Method and system for judging material overrun through light opening

Abstract

The invention relates to the technical field of material overrun detection, and particularly discloses a method and system for judging material overrun through an optical switch, and the method comprises the steps: obtaining foreign matter characteristic parameters according to the light wavelength of a photoelectric switch transmitting end and a foreign matter; according to the Lambert-Beer law and the relation between the power P of the transmitting end of the photoelectric switch and the incident light intensity I0, the foreign matter penetration threshold Imin1 and the material overrun threshold Imin2 are calculated in combination with the detection distance L between the transmitting end of the correlation light switch and the receiving end of the correlation light switch, the environment attenuation coefficient K and the foreign matter characteristic parameters; the transmitting power P of the photoelectric switch is deduced according to the relation between the transmitting end power P of the photoelectric switch and the incident light intensity I0; the light intensity Iout1 of the receiving end of the photoelectric switch is compared with a foreign matter penetration threshold value Imin1 and a material over-limit threshold value Imin2 to judge whether the material is over-limit or not; through double-threshold models Imin1 and Imin2 of the Lambert-Beer law, foreign matter shielding and material overrun can be accurately distinguished.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material over-limit detection, and particularly relates to a method and system for determining material over-limit by light opening. BACKGROUND

[0002] In the logistics industry, a common optical reflection type photoelectric switch installed on a loading platform is usually used to detect whether the goods are over-limited. The detection principle is that the transmitting end of the reflection light opening transmits visible light or infrared light, and then the receiving end detects whether the light intensity is blocked. If the light intensity is blocked, it is determined that the goods are over-limited. At this time, the stacker will immediately issue an alarm and stop to prevent the over-limited goods from colliding with the loading platform or further colliding with the shelves in the stereoscopic warehouse, resulting in a serious accident. The conventional common optical reflection type photoelectric switch only determines whether the goods on the loading platform are over-limited according to whether the received light intensity is lower than a fixed threshold value, and does not distinguish whether it is actually material blocking or foreign matter blocking. In actual industrial applications, the surface of the material on the stacker is often attached with label paper or packaging film. When these objects are not closely attached, they will float out of the material surface. The prior art scheme will misjudge this kind of foreign matter blocking as material over-limit, thereby causing the stacker to stop, affecting the production operation and efficiency, and at the same time, manual high-altitude inspection of over-limited materials is required, which has great safety hazards. SUMMARY

[0003] In view of the deficiencies of the prior art, the present application provides a method and system for determining material over-limit by light opening.

[0004] The method for determining material over-limit by light opening of the present application comprises the following steps: S1, obtaining the foreign matter characteristic parameters according to the wavelength of the light emitted by the photoelectric switch transmitting end and the foreign matter itself, the foreign matter characteristic parameters at least including the foreign matter thickness d, the foreign matter penetration rate T and the foreign matter absorption coefficient μ of the light; S2, calculating the foreign matter penetration threshold I according to the Lambert-Beer law and the relationship between the photoelectric switch transmitting end power P and the incident light intensity I0, combining the detection distance L of the reflection light opening transmitting end and the reflection light opening receiving end, the environmental attenuation coefficient K and the foreign matter characteristic parameters; min1 And the material over-limit threshold I min2 ; Foreign matter penetration threshold: ; Material over-limit threshold: ; Wherein is the penetration rate of the material to the light; S3, calculating the foreign matter penetration threshold I min1And the relationship between the photoelectric switch emission power P and the incident light intensity I0, the emission power P of the photoelectric switch is derived by using the "Lambert-Bill Law"; S3.1, the relationship between the photoelectric switch emission power P and the incident light intensity I0 The "Lambert-Bill Law" is used to express the light intensity I of the light penetrating the foreign matter reaching the receiver out1 Relationship In; S3.2, ensure The required emission power P is obtained by back calculation, ; S4, install the photoelectric switch emission end power P light on the material detection station; S5, when the material enters the detection station, the photoelectric switch emission end with power P emits light, and the light intensity I out1 Compared with the foreign matter penetration threshold I min1 And the material overrun threshold I min2 Determine whether the material is overrunning; S5.1, compare I out1 With I min1 , I min2 Output the determination result: If I out1 ≥ I min1 , it is determined that "no overrun (no shielding or foreign matter shielding)". If I min2 ≤ I out1 <I min1 , it is determined that "no overrun (foreign matter shielding exists)". If I out1 <I min2 , it is determined that "the material is overrunning".

