JP2015052506A - Laser radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laser radar device achieving stable target detection while ensuring an S/N ratio of reflected light from a target object with respect to a radiated laser beam, and achieving target ranging with secure irradiation direction control and high accuracy based on the stable target detection.SOLUTION: Polarizers (#1) 12 and (#2) 15 and polarizer drive units (#1) 13 and (#2) 16 rotating the polarizers (#1) 12 and (#2) 15 to make polarization directions thereof variable are provided just in front of light-receiving passages of a reflected light receiver 14 and an imaging unit 17, respectively. The reflected light receiver 14 and the imaging unit 17 receive reflected light via their respective polarizers (#1) 12 and (#2) 15, a received light processing unit 22 and an image processing unit 25 at the later stages detect a target from the reflected light, and the polarizers (#1) 12 and (#2) 15 are rotated so that the polarization direction of each of the polarizers (#1) 12 and (#2) 15 matches a polarization direction of the reflected light to achieve a highest S/N ratio of the target at the time of detection.

Description

  Embodiments described herein relate generally to a laser radar device.

  The laser radar device measures the distance to the target object by, for example, irradiating the laser beam generated by the laser generator in the direction of the target object, receiving the reflected light at the light receiver, and performing a distance measurement process. To do. When the target object moves, for example, an imaging unit such as a camera is further provided, and the irradiation direction of the laser light follows the direction of the target object based on the target object imaged by the imaging unit and its reflected light. In this manner, the directivity directions of the laser generator and the light receiver are driven and controlled. Then, the moving target object is surely irradiated with laser light, and the reflected light is continuously received, whereby the distance to the target object is continuously acquired.

Japanese Patent Laid-Open No. 1-156690

  By the way, in this type of laser radar apparatus, in consideration of safety and the like, laser light in the infrared region is often adopted as the laser light to be used. However, the target object often exists in a background including infrared rays. In addition, the target object itself may emit a lot of infrared rays. In particular, when the infrared level from the background of the target object is high, or when the infrared emission level of the target object itself is high, these become noise and the S / N ratio (signal-to-noise ratio) of the reflected light decreases. . Furthermore, when the reflected light itself is weak, the S / N ratio is further deteriorated.

  For this reason, it is impossible to secure a sufficient S / N ratio of the reflected light in any of the reflected light in the image acquired by the imaging unit and the reflected light received by the light receiving unit. In some cases, it is difficult to discriminate the original reflected light from the laser beam and the other, and detection of the target object and distance measurement may not be stable.

  The embodiment of the present invention has been made in consideration of the above-described circumstances, and performs stable target detection while ensuring an S / N ratio of reflected light from a target object with respect to irradiated laser light, and based on it. An object of the present invention is to provide a laser radar device that enables reliable control of an irradiation direction and distance measurement of a target object with good accuracy.

  In order to achieve the above object, the laser radar device according to the first embodiment irradiates a laser beam toward a target, and continues the distance from the target while controlling the irradiation direction based on the reflected light. A laser radar device for obtaining a laser light generator for generating and irradiating linearly polarized laser light, a first polarizing plate that transmits light in a predetermined polarization direction, and rotating the first polarizing plate A first polarizing plate drive control unit that changes a polarization direction of the first polarizing plate, receives reflected light of the laser light through the first polarizing plate, detects a target from the reflected light, and A distance measurement processing unit that acquires a distance, a second polarizing plate that transmits light in a predetermined polarization direction, and a second polarizing plate drive control that rotates the second polarizing plate to change the polarization direction. And a predetermined range with respect to the irradiation direction of the laser beam generator An image obtained by imaging the field through the second polarizing plate is acquired, the target is detected from the reflected light of the laser light imaged in the image, and the position information in the image of the target is used. An irradiation direction control unit that controls the irradiation direction of the laser light emitted from the laser light generation unit, and the first polarizing plate drive control unit sets the light reception level of the reflected light from the target in the distance measurement processing unit. The first polarizing plate is rotated on the basis thereof to change the polarization direction thereof, and the second polarizing plate drive control unit is configured to change the polarization direction based on the light reception level of the reflected light from the target in the irradiation direction control unit. The second polarizing plate is rotated to change the polarization direction.

