Transverse displacement detection sensor system based on two-dimensional PSD

Abstract

According to the transverse displacement detection sensor system based on the two-dimensional PSD, the signal conditioning module is arranged to sequentially carry out current-voltage conversion, adjustable gain amplification, bias voltage superposition and high-frequency filtering processing on weak current signals output by the two-dimensional PSD optical receiving module, and noise interference in the signal transmission process is effectively restrained; a stable voltage signal adaptive to the acquisition range of the data processing module is output, so that the displacement detection precision is improved; meanwhile, through cooperation of the data processing module and the laser switch control module, intelligent control over the on-off state of the laser emission module is achieved, the laser is prevented from being continuously turned on, and the service life of the system is prolonged.

Description

Technical Field

[0001] This invention relates to the field of lateral displacement detection technology, and in particular to a lateral displacement detection sensor system based on a two-dimensional PSD. Background Technology

[0002] Lateral displacement detection technology is widely used in fields such as large-scale structural health monitoring, industrial automation, and precision positioning. Position-sensitive detectors (PSDs) have become an important technical means for lateral displacement detection due to their advantages such as high resolution, fast response, and non-contact measurement.

[0003] However, existing PSD-based lateral displacement detection systems face a core problem in practical applications: how to achieve high-precision, high-stability, and long-term reliable detection under long-distance measurement conditions.

[0004] Specifically, as the measurement distance increases, laser spot divergence leads to uneven energy distribution. The weak current signal output by the PSD device is highly susceptible to environmental electromagnetic interference. After signal conditioning and data processing, the final displacement measurement results exhibit decreased accuracy and poor stability. Furthermore, the continuous operation of the laser in existing systems not only causes light pollution to the measurement environment but also significantly shortens the laser's lifespan, making it difficult to meet the practical needs of long-term continuous operation in engineering monitoring.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] This invention discloses a lateral displacement detection sensor system based on a two-dimensional PSD, which aims to solve the problems of weak current signals being easily interfered with, low processing accuracy, and shortened lifespan caused by continuous laser illumination in existing PSD lateral displacement detection systems.

[0007] This invention provides a lateral displacement detection sensor system based on a two-dimensional PSD, including a laser emitting module, a two-dimensional PSD optical receiving module, a signal conditioning module, a data processing module, a laser switch control module, and a communication module; The output end of the laser emitting module is positioned facing the two-dimensional PSD optical receiving module; The signal output terminal of the two-dimensional PSD optical receiving module is connected to the input terminal of the signal conditioning module; The output terminal of the signal conditioning module is connected to the signal acquisition terminal of the data processing module; The data processing module is connected to the laser switch control module and the communication module, respectively. The laser switch control module is connected to the laser emission module; The signal conditioning module is used to sequentially perform current-to-voltage conversion, adjustable gain amplification, bias voltage superposition, and high-frequency filtering on the weak current signal output by the two-dimensional PSD optical receiving module, and output a voltage signal adapted to the acquisition range of the data processing module.

[0008] Preferably, the signal conditioning module includes an IV conversion unit, a signal amplification unit, and a filtering unit connected in sequence; The IV conversion unit uses a low-noise operational amplifier to convert the four current signals output by the two-dimensional PSD optical receiving module into four voltage signals. The signal amplification unit uses an adjustable gain amplifier to adjust the voltage signal to the range of 0-3.3V and superimpose a bias voltage to adapt to bipolar signal processing. The filtering unit includes filtering capacitors disposed at the input and output terminals of the operational amplifier.

[0009] Preferably, the laser switch control module is configured to keep the laser emitting module constantly lit for a first preset duration after the system is powered on, and thereafter only control the laser emitting module to turn on for a second preset duration when a displacement measurement command is received.

[0010] Preferably, the two-dimensional PSD optical receiving module includes a two-dimensional position-sensitive detector soldered onto a PCB board, which outputs four current signals after receiving the laser beam.

[0011] Preferably, the data processing module is configured with four 12-bit ADC channels for synchronously acquiring the voltage signal output by the signal conditioning module and calculating the two-dimensional center coordinates of the laser spot in real time according to the PSD characteristic formula.

[0012] Preferably, the method further includes: smoothing the two-dimensional center coordinates using a moving average algorithm or a Kalman filter algorithm.

