Safety light curtain adaptive signal adjusting system

Abstract

The invention discloses a safety light curtain adaptive signal adjusting system comprising a signal transmitting module used for generating a periodic modulation light signal; the signal receiving module is used for receiving the periodic modulation optical signal generated by the signal transmitting module; the adjustable gain amplifier is connected to the signal receiving module; the signal intensity detection module is used for collecting amplitude characteristics of the output signal of the signal receiving module in real time; and the control module is used for automatically calculating and outputting a gain adjusting instruction through a closed-loop feedback mechanism based on the signal intensity data output by the signal detection module so as to dynamically adjust the gain coefficient of the adjustable gain amplifier. Through a closed loop feedback control mechanism, the amplification gain of the received signal is adjusted in real time, the technical problems that a traditional safety light curtain is poor in working distance adaptability and sensitive to environmental interference are solved, and stable working of the safety light curtain in a wide distance range is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of safety light curtains, and in particular relates to a safety light curtain adaptive signal adjustment system, which is suitable for industrial safety protection, automated production lines, and various scenarios requiring photoelectric safety protection. Background Art

[0002] As an important non-contact safety protection device, safety light curtains are widely used in industrial environments to protect operator safety. However, traditional safety light curtain systems still have many technical defects:

[0003] 1) The fixed gain design limits the installation distance, and once the installation position is determined, it is difficult to adjust;

[0004] 2) Ambient light interference and dust pollution can cause system false alarms or failures;

[0005] 3) Manual recalibration is required at different installation distances, which results in high maintenance costs, or the use of models with different detection distances;

[0006] 4) The working distance adaptability is poor, and it is difficult to maintain stable performance in a wide range of 0.1 meters to 20 meters.

[0007] The above problems seriously restrict the application effect of safety light curtains in complex industrial environments. At present, an adaptive adjustment mechanism is urgently needed to solve these technical difficulties. Summary of the Invention

[0008] In response to the shortcomings or deficiencies of the above-mentioned existing technologies, the technical problem to be solved by this application is a safety light curtain adaptive signal adjustment system, which adjusts the amplification gain of the received signal in real time through a closed-loop feedback control mechanism, overcomes the technical problems of poor adaptability of the working distance and sensitivity to environmental interference of traditional safety light curtains, and realizes stable operation of the safety light curtain over a wide distance range.

[0009] To solve the above technical problems, this application is implemented through the following technical solutions:

[0010] On one hand, the present application proposes a safety light curtain adaptive signal conditioning system, comprising:

[0011] A signal transmitting module, which is used to generate a periodically modulated optical signal;

[0012] a signal receiving module, configured to receive the periodically modulated optical signal generated by the signal transmitting module;

[0013] an adjustable gain amplifier connected to the signal receiving module;

[0014] A signal strength detection module, which is used to collect the amplitude characteristics of the output signal of the signal receiving module in real time;

[0015] and a control module, which automatically calculates and outputs a gain adjustment instruction based on the signal strength data output by the signal detection module through a closed-loop feedback mechanism, so as to dynamically adjust the gain coefficient of the adjustable gain amplifier.

[0016] Optionally, the signal strength detection module includes:

[0017] A photodiode array for converting light signals into current signals;

[0018] a transimpedance amplifier, configured to convert the current signal output by the photodiode array into a voltage signal;

[0019] a peak hold circuit, electrically connected to the transimpedance amplifier and used to extract the signal envelope amplitude;

[0020] and an analog-to-digital converter (ADC) electrically connected to the peak hold circuit, for converting the analog voltage into a digital signal for output.

[0021] Optionally, the peak hold circuit includes: a bandpass filter, the bandpass filter is used to receive the voltage signal of the transimpedance amplifier, and the filtered signal after filtering by the bandpass filter is transmitted to the analog-to-digital converter (ADC).

[0022] Optionally, the peak hold circuit further includes: a peak detection circuit electrically connected to the bandpass filter, and an output end of the peak detection circuit is also connected to the analog-to-digital converter (ADC).

[0023] Optionally, the adjustable gain amplifier adopts a digitally controlled variable gain amplifier, whose gain adjustment range includes a dynamic range of at least 60 dB, covering the installation distance requirement of 0.5 m to 20 m.

[0024] Optionally, a status indication module is further included, which is electrically connected or communicatively connected to the control module.

[0025] The status indication module is configured with: a dual-color LED indicator light and a digital display screen, wherein the green light of the dual-color LED indicator light indicates a normal working range, and the red light indicates a state close to saturation or runt;

[0026] The digital display screen is used to display the current gain multiple and signal strength percentage in real time.

