Method for Measuring Cigarette Length, Circumference, Roundness and Cylindricity Based on Machine Vision

Abstract

The present invention provides a method for measuring the length, circumference, roundness and cylindricity of cigarette rods based on machine vision: First, two contour sensors are used to measure the surface contour of the cigarette rod to be measured, and based on this, a three-dimensional contour body of the cigarette rod to be measured is drawn; Then, an image recognition algorithm is used to calculate the maximum axial distance between the two end faces of the three-dimensional contour body, which is the length of the cigarette rod; Then, the three-dimensional contour body is dissected by an image segmentation algorithm to obtain n cross-sectional approximate circles, and the mean value is calculated as the circumference of the cigarette rod after calculating the circumference of each cross-sectional approximate circle; Then, for any cross-sectional approximate circle, an image recognition algorithm is used to identify and calculate the radius of the theoretical circle, and at the same time, the maximum inscribed circle of the cross-sectional approximate circle is made and the radius is calculated to calculate the roundness of the cigarette rod: Then, for all cross-sectional approximate circles, the maximum and minimum values of the maximum inscribed circle radius are calculated to calculate the cylindricity of the cigarette rod. The present invention can break through the bottlenecks of the single cigarette rod detection method and cumbersome operation at the present stage.

Description

Technical Field

[0001] The present invention relates to a measurement method, and more specifically to a method for measuring the length, circumference, roundness, and cylindricity of cigarette rods based on machine vision. Background Art

[0002] Roundness refers to the degree to which the cross-section of a workpiece approaches a theoretical circle. In length measurement technology, roundness is generally represented by roundness error. When the difference between the maximum radius and the minimum radius is 0, the roundness is 0, indicating "the roundest". Common roundness measurement methods include the axis of rotation method, the three-point method, the two-point method, the projection method, and the coordinate method, etc. According to different measurement methods, common measuring instruments include roundness meters, micrometers, vernier calipers, projectors, coordinate measuring machines with computers, etc. And there are mainly 4 methods for evaluating roundness error, namely the minimum zone method, the least squares circle method, the minimum circumscribed circle method, and the maximum inscribed circle method.

[0003] Cylindricity refers to the condition that all points on the outer contour of the cylindrical surface of a workpiece are equidistant from its axis, which is the synthesis of the roundness of a cylinder and the straightness of its generatrix. In length measurement technology, cylindricity is generally represented by cylindricity error. Cylindricity error includes errors in both the axial section and the cross-section. The radial distance between two coaxial cylindrical surfaces is the cylindricity error. If it is necessary to measure several cross-sections, take half of the difference between the maximum value and the minimum value of all the readings obtained from each section as the cylindricity error of the measured cylinder. Usually, cylindricity error is measured with a roundness meter or a coordinate measuring device equipped with a computer.

[0004] In recent years, with the rapid development of cigarette production automation technology and the continuous improvement of production management informatization, each cigarette production enterprise has put forward higher requirements for the rolling quality of cigarette rods. The length, circumference, roundness, and cylindricity of cigarette rods are important indicators for evaluating the rolling quality of cigarette rods. Whether these indicators are qualified not only concerns the production efficiency of the enterprise, but also concerns the competitiveness of cigarette products in the terminal market. Currently, the vast majority of cigarette production enterprises focus more on the measurement of the length and circumference of cigarette rods when evaluating the rolling quality of cigarette rods, while paying little attention to the roundness and cylindricity of cigarette rods, and there are few public reports on special measuring instruments for the roundness and cylindricity of cigarette rods. In addition, the measuring instruments for the length and roundness of cigarette rods currently used by each enterprise are mostly split-type, either measuring the length first and then the circumference, or measuring the circumference first and then the length. The measurement process is cumbersome and time-consuming. Therefore, it is particularly important to establish a high-efficiency and high-performance measuring device to synchronously measure the length, circumference, roundness, and cylindricity of cigarette rods, whether for cigarette production enterprises or quality supervision and inspection departments. Summary of the Invention

