A 3D scanning lidar based on a MEMS galvanometer

Abstract

The present invention discloses a three-dimensional scanning lidar based on a MEMS galvanometer, which includes a control module, multiple groups of transmitting modules, and multiple groups of receiving modules. The transmitting module is used for continuously scanning and transmitting in sub-regions in the pitch direction and the horizontal direction. The receiving module is used for receiving detection echoes in sub-regions in each direction. The control module is used to control the transmitting module to emit optical pulses with different encodings, control the receiving module to receive the optical pulses, decode the optical pulses, and finally form a point cloud pattern based on the acquired data. In the three-dimensional scanning lidar provided by the present invention, the transmitting module uses a combination of two galvanometers and optical elements for transmitting, and the receiving module uses a receiving lens, an array optical switch, and a surface detector for combined reception. The three-dimensional scanning lidar provided by the present invention has a compact structure, reduces the volume and weight, lowers the cost, and improves the heat dissipation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of laser detection, and particularly to a three-dimensional scanning lidar based on a MEMS galvanometer mirror. Background Art

[0002] Laser scanning ranging radars can be used to detect the position, contour, and speed of targets. The application fields of laser ranging radars have been gradually expanded, including precise measurement, navigation and positioning, safety obstacle avoidance, and it has started to be applied in unmanned driving technology. Currently, three-dimensional scanning lidars perform multi-layer scanning in the vertical direction, which can well reflect the characteristic information of the object to be measured and are applicable to multiple fields, such as navigation for unmanned driving and shape contour detection.

[0003] Most current three-dimensional scanning lidars adopt a multi-line scanning method, that is, multiple laser tubes are used to emit sequentially. The structure is that multiple laser tubes are arranged longitudinally, with a certain angle between each laser tube. The vertical emission field of view is 30° to 40°. The receiving module receives at the corresponding angles, and each receiving detector corresponds to one emission angle. The structure is that the receiving module and the transmitting module are symmetrically arranged on both sides, and a reflecting mirror is used inside for optical path turning, and then three-dimensional scanning ranging is achieved by rotating in the horizontal direction. The existing three-dimensional scanning lidars can quickly obtain scanning test information and collect more characteristic information to improve the dot matrix pixels. The multi-line lidars use multiple emitting diodes to emit sequentially in the vertical direction, and at the same time, the same number of receiving detectors are installed corresponding to multiple emitting diodes, resulting in an increase in volume in the vertical direction, an increase in power consumption and heat dissipation, and the need for wireless power supply and wireless transmission. Therefore, the cost remains high, restricting the development of multi-line lidars. Summary of the Invention

[0004] To solve the limitations and defects existing in the prior art, the present invention provides a three-dimensional scanning lidar based on a MEMS galvanometer mirror, including a control module, multiple groups of transmitting modules, and multiple groups of receiving modules; the transmitting module includes a first MEMS galvanometer mirror, a second MEMS galvanometer mirror, a focusing lens, a free-form surface mirror, a beam splitter, a CCD lens, a CCD detector, and an optical fiber receiving lens; the receiving module includes a receiving lens, an array optical switch, and a area array detector.

[0005] The free-form surface mirror is a concave mirror, and the concave mirror includes at least one of an ellipsoidal mirror, a spherical mirror, and a parabolic mirror; the array optical switch is a DMD micromirror array or a MEMS galvanometer mirror array.

[0006] The control module is used to control the transmitting module to emit optical pulses with different encodings.

[0007] The transmitting module is used to perform continuous scanning and emitting in sub-regions in the pitch direction and the horizontal direction.

[0008] The control module is used to control the receiving module to receive the optical pulse and decode the optical pulse.

[0009] The receiving module is used to detect echoes in sub-regions in each direction.

[0010] The control module is used to form a point cloud pattern based on the obtained data.

[0011] Optionally, the emitted light beam is focused by the focusing lens, irradiated onto the first MEMS galvanometer, then scanned and irradiated onto the free-form surface mirror, reflected to the second MEMS galvanometer, and finally emitted through the beam splitter.