[0027] Optionally, when the amplitude detected by the signal detection module exceeds a preset upper limit threshold, the control module controls to reduce the gain of the adjustable gain amplifier; when the signal amplitude is lower than a preset lower limit threshold, the control module controls to increase the gain of the adjustable gain amplifier.

[0028] Optionally, when the signal detected for N consecutive cycles is oversaturated, the control module controls the automatic insertion of an attenuation network; under the control of the control module, when the gain adjustment of the adjustable gain amplifier reaches the limit value and still cannot meet the requirements, the system alarm output is triggered.

[0029] Optionally, it further includes: a fixed gain low noise amplifier and a power driver amplifier,

[0030] The fixed gain low noise amplifier is arranged between the adjustable gain amplifier and the signal receiving module.

[0031] The power driving amplifier is connected between the signal receiving module and the signal detecting module, and the signal amplified by the power driving amplifier is controlled by the control module.

[0032] Optionally, the control module implements closed-loop control based on a PID algorithm.

[0033] Compared with the existing technology, this application has the following technical effects:

[0034] This application uses a closed-loop feedback control mechanism to adjust the amplification gain of the received signal in real time, overcoming the technical problems of traditional safety light curtains such as poor adaptability to working distance and sensitivity to environmental interference, and achieving stable operation of the safety light curtain over a wide range of distances;

[0035] This application can achieve adaptive adjustment of the installation distance from 0.5m to 20m, greatly expanding the application scenarios; reducing the complexity of installation and debugging, and adapting to environmental changes without manual calibration; reducing the signal blind area from the ±15% distance range of the traditional solution to within ±5%; through this application, the ability to resist environmental interference can be enhanced, the system stability and reliability can be improved, and the automatic diagnosis function can provide early warning of system performance degradation, reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0037] Figure 1 : A structural block diagram of the adaptive signal adjustment system for a safety light curtain according to an embodiment of the present application;

[0038] Figure 2 : Circuit schematic diagram of a signal strength detection module in one embodiment of the present application;

[0039] Figure 3 : Signal flow diagram of the PID control algorithm in one embodiment of the present application;

[0040] Figure 4: Gain automatic adjustment curve diagram under different installation distances in one embodiment of the present application;

[0041] Figure 5 : State transition diagram of the abnormal protection mechanism in one embodiment of the present application. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] like Figure 1 As shown, in one embodiment of the present application, a safety light curtain adaptive signal conditioning system includes:

[0044] A signal transmitting module, which is used to generate a periodically modulated optical signal;

[0045] a signal receiving module, configured to receive the periodically modulated optical signal generated by the signal transmitting module;

[0046] an adjustable gain amplifier connected to the signal receiving module;

[0047] A signal strength detection module, which is used to collect the amplitude characteristics of the output signal of the signal receiving module in real time;

[0048] and a control module, which automatically calculates and outputs a gain adjustment instruction based on the signal strength data output by the signal detection module through a closed-loop feedback mechanism, so as to dynamically adjust the gain coefficient of the adjustable gain amplifier.

[0049] Among them, preferably, in this embodiment, the adjustable gain amplifier is connected to the signal receiving module through a DAC (D / A converter) output; similarly, the control module is connected to the signal detection module through a DAC output.

[0050] In this embodiment, the closed-loop feedback control mechanism is used to adjust the amplification gain of the received signal in real time, which can effectively overcome the technical problems of poor adaptability of the traditional safety light curtain working distance and sensitivity to environmental interference, and realize stable operation of the safety light curtain over a wide distance range.

[0051] Furthermore, in this embodiment, the signal transmission module uses a 38kHz modulated carrier to transmit periodic optical signals through an infrared light emitting diode array. This frequency selection can effectively suppress ambient light interference while ensuring sufficient signal penetration.

[0052] The signal receiving module includes a corresponding photodiode array, which is used to receive the transmitted modulated light signal and convert it into an electrical signal. The output signal strength of the signal receiving module is inversely proportional to the distance between the transmitter and the receiver.

[0053] like Figure 1 As shown, in one embodiment, a status indication module is further included, which is electrically connected or communicatively connected to the control module.

[0054] The status indication module is configured with: a dual-color LED indicator light and a digital display screen, wherein the green light of the dual-color LED indicator light indicates a normal working range, and the red light indicates a state close to saturation or runt;

[0055] The digital display screen is used to display the current gain multiple and signal strength percentage in real time.

[0056] Specifically, the status indication module displays the working status of the indicator light system through the dual-color LED:

[0057] Green light: normal operation (signal strength 30%-90%);

[0058] Red light: Warning state (signal strength <10% or >95%).