[0005] The present invention aims to solve the above technical problems, and for this purpose, a method for measuring the length, circumference, roundness, and cylindricity of cigarette rods based on machine vision is proposed, with the expectation of breaking through the bottlenecks of single detection methods, cumbersome operations, and insufficient instrument performance in the current field of physical quality detection of cigarette rods.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for measuring the length, circumference, roundness, and cylindricity of cigarette rods based on machine vision includes the following steps:

[0008] Step 1: Establish a three-dimensional contour body of the cigarette rod

[0009] Use the first contour sensor and the second contour sensor to measure the surface contour of the cigarette rod to be measured, and draw a three-dimensional contour body of the cigarette rod to be measured according to the measurement results; the measurement results include the axial contour data obtained by the first contour sensor measuring along the central axis direction of the cigarette rod, and the circumferential contour data obtained by the second contour sensor measuring around the cigarette rod for one week along the circumferential direction;

[0010] Step 2: Calculate the length of the cigarette rod

[0011] Use an image recognition algorithm to calculate the maximum axial distance L between the two end faces of the three-dimensional contour body, which is the length L of the cigarette rod;

[0012] Step 3: Calculate the circumference of the cigarette rod

[0013] Use an image segmentation algorithm to dissect the three-dimensional contour body along the direction perpendicular to the axis of the three-dimensional contour body to obtain n cross-sectional approximate circles, and then use an image recognition algorithm to calculate the circumference C of each cross-sectional approximate circle i , and calculate the circumference C of the cigarette rod from the formula (1):

[0014]

[0015] In formula (1), C is the circumference of the cigarette rod, with the unit of mm; C i is the circumference of a cross-sectional approximate circle of the three-dimensional contour body, with the unit of mm;

[0016] Step 4: Calculate the roundness of the cigarette rod

[0017] For any cross-sectional approximate circle of the three-dimensional contour body, with the circumference C i of this cross-sectional approximate circle as a condition, make a theoretical circle, and use an image recognition algorithm to identify and calculate the radius r Ti of the theoretical circle. At the same time, make the largest inscribed circle of this cross-sectional approximate circle, and use an image recognition algorithm to identify and calculate the radius r Mi of the largest inscribed circle, and calculate the roundness O of the cigarette rod from the formula (2):

[0018]

[0019] In formula (2), O is the roundness of the cigarette rod; r Mi is the radius of the largest inscribed circle of an approximately circular cross-section of any three-dimensional contour body, with the unit of mm; r Ti is the radius of the theoretical circle of an approximately circular cross-section of any three-dimensional contour body, with the unit of mm;

[0020] Step 5: Calculate the cylindricity of the cigarette rod

[0021] For all the approximately circular cross-sections of the three-dimensional contour body obtained by dissection in Step 3, use an image recognition algorithm to identify and calculate the maximum value (r Mi ) Mi and the minimum value (r max ) Mi ) min of the radius of the largest inscribed circle, and calculate the cylindricity Φ of the cigarette rod according to formula (3):

[0022]

[0023] In formula (3), Φ is the cylindricity of the cigarette rod; (r Mi ) max and (r Mi ) min are respectively the maximum value and the minimum value of the radius of the largest inscribed circle of all the approximately circular cross-sections of the three-dimensional contour body, with the unit of mm; O is the roundness of the cigarette rod.

[0024] Further set:

[0025] The cigarette rod types include flue-cured tobacco cigarettes, blended cigarettes, machine-made cigars, hand-made cigars, heat-not-burn cigarettes, and cigarette filters.

[0026] The first contour sensor and the second contour sensor are CCD contour scanning sensors or laser contour scanning sensors.

