Strobe-assisted manual online cable surface printing inspection method

Abstract

The invention discloses a stroboscopic-assisted manual online inspection method for cable surface lettering. The method comprises the following steps: (1) establishing an online inspection production station for cable surface lettering; and (2) an operator is in place and checks. In the step (1), stroboscopic equipment capable of automatically starting, following and adjusting brightness is erected on a production station. The stroboscopic device collects background environment light intensity, operator in-place information, cable production linear speed and reflected light intensity of the stroboscopic instrument on the surface of the cable, and the controller calculates and feeds back and controls the flicker frequency and stroboscopic light intensity of the stroboscopic instrument. In the step (2), the controller calculates the flicker frequency and brightness of the stroboscope and controls the stroboscope to work according to various conditions on site, so as to assist operators to observe letters printed on the surface of the cable with naked eyes. The flicker frequency of the stroboscope can be automatically adjusted according to information such as the linear speed of a production line, the brightness of the stroboscope can be automatically adjusted according to the brightness of background light, full-automatic work can be achieved, and personnel intervention is not needed.

Description

Technical Field

[0001] The invention relates to a cable production quality inspection technology, in particular to a stroboscopically assisted manual online inspection method for cable surface printing. Background Art

[0002] During cable production, it is a routine process requirement to use a printer or laser machine to print or engrave the model, specifications and other parameters of the product on the surface. Therefore, it is also necessary for workers to regularly check the printing content and printing effect.

[0003] When the cable runs at a low speed, workers can observe the condition of the cable surface with the naked eye. When the line speed is high, it is difficult to observe with the naked eye, and a stroboscope is usually used to assist the naked eye. A stroboscope is an optical measuring instrument that controls the light source to flash rapidly at a specific frequency. A stroboscope can emit short and frequent flashes. When the flash frequency is close to or synchronized with the speed of the object being measured, the surface quality or running condition of the high-speed moving object can be easily observed by using the visual persistence of the eyes or video synchronization.

[0004] However, when the background ambient light changes, if the brightness of the stroboscope is close to or less than the ambient light, there will be no stroboscopic effect. If the brightness of the stroboscope greatly exceeds the ambient light, it will be dazzling and affect observation.

[0005] The common solution now is to use a handheld stroboscope or a fixed-mounted stroboscope to observe the cable surface. It is necessary to manually adjust the strobe frequency and brightness according to the on-site conditions. The operation is cumbersome and the brightness is inaccurate. Summary of the invention

[0006] The present invention provides a method for online inspection of cable surface printing. In the method, the automatic start, automatic line speed following and automatic brightness adjustment of the stroboscope are controlled according to the on-site conditions to assist the manual online inspection of cable surface printing.

[0007] A method for manually checking cable surface printing online with the aid of stroboscopic light, comprising the following steps:

[0008] (1) Establish an online inspection production station for cable surface printing;

[0009] (2) The operating personnel are in place and carry out inspection work;

[0010] In the step (a), a strobe device that automatically starts, follows and adjusts the brightness is set up at the production station;

[0011] The stroboscopic device comprises a frame, and a stroboscope, a first brightness sensor, a light curtain, an encoder and a second brightness sensor are installed on the frame; the stroboscopic device is controlled by a controller; wherein the stroboscope is an auxiliary observation component; the first brightness sensor is used to detect the intensity of background ambient light; the light curtain is used to detect whether there are observation operators on site; the printed content on the surface of the cable is the observation object; the encoder is used to detect the line speed of cable production; the second brightness sensor is used to detect the intensity of reflected light from the stroboscope on the surface of the cable;

[0012] On both sides of the cable's forward path are the stroboscope and the operator's position; the position of the light curtain corresponds to the operator's position;

[0013] When the light curtain detects that the operator is in place, it transmits the corresponding signal to the controller, and the controller starts the stroboscope;

[0014] The controller obtains the length L of repeated printing of the content by communicating with the inkjet printer; obtains the linear speed V of the cable through the pulse signal of the encoder; and calculates the flashing frequency f.

[0015]

[0016] When the linear speed is lower than L, the human eye can directly observe the printed characters, and the stroboscope is always on.

