CN109782264A - A MEMS galvanometer synchronization signal feedback device, method and lidar - Google Patents

Abstract

The invention provides a MEMS galvanometer synchronization signal feedback device, method and laser radar. The laser emitting unit emits laser light and undergoes beam shaping by a beam shaping unit. The object plane scans the field of view; the photodetector is used to feed back an electrical signal to the signal control and processing unit when it is detected that the MEMS emitting unit is at the maximum deflection angle, so that the signal control and processing unit can control the laser driving unit according to the electrical signal. Control the synchronization of the MEMS emitting unit and the laser emitting unit. The MEMS galvanometer synchronization signal feedback device provided by the present invention introduces a feedback signal to control the laser emission unit to achieve synchronization and form a closed-loop control. The device as a whole has flexibility and stability, and can realize uniform or non-uniform multi-line scanning. Compared with the current commonly used mechanical rotating lidar device technology, it has the characteristics of small size, simple structure and easy integration.

Description

A MEMS galvanometer synchronization signal feedback device, method and lidar

technical field

The invention relates to the technical field of laser radar, in particular to a MEMS galvanometer synchronization signal feedback device, method and laser radar.

Background technique

Lidar detects information such as target azimuth and speed by emitting laser beams. It has the advantages of high ranging accuracy, strong directionality, fast response, and is not affected by ground clutter. It has been widely used in various fields of society. And lidar can form three-dimensional environment map data with an accuracy of up to centimeters, so it has important applications in advanced driver assistance systems (ADAS) and unmanned systems.

At present, the technical solutions applied to scanning lidar systems are mainly based on mechanical rotating parts, the motor structure is complex, the size is large, and it is not easy to integrate; in addition, there are technical solutions that use the resonance of MEMS galvanometers to change the optical path to complete multi-beam scanning. The stability of the overall system is improved, and it has the characteristics of small size, simple structure and low cost. However, because the real-time position information of the MEMS galvanometer during the vibration process and the control signal of the laser emitting unit are difficult to achieve synchronous control, it brings great difficulty to the system design and debugging.

SUMMARY OF THE INVENTION

In view of the defects in the prior art, the present invention provides a MEMS galvanometer synchronization signal feedback device, method and laser radar. The present invention can realize the synchronous control of laser emission and MEMS galvanometer oscillation, and has a simple structure, easy implementation and low cost. , good stability.

For achieving the above object, the present invention provides the following technical solutions:

In a first aspect, the present invention provides a MEMS galvanometer synchronization signal feedback device, including: a laser driving unit, a laser emitting unit, a beam shaping unit, a MEMS driving unit, a MEMS emitting unit, a photodetector, and a signal control and processing unit, The signal control and processing unit is respectively connected with the laser driving unit and the photodetector;

The laser emitting unit emits laser light under the driving of the laser driving unit, and after beam shaping is performed by the beam shaping unit, the laser emitting unit is incident on the MEMS emitting unit driven by the MEMS driving unit and resonated by the MEMS emitting unit. After the reflection, the plane of the object to be measured is scanned in the field of view; wherein, the MEMS driving unit drives the MEMS transmitting unit to oscillate according to the preset resonant frequency, so as to ensure the actual scanning field of view range of the laser after the resonant reflection of the MEMS transmitting unit w ₁ is greater than the field of view range w ₂ of the object plane to be measured;

The photodetector is located within the field of view of the actual scanning and is located outside the field of view of the object plane. Sending an electrical signal to the signal control and processing unit when it is detected that the MEMS transmitting unit is at the maximum deflection angle;

The signal control and processing unit controls the laser driving unit when receiving the electrical signal, so as to realize the synchronization of the MEMS emitting unit and the laser emitting unit.

Further, the number of the photodetectors is one, and the photodetector is used to detect the positive maximum deflection angle or the negative maximum deflection angle of the MEMS emitting unit, wherein the photodetector is placed in a position that can only receive The position where the beam reflected from the positive maximum deflection angle or the negative maximum deflection angle cannot receive the beam reflected from other deflection angles.