[0013] Preferably, the real-time calculation of the two-dimensional center coordinates of the laser spot based on the PSD characteristic formula specifically involves the following calculation process:

[0014] Where (X, Y) represents the specific coordinates of the center of the light spot falling on the photosensitive surface, and L represents the side length of the photosensitive area of ​​the position-sensitive detector. , , , These represent the four signal amplification units converting the current signal of the PSD into a voltage signal.

[0015] Based on the lateral displacement detection sensor system based on a two-dimensional PSD provided by this invention, a signal conditioning module sequentially performs current-to-voltage conversion, adjustable gain amplification, bias voltage superposition, and high-frequency filtering on the weak current signal output by the two-dimensional PSD optical receiving module. This effectively suppresses noise interference during signal transmission and outputs a stable voltage signal adapted to the acquisition range of the data processing module, thereby improving displacement detection accuracy. Simultaneously, through the cooperation of the data processing module and the laser switch control module, intelligent control of the on / off state of the laser emitting module is achieved, preventing the laser from remaining continuously lit and extending the system's lifespan. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a lateral displacement detection sensor system based on a two-dimensional PSD provided by the present invention; Figure 2 This is a circuit diagram of the signal conditioning module provided by the present invention; Figure 3 This is a circuit diagram of the signal processing module provided by the present invention; Figure 4 This is a circuit diagram of the laser switch control module provided by the present invention; Figure 5 This is a circuit diagram of the communication module provided by the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0018] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] This invention discloses a lateral displacement detection sensor system based on a two-dimensional PSD, which aims to solve the problems of weak current signals being easily interfered with, low processing accuracy, and shortened lifespan caused by continuous laser illumination in existing PSD lateral displacement detection systems.

[0020] Please see Figure 1This invention provides a lateral displacement detection sensor system based on a two-dimensional PSD, including a laser emitting module 1, a two-dimensional PSD optical receiving module 2, a signal conditioning module 3, a data processing module 4, a laser switch control module 5, and a communication module 6. The output end of the laser emitting module 1 is positioned facing the two-dimensional PSD optical receiving module 2; the signal output end of the two-dimensional PSD optical receiving module 2 is connected to the input end of the signal conditioning module 3; the output end of the signal conditioning module 3 is connected to the signal acquisition end of the data processing module 4; the data processing module 4 is connected to the laser switch control module 5 and the communication module 6 respectively; the laser switch control module 5 is connected to the laser emitting module 1. The signal conditioning module 3 is used to sequentially perform current-to-voltage conversion, adjustable gain amplification, bias voltage superposition, and high-frequency filtering on the weak current signal output by the two-dimensional PSD optical receiving module 2, and output a voltage signal that is compatible with the acquisition range of the data processing module 4.

[0021] In one possible implementation of the present invention, the laser emitting module 1 employs a 650 nm semiconductor laser, optically designed in conjunction with a focusing lens group. The laser output power is stable, and the beam divergence angle is small, ensuring that the spot diameter is less than 3 mm within the measurement distance range, effectively suppressing energy attenuation and spot diffusion during long-distance transmission. The laser emitting module 1 is installed at the measurement reference point, with its output end facing the two-dimensional PSD optical receiving module 2, and the emitted laser beam directly irradiates the PSD photosensitive surface.

[0022] The two-dimensional PSD optical receiving module 2 adopts a two-dimensional position-sensitive detector with high sensitivity and low noise characteristics. The detector is directly soldered on the PCB board. After receiving the laser beam, it generates four weak current signals X1, X2, Y1, and Y2. These four signals are transmitted to the signal conditioning module 3 through shielded cables. The use of shielded cables can effectively reduce the influence of external electromagnetic interference on weak signals.

[0023] Please combine Figure 2The input of signal conditioning module 3 is connected to the signal output of two-dimensional PSD optical receiving module 2, and is used to process four weak current signals. Specifically, signal conditioning module 3 first converts the current signal into a voltage signal through IV conversion unit 31, which uses a low-noise operational amplifier to achieve high-precision current-to-voltage conversion; then, the voltage signal is processed by signal amplification unit 32, which uses an adjustable gain amplifier to adjust the signal amplitude to the range of 0 to 3.3 volts, while superimposing a bias voltage to meet the processing requirements of bipolar signals; finally, high-frequency noise is suppressed by filtering unit 33, which connects 100nF and 10μF ceramic capacitors in parallel at the input and output of the operational amplifier to achieve low-pass filtering function, and integrates Zener diodes and current-limiting resistors to prevent overvoltage or electrostatic discharge from damaging the subsequent circuits. After the above processing, signal conditioning module 3 outputs four stable voltage signals V1, V2, V3, and V4 to data processing module 4.