  The laser radar device according to the second embodiment is a laser radar device that irradiates laser light toward a target and continuously acquires the distance from the target while controlling the irradiation direction based on the reflected light. A laser beam generator for generating and irradiating linearly polarized laser light, a polarizing plate that transmits light of a predetermined polarization direction, and a polarizing plate drive control that rotates the polarizing plate to change its polarization direction. And a distance measurement processing unit that receives the reflected light of the laser light through the polarizing plate, detects a target from the reflected light, and obtains a distance from the target, and an irradiation direction of the laser light generating unit An image obtained by imaging the field of view within a predetermined range through the polarizing plate is acquired, the target is detected from the reflected light of the laser light imaged in the image, and based on position information in the target image The above An irradiation direction control unit that controls the irradiation direction of the laser light emitted from the laser light generation unit, the polarizing plate drive control unit, the light reception level of the reflected light from the target in the distance measurement processing unit, The polarization direction is varied by rotating the polarizing plate based on one or both of the received light level of the reflected light from the target in the irradiation direction control unit.

The block diagram which shows the structure of the 1st Example of the laser radar apparatus which concerns on this embodiment. 3 is a flowchart for explaining the operation of the laser radar device 1 illustrated in FIG. 1. The block diagram which shows the structure of the 2nd Example of the laser radar apparatus which concerns on this embodiment. FIG. 4 is a flowchart for explaining the operation of the laser radar apparatus 2 illustrated in FIG. 3. FIG.

  The best mode for carrying out the laser radar device according to the present embodiment will be described below with reference to FIGS.

  FIG. 1 is a block diagram showing a configuration of a first example of the laser radar apparatus according to the present embodiment. As illustrated in FIG. 1, the laser radar device 1 includes a light transmitting / receiving unit 10, a control unit 20, and a driving unit 30. The light transmitting / receiving unit 10 emits and irradiates linearly polarized laser light at a predetermined timing, receives the reflected light through a polarizing plate having a variable polarization direction, converts the reflected light into an electric signal, and transmits the electric signal to the control unit 20. Further, the driving unit 30 described later is driven so that the direction of laser light transmission / reception is directed toward the target direction.

  The control unit 20 controls the laser light emission timing of the light transmitting / receiving unit 10 and, based on the reflected light signal (electrical signal) received from the light transmitting / receiving unit 10 and received through the polarizing plate, The drive unit 30 is controlled so that the irradiation is continued, and the distance from the target is continuously acquired while the light transmitting / receiving unit 10 is directed in the target direction. In this embodiment, as will be described later, focusing on the target S / N ratio in the reflected light received through the polarizing plate, the polarization of the light transmitting / receiving unit 10 is optimized so that the target S / N ratio is the best. Control the polarization direction of the plate. Based on the control from the control unit 20, the drive unit 30 drives the light transmitting / receiving unit 10 around two axes, the azimuth angle direction and the elevation angle direction, and directs the direction of light transmission / reception in a target direction.

  Next, the configuration of the light transmitting / receiving unit 10 and the control unit 20 will be described in detail. First, the light transmitting / receiving unit 10 includes a laser light emitting unit 11, a polarizing plate (# 1) 12, a polarizing plate driving unit (# 1) 13, a reflected light receiver 14, a polarizing plate (# 2) 15, a polarizing plate driving unit ( # 2) 16 and the imaging unit 17 are provided. The laser light emitting unit 11 emits linearly polarized laser light based on a light emission timing signal from a light emission timing control unit 21 in the control unit 20 described later, and irradiates it in the target direction. In this embodiment, the laser beam is emitted in a pulse shape.