[0005] Among them: I0: the incident light intensity of the photoelectric switch emission, which is positively related to the emission power; T: the penetration rate of the foreign matter to the light; 1 / L 2 : light intensity square inverse attenuation, L is the detection distance between the emission end of the light and the receiving end of the light; K: environmental attenuation coefficient; η: photoelectric conversion efficiency of the emission tube; θ: half-power angle of the photoelectric switch emission angle; A: the light spot area of the incident light irradiated to the label paper.

[0006] A system for determining whether the material is overrunning by using the light, the above method for determining whether the material is overrunning by using the light is applied, comprising: Foreign matter characteristic parameter input storage module: for inputting and storing foreign matter characteristic parameters, the foreign matter characteristic parameters at least including foreign matter thickness d, foreign matter light penetration T and absorption coefficient μ; Threshold calculation module, by "Lambert-Beer's law", combining detection distance L, environmental attenuation coefficient K and the foreign matter characteristic parameters, determining foreign matter penetration threshold I min1 and material over-limit threshold I min2 , and through foreign matter penetration threshold I min1 and material over-limit threshold I min2 Deduce photoelectric switch emission end power P; Light emission module: for photoelectric switch emission end to emit light at power P; Light receiving module: oppositely arranged with the light emission module, for receiving light emitted by the light emission module; the light receiving module is built-in narrowband filter matched with the output wavelength of the light emission module, which can output real-time received light intensity I out1 ; Over-limit determination module, for comparing I out1 and I min1 , I min2 , output determination result.

[0007] The power of the light emission module is adjustable, and has light signal modulation function, which converts the continuous light signal output by the near-infrared emission module into pulse light signal of specific frequency (industrial commonly used 38kHz or 50kHz), and makes the light receiving module only respond to the specific frequency light signal, so as to realize shielding of environmental stray light; It also includes an adaptive power adjustment module for adjusting the power of the light emission module; according to the foreign matter characteristic parameters in the foreign matter characteristic parameter input storage module, the power of the photoelectric switch emission end is adjusted by the light emission module.

[0008] It also includes an alarm module electrically connected with the over-limit determination module, which sends signals according to the determination result of the over-limit determination module; The alarm module can send alarm sound and light information by itself, or the alarm module is electrically connected with the device operation system installed with the system, and the device is stopped through the signal sent by the alarm module.

[0009] The emission of the photoelectric switch emission end is near-infrared light, and the wavelength of the near-infrared light is 850nm or 940nm.

[0010] The foreign matter is white wood pulp label paper or plastic film, the thickness d of the white wood pulp label paper is 0.08~0.2mm, the light penetration T is 30%~60%, and the light absorption coefficient μ is 5~10cm -1 ; The thickness of the plastic film is d=0.05~0.15mm, the penetration rate of light is T=50%~70%, and the absorption coefficient of light is μ=3~6cm -1 ; The penetration rate of the material to near-infrared light is T material ≤5%.

[0011] Compared with the prior art, the beneficial effects of the present application are as follows: 1. When the light opening is used as a photoelectric switch when the material is over-limited, the present application can accurately distinguish between "foreign matter shielding" and "material over-limit": by using the double-threshold model I min1 (the foreign matter penetration threshold) and Im in2 (the material over-limit threshold) based on the modified Lambert-Beer law, the light intensity boundaries of "foreign matter partial light transmission" and "material light transmission" are clearly defined, such as label paper penetration light intensity ≥3μW / cm² and material shielding light intensity <0.5μW / cm², which completely solves the industry pain point that the existing ordinary optical opposite shooting type misjudges "label paper, film, dust" and other foreign matters as "material over-limit", and avoids economic losses such as unplanned shutdown of the production line.

[0012] 2. The present application not only can accurately distinguish between "foreign matter shielding" and "material over-limit", and remove the interference of foreign matter on material over-limit determination, but also can adjust the power of the photoelectric switch emission end according to the foreign matter characteristic parameters by the self-adaptive power adjustment module, so that when the foreign matter on the production line is determined, the minimum power of the photoelectric switch emission end can be determined according to the maximum value of the foreign matter penetration threshold I min1 , thereby effectively avoiding energy waste caused by excessive power.

[0013] 3. When the over-limit determination module determines that the material is over-limited, the alarm module timely alarms or outputs a shutdown signal, which can effectively prevent safety hazards such as material overflow and collision between material and equipment, and reduce the equipment maintenance cost and production interruption loss caused by over-limit. DETAILED DESCRIPTION

[0014] In the following, several embodiments of the present application will be disclosed by examples. For the purpose of clear illustration, many details of the actual objects will be described in the following description. However, it should be understood that these details of the actual objects should not be used to limit the present application. That is, in some embodiments of the present application, these details of the actual objects are unnecessary. In addition, for the purpose of simplifying the examples, some conventional and commonly used structures and components will be shown in a simple schematic manner in the examples.

