CN112859048A - Light beam scanning apparatus, laser radar including the same, and control method - Google Patents
Light beam scanning apparatus, laser radar including the same, and control method Download PDFInfo
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- CN112859048A CN112859048A CN201911183193.8A CN201911183193A CN112859048A CN 112859048 A CN112859048 A CN 112859048A CN 201911183193 A CN201911183193 A CN 201911183193A CN 112859048 A CN112859048 A CN 112859048A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4911—Transmitters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/491—Details of non-pulse systems
- G01S7/4912—Receivers
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/0816—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements
- G02B26/0833—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD
- G02B26/085—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light by means of one or more reflecting elements the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD the reflecting means being moved or deformed by electromagnetic means
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
- G02B26/10—Scanning systems
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- Optics & Photonics (AREA)
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- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The invention relates to a beam scanning device for a lidar comprising: a housing; a mirror supported in the housing and movable within a preset range; a measuring device disposed in the housing and configured to measure a position and/or an angle of the mirror; a driving device disposed in the housing, connected to the mirror, and configured to drive the mirror to move within the preset range according to a measurement result of the measuring device. According to embodiments of the present invention, the number of light emitters and detectors may be greatly reduced, so that the overall size of the lidar may be significantly smaller. In addition, the two groups of completely synchronous micro-motion mechanisms can expand or combine the incident light beams and the received light beams, so that a higher wiring harness is realized by fewer receiving and transmitting modules.
Description
Technical Field
The present invention generally relates to the field of optoelectronic technologies, and in particular, to a light beam scanning apparatus, a laser radar including the light beam scanning apparatus, and a control method thereof.
Background
The unmanned automobile is an intelligent automobile which senses road environment through a vehicle-mounted sensing system, automatically plans a driving route and controls the automobile to reach a preset target. The vehicle-mounted sensor is used for sensing the surrounding environment of the vehicle, and controlling the steering and the speed of the vehicle according to the road, the vehicle position and the obstacle information obtained by sensing, so that the vehicle can safely and reliably run on the road.
The in-vehicle sensor is an in-vehicle device necessary to implement the unmanned automobile. The laser radar has the characteristics of long detection distance, high resolution, small environmental interference and the like, and is indispensable vehicle-mounted equipment of the unmanned automobile. The operating principle of lidar is roughly as follows: laser beam is launched to laser radar's transmitter, and after laser beam met the object, through diffuse reflection, return to laser receiver, radar module multiplies the velocity of light according to the time interval of sending and received signal, divides by 2 again, can calculate the distance of transmitter and object. In addition to range information, the lidar may also acquire other information of the target object, such as orientation, velocity, size, shape, reflectivity, etc.
Early lidar was a single line lidar, i.e., having only one laser and detector, which scanned a limited range of targets, and was prone to loss of detected targets. To compensate for the shortcomings of the single line lidar, the multiline lidar is becoming the focus of research and commercial use.
However, the existing multi-line laser radar often has the problems of high cost and overlarge energy consumption. The scanner can reduce the number of the used receiving and transmitting units, so that the material cost and the labor cost such as accurate assembly and adjustment can be effectively reduced, and the common modes comprise a motor-driven rotation mode, a rotating mirror mode, a vibrating mirror mode and the like. The motor itself can provide a large scanning field due to reliability limitation, but is difficult to be used as a high-speed scanner, while the galvanometer has a high scanning frequency, but the aperture is limited, and quasi-static scanning and synchronization among a plurality of devices cannot be realized.
The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in the field.
Disclosure of Invention
In view of at least one of the drawbacks of the prior art, the present invention provides a beam scanning apparatus usable with a lidar, comprising:
a housing;
a mirror supported in the housing and movable within a preset range;
a measuring device disposed in the housing and configured to measure a position and/or an angle of the mirror;
a driving device disposed in the housing and configured to drive the mirror to move within the preset range according to a measurement result of the measuring device.