  A polarizing plate (# 1) 12 as a first polarizing plate is provided immediately before the light receiving path (not shown) of the reflected light receiver 14, reflected light with respect to the laser light emitted from the laser light emitting unit 11, and Transmits light in a predetermined polarization direction from incoming light including background light. The polarizing plate drive unit (# 1) 13 rotates the polarizing plate (# 1) 12 in accordance with the drive signal from the polarizing plate drive signal generation unit (# 1) 24 in the control unit 20 to change the polarization direction. Variable setting. The reflected light receiver 14 receives the light transmitted through the polarizing plate (# 1) 12, converts it into an electrical signal, and sends it to the light receiving processor 22 in the controller 20.

  A polarizing plate (# 2) 15 as a second polarizing plate is provided immediately before a light receiving path (not shown) of the imaging unit 17 and is irradiated from the laser light emitting unit 11 in the same manner as the polarizing plate (# 1) 12. The light having a predetermined polarization direction is transmitted from the reflected light with respect to the laser beam and the incoming light including the background light. The polarizing plate drive unit (# 2) 16 rotates the polarizing plate (# 2) 16 and changes the polarization direction by the drive signal from the polarizing plate drive signal generation unit (# 2) 26 in the control unit 20. Set. The imaging unit 17 is, for example, a camera or the like, and has a two-dimensional field of view in a predetermined range with respect to the irradiation direction of the laser light emitting unit 11 and acquires a two-dimensional image obtained by imaging this field of view through the polarizing plate (# 2) 15. Then, it is sent as an image signal to the image processing unit 25 in the control unit 20.

  Next, the control unit 20 includes a light emission timing control unit 21, a light reception processing unit 22, a distance measurement analysis unit 23, a polarizing plate driving signal generation unit (# 1) 24, an image processing unit 25, and a polarizing plate driving signal generation unit (# 2) 26 and a drive signal generator 27 are provided. The light emission timing control unit 21 generates a light emission timing signal for causing the laser light emission unit 11 to emit pulses, and sends the light emission timing signal to the laser light emission unit 11 and the distance measurement analysis unit 23.

  The light reception processing unit 22 detects the target from the reflected wave signal received from the reflected light receiver 14, notifies the detection timing to the distance analysis unit 23, and sets the target S in the reflected signal at the time of target detection. The / N ratio is acquired and sent to the polarizing plate drive signal generator (# 1) 24. The distance measurement analysis unit 23 calculates the distance to the detected target based on the light emission timing signal from the light emission timing control unit 21 and the target detection timing signal from the light reception processing unit 22, and outputs the result as a distance measurement result. .

  The polarizing plate drive signal generation unit (# 1) 24 receives the target S / N ratio acquired by the light reception processing unit 22, and in the reflected wave signal from the reflected light receiver 14, the target S / N ratio. Is generated, and a drive signal for setting the polarization direction of the polarizing plate (# 1) 12 is generated and sent to the polarizing plate drive unit (# 1) 13. The image processing unit 25 receives the image signal from the imaging unit 17 to detect a target, acquires position information within the visual field of the detected target, and sends it to the drive signal generation unit 27. Further, the target S / N ratio in the image signal at the time of target detection is acquired and sent to the polarizing plate drive signal generation unit (# 2) 26.

  The polarizing plate drive signal generation unit (# 2) 26 receives the target S / N ratio acquired by the image processing unit 25, and the target S / N ratio is the best in the image signal from the imaging unit 17. Thus, a drive signal for setting the polarization direction of the polarizing plate (# 2) 15 is generated and sent to the polarizing plate drive unit (# 2) 16. The drive signal generation unit 27 receives the target position information in the field of view of the imaging unit 17 acquired by the image processing unit 25, and sets the drive unit 30 to an azimuth angle so that the light transmitting / receiving unit 10 is oriented in the target direction. A drive signal for driving in the direction and the elevation direction is generated and sent to the drive unit 30.