Further, the number of the photodetectors is two, wherein the first photodetector is used to detect the positive maximum deflection angle of the MEMS emission unit, and the second photodetector is used to detect the negative direction of the MEMS emission unit. Maximum deflection angle; where the first photodetector is placed in a position that can only receive beams reflected at the forward maximum deflection angle and cannot receive beams reflected at other deflection angles; the second photodetector is placed in a position that can only receive To the position where the beam reflected at the reverse maximum deflection angle is not received by the beam reflected at other deflection angles.

Further, the device further includes: a light beam receiving unit, the light beam receiving unit is used for converging the laser echo signal reflected from the plane of the object to be measured onto the photodetector.

Further, the light beam receiving unit is composed of two or more lenses or field lenses.

Further, the lens or field lens is made of a material with high transmittance to near-infrared.

Further, the driving manner of the MEMS driving unit includes one or more of piezoelectric driving, electrothermal driving, electrostatic driving and electromagnetic driving.

Further, the beam shaping unit is composed of more than two aspherical or free-form surface lenses or more than two ordinary lenses, and is used for shaping the laser beam emitted by the laser emitting unit.

In a second aspect, the present invention also provides a MEMS galvanometer synchronization signal feedback method based on the above-mentioned MEMS galvanometer synchronization signal feedback device, including:

S1. The MEMS transmitting unit oscillates according to a preset resonant frequency under the driving of the MEMS driving unit, wherein the actual scanning field of view of the laser after resonance reflection by the MEMS transmitting unit is larger than the field of view of the object to be measured. scope;

S2, the laser emitting unit emits a laser beam under the driving of the laser driving unit;

S3. The photodetector is used to detect whether the MEMS transmitting unit is at the maximum deflection angle, and when detecting that the MEMS transmitting unit is at the maximum deflection angle, feedback an electrical signal to the signal control and processing unit;

S4, the signal control and processing unit controls the laser driving unit according to the electrical signal, so as to realize the synchronization of the MEMS emitting unit and the laser emitting unit;

S5. Steps S2 to S4 are executed cyclically to realize a real-time field-of-view beam angle uniform or sparse and dense multi-line scanning.

In a third aspect, the present invention also provides a laser radar, including the MEMS galvanometer synchronization signal feedback device as described above.

It can be seen from the above technical solutions that the MEMS galvanometer synchronization signal feedback device provided by the present invention utilizes the photodetector to obtain the real-time position information (maximum deflection angle) of the MEMS transmitting unit during the vibration process in real time, and feeds back the position information of the MEMS transmitting unit to the MEMS transmitting unit. The laser driving unit enables the laser driving unit to drive the laser emitting unit according to the position information of the MEMS emitting unit, thereby realizing synchronous control of the laser emitting unit emitting light and the MEMS emitting unit oscillation. Further, the MEMS galvanometer synchronization signal feedback device provided by the present invention has the advantages of small size, simple structure, easy implementation, low cost, good stability, and easy integration, etc.

Description of drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic structural diagram of a MEMS galvanometer synchronization signal feedback device provided by an embodiment of the present invention;

2 is a schematic diagram of the working principle of a MEMS galvanometer synchronization signal feedback device provided by an embodiment of the present invention;

3 is a schematic diagram of the relationship between a laser drive signal, a MEMS galvanometer drive signal, and a MEMS oscillation signal provided by an embodiment of the present invention;

4 is a flowchart of a MEMS galvanometer synchronization signal feedback method provided by another embodiment of the present invention;

Among them, the meanings of the symbols in the above figures are as follows:

