CN111006595A - High-precision laser displacement sensor system based on CMOS - Google Patents
High-precision laser displacement sensor system based on CMOS Download PDFInfo
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- CN111006595A CN111006595A CN201911345610.4A CN201911345610A CN111006595A CN 111006595 A CN111006595 A CN 111006595A CN 201911345610 A CN201911345610 A CN 201911345610A CN 111006595 A CN111006595 A CN 111006595A
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- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
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Abstract
The utility model provides a high accuracy laser displacement sensor system based on CMOS, belongs to accurate automatic measure technical field, its characterized in that: the digital signal processing module, the semiconductor laser diode module and the image sensing module are electrically connected with the power supply module; the digital signal processing module is respectively and electrically connected with the semiconductor laser diode module and the image sensing module; the semiconductor laser diode module is electrically connected with the direct projection type triangulation module; the direct projection type triangulation module is electrically connected with the image sensing module; the image sensing module is electrically connected with the digital signal processing module through the differential subtraction circuit; the image sensing module adopts a CMOS image sensor. The CMOS image sensor is used as a photoelectric device by improving the existing displacement sensor, so that the measurement precision and stability are improved, and a peripheral circuit is simplified; the digital signal processing module adopts a DSP chip as a main control chip, simplifies the mechanical and circuit structure, reduces the system volume and reduces the cost.
Description
Technical Field
The invention belongs to the technical field of precise automatic measurement, and particularly relates to a high-precision laser displacement sensor system based on a CMOS (complementary metal oxide semiconductor).
Background
The laser displacement sensor realizes non-contact on-line measurement of displacement by virtue of excellent measurement performance, and dynamically monitors micro deformation of an important component during bearing. In recent years, especially with the continuous development of modern photoelectric technology, laser displacement sensors are becoming the mainstream of non-contact detection products, and non-contact measurement methods are widely used in foreign countries for high-precision detection.
The photoelectric device used by the existing laser displacement sensor mainly comprises a position sensitive detector PSD and a charge coupled device CCD. The method adopts a direct-injection or oblique-injection triangulation method meeting the Scheimpflug condition as a measurement basis, realizes the sequential control of the optoelectronic device, the control of a semiconductor laser circuit and the acquisition of digital signals through an FPGA, realizes the AD conversion of analog output signals of the optoelectronic device through an A/D conversion circuit, and realizes the processing and the output of the digital signals through the interaction of a DSP and the FPGA. The sensor adopts PSD or CCD as a sensor photoelectric device, so that the measurement precision is not high, the peripheral circuit and the time sequence control are complex, and simultaneously, the mechanical structure and the circuit of the laser displacement sensor are more complex, the volume is increased and the manufacturing cost is high because the DSP + FPGA double chips are used for completing the functions of time sequence control, AD conversion, digital signal acquisition and processing.
Disclosure of Invention
The present invention is directed to solve the above problems, and provides a high-precision laser displacement sensor system based on CMOS, so as to simplify peripheral circuits and improve measurement precision.
The high-precision laser displacement sensor system based on the CMOS comprises a power supply module, a semiconductor laser diode module, a digital signal processing module, an image sensing module, a direct projection type triangulation module and a differential subtraction circuit, wherein the digital signal processing module, the semiconductor laser diode module and the image sensing module are electrically connected with the power supply module; the digital signal processing module is respectively and electrically connected with the semiconductor laser diode module and the image sensing module; the semiconductor laser diode module is electrically connected with the direct projection type triangulation module; the direct projection type triangulation module is electrically connected with the image sensing module; the image sensing module is electrically connected with the digital signal processing module through a differential subtraction circuit; the image sensing module adopts a CMOS image sensor.
According to the high-precision laser displacement sensor system based on the CMOS, the digital signal processing module comprises an electrifying control sub-module, a time sequence control sub-module, an AD acquisition sub-module and an operation output sub-module; the power-up control sub-module is electrically connected with the semiconductor laser diode module; the time sequence control submodule is electrically connected with the image sensing module; the differential subtraction circuit is electrically connected with the operation output submodule through the AD acquisition submodule. The power-up control sub-module is used for providing power-up control for the semiconductor laser diode module; the time sequence control sub-module is used for providing time sequence control for the image sensing module; the AD acquisition sub-module is used for carrying out AD acquisition on the analog output signal of the image sensing module; the operation output sub-module is used for performing operation processing on the digital signals acquired by the AD acquisition sub-module and outputting the processing result in a digital mode.