  In the configuration described above, the laser light generation unit 11 and the light emission timing control unit 21 correspond to the laser light generation unit. A polarizing plate (# 1) 12 corresponds to the first polarizing plate. The first polarizing plate drive control unit corresponds to the polarizing plate drive unit (# 1) 13 and the polarizing plate drive signal generation unit (# 1) 24. The distance measurement processing unit corresponds to the reflected light receiver 14, the light reception processing unit 22, and the distance measurement analysis unit 23. A polarizing plate (# 2) 15 corresponds to the second polarizing plate. The second polarizing plate drive control unit corresponds to a polarizing plate drive unit (# 2) 16 and a polarizing plate drive signal generation unit (# 2) 26. The imaging unit 17, the image processing unit 25, the drive signal generation unit 27, and the drive unit 30 correspond to the irradiation direction control unit.

  The laser light generation unit irradiates linearly polarized laser light, and the distance measurement processing unit detects the distance from the reflected light that has passed through the first polarizing plate and measures the distance. The plate drive control unit rotates the first polarizing plate and changes the polarization direction so that the target S / N ratio in the reflected light is the best. Thereby, the distance measurement processing unit can measure the target under a good S / N ratio.

  The irradiation direction control unit detects the target from the reflected light that has passed through the second polarizing plate to control the irradiation direction of the laser light, and the second polarizing plate drive control unit includes the second polarizing plate. The plate is rotated and its polarization direction is varied so that the target S / N ratio in the reflected light is the best. Thus, the irradiation direction control unit can control the irradiation direction of the laser light based on the target direction acquired under a good S / N ratio.

  Next, the operation of the laser radar apparatus 1 of the present embodiment configured as described above will be described with reference to the flowcharts of FIG. 1 and FIG. In the following description, as an example, the target is a moving target, and the distance is set while controlling the irradiation direction as the target moves so that the moving target is continuously irradiated with laser light. The scenes that are acquired continuously are taken up and explained. FIG. 2 is a flowchart for explaining the operation of the laser radar apparatus 1.

  When the operation start of the laser radar apparatus 1 is instructed, each part in the apparatus is initialized and necessary initial settings are made. This initial setting includes setting the polarization directions of the polarizing plate (# 1) 12 and the polarizing plate (# 2) 15 (ST21). Next, based on the light emission timing signal from the light emission timing control unit 21, linearly polarized laser light is emitted in the target direction from the laser light emitting unit 11 of the light transmitting / receiving unit 10 (ST22).

  The reflected light with respect to the irradiated laser light is received through the polarizing plate (# 1) 12 and the polarizing plate (# 2) 15. In this embodiment, since the target moves, the reflected laser beam is received, and the laser radar device 1 controls the irradiation direction so that the laser beam is continuously irradiated to the target. While continuing to get the distance to the target. That is, the operation for controlling the irradiation direction and the operation for ranging are executed in parallel. Here, the operation for the irradiation direction control is shown as an operation step of ST23 in FIG. 2, and the operation for distance measurement is shown as an operation step of ST24. Hereinafter, these two operation steps will be described.

  First, the operation step of ST23 for controlling the irradiation direction will be described. The reflected light from the target including background light is imaged by the imaging unit 17 through the polarizing plate (# 2) 15. At this time, the light transmitted through the polarizing plate (# 2) 15 is light having the same polarization direction as that of the polarizing plate (ST231). The imaging unit 17 has a two-dimensional field of view in the laser light irradiation direction, and images the field of view including the target and its reflected light through the polarizing plate (# 2) 15, and acquires the two-dimensional image. . In imaging, for example, imaging can be performed by applying a distance gate set based on distance information to the target. The acquired two-dimensional image is sent to the image processing unit 25 as an image signal (ST232).