101 denotes a laser drive unit; 102 denotes a laser emission unit; 103 denotes a beam shaping unit; 104 denotes a MEMS drive unit; 105 denotes a MEMS emission unit; 109 represents the signal control and processing unit; 201 represents the light position of the main optical axis; 1061 represents the object plane to be measured; 1062 represents the first reference object plane; 1063 represents the second reference object plane.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The technical difficulty in existing laser radars that use MEMS galvanometers to achieve multi-line beam scanning is that it is difficult to achieve synchronization between laser emission and MEMS galvanometer vibration. To solve this problem, an embodiment of the present invention provides a MEMS galvanometer synchronization signal feedback device, see FIG. 1 and FIG. 2 , the feedback device includes: a laser driving unit 101 , a laser emitting unit 102 , a beam shaping unit 103 , a MEMS A driving unit 104, a MEMS emitting unit 105, photodetectors 107 and 108, and a signal control and processing unit 109, which are respectively connected to the laser driving unit 101 and the photodetectors 107 and 108 It can be understood that the MEMS transmitting unit 105 is realized by using a MEMS galvanometer; the beam shaping unit 103 is composed of more than 2 aspherical or free-form surface lenses or more than 2 ordinary lenses, which are used for the laser emitting unit. The laser beam emitted by 102 is shaped; the main optical axes between the laser emission unit 102 and the MEMS emission unit 105 and the mirror group of the beam shaping unit 103 are kept coincident;

The laser emitting unit 102 emits laser light under the driving of the laser driving unit 101, and after beam shaping is performed by the beam shaping unit 103, the laser emitting unit 102 is incident on the MEMS emitting unit 105 driven by the MEMS driving unit 104 and driven by the MEMS driving unit 104. After the MEMS transmitting unit 105 performs resonant reflection, the plane of the object to be measured scans the field of view; wherein, the MEMS driving unit 104 drives the MEMS transmitting unit 105 to oscillate according to a preset resonant frequency to ensure that the MEMS transmitting unit 105 resonates and reflects The actual scanning field of view range w ₁ of the latter laser is greater than the field of view range w ₂ of the object plane to be measured; it can be understood that the MEMS driving unit 104 can change the frequency of the MEMS transmitting unit 105 by adjusting the frequency of the driving circuit. The resonant frequency, thereby changing the actual scanning field of view of the MEMS transmitting unit 105; it can be understood that the driving mode of the MEMS driving unit 104 may include one of piezoelectric driving, electrothermal driving, electrostatic driving and electromagnetic driving. one or more.

Wherein, the photodetector is located within the actual scanning field of view and is located outside the field of view of the object plane. For example, the photodetector is located at a position where the laser beam reflected by the MEMS emitting unit 105 at the maximum deflection angle can pass the photodetector and the laser beam reflected at other deflection angles cannot pass the photodetector, so that The photodetector can detect whether the MEMS transmitting unit 105 is at the maximum deflection angle according to whether the light signal is received, and send the signal to the signal control and processing unit 109 when detecting that the MEMS transmitting unit 105 is at the maximum deflection angle electric signal;

The signal control and processing unit 109 controls the laser driving unit 101 when receiving the electrical signal, so as to realize the synchronization of the MEMS emitting unit 105 and the laser emitting unit 102 .

It can be seen that the MEMS galvanometer synchronization signal feedback device provided by the embodiment of the present invention realizes closed-loop synchronization control.

It can be understood that, since the laser emitted by the laser emitting unit 102 is a periodic pulse signal, and the MEMS emitting unit 105 is in a resonant state, its deflection angle has a sine function relationship with time. The MEMS emitting unit has a positive maximum deflection angle and a negative maximum deflection angle, so the laser emitting unit can be controlled to emit light synchronously according to the detected positive maximum deflection angle or negative maximum deflection angle of the MEMS emitting unit, so as to realize laser light. Synchronization of the firing unit and the MEMS firing unit. FIG. 3 is a schematic diagram of the relationship between a laser drive signal, a MEMS galvanometer drive signal, and a MEMS oscillation signal provided by an embodiment of the present invention. As can be seen from Figure 3, when the MEMS galvanometer is in the resonant state, its deflection angle has a sine function relationship with time. During a cycle change, the MEMS drive voltage signal is triggered by a square wave signal, and the edge of its rising edge corresponds to The maximum deflection angle of the MEMS galvanometer, and the laser drive signal is a periodic pulse signal.