According to an aspect of the present invention, wherein the measuring device includes a magnet, and a hall sensor disposed opposite to the magnet, one of the magnet and the hall sensor is disposed on the mirror, and the other is disposed on the housing, the hall sensor outputs a voltage value representing a distance thereof from the magnet.
According to one aspect of the present invention, the optical beam scanning apparatus further comprises a control unit coupled to the hall sensor and receiving a voltage value output from the hall sensor to determine the current position and/or angle of the mirror,
the control unit is coupled with the driving device and controls the driving device according to the current position and/or angle of the reflecting mirror.
According to one aspect of the invention, the mirror has a rotation axis and is swingable around the rotation axis, and the measuring device includes two sets of magnets and hall sensors respectively provided on both sides of the rotation axis.
According to one aspect of the invention, the axis of rotation of the mirror is in the form of a torsion beam
According to one aspect of the invention, the control unit determines the current position and/or angle of the mirror according to the voltages output by the two hall sensors.
According to an aspect of the present invention, the driving means includes a magnet provided on the mirror and a coil provided on the housing, the coil being opposed to the magnet to drive the mirror.
According to an aspect of the present invention, the optical beam scanning apparatus further comprises a reset device connected between the housing and the mirror to restore the mirror to its original position when the coil is de-energized.
According to an aspect of the invention, the housing includes a stopper portion to define a maximum movement range of the mirror.
According to one aspect of the invention, the measuring device comprises a PSD position sensor disposed on the housing and a light source configured to emit a test beam toward a surface of the reflector, the test beam being reflected by the surface and incident on the PSD position sensor, wherein a current signal output by the PSD position sensor is indicative of an incident position of the test beam to determine a position and/or an angle of the reflector.
The invention also relates to a lidar comprising a beam scanning device as described above.
According to one aspect of the invention, the lidar further comprises at least one light emitter for emitting a probe beam, wherein the beam scanning device comprises a first beam scanning device for reflecting the probe beam, the first beam scanning device being arranged in the optical path downstream of the light emitter for receiving and reflecting the probe beam.
According to an aspect of the invention, the lidar further comprises a photosensor for receiving an echo beam, and the beam scanning device further comprises a second beam scanning device arranged upstream of the photosensor and configured to reflect the echo beam onto the photosensor.
The present invention also relates to a method of controlling an optical beam scanning apparatus as described above, comprising:
acquiring a target position of the reflector;
driving the mirror by the driving means;
measuring, by the measuring device, a position and/or an angle of the mirror;
the position of the mirror is adjusted by the drive means in dependence on the position and/or angle of the mirror.
According to embodiments of the present invention, the number of light emitters and detectors may be greatly reduced, so that the overall size of the lidar may be significantly smaller. In addition, the two groups of completely synchronous micro-motion mechanisms can expand or combine the incident light beams and the received light beams, so that higher wiring harnesses are realized by fewer receiving and transmitting modules.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 shows an optical beam scanning apparatus according to one embodiment of the present invention;
FIG. 2 shows an optical beam scanning apparatus according to another embodiment of the present invention;
FIG. 3 shows a schematic diagram of the use of a PSD sensor to measure the angle of a mirror;
FIG. 4 shows an optical beam scanning apparatus according to another embodiment of the present invention;
FIG. 5 is a schematic view showing an angle of a measuring mirror in the optical beam scanning apparatus of FIG. 4;
FIG. 6 shows a schematic diagram of a lidar in accordance with one embodiment of the invention;
FIG. 7 is a schematic structural diagram of the first optical beam scanning device 22 and the second optical beam scanning device 23 in the embodiment of FIG. 6; and
fig. 8 shows a control method of the optical beam scanning apparatus according to an embodiment of the present invention.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
In the description of the present invention, it should be noted that unless otherwise explicitly stated or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.
The following disclosure provides many different embodiments or examples for implementing different features of the invention. To simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
Fig. 1 shows a beam scanning apparatus 1 according to an embodiment of the present invention, which can be used in a laser radar to perform reflection scanning of a beam incident thereon. The following detailed description refers to the accompanying drawings.
