Laser displacement sensor and displacement detection method thereof

Abstract

The application discloses a kind of laser displacement sensor and its displacement detection method, including multi-wavelength light source module, transmitting lens, receiving lens, linear array receiving tube and central processing circuit, it is also provided with adjusting mechanism;Reflecting mirror is provided in receiving optical path;And, the central processing circuit is configured as: can according to the surface reflection characteristic of measured object, from the multi-wavelength light source module, intelligently select one optimal wavelength laser to work, to calculate displacement value, displacement detection method correspondingly includes: the steps of intelligently selecting optimal working wavelength, controlling the wavelength laser emission, receiving signal by the folding optical path containing reflecting mirror, and calculating displacement value by the feature recognition algorithm processing signal.In retaining high precision, while reducing product volume, simplify the debugging process, solve the adaptability problem to different material surfaces, so that the sensor has more extensive scene applicability.

Description

Technical Field

[0001] The present invention relates to the field of precision measurement technology, and in particular to a laser displacement sensor and a displacement detection method thereof. Background Art

[0002] Displacement measurement is a key technology in industrial automation, precision manufacturing, and quality control. Among the many displacement measurement methods, laser displacement sensors are widely used due to their unique advantages, such as non-contact, fast response, high accuracy, and wide measuring range.

[0003] Currently, the most widely used laser displacement sensors on the market are based on the principle of laser triangulation (also known as triangulation ranging). The basic principle is that a laser emits a beam of laser light onto the surface of the object being measured. The reflected light is focused by a receiving lens and forms an image on a photosensitive device (such as a linear array receiver). When the object being measured moves, the position of the reflected light spot on the photosensitive device changes accordingly. By calculating this change in position, the object's displacement can be calculated.

[0004] However, as industrial applications place increasingly stringent demands on sensor performance, existing laser displacement sensors based on traditional triangulation principles still face the following problems in design and use:

[0005] The optical path structure of traditional sensors is usually fixed or linked after assembly, and the processing accuracy of optical parts and mechanical structures is extremely high. Minor processing or assembly errors may cause the output optical axis to deviate or focus incorrectly, and it is difficult to effectively compensate for it later. This makes the debugging and calibration processes in the production process very complicated and time-consuming, and the consistency and stability between products are difficult to guarantee. In the triangulation model, in order to obtain a larger measurement range and higher resolution, it is often necessary to ensure a longer optical baseline (that is, the distance or angle between the transmitting optical axis and the receiving optical axis), which can easily lead to an increase in the physical size of the sensor, especially its axial (depth) direction. This runs counter to the development trend of modern industrial equipment in pursuit of miniaturization and compactness. In many installation scenarios with limited space, existing large-size, high-performance sensors are difficult to apply;

[0006] In addition, traditional sensors generally use the "center of gravity method" algorithm to calculate the geometric center of the light energy distribution to calculate the center of the light spot. Although this algorithm is simple, it is very sensitive to the shape and quality of the light spot. When the surface material of the measured object is uneven, tilted, or there is mirror reflection, the shape of the light spot will become irregular or asymmetric (such as generating smear and halo); at the same time, ambient light noise and circuit noise will also interfere with the signal. In these cases, the center position calculated by the "center of gravity method" will produce a large deviation, which will seriously affect the final accuracy and reliability of the measurement. Therefore, a laser displacement sensor and its displacement detection method are urgently needed. Summary of the Invention

[0007] The purpose of the present invention is to solve the technical problems of existing laser displacement sensors, such as poor adaptability when facing surfaces of different materials, low measurement accuracy, and difficulty in balancing compact size and convenient debugging, and to propose a laser displacement sensor and its displacement detection method.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A digital intelligent laser displacement sensor is used to measure the displacement between the sensor and the object being measured. The sensor includes a laser transmitting tube, a transmitting lens, a receiving lens, a linear array receiving tube and a central processing circuit. The sensor is characterized in that it also includes:

[0010] An adjustment mechanism is configured to independently adjust the focus of the emission lens and the emission direction of the laser emission tube to optimize the quality of the light spot projected on the object to be measured;

[0011] a reflector, arranged on the receiving light path between the receiving lens and the linear array receiving tube, for changing the propagation direction of the received light beam and reducing the axial size of the sensor;

[0012] Furthermore, the central processing circuit is configured to process the light spot signal received by the linear array receiving tube and formed by reflection of the measured object based on a preset light spot signal feature recognition algorithm to calculate the displacement value.