[0012] Optionally, the splitting ratio range of the beam splitter is from 1:20 to 1:8, and the CCD lens is arranged on the side with a smaller splitting ratio of the beam splitter.

[0013] Optionally, the CCD detector is used to receive part of the light source of the beam splitter, and the fiber optic receiving lens is used to receive the other part of the light source of the beam splitter and conduct this part of the light source to the receiving module.

[0014] Optionally, the optical pulse is pulse intensity modulation, pulse width modulation or phase modulation.

[0015] Optionally, the control module is used to control the array optical switch to open and close at corresponding receiving angles according to different irradiation angles.

[0016] Optionally, it further includes an AD acquisition module, a filtering and fitting module, and a scanning dot matrix module. The AD acquisition module is respectively connected to the control module and the filtering and fitting module, and the scanning dot matrix module is connected to the filtering and fitting module.

[0017] The control module is used to decode the obtained signal, the AD acquisition module is used to acquire the signal after decoding, the filtering and fitting module is used to process the acquired information according to the filtering algorithm and the TFT fitting algorithm, the control module is used to calculate the distance based on the processed signal, and the scanning dot matrix module is used to form the point cloud pattern according to the emission angle and the test distance.

[0018] Optionally, the free-form surface mirror is an elliptical surface mirror, the first MEMS galvanometer is arranged at the focal length position of the elliptical surface mirror, and the second MEMS galvanometer is arranged at the focal length position of the elliptical surface mirror.

[0019] The present invention has the following beneficial effects:

[0020] The 3D scanning lidar based on an MEMS galvanometer mirror provided by the present invention includes a control module, multiple groups of transmitting modules, and multiple groups of receiving modules. The transmitting modules are used to continuously scan and transmit in sub-regions in the pitch direction and the horizontal direction. The receiving modules are used to receive detection echoes in sub-regions in each direction. The control module is used to control the transmitting modules to emit optical pulses with different encodings, control the receiving modules to receive the optical pulses, decode the optical pulses, and finally form a point cloud pattern based on the acquired data. In the 3D scanning lidar provided by the present invention, the transmitting modules use a combination of double galvanometer mirrors and optical elements for transmitting, and the receiving modules use a combination of receiving lenses, array optical switches, and area detectors for receiving. The 3D scanning lidar provided by the present invention has a compact structure, reduces the volume and weight, lowers the cost, and improves the heat dissipation effect. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the transmitting and receiving optical paths of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention.

[0022] Figure 2 It is a schematic diagram of the transmitting optical path of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention.

[0023] Figure 3 It is a schematic diagram of the control flow of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention. Detailed Description of the Embodiment

[0024] To enable those skilled in the art to better understand the technical solutions of the present invention, the 3D scanning lidar based on an MEMS galvanometer mirror provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0025] Embodiment 1

[0026] A laser scanning lidar forms a scanning cross-section by scanning and emitting the emitted laser beam, thereby testing the characteristic information of the object to be measured. Figure 1 It is a schematic diagram of the transmitting and receiving optical paths of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention, Figure 2 It is a schematic diagram of the transmitting optical path of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention, Figure 3 It is a schematic diagram of the control flow of the 3D scanning lidar based on an MEMS galvanometer mirror provided in Embodiment 1 of the present invention. As Figures 1 - 3As shown in the figure, the 3D scanning lidar based on MEMS galvanometer provided in this embodiment includes a control module, multiple groups of transmitting modules, and multiple groups of receiving modules. The transmitting module is used for continuous scanning and transmitting in regions in the pitch direction and the horizontal direction. The receiving module is used for receiving detection echoes in regions in each direction. The control module is used to control the transmitting module to emit optical pulses with different codes, control the receiving module to receive the optical pulses, decode the optical pulses, and finally form a point cloud pattern based on the collected data. The 3D scanning lidar provided in this embodiment has a compact structure, reduces the volume and weight, lowers the cost, and improves the heat dissipation effect.