As shown in FIG. 1, the optical beam scanning apparatus 1 includes a housing 11, a mirror 12, a measuring device 13(131,132), and a driving device 14(141, 142). The housing 11 is used to support or house various electromechanical components and optics of the optical beam scanning apparatus 1. The housing 1 is made of metal or plastic, for example. The mirror 12 is disposed and supported in the housing 11 and is movable within a predetermined range. The upper surface of the mirror 12 is used for reflective scanning of the incident light beam, and the lower surface faces the inside of the housing 11. The predetermined range includes, but is not limited to, pivoting, translational movement, and a combination of translational movement and pivoting, etc.
In fig. 1 it is shown that the mirror 12 can be swung back and forth in the plane of the paper about a central pivot axis 15, the maximum swing range being, for example, less than or equal to 5 degrees in both the counterclockwise and clockwise directions relative to the horizontal position (i.e. the position corresponding to the state when the mirror 12 is not affected by an external force). It will be readily understood by those skilled in the art that for an incident beam of the same angle, the direction of the reflected beam will also change when the mirrors are at different positions and/or angular orientations, thereby enabling scanning of the beam. The pivoting shown in fig. 1 is used as an example to illustrate the present invention, but the present invention is not limited thereto, and the mirror 12 may have other movement modes, and the concept and principle of the present invention may be applied. In an embodiment of the present invention, a mode similar to a galvanometer may be adopted, and a structural sheet is twisted to realize the optical beam scanning device, that is, the rotating shaft may be arranged in a form of a twisted beam, and because the swing of the optical beam scanning device in the present application is small and does not need to work on a structural resonance point, the rigidity of the twisted beam may be made relatively high, and thus, the optical beam scanning device may have high reliability and capability of resisting environmental excitation. A drive device 14 is disposed in the housing 11 and is at least partially connected to the mirror 12 for driving the mirror 12 within the predetermined range. The optical beam scanning apparatus 1 may be used to reflectively scan an incident optical beam. At a certain time, the mirror 12 of the optical beam scanning apparatus 1 needs to be set at a specific position and/or angle to achieve a desired reflection angle, and at this time, the driving apparatus 14 drives the mirror 12 to the target position and/or angle in accordance with the target position and/or angle. However, the mirror 12 often cannot be driven or positioned accurately due to limited control accuracy or for some other reason. Therefore, in the embodiment of the present invention, the optical beam scanning apparatus 1 further includes the measuring device 13, and the measuring device 13 is disposed in the housing 11 and is used for detecting the current position and/or angle of the reflecting mirror, so that the driving device 14 can obtain the difference between the target position and/or angle and the current position and/or angle according to the measurement result of the measuring device 13 and drive the reflecting mirror 12 according to the difference, so that the reflecting mirror 12 can be driven and positioned more accurately.
The foregoing has described the concepts and principles of the invention. Various preferred embodiments of the present invention are described in detail below.
As shown in fig. 1, according to a preferred embodiment of the present invention, the measuring device 13 includes a magnet 131, and a hall sensor 132 disposed opposite to the magnet 131. As shown in fig. 1, the magnet 131 is provided on the lower surface of the reflector 12, and the hall sensor 132 is provided on the housing 11 in an opposed relationship. It is of course possible to arrange the magnet 131 on the housing 11 and the hall sensor 132 on the lower surface of the reflector 12, all within the scope of the present invention. Preferably, the measuring device 13 is arranged at a distance of the mirror half way from the axis of rotation 15.