[0027] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0028] 1. The present invention can be applied to the simultaneous measurement of the length, circumference, roundness, and cylindricity of cigarette rods. The collected data has a high dimension, and the established roundness and cylindricity are unitless values, with a numerical range of 0-1, rather than the commonly used tolerance values at present, which can more intuitively represent the "roundness" and "cylindricity" of the measured object;

[0029] 2. The present invention uses the first profile sensor and the second profile sensor to jointly scan and map, and the collected data has high precision. Moreover, it is a non-contact measurement, which will not damage the surface of the object to be measured, is friendly to the object to be measured with a soft texture, and can achieve non-destructive measurement, enabling the sample to be reused after the measurement is completed;

[0030] 3. The present invention can also be applied to the simultaneous measurement of the length, circumference, roundness and cylindricity of other cylindrical objects, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of cigarette rod profile mapping and cross-section segmentation processing of a three-dimensional profile body;

[0032] Figure 2 is a schematic diagram for calculating the theoretical circle radius and the maximum inscribed circle radius of an approximate circle of any cross-section of a cigarette rod three-dimensional profile body;

[0033] Figure 3 is an example diagram of the device for implementing the present invention;

[0034] Figure 4 is Figure 3 a schematic structural diagram of the sample inlet unit in

[0035] Figure 5 is Figure 3 a partial schematic structural diagram of the sample feeding unit in

[0036] Figure 6 is Figure 3 a schematic cross-sectional structural diagram of the detection chamber in

[0037] In the figure:

[0038] 1. Sample inlet unit; 11. Sample feeding hopper; 12. Indicator arrow; 13. Feeding section; 14. Attitude adjustment block; 15. Discharge section; 16. First discharge gate; 17. Second discharge gate;

[0039] 2. Sample feeding unit; 21. Pulse motor; 22. Gear transmission mechanism; 23. Sample holder; 24. Sample feeding tray;

[0040] 3. Detection unit; 31. Electric telescopic push rod; 32. Detection chamber; 33. First profile sensor; 34. Second profile sensor; 35. Electric slide rail;

[0041] 4. Swing rod;

[0042] 51. Signal controller; 52. Data collector; 53. Computer;

[0043] 6. Support platform; 61. Sample collection bucket;

[0044] 7. Cigarette rod. DETAILED DESCRIPTION OF THE INVENTION

[0045] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0046] Please refer to Figure 1 and Figure 2 , the method for measuring the length, circumference, roundness and cylindricity of cigarette rods based on machine vision in this embodiment includes the following steps:

[0047] Step 1: Establish a three-dimensional contour body of a cigarette rod

[0048] Use the first contour sensor and the second contour sensor to measure the surface contour of the cigarette rod to be measured, and draw a three-dimensional contour body of the cigarette rod to be measured according to the measurement results; the measurement results include axial contour data obtained by the first contour sensor measuring along the central axis direction of the cigarette rod, and circumferential contour data obtained by the second contour sensor measuring around the cigarette rod once along the circumferential direction;

[0049] Step 2: Calculate the length of the cigarette rod

[0050] Use an image recognition algorithm to calculate the maximum axial distance L between the two end faces of the three-dimensional contour body, which is the length L of the cigarette rod;

[0051] Step 3: Calculate the circumference of the cigarette rod

[0052] Use an image segmentation algorithm to dissect the three-dimensional contour body along the direction perpendicular to the axis of the three-dimensional contour body to obtain n cross-sectional approximate circles, and then use an image recognition algorithm to calculate the circumference C of each cross-sectional approximate circle i , and calculate the circumference C of the cigarette rod from the formula (1):

[0053]

[0054] In formula (1), C is the circumference of the cigarette rod, with the unit of mm; C i is the circumference of a cross-sectional approximate circle of the three-dimensional contour body, with the unit of mm;

[0055] Step 4: Calculate the roundness of the cigarette rod

[0056] For any cross-sectional approximate circle of the three-dimensional contour body, with the circumference C i of this cross-sectional approximate circle as a condition, make a theoretical circle, and use an image recognition algorithm to identify and calculate the radius r of the theoretical circle Ti, simultaneously make the largest inscribed circle of the approximate circle of the cross-section, and use the image recognition algorithm to identify and calculate the radius r of the largest inscribed circle Mi , calculate the roundness O of the cigarette rod by formula (2):