[0013] Furthermore, the adjustment mechanism includes a printed circuit board for supporting the laser emitting tube and a fastening screw for fixing the printed circuit board, wherein the fastening screw is configured to allow the printed circuit board to be slightly adjusted in a plane perpendicular to the emission optical axis when loosened to achieve adjustment of the emission direction.

[0014] Furthermore, the light spot signal feature recognition algorithm is configured to determine the center position of the light spot signal by analyzing the waveform profile features of the light spot signal, so as to improve the measurement accuracy compared to the centroid method algorithm that only calculates the geometric center.

[0015] Furthermore, the sensor further includes an emission drive circuit and a power protection circuit. The emission drive circuit includes a photodiode for monitoring the intensity of light emitted by the laser emission tube. The central processing circuit controls the emission drive circuit based on a monitoring signal from the photodiode to stabilize the intensity of the emitted light for measurement.

[0016] The power protection circuit is configured to provide at least one of power reverse connection protection, output overcurrent protection, electrostatic protection, and surge protection.

[0017] Furthermore, the sensor also includes a multi-wavelength light source module comprising at least two laser emitting tubes of different wavelengths, and the central processing circuit is further configured to intelligently select a laser emitting tube with an optimal wavelength from the multi-wavelength light source module for operation based on the surface reflection characteristics of the object being measured.

[0018] Furthermore, the central processing circuit is configured to intelligently select the optimal wavelength by quickly probing and analyzing the signal-to-noise ratio of the reflected light spots of lasers of different wavelengths before performing the measurement.

[0019] A laser displacement detection method, applied to the above-mentioned laser displacement sensor, comprises the following steps:

[0020] S1: Control the laser emitting tube to emit a laser beam to the object to be measured;

[0021] S2: receiving the light spot signal formed by reflection of the measured object on the linear array receiving tube through the receiving light path, wherein the receiving light path changes the propagation direction through the reflector;

[0022] S3: processing the light spot signal based on the preset light spot signal feature recognition algorithm to calculate the displacement value of the measured object;

[0023] S4: converting the calculated displacement value into a standard voltage or current analog signal through an analog output circuit for output, or directly outputting a digital signal through a digital output circuit.

[0024] Furthermore, in step S3, the step of processing the spot signal based on the preset spot signal feature recognition algorithm is specifically: determining the center position of the spot signal by analyzing the waveform profile characteristics of the spot signal to improve the measurement accuracy compared to the centroid method algorithm that only calculates the geometric center.

[0025] Furthermore, the method includes the following quality control steps:

[0026] Calibration is performed before measurement is performed, and this step includes adjusting the focus of the emission lens and the emission direction of the laser emission tube; and

[0027] In the step of emitting the laser beam, the emission light intensity of the laser emitting tube is monitored in real time through the feedback receiving tube, and the emission driving current is feedback controlled according to the monitoring signal to stabilize the emission light intensity for measurement.

[0028] Furthermore, the method further includes steps before controlling the laser emitting tube to emit the laser beam, and the specific process is as follows:

[0029] Based on the surface reflection characteristics of the object being measured, a laser emitting tube with the optimal wavelength is intelligently selected from a multi-wavelength light source module containing at least two laser emitting tubes with different wavelengths;

[0030] Furthermore, the subsequent emission step is to control the laser emitting tube of the selected optimal wavelength to emit.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] By providing an adjustment mechanism, independent adjustment of the two degrees of freedom (DOF) of focus and direction in the transmitting optical path is achieved, allowing precise compensation for processing and assembly errors after assembly, thereby simplifying the production calibration process, shortening debugging time, and significantly improving product consistency and yield. A reflector is introduced into the receiving optical path. By folding the optical path, the axial size of the sensor can be effectively reduced without sacrificing optical performance, resolving the conflict between measurement performance and product volume in the prior art. This enables the sensor of the present invention to achieve high-performance measurement in a more compact body, making it easy to integrate into compact or complex automation equipment.