It can be understood that the number of the photodetectors can be one, and when the number of photodetectors can be one, the photodetector is used to detect the maximum positive deflection angle or the negative maximum deflection angle of the MEMS emitting unit. Deflection angle; wherein, the photodetector is placed in a position where it can only receive the beam reflected by the maximum deflection angle in the positive direction or the maximum deflection angle in the negative direction, and cannot receive the beam reflected by other deflection angles.

It can be understood that the number of the photodetectors can also be two, and when the number of photodetectors can be two, the first photodetector is used to detect the maximum forward deflection angle of the MEMS emitting unit. , the second photodetector is used to detect the negative maximum deflection angle of the MEMS emitting unit; wherein, the first photodetector is placed in a position where the first photodetector can only receive the beam reflected by the positive maximum deflection angle and cannot receive other deflection angle reflections position of the beam; the second photodetector is placed in a position where it can only receive the beam reflected at the reverse maximum deflection angle and not the beam reflected at other deflection angles.

Referring to FIG. 1 and FIG. 2 , in this embodiment, the object plane defined within the actual scanning field of view and outside the field of view of the object plane to be measured is called the reference object plane ( 1062 and 1063 ). The measuring object plane (1061) and the reference object planes (1062 and 1063) together constitute the scanning area object plane 106 in FIG. 1 . The reference object plane includes the first reference object plane 1062 and the second reference object plane 1063 shown in FIG. 2 . In this embodiment, the optical signal scanned onto the reference object plane is also defined as the reference optical signal. The signals include a first reference light signal scanned onto the first reference object plane 1062 and a second reference light signal scanned onto the second reference object plane 1063 . The first photodetector 107 and the second photodetector 108 shown in FIG. 2 are respectively used to detect the edge light signal within the field of view of the first reference light signal and the edge light signal within the field of view of the second reference light signal . When the first photodetector 107 detects an edge light signal within the field of view of the first reference light signal, it means that the MEMS emitting unit 105 is at the maximum deflection angle in the forward direction. When the second photodetector 108 detects the first When the edge light signal is within the field of view of the reference light signal, it means that the MEMS emitting unit 105 is at a negative maximum deflection angle at this time. It can be seen that in the embodiment of the present invention, the photoelectric effect of the photodetector is used to convert the optical signal into an electrical signal, and the electrical signal is transmitted to the signal control and processing unit 109, and then the signal control and processing unit 109 performs the laser driving unit 101. Control to realize the synchronization of the MEMS emitting unit 105 and the laser emitting unit 102 .

It can be understood that, if the actual scanning field of view corresponding to the MEMS transmitting unit 105 at the maximum deflection angle is w ₁ =35°, and the field of view corresponding to the object plane is w ₂ =30°, then the first photoelectric The detector is placed in the actual position where it can only receive θ=+17.5 ^° ; the second photodetector is placed at the actual position where it can only receive θ=-17.5 ^° .

It can be understood that when the signal feedback based on the two photodetectors shown in FIG. 2 is used, it means that the MEMS galvanometer synchronization signal feedback device has performed two synchronization calibrations within one resonance period, so that it can be more accurate. The synchronization of the MEMS emitting unit and the laser emitting unit can be realized.

In addition, in order to reduce equipment cost and complexity, the number of the photodetectors can also be one, and one photodetector can be used to detect the positive maximum deflection angle or the negative maximum deflection angle of the MEMS emitting unit. When When the number of the photodetectors is one, it is equivalent to performing one synchronization calibration for one resonance period.

In addition, it should be noted that the number of photodetectors and the specific installation positions are not limited in this embodiment, as long as the photodetectors can detect whether the MEMS emission unit is at the maximum deflection angle and cannot detect the MEMS Other deflection angles of the transmitting unit can be used.