[0057]

[0058] In formula (2), O is the roundness of the cigarette rod; r Mi is the radius of the largest inscribed circle of the approximate circle of any cross-section of the three-dimensional contour body, with the unit of mm; r Ti is the radius of the theoretical circle of the approximate circle of any cross-section of the three-dimensional contour body, with the unit of mm;

[0059] Step 5, calculate the cylindricity of the cigarette rod

[0060] For all the approximate circles of the cross-sections of the three-dimensional contour body obtained by dissecting in step 3, use the image recognition algorithm to identify and calculate the maximum value (r Mi ) Mi ) max and the minimum value (r Mi ) min of the radius r, and calculate the cylindricity Φ of the cigarette rod by formula (3):

[0061]

[0062] In formula (3), Φ is the cylindricity of the cigarette rod; (r Mi ) max and (r Mi ) min are respectively the maximum value and the minimum value of the radii of the largest inscribed circles of all the approximate circles of the cross-sections of the three-dimensional contour body, with the unit of mm; O is the roundness of the cigarette rod.

[0063] The above measurement method can be applied to the measurement of the length, circumference, roundness and cylindricity of various columnar products such as flue-cured tobacco cigarettes, blended cigarettes, machine-made cigars, hand-made cigars, heat-not-burn cigarettes, and cigarette filters.

[0064] The first contour sensor and the second contour sensor can be non-contact contour scanning sensors such as CCD contour scanning sensors and laser contour scanning sensors.

[0065] Such as Figures 3 to 6 , the following gives an example of a device for implementing the measurement method of the length, circumference, roundness and cylindricity of cigarette rods based on machine vision. The device includes:

[0066] The sample feeding unit 1 is used to batch receive the cigarette rods 7 to be measured and output them to the sample sending unit 2 one by one, and the output cigarette rods 7 are in an inverted posture with the filter tip facing down;

[0067] The sample feeding unit 2 receives and fixes the cigarette 7 output by the sample injection unit 1 through the sample holder 23. A plurality of sample holders 23 are circumferentially and equidistantly spaced on the sample feeding tray 24. The sample feeding tray 24 is driven by a pulse motor 21 and can rotate around the central axis of the tray body. Any sample holder 23 can synchronously rotate with the sample feeding tray 24 to directly below the discharge port of the sample injection unit 1. There is a vertical gap between the top end and the discharge port of the sample injection unit 1. It is connected to the received cigarette 7 at the filter tip end of the cigarette 7, and can be displaced to the detection position directly below the detection component as the sample feeding tray 24 continues to rotate;

[0068] The detection unit 3 is used for measuring the surface contour of the cigarette 7 at the detection position, including a detection chamber 32. The detection chamber 32 is initially suspended directly above the detection position and can be driven by an electric telescopic push rod 31 to descend to cover the cigarette 7 at the detection position. In the middle of the top end inside the chamber, there is a first contour sensor 33. A circular electric slide rail 35 is arranged in a ring on the inner peripheral wall of the chamber. The second contour sensor 34 is arranged on the electric slide rail 35. The detection component uses the first contour sensor 33 to measure along the central axis direction of the cigarette 7 to obtain the axial contour data of the cigarette 7, and uses the second contour sensor 34 to measure around the cigarette 7 along the electric slide rail 35 for one week to obtain the circumferential contour data of the cigarette 7;

[0069] The sample unloading unit is used for unloading the cigarette 7 at the detection position after the detection is completed;

[0070] The data acquisition and processing component includes a signal controller 51 and a computer 53, which are used for the automatic control of the sample injection unit 1, the sample feeding unit 2, the detection unit 3, and the sample unloading unit. It also includes a data collector 52, which is used for collecting the measurement data of the first contour sensor 33 and the second contour sensor 34 and sending them to the computer 53 for calculation and processing.