According to the high-precision laser displacement sensor system based on the CMOS, the DSP chip is adopted as the digital signal processing module.
According to the high-precision laser displacement sensor system based on the CMOS, the semiconductor laser diode module comprises a constant current source circuit, a protection circuit and a slow start circuit which are sequentially and electrically connected. The constant current source circuit is used for providing 20mA constant current power supply for the semiconductor laser diode module; the slow starting circuit is used for providing a delay starting time for the semiconductor laser diode module and preventing the current spike surge from damaging the laser diode; the protection circuit prevents the semiconductor laser diode module from breakdown due to excessive voltage.
The invention discloses a high-precision laser displacement sensor system based on CMOS, wherein a direct-injection type triangulation module comprises: the device comprises a semiconductor laser diode, a collimating lens, an optical filter and an imaging lens; the wavelength lambda of the semiconductor laser diode is 650nm, the exit pupil power is 0.8-1 mW, and the beam divergence angle is less than 0.3 mrad; the collimating lens adopts an aspheric plastic lens with a focal length of 7.8-8 mm; the central wavelength lambda of the optical filter is 650nm, the spectral width is 624.5 nm-697.5 nm, and the peak transmittance is more than or equal to 85%; the imaging lens is an aspheric lens with a focal length of 8-10 mm. And the positions of all devices in the direct-injection type triangulation module meet the Scheimpflug condition.
According to the high-precision laser displacement sensor system based on the CMOS, the image sensing module adopts a high-speed linear array CMOS image sensor, four pixel point modes of 128, 256, 512 and 1024 are arranged, and two output modes of a full photo frame and dynamic pixels are arranged.
According to the high-precision laser displacement sensor system based on the CMOS, the digital signal processing module is subjected to PGF thin square flat packaging and is used for respectively providing power-on control and time sequence control for the semiconductor laser diode module and the image sensing module, and meanwhile AD acquisition is carried out on analog output signals of the image sensing module, and operation processing and digital output of processing results are carried out.
According to the high-precision laser displacement sensor system based on the CMOS, the power supply module adopts a DCDC power supply chip and is used for completing system electrification, namely, power is provided for the work of the semiconductor laser diode module, the digital signal processing module and the image sensing module.
The high-precision laser displacement sensor system based on the CMOS comprises a power supply module, a semiconductor laser diode module, a digital signal processing module, an image sensing module, a direct projection type triangulation module and a differential subtraction circuit, and not only is the measurement precision and stability improved, but also a peripheral circuit is simplified by taking the CMOS image sensor as a photoelectric device through improving the conventional displacement sensor; the digital signal processing module adopts a DSP chip as a main control chip, simplifies the mechanical and circuit structure, reduces the system volume and reduces the cost.
Drawings
FIG. 1 is a schematic block diagram of a CMOS-based high-precision laser displacement sensor system according to the present invention;
FIG. 2 is a block diagram schematically illustrating the structure of the digital signal processing module according to the present invention;
FIG. 3 is a schematic diagram of a direct triangulation module according to an embodiment of the invention;
FIG. 4 is a circuit diagram of a semiconductor laser diode module according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a differential subtraction circuit according to an embodiment of the present invention;
wherein, the device comprises 1-collimating lens, 2-optical filter, 3-imaging lens, 4-CMOS image sensor and 5-measured object.
Detailed Description
The CMOS-based high-precision laser displacement sensor system according to the present invention will be described in detail with reference to the accompanying drawings and embodiments.
As shown in fig. 1, the CMOS-based high-precision laser displacement sensor system according to this embodiment includes a power module, a semiconductor laser diode module, a digital signal processing module, an image sensing module, a direct triangulation module, and a differential subtraction circuit. The power supply module adopts a DCDC power supply chip to supply power to the system, the power supply chip adopts a model of MP2565, the input voltage is 12-24V, the output voltage is 5V, and the maximum output current is 2.5A, and is used for completing system electrification, namely, the power supply is provided for the work of the semiconductor laser diode module, the digital signal processing module and the image sensing module; the semiconductor laser diode module is used for providing a laser source for the direct projection type triangulation module; a digital signal processing module, in this embodiment, a TMS320 series DSP chip is selected, and PGF thin square flat package is adopted, for providing power-on control and timing control for the semiconductor laser diode module and the image sensing module, respectively, and performing AD acquisition on analog output signals of the image sensing module, and performing operation processing and digital output of processing results; the image sensing module is used for finishing light spot sensing and analog signal output and receiving infrared laser of the semiconductor laser diode module passing through the direct projection type triangulation module, in the embodiment, the image sensing module adopts a high-speed linear array CMOS image sensor 4 with an ELIS-1024A series model, the CMOS image sensor 4 adopts DC5V for power supply, wherein, four pixel point modes of 128, 256, 512 and 1024 can be selected, and the CMOS image sensor 4 has two output modes of a full photo frame and dynamic pixels; the direct-injection triangulation module meets a laser triangulation structure of a direct-injection triangulation method under a cheimpflug condition, and provides an optical environment for the image sensing module; the differential subtraction circuit is used for controlling the 2-5V analog signal output by the image sensing module within the range of 0-3V and outputting the analog signal to the digital signal processing module.