[0033] In addition, by analyzing the waveform profile characteristics of the light spot signal and using a dynamic adaptive weight model for calculation, the error caused by changes in the light spot morphology caused by factors such as the measured surface and ambient light can be effectively suppressed to improve the accuracy and stability of the measurement. Especially when dealing with complex working conditions, it can show stronger robustness, thereby ensuring high precision and high reliability while ensuring the compact structure of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0035] Figure 1 is an overall circuit block diagram of a laser displacement sensor in an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the optical path principle of the laser displacement sensor in an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of the structure of the emission light path mounting bracket in an embodiment of the present invention;

[0038] Figure 4 is a circuit diagram of a transmitting circuit unit in an embodiment of the present invention;

[0039] Figure 5 is a circuit diagram of an analog output circuit in an embodiment of the present invention;

[0040] Figure 6 is a circuit diagram of a digital output circuit in an embodiment of the present invention;

[0041] Figure 7 Schematic diagram of the flow of the displacement detection method in an embodiment of the present invention;

[0042] Figure 8 is a schematic diagram of a dual-wavelength light source module in an embodiment of the present invention;

[0043] Figure 9 Schematic diagram of the overall structure of the laser displacement sensor of the present invention;

[0044] Figure 10 Schematic diagram of the internal structure of the laser displacement sensor of the present invention;

[0045] Figure 11 This is a structural diagram of the emission light path mounting bracket using a multi-wavelength light source module in an embodiment of the present invention. Description of the drawings:

[0047] 10. Adjustment mechanism; 11. Printed circuit board; 12. Fastening screws; 13. Mounting bracket; 20. Reflector; 30. Multi-wavelength light source module; 31. First laser emitting tube; 32. Second laser emitting tube; 40. Laser emitting tube; 50. Transmitting lens; 60. Linear array receiving tube; 70. Receiving lens; 80. Lens barrel. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0050] An embodiment of the present invention provides a laser displacement sensor and a displacement detection method thereof, wherein the sensor is used to measure the displacement between the sensor and an object to be measured.

[0051] like Figures 1 to 3 and Figures 9 to 11As shown, a laser displacement sensor includes a laser emitting tube 40, an emitting lens 50 for focusing the light beam emitted by the laser emitting tube 40, a receiving lens 70 for converging the reflected light beam, a linear array receiving tube 60 for receiving the light spot signal, and a central processing circuit as the control core. Through the coordinated design of structure, optical path and algorithm, the contradiction between accuracy, volume and ease of use in the existing technology is jointly solved.

[0052] The laser displacement sensor has two hardware structures. One is an adjustment mechanism 10, which is used to independently adjust two key parameters of the emission light path, thereby adjusting both the focus of the emission lens 50 and the emission direction of the laser emission tube 40. Through the decoupled adjustment method, the quality of the light spot projected on the object under test can be conveniently and accurately optimized during on-site calibration or assembly, serving as the physical basis for achieving high-precision measurement.

[0053] The second is the reflector 20, which is arranged on the receiving light path between the receiving lens 70 and the linear array receiving tube 60. It is used to change the propagation direction of the received light beam by folding the light path, thereby greatly reducing the axial size of the sensor while ensuring sufficient optical image distance, thereby making the device more compact and small.

[0054] In addition, a preset light spot signal feature recognition algorithm is running inside the central processing circuit. When the sensor is working, the central processing circuit executes the displacement detection method of the present invention, which specifically includes the following steps:

[0055] First, the laser emitting tube 40 is controlled to emit a laser beam to the object to be measured via the emission optical path;

[0056] Then, the light spot signal formed by the reflection of the measured object is received on the linear array receiving tube 60 through the receiving optical path including the reflector 20;

[0057] Finally, the light spot signal feature recognition algorithm is called to perform in-depth processing and analysis on the received light spot signal to accurately calculate the displacement value of the measured object.