[0017] When the linear velocity is greater than L, the controller outputs a pulse signal with a frequency of f to the stroboscope to control its flashing frequency;

[0018] Acquire the background ambient light brightness through the first brightness sensor, and use it as a reference for the given light brightness;

[0019] In order to prevent the background light from being affected by instantaneous light changes, the collected background light brightness is processed by discrete low-pass filtering as follows:

[0020]

[0021] Among them, Lg n+1 is the output value after filtering in each cycle, Lg n is the output value after filtering in the previous cycle, a is the filtering coefficient, where T c is the sampling period, τ is the integration time constant;

[0022] Finally, the given signal is Lg n+1 +Val_diff

[0023] Among them, Val_diff is the illuminance contrast value where the stroboscopic effect can be observed;

[0024] The light intensity reflected by the stroboscope on the cable surface is obtained through the second brightness sensor, the brightness output by the stroboscope is obtained through the PID algorithm, and the analog voltage of 0 to 10V is output to the stroboscope to control its flashing brightness;

[0025] Since the maximum brightness of the stroboscope is limited, in order to prevent the integral saturation caused by long-term background strong light, the PID algorithm is improved to obtain a PID algorithm with integral separation, which is as follows after discretization:

[0026]

[0027] Among them, Lg_out is the final light intensity output value, K p is the proportionality coefficient, e(k) is the deviation value of the light intensity in each cycle, e(k-1) is the deviation value of the light intensity in the previous cycle, e(0) is the deviation value of the light intensity in the first cycle, Tc is the processor cycle time, K i is the integration coefficient, K d is the differential coefficient, index is the integral separation coefficient, which is 1 when the integral term does not exceed the output cutoff value, and 0 when the integral term exceeds the output cutoff value;

[0028] In the step (ii), the operator reaches the working position and blocks the infrared rays between the infrared transceivers of the light curtain, and the stroboscope starts to work;

[0029] At the same time, the production line is running, the cable moves along its path, and the inkjet printer prints; the first brightness sensor detects the intensity of the background ambient light, the encoder detects the line speed of cable production, and the second brightness sensor detects the intensity of the reflected light from the stroboscope on the cable surface; this information is transmitted to the controller, which calculates the flashing frequency and brightness of the stroboscope to assist operators in observing the printing on the cable surface with the naked eye.

[0030] The first brightness sensor obtains the brightness of the background ambient light, and a constant β is added to it as the given brightness. The stroboscopic effect will only be effective if there is a certain brightness difference between the given light and the background light.

[0031] Compared with the prior art, the beneficial effects of the present invention are that the present invention can automatically adjust the flashing frequency of the stroboscope according to the line speed of the production line, can automatically adjust the brightness of the stroboscope according to the brightness of the ambient light and the reflected light of the cable, can realize fully automatic operation without the need for human intervention, thereby ensuring the quality of human work, reducing the labor intensity of human workers, and reducing their work fatigue. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the online inspection production station of the present invention;

[0033] Figure 2 This is a schematic diagram of printing on the cable surface;

[0034] Figure 3 The hardware topology diagram of the stroboscopic device used in the present invention;

[0035] In the figure, there are a stroboscope 1, a first optical fiber sensor 2, a light curtain 3, a cable 4, an encoder 5, a second optical fiber sensor 6, a controller 11, and an inkjet printer 12. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] The method for manually checking cable surface printing online with the aid of stroboscopic light of the present invention comprises the following steps:

[0038] (1) Establish an online inspection production station for cable surface printing;

[0039] (2) The operating personnel are in place and conduct inspections;

[0040] In the step (a), a strobe device that automatically starts, follows and adjusts the brightness is set up at the production station;

[0041] The stroboscopic device comprises a frame, on which a stroboscope, a first brightness sensor, a light curtain, an encoder and a second brightness sensor are installed; the stroboscopic device is controlled by a controller; wherein the stroboscope is an auxiliary observation component; the first brightness sensor is used to detect the intensity of background ambient light; the light curtain is used to detect whether there are observation operators on site; the printed content on the surface of the cable is the observation object; the encoder is used to detect the line speed of cable production; the second brightness sensor is used to detect the intensity of reflected light from the stroboscope on the surface of the cable;

[0042] On both sides of the cable's forward path are the stroboscope and the operator's position; the position of the light curtain corresponds to the operator's position;

[0043] When the light curtain detects that the operator is in place, it transmits the corresponding signal to the controller, and the controller starts the stroboscope;

[0044] The controller obtains the length L of repeated printing of the content by communicating with the inkjet printer; obtains the linear speed V of the cable through the pulse signal of the encoder; and calculates the flashing frequency f.

[0045]

[0046] When the linear speed is lower than L, the human eye can directly observe the printed characters, and the stroboscope is always on.