[0027] See Figure 1 and Figure 2 , the transmitting module includes a first MEMS galvanometer, a second MEMS galvanometer, a focusing lens, a free-form surface mirror, a beam splitter, a CCD lens, a CCD detector, and an optical fiber receiving lens. The transmitting module provided in this embodiment uses a dual galvanometer and optical elements for combined transmission, and the receiving module uses a receiving lens, an array optical switch, and a surface detector for combined reception.

[0028] In this embodiment, the transmitted light beam is first focused by the focusing lens, irradiated onto the first MEMS galvanometer, scanned in the horizontal direction, then irradiated onto the free-form surface mirror, reflected to the second MEMS galvanometer, scanned in the vertical direction, and then transmitted after passing through the beam splitter.

[0029] See Figure 1 and Figure 2 , the focusing lens and the free-form surface mirror form a beam expansion system. The free-form surface mirror is a concave mirror, which can be an ellipsoidal mirror, a spherical mirror, or a parabolic mirror.

[0030] In this embodiment, when the free-form surface mirror is an ellipsoidal mirror, the first MEMS galvanometer is set at the first focal length position of the ellipsoidal mirror for horizontal scanning, and the second MEMS galvanometer is set at the second focal length position of the ellipsoidal mirror for pitch scanning. The light source is first focused and irradiated onto the ellipsoidal mirror, and its focusing focus is between the first MEMS galvanometer and the ellipsoidal mirror. After passing through the ellipsoidal mirror, all the scanning light is expanded, and then each beam of scanning collimated light is focused and irradiated onto the second MEMS galvanometer, and then emitted while maintaining collimation, and finally 3D scanning is performed. The above scanning method utilizes the characteristics of the ellipsoidal mirror. First, the focusing lens and the ellipsoidal mirror form a collimation and beam expansion system, and then the scanning emission light passing through the first focus of the ellipsoidal mirror will pass through the second focus, so as to irradiate the scanning light in the horizontal scanning direction onto the second MEMS galvanometer.

[0031] In this embodiment, the splitting ratio range of the beam splitter is from 1:20 to 1:8, and the CCD lens is arranged on the side of the beam splitter with a smaller splitting ratio. The CCD detector receives a small amount of light source from the beam splitter and is used to judge the pitch and horizontal angle positions after scanning by two MEMS galvanometers. Specifically, after the focusing lens or the collimating lens, a small amount of light source can be obtained through a small prism and transmitted to the receiving area array detector through the optical fiber receiving lens to generate an encoded signal, which is used to judge the pitch and horizontal angle positions after scanning by two MEMS galvanometers.

[0032] See Figure 1 and Figure 2 , the receiving module includes a receiving lens, an array optical switch, and an area array detector. Optionally, the array optical switch can be a DMD micromirror array or a MEMS galvanometer array, and the optical pulse is pulse intensity modulation, pulse width modulation, or phase modulation.

[0033] The control module provided in this embodiment is used to control the corresponding opening and closing of the receiving angle of the array optical switch according to different irradiation angles. The control module can control the corresponding opening and closing of the array optical switch according to different irradiation angles, so that the corresponding receiving detector receives the reflected light at the corresponding angle. In this embodiment, the array optical switch corresponding to the irradiated scanning angle area is opened, and the array optical switch corresponding to the non-irradiated angle area is closed, so that the detector does not receive the light source in the non-scanning area, thereby reducing the interference of the external environmental light source.

[0034] See Figure 3 , the 3D scanning lidar provided in this embodiment further includes an AD acquisition module, a filtering and fitting module, and a scanning dot matrix module. The AD acquisition module is respectively connected to the control module and the filtering and fitting module, and the scanning dot matrix module is connected to the filtering and fitting module. The control module is used to decode the obtained signal, the AD acquisition module is used to acquire the decoded signal, the filtering and fitting module is used to process the acquired information according to the filtering algorithm and the TFT fitting algorithm, the control module is used to calculate the distance according to the processed signal, and the scanning dot matrix module is used to form the point cloud pattern according to the emission angle and the test distance.