[0058] Example 2

[0059] like Figure 2 and Figure 3 As shown, based on the first embodiment, the basic optical path layout of the laser displacement sensor is as follows:

[0060] The emission optical axis formed by the light beam emitted by the laser emitting tube 40 and the receiving optical axis of the reflected light beam received by the linear array receiving tube 60 are located in the same plane and form an optimized preset angle between them. However, in order to overcome the accuracy degradation caused by part processing and assembly errors and ensure the optimization of the light spot quality at different distances, the sensor is also provided with an adjustment mechanism 10. The adjustment mechanism 10 is used to achieve independent adjustment of focus and direction. The specific process is as follows:

[0061] First, for focus adjustment, the emitting lens 50 is installed in a threaded lens barrel 80. By rotating the lens barrel 80 or adjusting the screw, the axial distance between the emitting lens 50 and the rear emitting laser tube can be changed, thereby changing the focus of the laser beam to ensure the formation of the clearest and most energy-concentrated light spot at the target working distance;

[0062] Secondly, for the adjustment of the emission direction, the emitting laser tube is fixed on a small printed circuit board, and the printed circuit board is then mounted on the mounting bracket 13 by fastening screws 12. During the initial assembly and calibration, it is only necessary to slightly loosen the fastening screws 12 to perform a slight translation up and down and left and right fine-tuning on the printed circuit board carrying the laser tube on the plane perpendicular to the emission optical axis, thereby effectively compensating for the initial optical axis deviation caused by processing or assembly, ensuring that the laser beam accurately points to the calibration center. After the adjustment is completed, tighten the fastening screws 12 to lock it firmly. In addition, the focus adjustment by rotating the lens and the direction adjustment by translating the substrate are mechanically completely decoupled and do not interfere with each other, thereby simplifying the debugging process and improving the efficiency and accuracy of calibration.

[0063] Corresponding to the above-mentioned mechanical structure, the displacement detection method of the present invention also includes a factory calibration step before performing batch measurement. In this step, the operator uses the adjustment mechanism 10 to independently adjust the focus of the emitting lens 50 and independently adjust the emission direction of the laser emitting tube 40 until the quality of the light spot projected on the standard block, such as clarity, roundness, and energy concentration, reaches the optimal state.

[0064] In a preferred embodiment, when the regulated laser beam is irradiated on the object to be measured and reflected back to the sensor, a light spot carrying precise position information is formed on the linear array receiving tube 60. The specific process of signal processing and calculation is as follows:

[0065] During the signal reception and digitization process, the linear array receiving tube 60 converts the light intensity distribution it senses into a series of original analog electrical signals. Figure 1 As shown, the analog signal is first sent to the receiving circuit. In the embodiment of the present invention, the receiving circuit can be more specifically referred to as Figure 5The receiving amplification circuit part includes a signal processing unit and an analog-to-digital sampling unit. The amplification and filtering circuit in the signal processing unit will perform preliminary amplification on the original analog signal to enhance its signal-to-noise ratio and filter out electromagnetic noise interference in the environment. Subsequently, the purified and enhanced analog signal is sent to the AD sampling unit. The AD sampling unit samples the analog signal waveform at an extremely high frequency and converts it into a series of discrete digital signal sequences that can be recognized by the central processing circuit, thereby converting the physical optical signal into a digital signal.

[0066] Then, if Figure 7 As shown, the central processing circuit starts to execute the light spot signal feature recognition algorithm.

[0067] Before executing the light spot signal feature recognition algorithm, the mathematical model underlying the algorithm is first established: Based on the principle of triangulation, there exists a definite nonlinear functional relationship D = f(x) between the displacement ΔD of the measured object and the position x of the imaging point of the light spot on the linear array receiving tube 60 (whose effective length is X). This functional relationship f(x) is accurately measured through initial geometric calibration (for example, multi-point calibration using higher-precision equipment such as a laser tracker) and is preset in the memory of the central processing circuit in the form of a look-up table or polynomial fitting formula. Therefore, the measurement process requires calculating the position x of the center point of the light spot.

