN-122009739-A - Automatic monitoring and correcting method for conveyor belt deviation based on depth map

CN122009739ACN 122009739 ACN122009739 ACN 122009739ACN-122009739-A

Abstract

The invention belongs to the technical field of belt conveyors, and particularly discloses an automatic monitoring and correcting method for conveyor belt deviation based on a depth map, which is characterized in that a belt datum line is automatically constructed through a visual unit, edge detection is carried out based on depth information, millimeter-level deviation distance can be directly output, and the method has definite engineering application value and is convenient to link with a control system; the visual unit captures the deviation state of the conveyer belt in real time and quantifies the deviation state into a digital signal, the PLC compares the detection signal with a set reference and generates a corresponding deviation rectifying instruction, the servo electric push rod accurately responds to the instruction to drive the aligning carrier roller to generate transverse deviation rectifying force, the moving track of the conveyer belt is dynamically corrected to realize deviation rectifying, and a dynamic feedback regulation mechanism is formed in the whole process until the conveyer belt is restored to be within a set allowable error range and keeps stable operation.

Inventors

SONG ZHIYONG
ZHOU SUQIN
SU BO
WANG ZIJIAN
YANG LIXUAN
ZHANG WEITAO
LI GUOHAO
WANG HAITAO
MA YANGWEI
WANG ZETAO

Assignees

焦作市钰欣机械有限公司

Dates

Publication Date: 20260512
Application Date: 20260403

Claims (5)

1. The automatic monitoring and correcting method for the conveyor belt deviation based on the depth map is characterized by comprising the following steps of: The automatic centering device comprises a belt conveyor, an industrial camera, a PLC (programmable logic controller), a servo motor, a servo controller, a PLC controller and an industrial camera, wherein the industrial camera is fixed above a conveying belt of the belt conveyor and is used for collecting images comprising the conveying belt; S2, continuously acquiring an image sequence containing the conveyer belt through an industrial camera and transmitting the image sequence to an upper computer after the belt conveyer is started in a normal running state, extracting the left and right edges of the conveyer belt based on the acquired images by the upper computer, and calculating the reference center line position of the conveyer belt; S3, after the belt conveyor enters a normal operation stage, the industrial camera starts to continuously collect images containing the conveying belt in real time and transmits the images to the upper computer, the upper computer calculates the average value of transverse coordinates of left and right edge points detected in the current frame image respectively, takes the middle point of the average position of the left and right edges as the center position of the current conveying belt, calculates real-time deviation direction and offset, transmits the real-time deviation direction and offset to the PLC as feedback signals, the PLC compares the received real-time deviation amount with a preset deviation rectifying threshold 10 mm, if the received real-time deviation rectifying amount exceeds the preset deviation rectifying threshold, calculates accurate deviation rectifying control amount, generates a control instruction and transmits the control instruction to the servo electric push rod, the carrier roller linear displacement of the servo electric push rod drives the deviation rectifying carrier roller frame to rotate, the stroke of the electric push rod and the carrier roller angle are converted into the rotating angle of the aligning carrier roller frame, and accordingly accurate transverse deviation rectifying force is applied to the conveying belt in operation, and the current center line of the conveying belt is driven to return to the reference center line position.
2. The automatic monitoring and correcting method for conveyor belt deviation based on depth map according to claim 1, wherein in the step S2, the specific process of extracting the left and right edges of the conveyor belt and calculating the reference center line position of the conveyor belt is as follows: 1) In a first frame of an acquired image sequence containing a conveyer belt, firstly selecting an interested region containing the conveyer belt region, generating a corresponding depth map for the interested region, and carrying out normalization processing on depth values; then, based on the depth mutation characteristic presented by the edge of the conveyer belt in the depth map, scanning gradually from the middle position of the image in the left-right direction, positioning the position where the significant depth gradient mutation appears for the first time in each row, and taking the position as a candidate point of the edge of the conveyer belt, wherein the scanning mode ensures that the real boundary between the conveyer belt body and the background is preferentially detected, and the false detection of the background structure is avoided; 2) When the number of the covering lines of the detected candidate points of the edge of the conveyor belt in the longitudinal direction reaches a preset proportion threshold, the preset proportion threshold is set to be 30-40, edge detection is considered to be effective, a robust straight line fitting method is respectively adopted for modeling the candidate point sets of the left edge and the right edge, a left reference edge line and a right reference edge line of the conveyor belt are obtained, and a reference center line is further calculated.
3. The automatic monitoring and correcting method for the deviation of the conveyor belt based on the depth map according to claim 1, wherein the specific process of the step S3 is as follows: 1) In the scanning process, identifying pixel positions conforming to depth transition characteristics as candidate edge points by comparing depth change conditions of adjacent pixels, and reserving only the first mutation point meeting the condition for each line to finally obtain a point set of the left and right edges of the conveyer belt in the current frame; 2) Respectively calculating the average value of the transverse coordinates of the left and right edge points detected in the current frame image, taking the middle point of the average position of the left and right edges and connecting the middle point into a straight line, and taking the straight line as the center position of the current conveyor belt; 3) The difference value between the current central position of the conveyer belt and the reference central line position of the conveyer belt in the horizontal direction is used as a pixel level deviation amount, the deviation direction is judged according to the positive value and the negative value of the pixel level deviation amount, wherein the positive value represents right deviation, and the negative value represents left deviation; 4) The PLC compares the received real-time deviation amount with a preset deviation rectifying threshold 10 mm, if the deviation rectifying threshold is exceeded, the accurate deviation rectifying control amount is calculated according to a PID control algorithm, a control instruction is generated and sent to the servo electric push rod, the linear displacement of the push rod of the servo electric push rod drives the deviation rectifying carrier roller frame to rotate, the stroke of the servo electric push rod and the carrier roller angle are converted into the rotating angle of the deviation rectifying carrier roller frame, and accordingly accurate transverse deviation rectifying force is applied to the running conveyor belt, and the current center line of the conveyor belt is driven to return to the reference center line position.
4. The automatic monitoring and correcting method for conveyor belt deviation based on depth map according to claim 3, wherein the PID control algorithm specifically comprises: The controller generates the control signal u (t) by a proportional-integral-derivative (PID) algorithm according to the deviation amount Δx (i.e., e (t) =Δx): (1) wherein e (t) =real-time run offset-target position; K i is an integral coefficient for eliminating steady-state errors and correcting long-term deviation of the system by accumulating historical deviation; The differential coefficient is used for inhibiting overshoot, and the adjustment fluctuation is reduced by prejudging the variation trend of the deviation; Is an integral variable, and t is time.
5. The automatic monitoring and correcting method for conveyor belt deviation based on depth map according to claim 3, wherein the method for converting the stroke of the electric push rod and the angle of the carrier roller into the rotation angle of the aligning carrier roller frame is as follows: 1) The conversion of the stroke of the servo electric push rod and the angle of the carrier roller is shown in figure 3. Servo electric push rod expansion amount s and carrier roller rotation angle The method meets the following conditions: s= (2) wherein: is a push rod and a roller frame the radius of the arm of force of the connecting point; 2) Relation between carrier roller angle and correction displacement of conveyor belt: rotation angle of carrier roller The conveyor belt can generate transverse correction displacement deltax, and the calculation formula is as follows: Δx= (3) Wherein L is the effective acting length of the carrier roller, namely the length of the carrier roller which is contacted with the conveyer belt and can generate effective transverse pushing action on the conveyer belt; is the rotation angle of the carrier roller.