It can be seen from the contents shown in FIG. 1 and FIG. 2 that the MEMS galvanometer synchronization signal feedback device provided by the embodiment of the present invention adopts the resonant vibration of the MEMS galvanometer to reflect the light beam emitted from the mirror surface of the MEMS galvanometer to a certain viewing angle. The target object in the field and distance range, and at the same time, the reference light signal is introduced in the fringe field of view outside the plane of the object to be tested to form a signal feedback control. Compared with devices that use mechanical scanning or motor drive to achieve laser scanning, MEMS galvanometers improve the stability, angular resolution and scanning frequency of scanning lidar, and are easy to integrate, which is conducive to promoting the miniaturization and lightness of lidar technology. and integrated development.

In an optional implementation manner, the MEMS galvanometer synchronization signal feedback device further includes: a beam receiving unit, the beam receiving unit is configured to converge the laser echo signal reflected from the plane of the object to be measured to the photodetector on the device. Preferably, the light beam receiving unit is composed of two or more lenses or field lenses, and the lenses or field lenses are made of materials with high transmittance to near infrared rays.

Further, since the laser emitting unit can emit a laser beam of any frequency, if the frequency and delay of the laser beam are controlled according to the electrical signal fed back by the photodetector, the angle uniform scanning or Uneven density scanning, for example, increases the luminous frequency in important parts of detection, increases the amount of data, and can more accurately identify the true state of the object under test; it makes the overall scanning of the system more reasonable and has wider application prospects.

It can be seen from the above description that the MEMS galvanometer synchronization signal feedback device provided by the embodiment of the present invention uses the photodetector to obtain the real-time position information (maximum deflection angle) of the MEMS transmitting unit during the vibration process in real time, and feeds back the position information of the MEMS transmitting unit. to the laser driving unit, so that the laser driving unit drives the laser emitting unit according to the position information of the MEMS emitting unit, so as to realize the synchronous control of the light emission of the laser emitting unit and the oscillation of the MEMS emitting unit. Further, the MEMS galvanometer synchronization signal feedback device provided by the embodiment of the present invention has the advantages of small size, simple structure, easy implementation, low cost, good stability, and easy integration, etc.

Based on the same inventive concept, another embodiment of the present invention provides a MEMS galvanometer synchronization signal feedback method based on the MEMS galvanometer synchronization signal feedback device described in the above embodiment. Referring to FIG. 4 , the method includes the following steps:

S1: The MEMS emitting unit oscillates according to a preset resonant frequency under the driving of the MEMS driving unit, wherein the actual scanning field of view of the laser after resonant reflection by the MEMS emitting unit is larger than the field of view of the object to be measured scope.

S2: The laser emitting unit emits a laser beam under the driving of the laser driving unit.

S3: The photodetector is used to detect whether the MEMS transmitting unit is at the maximum deflection angle, and when detecting that the MEMS transmitting unit is at the maximum deflection angle, feedback an electrical signal to the signal control and processing unit.

S4: The signal control and processing unit controls the laser driving unit according to the electrical signal, so as to realize the synchronization of the MEMS emitting unit and the laser emitting unit.

S5 : Steps S2 to S4 are executed cyclically to realize a real-time field-of-view beam angle uniform or sparse and dense multi-line scanning.

Since the MEMS galvanometer synchronization signal feedback method provided in this embodiment is implemented by the MEMS galvanometer synchronization signal feedback device described in the above embodiments, its principles and technical effects are similar, and details are not described herein again.

Based on the same inventive concept, another embodiment of the present invention provides a laser radar, where the laser radar includes the MEMS galvanometer synchronization signal feedback device described in the above embodiments.

Since the laser radar provided in this embodiment includes the MEMS galvanometer synchronization signal feedback device described in the above embodiment, its principles and technical effects are similar, and details are not repeated here.

The above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The recorded technical solutions are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions in the embodiments of the present invention.