[0024] Please combine Figure 3 The data processing module 4 uses an STM32F103C8T6 microcontroller. Its signal acquisition terminal is connected to the output terminal of the signal conditioning module 3. It synchronously samples the conditioned voltage signal through four built-in 12-bit ADC channels to ensure signal digitization accuracy. The microcontroller calculates the center coordinates (X and Y) of the laser spot within the photosensitive area in real time according to the characteristic formula of the PSD device. Specifically, the calculation process for the two-dimensional center coordinates of the laser spot based on the PSD characteristic formula is as follows:

[0025] Where (X, Y) represents the specific coordinates of the center of the light spot falling on the photosensitive surface, and L represents the side length of the photosensitive area of ​​the position-sensitive detector. , , , These represent the four signal amplification units that convert the current signal of the PSD into a voltage signal. Furthermore, a moving average algorithm or a Kalman filter algorithm is used to smooth the coordinate data, eliminating transient interference and improving measurement stability.

[0026] Please combine Figure 4 The data processing module 4 is connected to the laser switch control module 5 via pin PA6. The laser switch control module 5 is connected to the power supply circuit of the laser emitting module 1 and is used to control the on / off state of the laser. After the system is powered on, the laser switch control module 5 keeps the laser emitting module 1 constantly lit for 5 minutes to facilitate on-site installation and calibration. Afterward, it only turns on the laser emitting module 1 for 3 seconds to perform the measurement when the data processing module 4 issues a displacement measurement command. It automatically turns off after the measurement is completed. This control method effectively reduces the impact of the laser on the measurement environment and significantly extends the lifespan of the laser.

[0027] Please combine Figure 5 The data processing module 4 is also connected to the communication module 6. The communication module 6 adopts an isolated RS485 interface design, including a digital isolator to achieve electrical isolation between the microcontroller and the RS485 chip, and a DC-DC isolated power supply to provide an independent 5V operating power supply for the RS485 side, which can effectively suppress ground loop interference and high voltage surges. The communication module 6 transmits data based on the Modbus RTU protocol, supports function code 03 to read registers and function code 06 to write single registers. The data frame includes displacement coordinates X and Y, status flags, and CRC16 checksum. 120-ohm terminating resistors are connected to both ends of the bus to match the impedance. Twisted pair shielded wiring is used to ensure the reliability and real-time performance of data transmission. The data sampling frequency can be set and modified according to actual needs.

[0028] During the implementation of this invention, the inventors discovered that when the two-dimensional PSD optical receiving module 2 receives a laser beam, in addition to the target laser spot, it is also affected by ambient stray light. Especially in outdoor strong light environments or industrial sites with multiple light sources, stray light forms background light noise on the PSD photosensitive surface. When superimposed on the target laser signal, this causes a DC offset in the four current signals, resulting in a systematic error in the calculated spot coordinates. Traditional hardware filtering methods are difficult to distinguish between the target laser and ambient stray light because their frequency characteristics are similar.

[0029] Based on this, in this embodiment, the data processing module 4 and the laser switch control module 5 work together to perform differential background elimination processing through the following steps: First, the data processing module 4 sends a shutdown command to the laser switch control module 5 to control the laser emitting module 1 to be in the off state. At this time, the data processing module 4 acquires the voltage signal output by the signal conditioning module 3 through the ADC to obtain the background reference values ​​V1b, V2b, V3b, and V4b containing only ambient stray light; then, the data processing module 4 sends an activation command to the laser switch control module 5 to control the laser emitting module 1 to be activated. At this point, data processing module 4 again acquires voltage signals via ADC, obtaining mixed signal values ​​V1m, V2m, V3m, and V4m that include the superposition of target laser light and ambient stray light. Next, data processing module 4 performs differential operations on the mixed signal values ​​and the background reference values ​​to obtain effective signal values ​​V1=V1m-V1b, V2=V2m-V2b, V3=V3m-V3b, and V4=V4m-V4b that only reflect the target laser spot. Finally, data processing module 4 calculates the two-dimensional center coordinates of the laser spot using the effective signal values ​​according to the PSD characteristic formula. Through this processing method combining laser switch timing control and differential operations, the interference of ambient stray light on displacement detection is effectively eliminated without adding additional optical filtering devices, improving the measurement accuracy and adaptability of the system in complex lighting environments.