[0071] The above device is further arranged as follows:

[0072] The sample injection unit 1 is an automatic sampler, and its structure is arranged as follows:

[0073] It includes a sample feeding hopper 11, a material guiding section 13, a discharge section 15, a first discharge gate 16, and a second discharge gate 17. The sample feeding hopper 11 is a frustum-shaped shell structure with an open top as the feeding port and a discharge port at the bottom. The small end faces downward. It is successively connected to the material guiding section 13 and the discharge section 15 from the discharge port to form a through vertical discharge channel. The first discharge gate 16 is arranged between the discharge port of the sample feeding hopper 11 and the upper opening of the material guiding section 13 to control the opening / closing of the discharge port of the sample feeding hopper 11. The second discharge gate 17 is arranged at the bottom end of the discharge section 15 to control the opening / closing of the lower end of the discharge section 15. The vertical distance between the second discharge gate 17 and the lower opening of the discharge section 15 is less than the length of a single upright cigarette 7. The lower opening of the discharge section 15 is used as the discharge port of the sample injection unit 1;

[0074] The material guiding section 13 is a square-columnar shell structure. The width of the material guiding section 13 can only accommodate a single cigarette 7 to be placed horizontally and straight, and there are gaps between the two ends of the cigarette 7. The left and right side walls of the material guiding section 13 are parallel to the opening and closing direction of the first discharge gate 16. At the upper end of the left side wall, there is an attitude adjusting block 14 protruding outward towards the center of the material guiding section 13. On the sample feeding hopper 11, there is an indicating arrow 12 for indicating the placing orientation of the cigarette 7. The direction indicated by the indicating arrow 12 is perpendicular to the opening and closing direction of the first discharge gate 16 and is set towards the protruding direction of the attitude adjusting block 14.

[0075] The discharge section 15 is a long tubular structure. The outer diameter is smaller than the width of the material guiding section 13, and the inner diameter can accommodate a single cigarette 7 placed in an upright attitude.

[0076] Both the first discharge gate 16 and the second discharge gate 17 are electric gates. When one of the gates is in the open state, the other gate is in the closed state, and only one gate is always kept open.

[0077] Before sample injection, first adjust the opening degree of the discharge port of the sample feeding hopper 11 through the first discharge gate 16 so that it can only accommodate a single horizontally and straight cigarette 7 to pass through. At this time, the second discharge gate 17 remains closed. During sample injection, the operator aligns the filter tips of the batch of cigarettes 7 to be measured and, in a horizontally and straight attitude with the filter tips facing the direction indicated by the indicating arrow 12, puts them into the sample feeding hopper 11. The cigarettes 7 put in fall into the material guiding section 13 one by one through the first discharge gate 16, continue to fall under the action of their own weight, and collide with the attitude adjusting block 14. Under the collision of the attitude adjusting block 14, the cigarette 7 turns with the filter tip facing downwards and continues to fall under the action of its own weight, falls into the discharge section 15, and continues to fall in an upright attitude with the filter tip facing downwards. When it reaches the lower end position of the discharge section 15, the second discharge gate 17 opens and the first discharge gate 16 closes. The cigarette 7 falls through the discharge section 15 and is received by the sample holder 23 directly below; each cigarette 7 in the sample feeding hopper 11 repeats the above actions and is output to the sample feeding unit 2 one by one.

[0078] In the sample feeding unit 2, the pulse motor 21 can be of types such as electromechanical, magnetoelectric, linear, etc., and is driven by a gear transmission mechanism 22 with the sample tray 24. The sample holder 23 is a columnar body made of an electromagnetic wave blocking material such as metal or ceramic. In the middle of the top end face, there is a reusable adhesive. The adhesive is used to bond and fix the cigarette 7 falling from the sample feeding unit 1, so that it maintains an upright attitude with the filter tip facing downwards.