[0047] When the linear velocity is greater than L, the controller outputs a pulse signal with a frequency of f to the stroboscope to control its flashing frequency;

[0048] Acquire the background ambient light brightness through the first brightness sensor, and use it as a reference for the given light brightness;

[0049] In order to prevent the background light from being affected by instantaneous light changes, the collected background light brightness is processed by discrete low-pass filtering as follows:

[0050]

[0051] Among them, Lg n+1 is the output value after filtering in each cycle, Lg n is the output value after filtering in the previous cycle, a is the filtering coefficient, where T c is the sampling period, τ is the integration time constant;

[0052] Finally, the given signal is Lg n+1 +Val_diff

[0053] Among them, Val_diff is the illuminance contrast value where the stroboscopic effect can be observed;

[0054] The light intensity reflected by the stroboscope on the cable surface is obtained through the second brightness sensor, the brightness output by the stroboscope is obtained through the PID algorithm, and the analog voltage of 0 to 10V is output to the stroboscope to control its flashing brightness;

[0055] Since the maximum brightness of the stroboscope is limited, in order to prevent the integral saturation caused by long-term background strong light, the PID algorithm is improved to obtain a PID algorithm with integral separation, which is as follows after discretization:

[0056]

[0057] Among them, Lg_out is the final light intensity output value, K p is the proportionality coefficient, e(k) is the deviation value of the light intensity in each cycle, e(k-1) is the deviation value of the light intensity in the previous cycle, e(0) is the deviation value of the light intensity in the first cycle, Tc is the processor cycle time, K i is the integration coefficient, K d is the differential coefficient, index is the integral separation coefficient, which is 1 when the integral term does not exceed the output cutoff value, and 0 when the integral term exceeds the output cutoff value;

[0058] In the step (ii), the operator reaches the working position and blocks the infrared rays between the infrared transceivers of the light curtain, and the stroboscope starts to work;

[0059] At the same time, the production line is running, the cable moves along its path, and the inkjet printer prints; the first brightness sensor detects the intensity of the background ambient light, the encoder detects the line speed of cable production, and the second brightness sensor detects the intensity of the reflected light from the stroboscope on the cable surface; this information is transmitted to the controller, which calculates the flashing frequency and brightness of the stroboscope to assist operators in observing the printing on the cable surface with the naked eye.

[0060] See also Figure 1 to Figure 3 The stroboscopic device and the control method thereof used in the present invention are described in detail below. In this example, the first brightness sensor and the second brightness sensor are both optical fiber sensors, respectively referred to as the first optical fiber sensor and the second optical fiber sensor.

[0061] Online inspection of production stations such as Figure 1 As shown, the devices covered mainly include: stroboscope 1, first optical fiber sensor 2, light curtain 3, cable 4, encoder 5, and second optical fiber sensor 6. Among them, stroboscope 1 is an auxiliary observation component, optical fiber brightness sensor 2 is used to detect the intensity of background ambient light, light curtain 3 is used to detect whether there are operators, the printed content on the surface of cable 4 is the observed object, encoder 5 is used to detect line speed (one of the key variables for calculating the flashing frequency of the stroboscope), and second optical fiber sensor 6 is used to detect the intensity of light reflected by the stroboscope on the cable surface.

[0062] The hardware topology of the strobe device is as follows: Figure 3 As shown, the main components include: stroboscope 1, first optical fiber sensor 2, light curtain 3, encoder 5, second optical fiber sensor 6, controller 11, and inkjet printer 12. Among them, controller 11 is the core component for processing and calculation. The control principle is as follows:

[0063] Whether the operator is in place is detected through the digital input signal (DI) of the light curtain 3, so that the stroboscope 1 is controlled to start through the DO signal.

[0064] The controller obtains the length L (in mm, such as mm) of repeated printing of the content by communicating with the inkjet printer 12 via Modbus / TCP. Figure 2 As shown, Figure 2 The linear velocity V (in m / min) is obtained through the pulse signal of the encoder 5, and the flicker frequency f is calculated.

[0065]

[0066] When the line speed is lower than Lmin, the human eye can directly observe the printing quality, and the stroboscope can be always on. When the line speed is higher than Lmin, a pulse signal with a frequency of f is output to the stroboscope 1 to control the flashing frequency.

[0067] The background light brightness (unit: Lux) is obtained through the Profinet IO signal of the first optical fiber sensor 2, and a certain value β is added on this basis (the stroboscopic effect is effective only when there is a certain brightness difference between the given light and the background light) as the given light brightness.

[0068] In order to prevent the background light from being affected by instantaneous light changes, the collected background light brightness is processed by discrete low-pass filtering as follows:

[0069]

[0070] Among them, Lg n+1 is the output value after filtering in each cycle, Lg n is the output value after filtering in the previous cycle, a is the filtering coefficient, where T c is the sampling period, and τ is the integration time constant.

[0071] Finally, the given signal is Lg n+1 +Val_diff, Val_diff is the illuminance contrast value at which the stroboscopic effect can be observed.