[0015] In addition, the description such as "first", "second" in the present application is only for the purpose of description, and is not intended to particularly indicate the order or sequence, nor to limit the present application, which is merely to distinguish the components or operations described by the same technical terms, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the realization of the technical personnel in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the protection scope required by the present application.

[0016] Embodiment one: A method for determining material overrunning by light opening: S1, according to the wavelength of the light emitted by the photoelectric switch, and the foreign matter itself, the foreign matter characteristic parameters at least include the thickness d of the foreign matter, the penetration rate T of the foreign matter to the light and the absorption coefficient μ of the foreign matter to the light; When the material overrunning foreign matter is a common white wood pulp label paper with a thickness d of 0.2mm, and the light emitted by the photoelectric switch is near-infrared light, and the wavelength of the near-infrared light is 850nm or 940nm, T≈0.3~0.6; S2, according to "Lambert-Beer law" to express the light intensity I of the light reaching the receiver after penetrating the foreign matter out1 relationship , combined with the detection distance L of the development emission end of the opposite light and the receiving end of the opposite light, the environmental attenuation coefficient K and the foreign matter characteristic parameters obtained in S1, the foreign matter penetration threshold I min1 and the material overrun threshold I min2 ; Foreign matter penetration threshold: ; Material overrun threshold: ; Wherein the penetration rate T of the material to the near-infrared light material ≤5%, which is calculated according to the actual working condition of the material, such as industrial materials (such as plastic parts, metal parts, granular materials, etc.), which almost do not penetrate 850nm / 940nm near-infrared light, and the actual penetration rate is generally ≤5%, which is approximately completely opaque; Where e is the natural logarithm; S3, according to the detection distance L, the foreign matter characteristic parameters, the foreign matter penetration threshold I min1 and the relationship between the power P of the photoelectric switch emission end and the incident light intensity I0, the emission power P of the photoelectric switch is derived by using "Lambert-Beer law"; The relationship between the emission power P of the photoelectric switch and the incident light intensity I0 Substituting the values ​​into Lambert-Beer's Law, we can express the light intensity I reaching the receiver after the light penetrates the foreign object. out1 Relationship In China; ensure To reverse-engineer the required transmission power P, ; S4. Install the photoelectric switch with power P at the transmitting end of the photoelectric switch at the material detection station; S5. When the material enters the detection station, the photoelectric switch with power P emits light, and the photoelectric switch with light intensity I emits light. out1 Foreign body penetration threshold I min1 and material over-limit threshold I min2 Compare and determine whether the material exceeds the limit; Comparison I out1 with I min1 I min2 Output the judgment result: If I out1 ≥I min1 The result was determined to be "not exceeding the limit (no obstruction or obstruction by foreign objects)"; If I min2 ≤I out1 min1 The result was determined to be "not exceeding the limit (foreign object obstruction)"; If I out1 min2 The material was deemed to be "out of limit". When this method is used as a photoelectric switch for material exceeding limits, it can accurately distinguish between "foreign object obstruction" and "material exceeding limits": through a dual-threshold model I based on the modified "Lambert-Beer Law". min1 and I min2 This technology clearly defines the light intensity boundary between "light transmission through foreign objects" and "light transmission through materials." For example, the light intensity after the label paper penetrates the light is ≥3μW / cm², while the light intensity after the material blocks the light is <0.5μW / cm². This completely solves the industry pain point of existing ordinary optical through-beam systems misjudging foreign objects such as "label paper, film, and dust" as "material exceeding limits," thus avoiding economic losses such as unplanned production line downtime.

[0017] Among them, the "Lambert-Beer Law" is the core physical law describing the intensity attenuation of light when it penetrates a uniform medium. It is defined as follows: when parallel monochromatic light is incident perpendicularly on a uniform, non-scattering light-absorbing medium (such as a solid, liquid, or gas), the degree of light attenuation is proportional to the concentration, thickness, or absorption coefficient of the medium and is independent of the incident light intensity—that is, the light intensity decreases exponentially with the penetration distance. I out Light intensity after penetrating the label paper (unit: μW / cm²). I out1 ​​The light intensity (in μW / cm²) that reaches the receiver after penetrating the label must be greater than or equal to the receiver's minimum detection light intensity I. min ; I0: The intensity of incident light emitted by the photoelectric switch (unit: μW / cm²), which is positively correlated with the emission power; T: Infrared transmittance of the label paper (unitless). When the label paper is white with a wavelength of 850nm and the thickness of the label paper is 0.2mm, T≈0.3~0.6; μ: Absorption coefficient of the label paper for the infrared wavelength of the target (unit: cm) -1 At a wavelength of 850nm, the μ value of white label paper is approximately 5~10 cm. -1 ; d: Label paper thickness (unit: cm), e.g., 0.1mm = 0.01cm; 1 / L 2 Light intensity attenuation is inversely proportional to the square of the light intensity, and L is the distance between the photoelectric switch transmitter and the tag (unit: cm). K: Environmental attenuation coefficient (unitless). In this embodiment, after avoiding interference from ambient light and dust, K≈0.5~0.8.