As shown in fig. 2, the digital signal processing module includes a power-on control sub-module, a timing control sub-module, an AD acquisition sub-module, and an operation output sub-module. The power-up control sub-module realizes power-up control on the semiconductor laser diode module by outputting IO signals; the time sequence control sub-module provides a required time sequence for the image sensing module to enable the CMOS image sensor 4 to work normally; the AD acquisition submodule is electrically connected with the image sensing module and used for acquiring an analog signal within a range of 2-5V output by the image sensing module and controlling an analog output signal within a range of 0-3V through a differential subtraction circuit; the operation output sub-module is used for performing operation processing on the digital signals acquired by the AD acquisition sub-module and outputting the processing result in a digital mode.
The direct-projection triangulation module described in this embodiment includes a semiconductor laser diode, a collimating lens 1, an optical filter 2, and an imaging lens 3. The wavelength lambda of the semiconductor laser diode is 650nm, the exit pupil power is 0.8-1 mW, the working voltage is 2.8-3V, and the beam divergence angle is less than 0.3mrad, and the semiconductor laser diode is used for emitting infrared laser; the collimating lens 1 is an aspheric plastic lens with a focal length of 7.8-8 mm and is used for collimating laser emitted by the semiconductor laser diode; the optical filter 2 has a central wavelength λ of 650nm, a spectral width of 624.5nm to 697.5nm, and a peak transmittance of not less than 85%, and is used for filtering stray light reflected by laser irradiated on the object to be measured 5; the imaging lens 3 is an aspheric lens with a focal length of 8-10 mm and is used for irradiating the laser passing through the optical filter 2 on the CMOS image sensor 4 to form clear light spots.
As shown in fig. 3, the positions of the devices in the direct triangulation module satisfy the triangulation characteristic of the Scheimpflug condition, so that the image sensing module receives the correct light spots. The triangulation method satisfying the Scheimpflug condition is characterized in that the emission optical axis of the semiconductor laser diode, the extension axis of the imaging lens 3, and the extension axis of the CMOS image sensor 4 are converged to one point, while the collimator lens 1 and the filter 2 are perpendicular to the emission optical axis, and satisfies the following relation:
when the focal length of the imaging lens 3 is 10mm, a is 40mm, b is 13.33mm, α is 45 °, β is 71.56 °, when the measured object 5 moves along the emitting optical axis of the semiconductor laser diode, the moving distance of the optical spot on the CMOS image sensor 4 is x, and the actual displacement of the measured object 5 is calculated as y.
The semiconductor laser diode module according to the present embodiment includes a constant current source circuit, a slow start circuit, and a protection circuit as shown in fig. 4. Wherein: the constant current source circuit is used for providing a constant current source with the current of 20mA for the semiconductor laser diode module through the three-end voltage-stabilizing integrated block LM 317; the slow starting circuit is used for providing a delay starting time for the semiconductor laser diode module through the RC circuit so as to prevent the damage of current spike surge to the laser diode; the protection circuit consists of one voltage stabilizing diode and three forward diodes and provides protection for breakdown of the semiconductor laser diode module due to overlarge voltage.
In this embodiment, as shown in fig. 5, the differential subtraction circuit satisfies the following relation:
in the formula, R1, R2, R3 and Rf are parameter resistors, v1 is an analog output voltage value of the image sensing module, v0 is a reference voltage value, and v2 is an analog voltage value output to the AD acquisition sub-module. The analog voltage V2 transmitted to the AD acquisition submodule can be deduced to be in the range of 0-3V by taking V0 as 2V, R1 as R2 as R3 as Rf as 1k Ω, and the analog voltage V1 output by the image sensing module is in the range of 2-5V.
