Position change detection device based on laser triangulation method

Abstract

The utility model provides a position change detection device based on laser triangulation, which comprises a shell, and a transmitting module, a receiving module and a control module which are arranged in the shell, the transmitting module comprises a laser, a collimating lens and a cylindrical mirror which are sequentially and linearly arranged at a transmitting end, the receiving module is positioned at a receiving end, and the control module is positioned at the receiving end. Comprising a first band-pass filter, an imaging objective lens, a reflector, a second band-pass filter and a detector, the control module is connected with the transmitting module and the receiving module, and the control module comprises a feedback regulation circuit and is used for feeding back and controlling the exposure time of the laser. The measurement precision is higher, the stability is higher, and the adaptability is also higher.

Description

Technical Field

[0001] The utility model relates to the field of displacement sensors, and particularly to a position change detection device based on the laser triangulation method. Background Art

[0002] The laser triangulation method is a measurement method for determining the absolute distance of a point on the surface of an object relative to a reference plane. It belongs to the point measurement method and is similar to a mechanical probe. The measured distance corresponds to a one-dimensional measurement value, and it is a non-contact optical measurement method. The laser triangulation displacement sensor is a position change detection sensor based on the laser triangulation method. The relevant foreign technologies are relatively more mature than domestic technologies. There are still some defects in the measurement speed, accuracy, and measurement stability of the domestically independently developed laser triangulation displacement sensors. For example, they are extremely sensitive to the interference of external stray light, have poor adaptability to the surfaces of different measured objects, and especially in some application scenarios such as high temperature, they have a greater impact on the measurement accuracy and stability. Summary of the Utility Model

[0003] In view of the above, the utility model provides a position change detection device based on the laser triangulation method, which has higher measurement accuracy, higher stability, and higher adaptability.

[0004] The utility model specifically adopts the following technical solutions: A position change detection device based on the laser triangulation method includes a housing and an emission module, a reception module, and a control module arranged therein. The emission module includes a laser, a collimating lens, and a cylindrical lens arranged in a straight line sequence at the emission end. The reception module includes a first band-pass filter, an imaging objective lens, a reflector, a second band-pass filter, and a detector arranged at the reception end. The control module is connected to the emission module and the reception module, and the control module includes a feedback adjustment circuit for feedback controlling the exposure time of the laser.

[0005] Further, the first band-pass filter is located at the front end of the reception end, and the second band-pass filter is located between the linear array detector and the reflector.

[0006] Further, the control module further includes a temperature monitoring and compensation circuit for monitoring the temperature of the laser and compensating the measurement data.

[0007] Further, the control module further includes a PWM control circuit for adjusting the laser output power.

[0008] Further, the detector is a linear array detector.

[0009] Further, the laser is arranged in the housing through a rotating base.

[0010] The position change detection device based on the laser triangulation method of the present utility model, through optimization, further overcomes the influence of mechanical errors on the measurement accuracy. A rotating base is set to adjust the laser, so that when the laser light is reflected back to the linear array detector, the long axis direction of the elliptical light spot is perpendicular to the photosensitive direction of the linear array detector, and the linear array detector receives the short axis light intensity signal of the elliptical light spot, thereby reducing the installation error. Two band-pass filters are set at the receiving end to perform primary filtering when the reflected light just enters the receiving module, and perform secondary filtering again before the detector receives the image. The secondary filtering can effectively filter out the interference of stray light and specific wavelength light in the environment, significantly improve the purity of the signal, and improve the accuracy of the measurement system. Moreover, a feedback adjustment circuit and a PWM control circuit are set in the control system. For different measured objects and different color characteristics, a stable light spot output image can be obtained through adaptive exposure adjustment and PWM laser output power control adjustment to ensure the stability of the measurement system and improve the adaptability. In addition, a temperature monitoring and compensation circuit is also set in the control system to monitor the temperature change of the system in real time. When the temperature changes, the measurement error corresponding to the temperature is automatically compensated into the measurement data to ensure the accuracy and stability of the measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. is a schematic structural diagram of the position change detection device based on the laser triangulation method of the present utility model.

[0012] Figure 2 FIG. is a schematic diagram of overexposed, normal, and underexposed waveforms.

[0013] Figure 3 FIG. is a schematic diagram of the exposure adjustment process. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The present utility model will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present utility model, rather than limiting the present utility model. In addition, it should be noted that for the sake of description, only parts related to the present utility model are shown in the drawings, rather than all the structures.

[0015] Refer to Figure 1, A position change detection device based on the laser triangulation method in this embodiment includes a housing 1 and a transmitting module 2, a receiving module 3, and a control module 4 arranged therein. The transmitting module 2 includes a laser 21, a collimating lens 22, and a cylindrical lens 23 arranged in a straight line in sequence at the transmitting end. The laser light source is shaped into a parallel beam by the collimating lens 22, and the parallel beam is secondarily shaped by the cylindrical lens 23 into a parallel elliptical beam. The laser 21 is arranged in the housing through a rotating base 211, and the rotating base 211 can be manually screwed to adjust the angle of the laser 21 so that when the laser light is reflected back to the linear array detector after passing through the position of the object to be measured, the long axis direction of the elliptical light spot is perpendicular to the photosensitive direction of the linear array detector, and the linear array detector receives the short-axis light intensity signal of the elliptical light spot, reducing the installation error.