Claims (10)

1. a kind of MEMS galvanometer synchronization signal feedback device characterized by comprising laser drive unit, laser emission element, Beam shaping unit, MEMS driving unit, MEMS transmitting unit, photodetector and signal control and processing unit, it is described Signal control is connect with the laser drive unit and the photodetector respectively with processing unit；

The laser emission element emits laser under the driving of the laser drive unit and passes through the beam shaping unit After carrying out beam shaping, it is incident on by the MEMS transmitting unit of MEMS driving unit driving and by the MEMS transmitting unit Visual field scanning is carried out to object plane to be measured after carrying out tuned reflection；Wherein, the MEMS driving unit drives the MEMS transmitting Unit is vibrated according to preset resonance frequency, to guarantee the actual scanning of the laser after MEMS transmitting unit tuned reflection Field range w₁Greater than the field range w of object plane to be measured₂；

The photodetector is located at the field range within the actual scanning field range and being located at the object plane to be measured Except, the photodetector is used to detect whether the MEMS transmitting unit is in maximum deflection angle, and detecting It states and sends electric signal with processing unit to the signal control when MEMS transmitting unit is in maximum deflection angle；

The signal control and processing unit control the laser drive unit when receiving the electric signal, realize The MEMS transmitting unit is synchronous with the laser emission element.

2. the apparatus according to claim 1, which is characterized in that the number of the photodetector is one, which visits Survey positive maximum deflection angle or negative sense maximum deflection angle that device is used to detect the MEMS transmitting unit；Wherein, the photoelectricity Detector is placed on the light beam that can only receive positive maximum deflection angle or the reflection of negative sense maximum deflection angle and does not receive The position of the light beam of other deflection angles reflection.

3. the apparatus according to claim 1, which is characterized in that the number of the photodetector is two, the first photoelectricity Detector is used to detect the positive maximum deflection angle of the MEMS transmitting unit, and the second photodetector is described for detecting The negative sense maximum deflection angle of MEMS transmitting unit；Wherein, first photodetector, which is placed on, can only receive positive maximum Deflection angle reflection light beam and do not receive other deflection angles reflection light beam position；Second photodetector is placed The light beam and the position for not receiving the light beam of other deflection angles reflection that reversed maximum deflection angle reflects can only received.

4. the apparatus according to claim 1, which is characterized in that further include: beam reception unit, the beam reception unit For the photodetector will to be converged to from the laser echo signal of determinand plane reflection.

5. device according to claim 4, which is characterized in that the beam reception unit is by 2 or more lens or field lens Composition.

6. device according to claim 5, which is characterized in that the lens or field lens are using having high transmittance to near-infrared Material be made.

7. the apparatus according to claim 1, which is characterized in that the driving method of the MEMS driving unit includes that piezoelectricity drives One of dynamic, electrothermal drive, electrostatic drive and electromagnetic drive are a variety of.

8. the apparatus according to claim 1, which is characterized in that the beam shaping unit by 2 or more it is aspherical or from Formed by the lens of curved surface or by 2 or more ordinary lens, the laser beam for emitting the laser emission element into Row shaping.

9. a kind of MEMS galvanometer based on MEMS galvanometer synchronization signal feedback device as described in any one of claims 1 to 8 is same Walk signal feedback method characterized by comprising

S1, the MEMS transmitting unit are vibrated under the driving of the MEMS driving unit according to preset resonance frequency, Wherein, the actual scanning field range of the laser after MEMS transmitting unit tuned reflection is greater than the visual field model of object plane to be measured It encloses；

S2, the laser emission element emit laser beam under the driving of the laser drive unit；

S3, the photodetector are being detected for detecting whether the MEMS transmitting unit is in maximum deflection angle When the MEMS transmitting unit is in maximum deflection angle, the control of Xiang Suoshu signal feeds back electric signal with processing unit；

S4, signal control according to the electric signal control the laser drive unit with processing unit, realize institute It is synchronous with the laser emission element to state MEMS transmitting unit；

S5, circulation execute step S2~S4, realize that real-time visual field beam angulation is uniform or the multi-thread scanning of density.

10. a kind of laser radar, which is characterized in that including MEMS galvanometer synchronization signal as described in any one of claims 1 to 8 Feedback device.