The hall sensor 132 is within the magnetic field of the magnet 131. When the mirror 12 moves between different positions, the position of the magnet 131 changes, so that the distance between the hall sensor 132 and the magnet 131 changes, and the hall sensor 132 outputs a voltage value which can represent the distance between the hall sensor 132 and the magnet 131 or the change of the distance. Taking the rotation around the axis as an example, the distance between the magnet 131 and the rotation axis 15 can be preset, so that the current angle of the reflecting mirror 12 can be calculated by the distance between the hall sensor 132 and the magnet 131. Depending on the current angle of the mirror 12, the drive 14 may adjust the position or angle of the mirror 12 closer to the target angle or position based on the difference between the current angle and the target angle.
The hall sensor is commercially available from texas instruments, usa, and a 350-degree samarium cobalt high temperature magnet (Sm2Co7) may be used to reduce the temperature decay of the magnetic field strength of the permanent magnet itself.
According to a preferred embodiment of the present invention, the optical beam scanning apparatus 1 further comprises a control unit (not shown) coupled to the hall sensor 132 and the driving device 14, respectively, so that the control unit can receive the voltage values output from the hall sensor to determine the current position and/or angle of the mirror, compare the current position and/or angle with the preset position and/or angle, and control the driving device 14 based on the difference.
In addition, according to a preferred embodiment of the present invention, the measuring device 13 includes two sets of magnets 131 and hall sensors 132, which are respectively disposed on both sides of the rotating shaft 15. So that the control unit 16 can determine the current position and/or angle of the mirror 12 according to the voltages output by the two hall sensors 132. For example, the two sets of magnets 131 and the hall sensors 132 are located at the same distance from the rotating shaft 15, so that the control unit 16 can obtain the current position and/or angle of the reflecting mirror 12 more accurately by averaging the outputs of the two sets of hall sensors 132.
It will be readily appreciated by those skilled in the art that the control unit may be integrated into the drive device 14 as an integral part of the drive device 14. Alternatively, the control unit may be a separate component, separate from the drive device 14, such as a single chip, or FPGA chip. These are all within the scope of the present invention.
As shown in fig. 1, the driving device 14 includes a magnet 141 provided on the mirror 12 and a coil 142 provided on the housing, and the coil 142 is opposite to the magnet 141 to drive the mirror 12. The coil 142 includes a coil fixed to the housing 11, and generates a magnetic field when an alternating current is applied thereto, the magnetic field generating a magnetic attraction or repulsion force to the magnet 141, thereby controlling the magnet 141 to approach or separate from the coil 142 and driving the mirror 12 to move around the rotation shaft 15. In an embodiment of the present invention, the coil may be provided on the mirror, and the magnet may be provided on the housing.
According to a preferred embodiment of the present invention, the driving device 14 includes two sets of magnets 141 and coils 142, respectively disposed on both sides of the rotating shaft 15.
According to a preferred embodiment of the present invention, the optical beam scanning apparatus 1 further comprises a reset device 17, wherein the reset device 17 is connected between the housing 11 and the reflecting mirror 12 to restore the reflecting mirror 12 to its original position when the coil 142 is de-energized. The initial position of the mirror 12 is, for example, a horizontal position. The driving device 14 drives the mirror 12 to rotate counterclockwise about the rotation shaft 15. When the coil 142 is de-energized, the magnetic force between the coil 142 and the magnet 141 disappears, at which time the mirror 12 returns to the horizontal position under the action of the resetting means 17. The reset means 17 is, for example, a reset spring, and may be connected between the housing 11 and the magnet 141, or between the housing 11 and another position of the reflector 12.
According to a preferred embodiment of the present invention, the housing 11 includes a stopper 111 to limit the maximum movement range of the reflecting mirror 12. As shown in fig. 1, the position-limiting portion 111 includes a protrusion extending from a side wall of the housing 11, and the protrusion extends in a direction parallel to the reflector 12, and is used for limiting the maximum mechanical stroke of the reflector 12 for protection. However, the reflector 12 does not directly contact the stopper 111 during normal operation or movement, so that the strain of the reflector 12 can be reduced and the reliability of the reflector 12 can be improved.