[0068] The specific process of the light spot signal feature recognition algorithm may include the following steps:

[0069] S1: Receives the digital signal sequence converted by the AD sampling unit and performs preprocessing;

[0070] S2: Set the dynamic threshold to accurately identify the effective area of ​​the spot signal from the signal sequence and eliminate the interference of background light noise and stray reflections;

[0071] S3: Perform in-depth analysis on the digital waveform of the effective spot area to extract multiple waveform profile features, including:

[0072] Peak position : The maximum point of the waveform intensity.

[0073] Edge Center : By taking the first-order differential derivative of the signal sequence, find the two points (the left edge and the right edge) with the largest absolute value of the slope and calculate the midpoint position.

[0074] Symmetry Factor :By comparing the areas on the left and right sides of the peak point of the spot waveform and To calculate, .

[0075] S4: The algorithm performs weighted calculations on the multiple features extracted in S3 based on a preset weight model to obtain the precise coordinate x that most accurately reflects the energy center of the light spot, including: using a dynamic adaptive weight model based on waveform symmetry to calculate the final center coordinate x. The model is simplified to:

[0076] x = * + *

[0077] Among them, the weight coefficient and is the symmetry factor When When the value is small (waveform symmetry is good), Get a larger value, the calculation depends more on the stable peak; when When the value is large (waveform is asymmetric), With larger values, the calculation relies more on steep edges which are less affected by smear.

[0078] S5: Substitute the calculated precise coordinate x into the preset function relationship D=f(x), and finally solve the precise displacement value D of the measured object, which is output as a standard industrial signal (such as 4-20mA current or RS-485 communication) through the digital or analog output circuit or displayed in real time on the display circuit.

[0079] Through the above steps, especially by analyzing the "shape" of the light spot rather than simply the "mass" distribution, the present invention can significantly improve the measurement accuracy and repeatability under different material surfaces and different ambient lighting conditions. In addition, in the data output stage, the central processing circuit outputs a voltage signal from the calculated digitized displacement value through a digital-to-analog converter (DAC). ,like Figure 5 As shown, the signal is then fed into the analog output circuit to generate a standard industrial analog signal. The analog output circuit includes an analog switch S1, which selects the input voltage according to the instruction of the central processing circuit. Sent to the current output path or voltage output path;

[0080] When current output is selected: It is sent to the constant current source drive circuit composed of operational amplifier U1B, transistor Q3 and resistor R8. The output current is proportional to Vin. The relationship can be determined by the formula

[0081]

[0082] The above is only an example and needs to be further determined based on actual circuit analysis to achieve standard current output such as 4-20mA.

[0083] When voltage output is selected: It is sent to the voltage follower and amplifier circuit composed of operational amplifier U1D and transistor Q5, and finally outputs a voltage The output is protected against short circuit and overcurrent by diode D3 and fuse F1.

[0084] In addition to analog output, in this embodiment, digital switch signal output can also be provided. The output circuit is as follows: Figure 6 The digital output mode switching circuit is a push-pull output stage that can be flexibly configured as the common PNP or NPN output mode in industry, where the central processing circuit outputs two complementary control signals. and .

[0085] When configured as PNP output: Control signal The upper PNP transistors Q3 and Q2 are driven to operate. When the sensor reaches the trigger condition, Q2 turns on, and the output terminal OUT is connected to the power supply (high level), providing a sourcing input signal to an external device such as a PLC.

[0086] When configured as an NPN output: The control signal OUT_NPN drives the NPN transistor Q4 in the lower half. When the sensor reaches the trigger condition, Q4 turns on, and the output terminal OUT is connected to ground (low level), providing a sinking input signal to the external device.

[0087] Diodes D2 and D3 provide protection for the output stage, allowing the sensor to seamlessly adapt to PLCs or data acquisition systems with different input types, thereby enhancing versatility.