[0016] The receiving module 3 is located at the receiving end and includes a first band-pass filter 31, an imaging objective lens 32, a plane mirror 33, a second band-pass filter 34, and a detector 35. The first band-pass filter 31 is located at the front end of the receiving end, that is, when the reflected light enters the receiving module 3, it first passes through the first band-pass filter 31. The second filter 34 is located between the detector 35 and the plane mirror 33. The two band-pass filters use a central wavelength of 655 nm and a half-peak width of 20 nm. By filtering through the two band-pass filters, and filtering once when the reflected light just enters the receiving module and filtering again before the detector receives the image, it can effectively filter out the stray light in the environment and the interference of light with a specific wavelength, further improving the purity of the signal and the accuracy of the measurement system.

[0017] The plane mirror 33 deflects the optical path, which can reduce the external dimension of the entire device, effectively save space, contribute to the product miniaturization and intensive design, make the overall design of the product more compact, and increase the adaptability of product installation. The detector 35 is a linear array detector.

[0018] The control module 4 is connected to the transmitting module 2 and the receiving module 3 to control the coordinated operation of the system such as the emission of laser, the reception and processing of signals. The control module 4 includes basic functional circuits, such as an input / output unit, a serial interface circuit, an analog-to-digital conversion circuit, and a signal processing circuit. The signal processing circuit performs processing such as denoising, filtering, and analysis and calculation on the image. The control module 4 also includes a feedback adjustment circuit, a temperature monitoring and compensation circuit, and a PWM control circuit (Pulse-Width Modulation).

[0019] The feedback adjustment circuit is used to feedback control the exposure time of the laser 21. In cases where the scattering characteristics of the surface of the object to be measured are different, such as objects to be measured with different materials or different colors, the scattered light intensity is different, and the waveform signal received by the imaging on the detector may be insufficient or overexposed, such as Figure 2Waveform signal display includes three cases: overexposure a, just right b, and underexposure c. If no adjustment is made, it will lead to a decrease in measurement accuracy. The feedback adjustment circuit of the control system can automatically control the exposure time. For example Figure 3 During the process, the light brightness received by the detector reaches the optimal state. Under the same lighting conditions, the detection characteristics are: U1 / U2 = T1 / T2; where T1 and T2 are the exposure times, and U1 and U2 are the signal input amplitudes corresponding to T1 and T2 respectively. Therefore, within the linear range of the detector, when the lighting conditions remain unchanged, given the current frame's exposure time T1, the corresponding output signal amplitude U1, and the desired output signal amplitude U2, the exposure time T2 that should be provided to obtain the amplitude U2 can be calculated. When the exposure time T2 that should be provided exceeds the parameter range set in the feedback adjustment circuit, the PWM control circuit (Pulse-Width Modulation) is activated. After adjusting the laser output power, the exposure time is further adjusted to avoid overexposure or underexposure of the detector element, thereby improving the adaptability and stability of the device.

[0020] The temperature monitoring and compensation circuit monitors the ambient temperature and the temperature of the laser in real time. Since the temperature of the laser will increase during long-term operation, to avoid the influence of temperature changes on the measurement structure, the temperature monitoring and compensation circuit monitors the temperature change of the system in real time. When the temperature changes, the measurement error corresponding to that temperature is automatically compensated into the measurement data to ensure the accuracy and stability of the measurement system. The temperature change and the corresponding compensation parameters are preset in the temperature monitoring and compensation circuit.

[0021] The device of this application is a high-speed and high-precision laser triangulation displacement sensor, with a detection frequency up to 200KHz, a measurement range of ±30mm, a measurement repeatability accuracy of 5um, and a stable offset characteristic of 0.05%FS / ℃.

[0022] In addition, the above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention. The understanding of this specification should be based on those skilled in the art of the relevant technical field. Although this specification has described the present invention in detail with reference to the above embodiments, those skilled in the art should understand that those skilled in the relevant technical field can still modify the present invention or make equivalent substitutions. All technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A position change detection device based on laser triangulation, characterized in that: The invention comprises a shell and a transmitting module, a receiving module and a control module arranged therein, wherein the transmitting module comprises a laser, a collimating lens and a cylindrical mirror arranged in sequence at the transmitting end, the receiving module comprises a first band-pass filter, an imaging objective lens, a reflecting mirror, a second band-pass filter and a detector arranged at the receiving end, the control module connects the transmitting module and the receiving module, and the control module comprises a feedback regulating circuit for feedback controlling the exposure time of the laser.

2. The position change detection device based on laser triangulation as claimed in claim 1, characterized in that: The second bandpass filter is located between the detector and the reflector.

3. The position change detection device based on laser triangulation as claimed in claim 1, characterized in that: The control module also includes a temperature monitoring and compensation circuit for monitoring the temperature of the laser to compensate for the measurement data.

4. The position change detection device based on laser triangulation as claimed in claim 1, characterized in that: The control module also includes a PWM control circuit for adjusting the laser output power.

5. The position change detection device based on laser triangulation as claimed in claim 1, characterized in that: The detector is a linear array detector.

6. The position change detection device based on laser triangulation as claimed in claim 1, characterized in that: The laser is arranged in the housing via a rotating seat.

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