Fig. 2 shows a preferred embodiment according to the present invention. Unlike the embodiment of fig. 1, the measuring device 13 includes a PSD position sensor 133 and a light source 134, which are disposed on the housing, wherein the light source 134 is configured to emit a test light beam to the lower surface of the reflector 12, the test light beam is reflected by the surface and then incident on the PSD position sensor, and a current signal output by the PSD position sensor can represent an incident position of the test light beam to determine the position and/or angle of the reflector.
The PSD position sensor is a light energy/position conversion device, and the light beam irradiates different positions on the PDS position sensor, and the output current varies, so that the incident position of the light beam can be determined by the output current. Taking the two-dimensional PSD sensor as an example, the photosensitive layers of the two-dimensional PSD sensor in the X and Y directions on the plane are independent and are used for sensing the change of the spot position in the X and Y directions, respectively. The current on the electrodes of the two-dimensional PSD position sensor is related to the coordinates of the light spot along the X and Y directions. The PSD sensor can thus be used to measure the angular deflection of a micro-mirror or mirror in a lidar.
Therefore, no matter the structure shown in fig. 1 or the structure shown in fig. 2, the optical beam scanning device in the embodiment of the present application can synchronously and quasi-statically operate, the swing angle is not large in general, but a larger aperture can be realized, so that the requirement of properly reducing the number of the transceiver units can be well satisfied. In addition, compared with a mechanical limit type swing mirror, the feedback type light beam scanning device has the advantages that the motion form is rich, and the scanning can be realized by various waveforms under a plurality of quasi-static states through control work.
Fig. 3 shows a schematic diagram of the use of a PSD sensor to measure the angle of a mirror. As shown in fig. 1, the mirror can oscillate back and forth within a certain range about its central axis. In fig. 3, the surface above the mirror is its working surface. The light source is used for receiving incident light and scanning and reflecting the incident light to form an emergent light beam. The lower surface of which can be used for angle measurement. As shown in fig. 3, the laser beam is incident on the lower surface of the mirror and reflected, and then incident on the PSD sensor. The reflected laser beam is different according to the angle of the reflectorThe location of the point of incidence of the beam on the PSD sensor will also vary. PSD sensor, for example, having four current output signals I1、I2、I3And I4The X-direction and Y-direction positions of the laser spot incident on the PSD sensor can be obtained by the following formula 1.
Measuring to obtain four current output signals I1、I2、I3And I4Then, the corresponding swing angle of the mirror can be obtained by performing the corresponding operation according to the following formula 2.
Wherein the content of the first and second substances,
indicating that the four current output signals are correspondingly operated, IsumThe sum of the four signals represents the light intensity. Wherein
In, the environmental influences are offset by two by mutual operations, IsumIncluding environmental influences.
The manner in which the two-dimensional PSD sensor measures angles is described above. In fig. 1, only one-dimensional PSD sensor may be used for angle measurement, and the principle and the calculation method are substantially the same, and are not described herein again.
Fig. 4 shows an optical beam scanning apparatus 1 according to a preferred embodiment of the present invention. In which a second mirror 135 is added to figure 4, as compared to the goniometric version of figures 2 and 3. A light beam emitted from the light source 134 (laser) is reflected by the lower surface of the reflecting mirror 12 and then incident on the second reflecting mirror 135, and then is reflected by the second reflecting mirror 135 and the lower surface of the reflecting mirror 12 in sequence and then incident on the PSD 133, thereby measuring and calculating the angle of the reflecting mirror.