[0035] The 3D scanning lidar based on a MEMS galvanometer mirror provided in this embodiment includes a control module, multiple groups of transmitting modules, and multiple groups of receiving modules. The transmitting module is used to continuously scan and transmit in regions in the pitch direction and the horizontal direction. The receiving module is used to receive detection echoes in regions in each direction. The control module is used to control the transmitting module to emit optical pulses with different encodings, control the receiving module to receive the optical pulses, decode the optical pulses, and finally form a point cloud pattern based on the acquired data. In the 3D scanning lidar provided in this embodiment, the transmitting module uses a dual galvanometer mirror and optical elements for combined transmission, and the receiving module uses a receiving lens, an array optical switch, and a surface detector for combined reception. The 3D scanning lidar provided in this embodiment has a compact structure, reduces the volume and weight, lowers the cost, and improves the heat dissipation effect.

[0036] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A three-dimensional scanning lidar based on a MEMS galvanometer mirror, characterized in that It includes a control module, multiple groups of transmitting modules, and multiple groups of receiving modules; the transmitting module includes a first MEMS galvanometer, a second MEMS galvanometer, a focusing lens, a free-form surface mirror, a beam splitter, a CCD lens, a CCD detector, and an optical fiber receiving lens; The free-form surface mirror is a concave mirror, and the concave mirror includes at least one of an ellipsoidal mirror, a spherical mirror, and a parabolic mirror; the array optical switch is a DMD micromirror array or a MEMS galvanometer array; The control module is used to control the transmitting module to emit optical pulses with different encodings; The transmitting module is used for continuous scanning and transmitting in sub-regions in the pitch direction and the horizontal direction; The control module is used to control the receiving module to receive the optical pulses and decode the optical pulses; The receiving module is used for detecting echoes in sub-regions in all directions; The control module is used to form a point cloud pattern according to the acquired data; The beam splitting ratio range of the beam splitter is from 1:20 to 1:8, and the CCD lens is arranged on the side with less beam splitting ratio of the beam splitter; the CCD detector is used to receive part of the light source of the beam splitter to judge the pitch and horizontal angle positions after scanning by two MEMS galvanometers; the optical fiber receiving lens is used to receive the other part of the light source of the beam splitter and conduct this part of the light source to the receiving module; The transmitted light beam is focused by the focusing lens, irradiated onto the first MEMS galvanometer, then scanned and irradiated onto the free-form surface mirror, reflected to the second MEMS galvanometer, and finally transmitted through the beam splitter; The control module is used to control the array optical switch to open, close, or remain in a corresponding receiving angle state according to different irradiation angles; It further includes an AD acquisition module, a filtering and fitting module, and a scanning dot matrix module. The AD acquisition module is respectively connected to the control module and the filtering and fitting module, and the scanning dot matrix module is connected to the filtering and fitting module; The control module is used to decode the acquired signal, the AD acquisition module is used to acquire the decoded signal, the filtering and fitting module is used to process the acquired information according to the filtering algorithm and the TFT fitting algorithm, the control module is used to calculate the distance according to the processed signal, and the scanning dot matrix module is used to form the point cloud pattern according to the emission angle and the measured distance; The free-form surface mirror is an ellipsoidal mirror, the first MEMS galvanometer is arranged at the focal length position of the ellipsoidal mirror, and the second MEMS galvanometer is arranged at the focal length position of the ellipsoidal mirror; When the free-form surface mirror is an elliptical mirror, the first MEMS galvanometer is set at the first focal length position of the elliptical mirror for horizontal scanning, and the second MEMS galvanometer is set at the second focal length position of the elliptical mirror for pitching scanning. The light source is first focused and irradiated onto the elliptical mirror, and its focal point is between the first MEMS galvanometer and the elliptical mirror. After passing through the elliptical mirror, all the scanning light is expanded, and then each beam of scanning collimated light is focused and irradiated onto the second MEMS galvanometer, and then emitted while maintaining collimation, and finally three-dimensional scanning is performed.

2. The 3D scanning lidar based on a MEMS galvanometer mirror according to claim 1, wherein The optical pulse is pulse intensity modulation, pulse width modulation or phase modulation.

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