[0018] η: Photoelectric conversion efficiency of the emitting diode (unitless), for infrared emitting diodes η≈0.2~0.5 (common 850nm emitting diodes); θ: Half-power angle of the photoelectric switch's emission angle (unit: °). Common values ​​for industrial photoelectric switches are θ = 10°~30°, and cosθ ≈ 0.94~0.87. A: Area of ​​the light spot on the label (unit: cm²), A=π(Ltanθ) 2 (The light spot is approximately circular.)

[0019] Example 2: A system for optically determining material exceeding limits, employing the method for optically determining material exceeding limits in Example 1, includes: Foreign object characteristic parameter input and storage module: used to input and store foreign object characteristic parameters, which include at least the foreign object thickness d, the light transmittance T of the foreign object, and the absorption coefficient μ; The threshold calculation module determines the foreign object penetration threshold I by using the Lambert-Beer Law, combined with the detection distance L, the environmental attenuation coefficient K, and the foreign object's characteristic parameters. min1 and material over-limit threshold I min2 And through the foreign object penetration threshold I min1 and material over-limit threshold I min2 Derive the power P of the photoelectric switch transmitter; Light emission module: used to emit near-infrared light at power P at the photoelectric switch transmitter. The power of the light emission module is adjustable and it has optical signal modulation function. An adaptive power adjustment module for adjusting the power of the light emitting module; based on the foreign object characteristic parameters input into the storage module, the power of the light emitting module at the photoelectric switch emission end is adjusted. Light receiving module: Located opposite the light emitting module, it receives light emitted by the light emitting module; the light receiving module has a built-in narrowband filter that matches the output wavelength of the light emitting module, and can output the real-time received light intensity I. out1 ; The over-limit determination module is used to compare I out1 with I min1 I min2 Output the judgment result.

[0020] It also includes an alarm module electrically connected to the over-limit determination module, which sends a signal based on the determination result of the over-limit determination module; The alarm module can automatically emit alarm sound and light information, or the alarm module can be electrically connected to the operating system of the equipment that has the system installed, and the alarm module can send a signal to stop the equipment.

[0021] During operation, this system can not only accurately distinguish between "foreign object obstruction" and "material exceeding limits," eliminating interference from foreign objects in the determination of material exceeding limits, but also enable the adaptive power adjustment module to adjust the power of the photoelectric switch emitter based on the foreign object's characteristic parameters. Once a foreign object is identified on the production line, it can be determined based on the foreign object penetration threshold I. min1 The maximum value is used to determine the minimum power at which the light emitting module enables the photoelectric switch to emit light, thereby effectively avoiding energy waste caused by excessive power. Furthermore, when the over-limit judgment module determines that "material exceeds the limit", the alarm module will promptly sound an alarm or output a shutdown signal, which can effectively prevent material overflow from causing safety hazards such as material colliding with equipment, and reduce equipment maintenance costs and production interruption losses caused by exceeding the limit.

[0022] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for determining material exceeding limits using optical emission control, characterized in that, The following steps are required: S1. Obtain the foreign object characteristic parameters based on the light wavelength of the photoelectric switch transmitter and the foreign object itself. The foreign object characteristic parameters include at least the foreign object thickness d, the light transmittance T of the foreign object, and the light absorption coefficient μ of the foreign object. S2. Based on the Lambert-Beer Law and the relationship between the power P of the photoelectric switch transmitter and the incident light intensity I0, combined with the detection distance L between the through-beam transmitter and receiver, the environmental attenuation coefficient K, and the aforementioned foreign object characteristic parameters, calculate the foreign object penetration threshold I. min1 and material over-limit threshold I min2 ; S3. Based on the detection distance L, foreign object characteristic parameters, and foreign object penetration threshold I min1 The relationship between the power P of the photoelectric switch transmitter and the incident light intensity I0 is also discussed, and the emission power P of the photoelectric switch is derived using the Lambert-Beer Law. S4. Install the photoelectric switch with power P at the transmitting end of the photoelectric switch at the material detection station; S5. When the material enters the detection station, the photoelectric switch with power P emits light, and the photoelectric switch with light intensity I emits light. out1 Foreign body penetration threshold I min1 and material over-limit threshold I min2 Compare and determine whether the material exceeds the limit.