[0088] like Figure 5 The current and voltage output circuit shown converts the digital value into a standard analog voltage signal (such as 0-10V) or current signal (such as 4-20mA) commonly used in industrial fields through a digital-to-analog converter (DAC). This output facilitates connection to traditional data acquisition cards or PLCs. The displacement value can also be directly output via a digital output circuit (such as an RS-485 or IO-Link communication interface), enabling high-speed, lossless data exchange with modern intelligent control systems. Furthermore, the value is sent to a display circuit for real-time display on the sensor's built-in screen.

[0089] In a preferred embodiment, the transmit drive circuit is integrated with an optical power closed-loop feedback control system, specifically:

[0090] like Figures 1-4 As shown. Inside the package of the laser emitting diode 40, a feedback receiving transistor (PD) is integrated for monitoring its light intensity. When the sensor is operating, a small portion of the light emitted by the LD is received by the PD, which generates a feedback current proportional to the light intensity. This feedback signal is processed by an amplification and comparison circuit consisting of components such as operational amplifiers (U1A and U1B) and then compared with a reference signal set by the central processing circuit (for example, controlled by the LD_CTRL signal). The comparison result dynamically adjusts the conduction level of the drive transistor Q1, thereby changing the current flowing through the laser emitting diode 40 (LD), thus forming a negative feedback closed loop: when the LD optical power increases for some reason, the PD signal becomes stronger, causing the drive current to decrease, thereby bringing the optical power back to the set value; and vice versa. Accordingly, the detection method of the present invention includes real-time monitoring and feedback control of the emitted light intensity through this closed-loop system during the laser beam emission process to ensure a constant light source. In addition, the circuit is also designed with a soft start function controlled by the LD_ON signal and a current limiting protection composed of resistor R5, etc., to ensure the safety of the laser when it is turned on and off and in abnormal conditions.

[0091] In a preferred embodiment, if Figure 1-8 As shown, the power supply protection circuit is also included. The power supply protection circuit is configured to provide multiple protections to ensure the long-term stability and safe operation of the sensor, including:

[0092] Power reverse polarity protection: A protection diode or dedicated MOSFET circuit is set at the power input end. Even if the user accidentally connects the positive and negative poles in reverse, it will not cause permanent damage to the internal circuit.

[0093] Overcurrent and overvoltage protection: The built-in detection circuit monitors the input voltage and operating current in real time. Once the safety threshold is exceeded, the protection mechanism is triggered (such as blowing a fuse or shutting down the circuit) to prevent surges or short circuits from impacting the sensor.

[0094] Electrostatic protection: All external interfaces are equipped with electrostatic protection devices such as TVS diodes, which can effectively absorb and release static electricity generated by the human body or equipment during operation, protecting sensitive chips such as the core central processing circuit.

[0095] In another preferred embodiment of the present invention: Figure 8 As shown, based on the above solution, a multi-wavelength light source module 30 and a corresponding light source intelligent selection module are further adopted.

[0096] In this embodiment, the laser emitting tube 40 of the laser displacement sensor is replaced by a multi-wavelength light source module 30. In a preferred embodiment, the multi-wavelength light source module 30 integrates a first laser emitting tube 31 and a second laser emitting tube 32 in parallel. The first laser emitting tube 31 is a conventional 650nm red laser tube, while the second laser emitting tube 32 is a 450nm blue laser tube with better penetration into highly reflective surfaces. Corresponding to this hardware, a light source intelligent selection module is added to the central processing circuit to automatically select the optimal light source before the sensor performs precise measurement. The specific method includes the following steps:

[0097] When the user triggers a measurement or the device is initialized, the central processing circuit will first enter a short (usually in milliseconds) "condition detection mode";

[0098] The first laser emitting tube 31 and the second laser emitting tube 32 are quickly lit in sequence, and the light spot signals reflected from each are collected for trial irradiation;

[0099] Subsequently, the signal-to-noise ratio and saturation of the two signals are quickly calculated, and the central processing circuit makes a judgment based on the preset decision logic. The specific example is as follows:

[0100] When facing a highly reflective metal surface, the red laser may cause some pixels of the receiving tube to be saturated due to excessive mirror reflection, resulting in a high calculated saturation and a low signal-to-noise ratio. However, the blue laser has a shorter wavelength, so the light spot it forms is more delicate, the saturation is moderate, and the signal-to-noise ratio is higher. At this time, the central processing circuit will determine that the blue laser is the optimal wavelength for this measurement.