In some application scenarios, the pivot angle of the mirror 12 may be so small that a high resolution is required for the angle sensor (PSD sensor in the figure). Of course, by increasing the optical path length L, it is still possible to measure a smaller tilt angle using the same PSD sensor, but this requires linearly increasing the size of the tilt mirror module in the optical path length direction. As shown in fig. 4, in addition to the angle measurement scheme directly reflecting onto the PSD sensor, a scheme of measuring the deflection magnification by the second mirror 135 is also proposed. When the reflector 12 deflects at a small angle, as shown in fig. 5, the spot offset x on the photosensitive surface of the PSD sensor and the swing angle θ of the reflector approximately satisfy the following relationship: x ≈ L1+L2)2 θ, it can be seen that if L1 and L2 are approximately equal to the optical path length L at direct incidence, the amount of spot shift on the PSD will be approximately 4 times magnified after a single mirror turn, and the optical lever magnification can be further increased similarly by adding a mirror. Assuming that the length of the photosensitive surface of the PSD is 3.5mm, the measurable optical angle range of the oscillating mirror field is 1.2 degrees under the 40mm optical path.
As shown in fig. 4, the optical beam scanning device 1 may further include a soft stopper portion 112, for example, instead of the stopper portion 111 shown in fig. 1 and 2, and is preferably disposed above and below the reflecting mirror 12. The soft limiting portion 112 is made of a soft material or an elastic material, and can limit the range of motion of the mirror 12 and protect the mirror.
The invention also relates to a lidar 2 comprising a beam scanning device as described above. The light beam scanning device can be used for reflecting and scanning a probe light beam and also can be used for receiving and scanning radar echo from the outside of the laser radar. As described in detail below.
As shown in fig. 6, the laser radar 2 includes at least one light emitter 21 for emitting a probe light beam, wherein the light beam scanning device includes a first light beam scanning device 22 for reflecting the probe light beam, and the first light beam scanning device 22 is disposed downstream of the light emitter 21 in the optical path for receiving and reflecting the probe light beam. As shown in fig. 6, for one light emitter 21, a plurality of outgoing probe beams can be realized by the first beam scanning device 22.
As shown in fig. 6, the laser radar 2 further includes a receiving lens (not shown) for receiving a reflected light beam (echo light beam) from outside the laser radar, and converging or collimating the reflected light beam, and a photosensor 24, and the beam scanning apparatus further includes a second beam scanning apparatus 23, and the second beam scanning apparatus 23 is disposed between the receiving lens and the photosensor 24 and upstream of the photosensor 24, or the receiving lens is disposed between the second beam scanning apparatus 23 and the photosensor 24 and is configured to reflect the echo light beam onto the photosensor 24.
With the solution of fig. 6, with one light emitter 21, multiple outgoing light beams can be generated; with one detector 24, multiple radar return beams may be received. Thus, the number of light emitters and detectors can be greatly reduced, so that the overall size of the lidar can be significantly smaller. In addition, the swing angles of the first and second optical beam scanning devices 22 and 23 can be controlled to be completely synchronized. Therefore, according to the embodiment of the invention, the two sets of completely synchronous micro-motion mechanisms can expand or combine the incident light beam and the received light beam, so that a higher wiring harness is realized by fewer transceiver modules.
Fig. 7 shows a schematic structural diagram of the first optical beam scanning device 22 and the second optical beam scanning device 23 of the embodiment of fig. 6. As shown in fig. 7, the first light beam scanning device 22 and the second light beam scanning device 23 are juxtaposed, and are used for scanning and emitting the light beam of the light emitter 21, and receiving and reflecting the radar echo onto the detector 24, respectively. The mirror (TX mirror) of the first optical beam scanning device 22 and the mirror (RX mirror) of the second optical beam scanning device 23 may adopt a master-slave relationship, that is, only one of the mirrors is driven and controlled, and the other mirror uses the same driving signal mode. Alternatively, the two mirrors may be driven in an independent relationship, as two completely independent sets of devices.
One of the mirrors is shown in figure 7 for scanning emission of the probe beam and the other mirror is for receiving radar returns. Alternatively, a mirror (a beam scanning device) may be used for both scanning the transmitted probe beam and receiving the radar echo.