The working process of the high-precision laser displacement sensor system based on the CMOS is as follows: the power supply module supplies power to the semiconductor laser diode module, the digital signal processing module and the image sensing module. The power-on control sub-module provides power-on control for the semiconductor laser diode module, the semiconductor laser diode module provides a laser source for the direct-injection type triangulation module, the direct-injection type triangulation module provides an optical environment for the image sensing module, and the time sequence control sub-module provides time sequence control for the image sensing module. The semiconductor laser diode module irradiates an image sensing module through infrared laser of the direct-injection type triangulation module, and the image sensing module completes light spot sensing and converts an optical signal into a 2-5V analog electric signal to be output. Analog electric signals output by the image sensing module are controlled within the range of 0-3V through a differential subtraction circuit and output to an AD acquisition sub-module for AD acquisition, acquired digital signals are output to an operation output sub-module, and the operation output sub-module performs operation processing on the digital signals and outputs digitized actual displacement.
The foregoing description is only an example of the present invention, and it will be apparent to those skilled in the art that various modifications and variations in form and detail can be made without departing from the principle and structure of the invention, but these modifications and variations are within the scope of the invention as defined in the appended claims.
Claims (8)
1. The utility model provides a high accuracy laser displacement sensor system based on CMOS, includes power module, semiconductor laser diode module, digital signal processing module, image sensing module, direct projection formula triangulation module and differential subtraction circuit, its characterized in that: the digital signal processing module, the semiconductor laser diode module and the image sensing module are all electrically connected with the power supply module; the digital signal processing module is respectively and electrically connected with the semiconductor laser diode module and the image sensing module; the semiconductor laser diode module is electrically connected with the direct projection type triangulation module; the direct projection type triangulation module is electrically connected with the image sensing module; the image sensing module is electrically connected with the digital signal processing module through a differential subtraction circuit; the image sensing module adopts a CMOS image sensor.
2. The CMOS based high precision laser displacement sensor system of claim 1, wherein: the digital signal processing module comprises a power-on control submodule, a time sequence control submodule, an AD acquisition submodule and an operation output submodule; the power-up control sub-module is electrically connected with the semiconductor laser diode module; the time sequence control submodule is electrically connected with the image sensing module; the differential subtraction circuit is electrically connected with the operation output submodule through the AD acquisition submodule.
3. The CMOS based high precision laser displacement sensor system of claim 2, wherein: the digital signal processing module adopts a DSP chip.
4. The CMOS based high precision laser displacement sensor system of claim 3, wherein: the semiconductor laser diode module comprises a constant current source circuit, a protection circuit and a slow start circuit which are sequentially and electrically connected.
5. The CMOS based high precision laser displacement sensor system of claim 4, wherein: the direct projection triangulation module includes: the device comprises a semiconductor laser diode, a collimating lens, an optical filter and an imaging lens; the wavelength lambda of the semiconductor laser diode is 650nm, the exit pupil power is 0.8-1 mW, and the beam divergence angle is less than 0.3 mrad; the collimating lens adopts an aspheric plastic lens with a focal length of 7.8-8 mm; the central wavelength lambda of the optical filter is 650nm, the spectral width is 624.5 nm-697.5 nm, and the peak transmittance is more than or equal to 85%; the imaging lens is an aspheric lens with a focal length of 8-10 mm.
6. The CMOS based high precision laser displacement sensor system of claim 5, wherein: the image sensing module adopts a high-speed linear array CMOS image sensor, is provided with four pixel point modes of 128, 256, 512 and 1024, and is provided with two output modes of a full photo frame and dynamic pixels.
7. The CMOS based high precision laser displacement sensor system of claim 6, wherein: the digital signal processing module is packaged in a PGF thin square flat mode.
8. The CMOS based high precision laser displacement sensor system of claim 7, wherein: the power module adopts a DCDC power chip.
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| CN201911345610.4A CN111006595A (en) | 2019-12-24 | 2019-12-24 | High-precision laser displacement sensor system based on CMOS |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114383514A (en) * | 2021-12-30 | 2022-04-22 | 广州市合熠智能科技股份有限公司 | CMOS contact displacement sensor and measuring method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114383514A (en) * | 2021-12-30 | 2022-04-22 | 广州市合熠智能科技股份有限公司 | CMOS contact displacement sensor and measuring method |
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Application publication date: 20200414 |