[0101] Conversely, if faced with a dark, light-absorbing material, the system may choose a red laser with a better signal-to-noise ratio.

[0102] Finally, after making the decision, the laser displacement sensor will lock and use the selected optimal wavelength laser tube for subsequent, high-precision displacement measurement.

[0103] In order to better understand the technical solution of the present invention, it is further explained below in conjunction with comparative experiments.

[0104] Embodiment: A laser displacement sensor adopting the complete technical solution mentioned in the embodiment of the present invention.

[0105] Comparative example: Use any well-known brand laser displacement sensor on the market that uses the traditional triangulation distance measurement principle and center of gravity method algorithm.

[0106] Experimental methods:

[0107] On an optical platform, a high-precision standard gauge block was used as the measured object, placed at 100.000 mm, 150.000 mm, and 200.000 mm from the sensor. At each distance point, 20 independent measurements were performed using the sensors of the embodiment and comparative example, and the average, absolute error, and standard deviation of the measurement results were recorded and calculated.

[0108] The experimental results and data are shown in Table 1.

[0109] Table 1

[0110] Standard distance (mm) Sensor Type Average measurement value (mm) Absolute error (mm) Standard deviation (mm) 100 Example 100.008 0.008 0.005 100 Comparative Example 100.042 0.042 0.02 150 Example 150.006 0.006 0.006 150 Comparative Example 150.05 0.05 0.023 200 Example 199.991 -0.009 0.007 200 Comparative Example 199.931 -0.069 0.031

[0111] It can be clearly seen from the data in the above table that at all test distance points, the technical solution of the present invention outperforms the solution using the comparative example in terms of two key performance indicators, absolute error and standard deviation, indicating that the accuracy and stability of the measurement have been greatly improved. The present invention can achieve unexpected and significant technological progress through the coordinated optimization of the mechanical adjustment structure, optical path design, and dynamic adaptive recognition algorithm, effectively solving the technical problems of insufficient accuracy and reliability in the existing technology.

[0112] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A laser displacement sensor for measuring displacement between a measured object, the sensor comprising a laser emitting tube (40), an emitting lens (50), a receiving lens (70), a linear array receiving tube (60) and a central processing circuit, characterized in that: The sensor further comprises: An adjustment mechanism (10) is configured to independently adjust the focus of the emission lens (50) and the emission direction of the laser emission tube (40) to optimize the quality of the light spot projected on the object to be measured; A reflector (20) is provided on the receiving light path between the receiving lens (70) and the linear array receiving tube (60), and is used to change the propagation direction of the received light beam and reduce the axial size of the sensor; Furthermore, the central processing circuit is configured to: process the light spot signal received by the linear array receiving tube (60) and formed by reflection of the measured object based on a preset light spot signal feature recognition algorithm to calculate a displacement value; The specific process of the light spot signal feature recognition algorithm includes the following steps: S1: Receives the digital signal sequence converted by the AD sampling unit and performs preprocessing; S2: Set the dynamic threshold to accurately identify the effective area of ​​the spot signal from the signal sequence and eliminate the interference of background light noise and stray reflections; S3: Perform in-depth analysis on the digital waveform of the effective spot area to extract multiple waveform profile features, including: Peak position : The maximum point of the waveform intensity; Edge Center : By taking the first-order differential derivative of the signal sequence, find the two points with the largest absolute value of the slope and calculate the position of their midpoints; Symmetry factor :By comparing the area to the left of the peak point of the spot waveform and the area on the right To calculate, ; S4: The algorithm performs weighted calculations on the multiple features extracted in S3 according to a preset weight model to obtain the precise coordinate x that can most realistically reflect the energy center of the light spot. This includes: using a dynamic adaptive weight model based on waveform symmetry to calculate the final center coordinate x. The model is simplified to: x = * + * Among them, the weight coefficient and is the symmetry factor function, when When the value is small, Get a larger value, the calculation depends more on the stable peak; when When the value is large, For larger values, the calculation relies more on steep edges that are less affected by smear; S5: Substitute the calculated precise coordinate x into the preset function relationship D=f(x), and finally solve the precise displacement value D of the measured object, which is output as a standard industrial signal through the digital or analog output circuit or displayed in real time on the display circuit.