[0072] The light intensity (in Lux) reflected by the stroboscope on the cable surface is obtained through the Profinet IO signal of the second optical fiber sensor 6, the output brightness Lux is controlled by the PID algorithm, and the flashing brightness is controlled by outputting a 0-10V analog voltage to the stroboscope;

[0073] Since the maximum brightness of the stroboscope is limited, in order to prevent the integral saturation caused by long-term background strong light, the PID algorithm is improved to obtain a PID algorithm with integral separation. After discretization, it is as follows:

[0074]

[0075] Among them, Lg_out is the final light intensity output value, K p is the proportionality coefficient, e(k) is the deviation value of the light intensity in each cycle, e(k-1) is the deviation value of the light intensity in the previous cycle, e(0) is the deviation value of the light intensity in the first cycle, Tc is the processor cycle time, K i is the integration coefficient, K d is the differential coefficient, index is the integral separation coefficient, which is 1 when the integral term does not exceed the output cutoff value, and 0 when the integral term exceeds the output cutoff value.

Claims

1. A method for manually checking the printing on the surface of a cable online with the aid of a strobe light, characterized by the following steps: include: (1) Establish an online inspection production station for cable surface printing; (2) The operating personnel are in place and conduct inspections; In the step (a), a strobe device that automatically starts, follows and adjusts the brightness is set up at the production station; The stroboscopic device comprises a frame, on which a stroboscope, a first brightness sensor, a light curtain, an encoder and a second brightness sensor are installed; the stroboscopic device is controlled by a controller; wherein the stroboscope is an auxiliary observation component; the first brightness sensor is used to detect the intensity of background ambient light; the light curtain is used to detect whether there are observation operators on site; the printed content on the surface of the cable is the observation object; the encoder is used to detect the line speed of cable production; the second brightness sensor is used to detect the intensity of reflected light from the stroboscope on the surface of the cable; On both sides of the cable's forward path are the stroboscope and the operator's position; the position of the light curtain corresponds to the operator's position; When the light curtain detects that the operator is in place, it transmits the corresponding signal to the controller, and the controller starts the stroboscope; The controller obtains the length L of repeated printing of the content by communicating with the inkjet printer; obtains the linear speed V of the cable through the pulse signal of the encoder; and calculates the flashing frequency f. When the linear speed is lower than L, the human eye can directly observe the printed characters, and the stroboscope is always on. When the linear velocity is greater than L, the controller outputs a pulse signal with a frequency of f to the stroboscope to control its flashing frequency; Acquire the background ambient light brightness through the first brightness sensor, and use it as a reference for the given light brightness; In order to prevent the background light from being affected by instantaneous light changes, the collected background light brightness is processed by discrete low-pass filtering as follows: Among them, Lg n+1 is the output value after filtering in each cycle, Lg n is the output value after filtering in the previous cycle, a is the filtering coefficient, where T c is the sampling period, τ is the integration time constant; Finally, the given signal is Lg n+1 +Val_diff Among them, Val_diff is the illuminance contrast value where the stroboscopic effect can be observed; The light intensity reflected by the stroboscope on the cable surface is obtained through the second brightness sensor, the brightness output by the stroboscope is obtained through the PID algorithm, and the analog voltage of 0 to 10V is output to the stroboscope to control its flashing brightness; Since the maximum brightness of the stroboscope is limited, in order to prevent the integral saturation caused by long-term background strong light, the PID algorithm is improved to obtain a PID algorithm with integral separation, which is as follows after discretization: Among them, Lg_out is the final light intensity output value, K p is the proportionality coefficient, e(k) is the deviation value of the light intensity in each cycle, e(k-1) is the deviation value of the light intensity in the previous cycle, e(0) is the deviation value of the light intensity in the first cycle, Tc is the processor cycle time, K i is the integration coefficient, K d is the differential coefficient, index is the integral separation coefficient, which is 1 when the integral term does not exceed the output cutoff value, and 0 when the integral term exceeds the output cutoff value; In the step (ii), the operator reaches the working position and blocks the infrared rays between the infrared transceivers of the light curtain, and the stroboscope starts to work; At the same time, the production line is running, the cable moves along its path, and the inkjet printer prints; the first brightness sensor detects the intensity of the background ambient light, the encoder detects the line speed of cable production, and the second brightness sensor detects the intensity of the reflected light from the stroboscope on the cable surface; this information is transmitted to the controller, which calculates the flashing frequency and brightness of the stroboscope and controls its operation to assist operators in observing the printing on the cable surface with the naked eye.

2. The method for manually checking the cable surface printing with the aid of stroboscopic light according to claim 1 is characterized in that The first brightness sensor acquires the background ambient light brightness, and a constant β is added thereto as a given light brightness.

3. The method for manually checking the cable surface printing with the aid of stroboscopic light according to claim 1 is characterized in that The first brightness sensor and the second brightness sensor are both optical fiber sensors, respectively referred to as the first optical fiber sensor and the second optical fiber sensor.

4. The method for manually checking the cable surface printing with the aid of stroboscopic light according to claim 3 is characterized in that The communication method between the controller and the inkjet printer is Modbus / TCP; the communication method between the first and second optical fiber sensors and the controller is Profinet IO.

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