[0079] In the detection unit 3, the opening end of the detection chamber 32 faces downward. To effectively prevent the electromagnetic waves emitted by the contour sensors inside the detection chamber 32 from spilling out of the chamber, the detection chamber 32 can be made of electromagnetic wave blocking materials such as metal and ceramic. Initially, the detection chamber 32 is suspended directly above the detection position. Under the control of the signal controller 51, the electric telescopic push rod 31 drives the detection chamber 32 to move downward or upward until it completely covers the cigarette rod 7 at the detection position to measure the surface contour data of the cigarette rod 7, or to return to the original position after the measurement is completed.

[0080] The sample unloading unit is an electric swing rod 4, which is made of metal, plastic or rubber. By swinging the swing rod 4, the cigarette rod 7 on the sample holder 23 is swept off, so that it detaches from the sample holder 23 and drops. The electric swing rod 4 includes a rotary drive device and the swing rod 4. The rotary drive device is used to drive the swing in the horizontal plane, and the central axis of its power output shaft is vertical. The rod body of the swing rod 4 is horizontal and is driven by the rotary drive device. It can rotate in the horizontal plane around the central axis of the power output shaft. When it swings to the detection position, it can contact the cigarette rod 7 on the sample holder 23 at the detection position, and as the rotation continues, the cigarette rod 7 is swept off, thus completing the unloading of the cigarette rod 7 at the detection position after the detection is completed.

[0081] The rotary drive device can be a motor. The output shaft of the motor serves as the power output shaft. One end of the swing rod 4 is sleeved on the output shaft of the motor through a sleeve, and the rod body is arranged along the radial direction of the sleeve and is fixedly connected to the outer wall of the sleeve.

[0082] It also includes a support platform 6. The sample loading unit 1, the sample feeding unit 2, the detection unit 3, the sample unloading unit, and the data acquisition and processing component are arranged on the support platform 6. A sample collection bucket 61 for collecting the cigarette rods 7 unloaded by the sample unloading unit is also provided on the support platform 6.

[0083] Taking the measurement of the length, circumference, roundness, and cylindricity of a certain regular-sized flue-cured tobacco cigarette of Huangshan brand (84×24.4mm (length 84mm, circumference 24.4mm)) as an example, the following steps are sequentially carried out using the above device according to the measurement process:

[0084] (1) Device startup: Check whether each unit is in good condition, start the power supply, and confirm whether each unit is operating normally;

[0085] (2) Sample loading: Batch the cigarette rods to be measured and put them into the sample loading unit. The sample loading unit disperses the cigarette rods and outputs them one by one to the sample feeding unit;

[0086] (3) Sample feeding: The signal controller controls the pulse motor to run, drives the sample feeding disk to rotate. The rotating sample feeding disk sequentially receives the cigarette rods output one by one by the sample loading unit through each sample holder. Each sample holder holding a cigarette rod moves to the detection position one by one as the sample feeding disk continues to rotate;

[0087] (4) Data acquisition: After the sample holder holding the cigarette is moved to the detection position, the signal controller controls the electric telescopic push rod to extend downward, driving the detection chamber to move downward to cover the outside of the sample holder. At this time, the second contour sensor orbits around the cigarette once along the electric slide rail, continuously scanning and mapping the cigarette in the circumferential direction. At the same time, the first contour sensor synchronously scans and maps the cigarette contour along the central axis direction. The data collector collects the measurement data of the first contour sensor and the second contour sensor;

[0088] (5) Data processing: The data collector sends the collected measurement data to the computer. The computer obtains the three-dimensional contour data of the cigarette through calculation and processing and draws the three-dimensional contour body of the cigarette. For the data processing process, please refer to Figure 1 ;

[0089] (6) Sample unloading: After measuring the cigarette on each sample holder, the signal controller controls the electric telescopic push rod to contract upward, driving the detection chamber to move upward. The sample unloading unit knocks on the cigarette to make the cigarette clamped on the sample holder fall off and drop into the sample collection bucket for centralized collection;

[0090] (7) Repeat steps (2) to (6) until all cigarettes are measured. Take the average values of the lengths, circumferences, roundnesses, and cylindricities of all cigarettes to obtain the average length, circumference, roundness, and cylindricity of the cigarettes in this batch of sample injections. In addition, the calculated values of length, circumference, roundness, and cylindricity can be stored in the computer.