2. The laser displacement sensor according to claim 1, characterized in that: The adjustment mechanism (10) includes a printed circuit board (11) for supporting the laser emitting tube (40) and a fastening screw (12) for fixing the printed circuit board (11), wherein the fastening screw (12) is configured to allow the printed circuit board (11) to be slightly adjusted on a plane perpendicular to the emission optical axis when loosened, so as to achieve adjustment of the emission direction.

3. The laser displacement sensor according to claim 1, wherein: The light spot signal feature recognition algorithm is configured to determine the center position of the light spot signal by analyzing the waveform profile features of the light spot signal, so as to improve the measurement accuracy compared to the centroid method algorithm that only calculates the geometric center.

4. The laser displacement sensor according to claim 1, wherein: The sensor further comprises an emission drive circuit and a power protection circuit, wherein the emission drive circuit comprises a photodiode for monitoring the intensity of light emitted by the laser emission tube (40), and the central processing circuit controls the emission drive circuit based on a monitoring signal of the photodiode to stabilize the intensity of the emitted light for measurement; The power protection circuit is configured to provide at least one of power reverse connection protection, output overcurrent protection, electrostatic protection, and surge protection.

5. The laser displacement sensor according to claim 1, wherein: The sensor further includes a multi-wavelength light source module (30), wherein the multi-wavelength light source module (30) includes a first laser emitting tube (31) and a second laser emitting tube (32), and the central processing circuit is further configured to intelligently select a laser emitting tube (40) with an optimal wavelength from the multi-wavelength light source module (30) for operation based on the surface reflection characteristics of the object to be measured.

6. The laser displacement sensor according to claim 5, characterized in that: The central processing circuit is configured to intelligently select the optimal wavelength by quickly probing and analyzing the signal-to-noise ratio of the reflected light spots of lasers with different wavelengths before performing measurement.

7. A laser displacement detection method, applied to the laser displacement sensor according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: controlling the laser emitting tube (40) to emit a laser beam to the object to be measured; S2: receiving the light spot signal formed by reflection from the object to be measured on the linear array receiving tube (60) through the receiving light path, wherein the receiving light path changes the propagation direction via the reflector (20); S3: processing the light spot signal based on the preset light spot signal feature recognition algorithm to calculate the displacement value of the measured object; S4: converting the calculated displacement value into a standard voltage or current analog signal through an analog output circuit for output, or directly outputting a digital signal through a digital output circuit.

8. The method according to claim 7, wherein: In step S3, the step of processing the spot signal based on the preset spot signal feature recognition algorithm is specifically: determining the center position of the spot signal by analyzing the waveform profile characteristics of the spot signal to improve the measurement accuracy compared with the centroid method algorithm that only calculates the geometric center.

9. The laser displacement detection method according to claim 7, wherein: The method includes the following quality control steps: Before performing the measurement and calibration, in this step, the focus of the emission lens (50) and the emission direction of the laser emission tube (40) are independently adjusted using the adjustment mechanism (10); And in the step of emitting a laser beam, the emission light intensity of the laser emitting tube (40) is monitored in real time by a photodiode, and the emission drive current is feedback-controlled according to the monitoring signal to stabilize the emission light intensity for measurement.

10. The laser displacement detection method according to claim 7, wherein: The method further includes steps before controlling the laser emitting tube (40) to emit a laser beam, and the specific process is as follows: Based on the surface reflection characteristics of the object to be measured, intelligently selecting a laser emitting tube (40) with an optimal wavelength from a multi-wavelength light source module (30) including at least two laser emitting tubes (40) with different wavelengths; Furthermore, the subsequent emission step is to control the laser emission tube (40) of the selected optimal wavelength to emit.

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