As shown in fig. 8, the present invention also relates to a control method 100 of the optical beam scanning apparatus described above, including:
in step S101, a target position of the mirror is acquired;
in step S102, the mirror is driven by the driving device;
in step S103, measuring the position and/or angle of the mirror by the measuring device;
in step S104, the position of the mirror is adjusted by the driving device according to the position and/or angle of the mirror.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (14)
1. A beam scanning apparatus usable with a lidar comprising:
a housing;
a mirror supported in the housing and movable within a preset range;
a measuring device disposed in the housing and configured to measure a position and/or an angle of the mirror;
a driving device disposed in the housing and configured to drive the mirror to move within the preset range according to a measurement result of the measuring device.
2. An optical beam scanning apparatus according to claim 1, wherein said measuring means includes a magnet, and a hall sensor disposed opposite said magnet, one of said magnet and said hall sensor being disposed on said mirror, the other being disposed on said housing, said hall sensor outputting a voltage value indicative of its distance from said magnet.
3. An optical beam scanning apparatus according to claim 2, further comprising a control unit coupled to the Hall sensor and receiving a voltage value output by the Hall sensor to determine a current position and/or angle of the mirror,
the control unit is coupled with the driving device and controls the driving device according to the current position and/or angle of the reflecting mirror.
4. An optical beam scanning apparatus according to claim 2 or 3, wherein the mirror has a rotation axis and is swingable around the rotation axis, and the measuring means comprises two sets of magnets and hall sensors, respectively, provided on both sides of the rotation axis.
5. An optical beam scanning apparatus according to claim 4, wherein the rotation axis of the mirror is in the form of a torsion beam.
6. An optical beam scanning apparatus according to claim 4, wherein the control unit determines the current position and/or angle of the mirror from the voltages output by the two Hall sensors.
7. An optical beam scanning apparatus according to any one of claims 1-2, wherein said driving means includes a magnet provided on said mirror and a coil provided on said housing, said coil being opposed to said magnet to drive said mirror.
8. An optical beam scanning apparatus according to claim 7, further comprising a reset device connected between the housing and the mirror to restore the mirror to its initial position when the coil is de-energized.
9. An optical beam scanning apparatus according to any one of claims 1 to 3, wherein the housing includes a limit portion to define a maximum range of motion of the mirror.
10. An optical beam scanning apparatus according to claim 1, wherein the measuring apparatus comprises a PSD position sensor disposed on the housing and a light source configured to emit a test beam toward a surface of the mirror, the test beam being reflected by the surface and incident on the PSD position sensor, and a current signal output by the PSD position sensor is indicative of an incident position of the test beam to determine the position and/or angle of the mirror.
11. A lidar comprising a beam scanning apparatus as claimed in any of claims 1-10.
12. The lidar of claim 11, further comprising at least one optical transmitter for transmitting a probe beam, wherein the beam scanning device comprises a first beam scanning device for reflecting the probe beam, the first beam scanning device being disposed in an optical path downstream of the optical transmitter for receiving and reflecting the probe beam.
13. The lidar of claim 12, further comprising a photosensor for receiving an echo beam, the beam scanning device further comprising a second beam scanning device disposed upstream of the photosensor and configured to reflect the echo beam onto the photosensor.
14. A control method of the optical beam scanning apparatus according to any one of claims 1 to 10, comprising:
acquiring a target position of the reflector;
driving the mirror by the driving means;
measuring, by the measuring device, a position and/or an angle of the mirror;
the position of the mirror is adjusted by the drive means in dependence on the position and/or angle of the mirror.
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| CN201911183193.8A CN112859048A (en) | 2019-11-27 | 2019-11-27 | Light beam scanning apparatus, laser radar including the same, and control method |
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| CN201911183193.8A CN112859048A (en) | 2019-11-27 | 2019-11-27 | Light beam scanning apparatus, laser radar including the same, and control method |
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Address after: No.2 building, no.468 xinlai Road, Jiading District, Shanghai, 201821 Applicant after: Shanghai Hesai Technology Co.,Ltd. Address before: No.2 building, no.468 xinlai Road, Jiading District, Shanghai, 201821 Applicant before: Shanghai Hesai Technology Co., Ltd |