Description

Automatic monitoring and correcting method for conveyor belt deviation based on depth map Technical Field The invention relates to the technical field of belt conveyors, in particular to a method for automatically monitoring and correcting conveyor belt deviation based on a depth map. Background Most of the existing conveying belt deviation correcting systems are used for carrying out deviation correction through deviation correcting carrier rollers, the deviation correcting carrier rollers are used for detecting the deviation of a belt, when the deviation is detected, the friction force of the belt, received by the deviation correcting side of the deviation correcting carrier rollers, is increased, the deviation correcting side carrier rollers are forced to rotate and deviate around the deviation correcting carrier roller rotating shaft, and the belt is enabled to move towards the direction of the central line of the belt conveyor to carry out deviation correction. The Chinese patent application with publication number CN 120348636A discloses an automatic deflection adjusting device for a conveyor belt, which comprises a frame which is horizontally arranged and used for bearing the conveyor belt, a pressure detection unit which comprises two rows of pressure detectors symmetrically arranged along the direction of the width of the conveyor belt, a double-row inclined conveyor roller which is symmetrically arranged on the frame through a support with rotation damping and is attached to the lower surface of the conveyor belt, an adjustable support assembly which comprises a top block which is arranged on the conveyor roller in a sliding manner, and a control unit which is electrically connected with the pressure detection unit and comprises a comparison module and a signal output module, wherein when the comparison module detects that pressure difference is generated on two sides of the same position of the conveyor belt, the signal output module sends a driving signal to the adjustable support assembly corresponding to the smaller pressure side, so that the top block is promoted to extend out of the surface of the conveyor roller. However, the existing conveyor belt deviation correcting system adopts a contact test, the conveyor belt deviation correcting system can not perform a function when the conveyor belt deviates to a sensor, and cannot achieve real-time deviation correction, and a plurality of groups of deviation correcting devices are required to be configured to achieve deviation correction. Therefore, how to effectively improve the correction efficiency of the conveyor and ensure the stability and reliability of correction becomes a problem to be solved in the field. Disclosure of Invention In order to solve the technical problems, the invention provides a method for automatically monitoring and correcting the deviation of a conveyor belt based on a depth map. In order to achieve the above purpose, the invention is implemented according to the following technical scheme: a method for automatically monitoring and correcting conveyor belt deviation based on a depth map comprises the following steps: The automatic centering device comprises a belt conveyor, an industrial camera, a PLC (programmable logic controller), a servo motor, a servo controller, a PLC controller and an industrial camera, wherein the industrial camera is fixed above a conveying belt of the belt conveyor and is used for collecting images comprising the conveying belt; S2, continuously acquiring an image sequence containing the conveyer belt through an industrial camera and transmitting the image sequence to an upper computer after the belt conveyer is started in a normal running state, extracting the left and right edges of the conveyer belt based on the acquired images by the upper computer, and calculating the reference center line position of the conveyer belt; S3, after the belt conveyor enters a normal operation stage, the industrial camera starts to continuously collect images containing the conveying belt in real time and transmits the images to the upper computer, the upper computer calculates the average value of transverse coordinates of left and right edge points detected in the current frame image respectively, takes the middle point of the average position of the left and right edges as the center position of the current conveying belt, calculates real-time deviation direction and offset, transmits the real-time deviation direction and offset to the PLC as feedback signals, the PLC compares the received real-time deviation amount with a preset deviation rectifying threshold 10 mm, if the received real-time deviation rectifying amount exceeds the preset deviation rectifying threshold, calculates accurate deviation rectifying control amount, generates a control instruction and transmits the control instruction to the servo electric push rod, the carrier roller linear displacement of the servo electric push rod drives th