[0059] Furthermore, in this embodiment, Figure 2 As shown, the signal strength detection module includes:

[0060] A photodiode array for converting light signals into current signals;

[0061] a transimpedance amplifier (TIA), configured to convert the weak current signal output by the photodiode array into a voltage signal;

[0062] a peak hold circuit, electrically connected to the transimpedance amplifier and used to extract the signal envelope amplitude;

[0063] and an analog-to-digital converter (ADC) electrically connected to the peak hold circuit, for converting the analog voltage into a digital signal for output.

[0064] The peak hold circuit includes: a bandpass filter (BPF), which can filter out interference signals other than the 38kHz carrier. The bandpass filter is used to receive the voltage signal of the transimpedance amplifier. The filtered signal after filtering by the bandpass filter is transmitted to the analog-to-digital converter (ADC). The sampling rate of the analog-to-digital converter (ADC) is preferably 100Hz.

[0065] Further preferably, in this embodiment, the control module implements closed-loop control based on the PID algorithm. Figure 3 As shown,

[0066] 1) Set the target signal amplitude to 70% of the full scale;

[0067] 2) Calculate the error e(n) between the current detection amplitude and the target value;

[0068] 3) Calculate the gain adjustment according to the PID algorithm: ΔG = Kp·e(n) + Ki·∑e(j) + Kd·[e(n)-e(n-1)];

[0069] 4) Update the gain setting of the adjustable gain amplifier: G(n) = G(n-1) + ΔG, that is, G(n) = G(n-1) + Kp·e(n) + Ki·∑e(j) + Kd·[e(n)-e(n-1)]; where e(n) is the deviation between the current sample value and the target value, and Kp, Ki, and Kd are configurable parameters;

[0070] 5) It has been verified that in one embodiment, when Kp=0.5, Ki=0.05, and Kd=0.2, the system responds quickly and has good stability.

[0071] In one embodiment, see below Figure 5 When the amplitude detected by the signal detection module exceeds a preset upper threshold (such as 90% of full scale), the control module controls the reduction of the gain of the adjustable gain amplifier; when the signal amplitude is lower than a preset lower threshold (such as 30% of full scale), the control module controls the increase of the gain of the adjustable gain amplifier, thereby achieving adaptive adjustment of the installation distance.

[0072] In one embodiment, the adjustable gain amplifier is a digitally controlled variable gain amplifier, and its gain adjustment range includes a dynamic range of at least 60 dB, covering the installation distance requirement of 0.5 m to 20 m.

[0073] More preferably, a three-stage amplification architecture is adopted: wherein,

[0074] Specifically, this embodiment also includes: a fixed gain low noise amplifier and a power driver amplifier,

[0075] The fixed gain low noise amplifier is arranged between the adjustable gain amplifier and the signal receiving module.

[0076] The power driving amplifier is connected between the signal receiving module and the signal detecting module, and the signal amplified by the power driving amplifier is controlled by the control module.

[0077] That is, in this embodiment, a three-stage amplification architecture is formed by a pre-fixed gain low noise amplifier (LNA) with a gain of 20dB, a variable gain amplifier (VGA) with a gain range of 0-60dB, preferably adjustable in 1dB steps, and a power driver amplifier with a fixed gain of 10dB, thereby forming a composite amplification channel to ensure that the system can obtain ideal signal gain within the installation distance range of 0.5m to 20m.

[0078] Furthermore, this embodiment also includes a distance calibration mode: automatically performing gain-distance characteristic curve calibration during the equipment installation phase; storing the optimal gain parameter combination in a non-volatile memory; calling the stored parameters as an adjustment reference during the operation phase. Through the setting of the above-mentioned distance calibration mode, the accuracy can be further adjusted.

[0079] Specifically, if Figure 4 As shown, the distance calibration mode described above is automatically executed after the system is installed: the system scans the entire gain range of 0-60dB in preset steps; records the signal strength at each gain setting; generates a gain-distance characteristic curve and stores it in EEPROM; and selects the optimal initial gain during operation based on this curve.

[0080] Further, see Figure 5 As shown, this embodiment is also equipped with an abnormal protection mechanism. When the signal detected for N consecutive cycles is oversaturated, the control module controls the automatic insertion of an attenuation network, where N is preferably 3. Under the control of the control module, when the gain adjustment of the adjustable gain amplifier reaches the limit value and still cannot meet the requirements, such as the gain reaches the maximum value and the signal is still less than 10% of the full scale, and the signal for three consecutive cycles is greater than 95% of the full scale, the system alarm output is triggered. At this time.

[0081] Specifically, when signal oversaturation (>95% full scale) is detected for three consecutive cycles, a 6dB attenuation network is automatically inserted; when the gain adjustment reaches the maximum value (60dB) and still cannot make the signal reach the minimum detection threshold (10% full scale), the system alarm is triggered, and the red light in the corresponding two-color LED indicator lights up, indicating a warning status.