[0091] The roundness values of several common figures are measured and calculated by using the measurement method of the embodiment of the present invention, and the results are shown in Table 1.

[0092] Table 1 Roundness values of several common figures

[0093]

[0094]

[0095] The cylindricity values of several common columnar objects are measured and calculated by using the measurement method of the embodiment of the present invention, and the results are shown in Table 2.

[0096] Table 2 Cylindricity values of several common columnar objects

[0097]

[0098] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for measuring the length, circumference, roundness and cylindricity of cigarette rods based on machine vision, characterized in that Including the following steps: Step 1: Establish a three-dimensional contour body of a cigarette Use a first contour sensor and a second contour sensor to measure the surface contour of the cigarette to be measured, and draw a three-dimensional contour body of the cigarette to be measured according to the measurement results; the measurement results include axial contour data obtained by the first contour sensor measuring along the central axis direction of the cigarette, and circumferential contour data obtained by the second contour sensor measuring around the cigarette once along the circumferential direction; Step 2: Calculate the length of the cigarette Use an image recognition algorithm to calculate the maximum axial distance L between the two end faces of the three-dimensional contour body, which is the cigarette length L; Step 3: Calculate the circumference of the cigarette Using an image segmentation algorithm, the three-dimensional contour body is dissected along a direction perpendicular to the axis of the three-dimensional contour body to obtain n cross-sectional approximate circles, and then an image recognition algorithm is used to calculate the circumference C of each cross-sectional approximate circle i , and the circumference C of the cigarette rod is calculated from formula (1): In formula (1), C is the circumference of the cigarette rod, in mm; C i is the circumference of an approximate circle of a certain cross-section of the three-dimensional contour body, in mm; Step 4: Calculate the roundness of the cigarette For any cross-section of the three-dimensional contour body that is approximately circular, using the circumference C of the approximately circular cross-section i as a condition, a theoretical circle is constructed, and the radius r of the theoretical circle is identified and calculated using an image recognition algorithm Ti . At the same time, the largest inscribed circle of the approximately circular cross-section is constructed, and the radius r of the largest inscribed circle is identified and calculated using an image recognition algorithm Mi . The roundness O of the cigarette rod is calculated by formula (2): In formula (2), O is the roundness of the cigarette rod; r Mi is the radius of the maximum inscribed circle of an approximate circle in any cross-section of the three-dimensional contour body, with the unit of mm; r Ti is the radius of the theoretical circle of an approximate circle in any cross-section of the three-dimensional contour body, with the unit of mm; Step 5: Calculate the cylindricity of the cigarette For all cross-sections of the three-dimensional contour body obtained by dissecting in step 3 being approximately circular, use an image recognition algorithm to identify and calculate the radius r of the maximum inscribed circle Mi of the maximum value (r Mi ) max and the minimum value (r Mi ) min , and calculate the roundness Φ of the cigarette by formula (3): In formula (3), Φ is the cylindricity of the cigarette rod; (r Mi ) max and (r Mi ) min are respectively the maximum and minimum values of the maximum inscribed circle radii of the approximate circles of all cross-sections of the three-dimensional contour body, with the unit of mm; O is the roundness of the cigarette rod.

2. The method for measuring the length, circumference, roundness and cylindricity of cigarette rods based on machine vision according to claim 1, characterized in that: The cigarette types include flue-cured tobacco cigarettes, blended cigarettes, machine-made cigars, hand-made cigars, heat-not-burn cigarettes, and cigarette filters.

3. The method for measuring the length, circumference, roundness and cylindricity of cigarette rods based on machine vision according to claim 1, wherein: The first contour sensor and the second contour sensor are CCD contour scanning sensors or laser contour scanning sensors.

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