[0030] Based on the lateral displacement detection sensor system based on a two-dimensional PSD provided by this invention, a signal conditioning module sequentially performs current-to-voltage conversion, adjustable gain amplification, bias voltage superposition, and high-frequency filtering on the weak current signal output by the two-dimensional PSD optical receiving module. This effectively suppresses noise interference during signal transmission and outputs a stable voltage signal adapted to the acquisition range of the data processing module, thereby improving displacement detection accuracy. Simultaneously, through the cooperation of the data processing module and the laser switch control module, intelligent control of the on / off state of the laser emitting module is achieved, preventing the laser from remaining continuously lit and extending the system's lifespan.

[0031] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A lateral displacement detection sensor system based on a two-dimensional PSD, characterized in that, It includes a laser emitting module, a two-dimensional PSD optical receiving module, a signal conditioning module, a data processing module, a laser switch control module, and a communication module; The output end of the laser emitting module is positioned facing the two-dimensional PSD optical receiving module; The signal output terminal of the two-dimensional PSD optical receiving module is connected to the input terminal of the signal conditioning module; The output terminal of the signal conditioning module is connected to the signal acquisition terminal of the data processing module; The data processing module is connected to the laser switch control module and the communication module, respectively. The laser switch control module is connected to the laser emission module; The signal conditioning module is used to sequentially perform current-to-voltage conversion, adjustable gain amplification, bias voltage superposition, and high-frequency filtering on the weak current signal output by the two-dimensional PSD optical receiving module, and output a voltage signal adapted to the acquisition range of the data processing module.

2. The lateral displacement detection sensor system based on a two-dimensional PSD according to claim 1, characterized in that, The signal conditioning module includes an IV conversion unit, a signal amplification unit, and a filtering unit connected in sequence. The IV conversion unit uses a low-noise operational amplifier to convert the four current signals output by the two-dimensional PSD optical receiving module into four voltage signals. The signal amplification unit uses an adjustable gain amplifier to adjust the voltage signal to the range of 0-3.3V and superimpose a bias voltage to adapt to bipolar signal processing. The filtering unit includes filtering capacitors disposed at the input and output terminals of the operational amplifier.

3. The lateral displacement detection sensor system based on a two-dimensional PSD according to claim 1, characterized in that, The laser switch control module is configured to keep the laser emitting module constantly lit for a first preset duration after the system is powered on, and thereafter only control the laser emitting module to turn on for a second preset duration when a displacement measurement command is received.

4. The lateral displacement detection sensor system based on a two-dimensional PSD according to claim 1, characterized in that, The two-dimensional PSD optical receiving module includes a two-dimensional position-sensitive detector soldered onto a PCB board. After receiving the laser beam, the two-dimensional position-sensitive detector outputs four current signals.

5. The lateral displacement detection sensor system based on a two-dimensional PSD according to claim 1, characterized in that, The data processing module is equipped with four 12-bit ADC channels, which are used to synchronously acquire the voltage signal output by the signal conditioning module and calculate the two-dimensional center coordinates of the laser spot in real time according to the PSD characteristic formula.

6. The lateral displacement detection sensor system based on a two-dimensional PSD according to claim 5, characterized in that, Also includes: The two-dimensional center coordinates are smoothed using a moving average algorithm or a Kalman filter algorithm.

7. A lateral displacement detection sensor system based on a two-dimensional PSD according to claim 5, characterized in that, The process of calculating the two-dimensional center coordinates of the laser spot in real time according to the PSD characteristic formula is as follows: Where (X, Y) represents the specific coordinates of the center of the light spot falling on the photosensitive surface, and L represents the side length of the photosensitive area of ​​the position-sensitive detector. , , , These represent the four signal amplification units converting the current signal of the PSD into a voltage signal.

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