[0082] In one of the embodiments, after experimental verification, the present application has the following technical effects compared with the traditional fixed-gain system: the effective working distance is extended from the original 0.5m~5m to 0.1m-20m; the signal blind area is reduced from ±15% to within ±5%; the environmental adaptability is improved, and it can still maintain stable operation under conditions of ±50% light changes; the system startup time is shortened by 80%, from 5 seconds to less than 1 second, which is a significant improvement compared to the technology.

[0083] This application uses a closed-loop feedback control mechanism to adjust the amplification gain of the received signal in real time, overcoming the technical issues of traditional safety light curtains, such as poor operating distance adaptability and sensitivity to environmental interference, and enabling stable operation of the safety light curtain over a wide range of distances. Compared to existing technologies, this application has promising market application prospects.

[0084] In the description of this application, unless otherwise expressly specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0085] In this application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0086] In the description of this embodiment, the terms "upper," "lower," "left," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0087] The above embodiments are intended only to illustrate the technical solutions of the present application and are not intended to limit the present application. The present application is described in detail with reference to the preferred embodiments. It should be understood by those skilled in the art that the technical solutions of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application and should be included within the scope of the claims of the present application.

Claims

1. A safety light curtain adaptive signal conditioning system, characterized in that: include: A signal transmitting module, which is used to generate a periodically modulated optical signal; a signal receiving module, configured to receive the periodically modulated optical signal generated by the signal transmitting module; an adjustable gain amplifier connected to the signal receiving module; A signal strength detection module, which is used to collect the amplitude characteristics of the output signal of the signal receiving module in real time; and a control module, which automatically calculates and outputs a gain adjustment instruction based on the signal strength data output by the signal detection module through a closed-loop feedback mechanism, so as to dynamically adjust the gain coefficient of the adjustable gain amplifier.

2. The safety light curtain adaptive signal conditioning system according to claim 1, characterized in that: The signal strength detection module includes: A photodiode array for converting light signals into current signals; a transimpedance amplifier, configured to convert the current signal output by the photodiode array into a voltage signal; a peak hold circuit, electrically connected to the transimpedance amplifier and used to extract the signal envelope amplitude; and an analog-to-digital converter (ADC) electrically connected to the peak hold circuit, for converting the analog voltage into a digital signal for output.

3. The safety light curtain adaptive signal conditioning system according to claim 2, characterized in that: The peak hold circuit includes a bandpass filter, which is used to receive the voltage signal of the transimpedance amplifier, and transmits the filtered signal after filtering by the bandpass filter to the analog-to-digital converter (ADC).

4. The safety light curtain adaptive signal conditioning system according to claim 3, characterized in that: The peak hold circuit further includes: a peak detection circuit electrically connected to the bandpass filter, and an output end of the peak detection circuit is also connected to the analog-to-digital converter (ADC).

5. The safety light curtain adaptive signal conditioning system according to claim 1, characterized in that: The adjustable gain amplifier adopts a digitally controlled variable gain amplifier, and its gain adjustment range includes a dynamic range of at least 60dB, covering the installation distance requirement of 0.5m to 20m.

6. The safety light curtain adaptive signal conditioning system according to claim 1, characterized in that: It also includes a status indication module, which is electrically connected or communicatively connected to the control module. The status indication module is configured with: a dual-color LED indicator light and a digital display screen, wherein the green light of the dual-color LED indicator light indicates a normal working range, and the red light indicates a state close to saturation or runt; The digital display screen is used to display the current gain multiple and signal strength percentage in real time.

7. The safety light curtain adaptive signal conditioning system according to any one of claims 1 to 6, characterized in that: When the amplitude detected by the signal detection module exceeds a preset upper threshold, the control module controls to reduce the gain of the adjustable gain amplifier; when the signal amplitude is lower than a preset lower threshold, the control module controls to increase the gain of the adjustable gain amplifier.

8. The safety light curtain adaptive signal conditioning system according to claim 7, characterized in that: When the signal detected for N consecutive cycles is oversaturated, the control module controls the automatic insertion of an attenuation network; under the control of the control module, when the gain adjustment of the adjustable gain amplifier reaches the limit value and still cannot meet the requirements, the system alarm output is triggered.

9. The safety light curtain adaptive signal conditioning system according to any one of claims 1 to 6, characterized in that: Also includes: Fixed gain low noise amplifier and power driver amplifier, The fixed gain low noise amplifier is arranged between the adjustable gain amplifier and the signal receiving module. The power driving amplifier is connected between the signal receiving module and the signal detecting module, and the signal amplified by the power driving amplifier is controlled by the control module.

10. The safety light curtain adaptive signal conditioning system according to any one of claims 1 to 6, characterized in that: The control module implements closed-loop control based on the PID algorithm.

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