2. The method for determining material exceeding limits using optical switching according to claim 1, characterized in that: According to the Lambert-Beer Law, the intensity I of light reaching the receiver after penetrating a foreign object is... out Relationship By combining the detection distance L between the through-beam transmitter and receiver, the environmental attenuation coefficient K, and the foreign object characteristic parameters, the foreign object penetration threshold I is calculated. min1 and material over-limit threshold I min2； Foreign object penetration threshold: ; Material exceeding the limit threshold: ; in The transmittance of the material to the light.

3. The method for determining material exceeding limits using optical switching according to claim 2, characterized in that: The specific derivation of the photoelectric switch's emission power P using the Lambert-Beer Law is as follows: S3.1, The relationship between the photoelectric switch's emission power P and the incident light intensity I0 Substituting the values ​​into the Lambert-Beer Law, we can express the light intensity I reaching the receiver after the light penetrates the foreign object. out1 Relationship middle; S3.2, Ensure To calculate the required transmission power P, ; in: I0: The intensity of the incident light emitted by the photoelectric switch, which is positively correlated with the emission power; 1 / L 2 : Light intensity inverse square attenuation, where L is the detection distance between the transmitter and receiver of the through-beam light source; η: Photoelectric conversion efficiency of the transmitter tube; θ: Half-power angle of the photoelectric switch's emission angle; A: The area of ​​the light spot that the incident light hits on the label paper.

4. The method for determining material exceeding limits using optical switching according to claim 1, characterized in that: S5.1, Comparison I out1 With Im in1 I min2 Output the judgment result: If I out1 ≥I min1 It was determined to be "not exceeding the limit"; If I min2 ≤I out1 min1 It was determined to be "not exceeding the limit";​ If I out1 min2 The material was deemed to be "out of limit".​ 5. A system for optically determining whether a material exceeds its limit, characterized in that, The system applies any one of claims 1-4 to the method for optically determining material exceeding limits, including: Foreign object characteristic parameter input and storage module: used to input and store foreign object characteristic parameters, which include at least the foreign object thickness d, the light transmittance T of the foreign object, and the absorption coefficient μ; The threshold calculation module determines the foreign object penetration threshold I by using the Lambert-Beer Law, combined with the detection distance L, the environmental attenuation coefficient K, and the foreign object's characteristic parameters. min1 and material over-limit threshold I min2 And through the foreign object penetration threshold I min1 and material over-limit threshold I min2 Derive the power P of the photoelectric switch transmitter; Light emission module: used by the photoelectric switch transmitter to emit light at power P; Light receiving module: Located opposite the light emitting module, it receives light emitted by the light emitting module; the light receiving module has a built-in narrowband filter that matches the output wavelength of the light emitting module, and can output the real-time received light intensity I. out1 ; The over-limit determination module is used to compare I out1 with I min1 I min2 Output the judgment result.

6. The system for optically determining material exceeding limits according to claim 5, characterized in that: The light emitting module has adjustable power and optical signal modulation function; It also includes an adaptive power adjustment module for adjusting the power of the light emitting module; based on the foreign object characteristic parameters input into the storage module, the power of the light emitting module at the photoelectric switch emission end is adjusted.

7. A system for optically determining material exceeding limits according to claim 5 or 6, characterized in that: It also includes an alarm module electrically connected to the over-limit determination module, which sends a signal based on the determination result of the over-limit determination module; The alarm module can automatically emit alarm sound and light information, or the alarm module can be electrically connected to the operating system of the equipment that has the system installed, and the alarm module can send a signal to stop the equipment.

8. The system for optically determining material exceeding limits according to claim 7, characterized in that: The photoelectric switch emits near-infrared light, and the wavelength of the near-infrared light is 850nm or 940nm.

9. The system for optically determining material exceeding limits according to claim 7, characterized in that: The foreign object is white wood pulp label paper or plastic film, wherein the white wood pulp label paper has a thickness d = 0.08–0.2 mm, a light transmittance T = 30%–60%, and a light absorption coefficient μ = 5–10 cm⁻¹. -1 ; The plastic film has a thickness d = 0.05~0.15mm, a light transmittance T = 50%~70%, and a light absorption coefficient of [missing information]. .

10. A system for determining material exceeding limits using optical switching according to claim 8, characterized in that: The material's transmittance T to near-infrared light material ≤5%.

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