  Next, the image processor 25 detects a target from the image signal (two-dimensional). Then, based on the detected position in the target image, target position information in the captured field of view is acquired and sent to the drive signal generation unit 27 (ST233). At the same time, the S / N ratio of the target at the time of target detection in the image signal is also acquired and sent to the polarizing plate drive signal generator (# 2) 26 (ST234).

  Next, in the polarizing plate drive signal generation unit (# 2) 26, the value is the best considering the polarization direction of the polarizing plate (# 2) 15 based on the target S / N ratio from the image processing unit 25. It is determined whether or not. That is, the target is detected from the reflected light received through the polarizing plate (# 2) 15, but the reflected light from the target and the polarization direction of the polarizing plate (# 2) 15 do not match. When the target is detected by the image processing unit 25, a sufficient S / N ratio may not be ensured. For this reason, it is determined whether or not the reflected light from the target is received at a high level and the other background light is received at a low level and the S / N ratio is the best (ST235).

  If it is determined that it is not the best (N in ST235), a driving signal is sent from the polarizing plate driving signal generation unit (# 2) 26 to the polarizing plate driving unit (# 2) 16, and the polarizing plate (# 2) The polarizing plate (# 2) 15 is rotated by the polarizing plate driver (# 2) 16 so that the polarization direction of 15 and the polarization direction of the reflected light from the target are better matched. As a result, the image processing unit 25 can detect the target in a state in which the best S / N ratio is secured with respect to the target, and can stably perform subsequent processing based on the target detection result. (ST236).

  Further, in parallel with the control operation of the polarization direction of the polarizing plate (# 2) 15 based on the target S / N ratio, the drive signal generation unit 27 is within the field of view of the imaging unit 17 acquired by the image processing unit 25. Based on the target position information at, the irradiation direction is controlled so that the laser beam from the laser beam emitter 11 is continuously irradiated to the target. That is, as the target moves, the position of the target in the field of view of the imaging unit 17 changes, but the drive signal generation unit 27 moves the light transmission / reception unit 10 to the azimuth and elevation so as to follow the change in position. A drive signal for driving in the direction is generated. The generated drive signal is sent to the drive unit 30, and the light transmitting / receiving unit 10 is driven by the drive unit 30 so as to be directed in the target direction.

  In this operation step, position information in the target visual field sent from the image processing unit 25 is used as input information. This position information is acquired under a good S / N ratio in the above-described operation steps ST231 to ST236. Thereby, the irradiation direction can be controlled more stably and reliably (ST237).

  Next, the operation step of ST24, which is an operation step for performing distance measurement, will be described. The reflected light from the target including the background light is received by the reflected light receiver 14 through the polarizing plate (# 1) 12. At this time, the light transmitted through the polarizing plate (# 1) 12 is light having the same polarization direction as that of the polarizing plate (ST241). The reflected light receiver 14 receives the reflected light through the polarizing plate (# 1) 12 and converts it into an electrical signal. The reflected wave converted into the electric signal is sent to the light receiving processing unit 22 as a reflected wave signal (ST242).

  Next, the light receiving processing unit 22 detects a target from the reflected wave signal. Then, the detection timing of the target in the reflected wave signal is acquired and notified to the ranging analysis unit 23. At the same time, the S / N ratio of the target at the time of target detection in the reflected wave signal is also acquired and sent to the polarizing plate drive signal generator (# 1) 24 (ST244).

  Next, the polarizing plate drive signal generation unit (# 1) 24 receives the target S / N ratio from the light receiving processing unit 22, and the value is the best considering the polarization direction of the polarizing plate (# 1) 12. It is determined whether or not (ST245). If it is determined that it is not the best (N in ST245), a driving signal is sent from the polarizing plate driving signal generation unit (# 1) 24 to the polarizing plate driving unit (# 1) 13, and the polarizing plate (# 1) ) The polarizing plate (# 1) 12 is rotated by the polarizing plate driver (# 1) 13 so that the polarization direction of 12 and the polarization direction of the reflected light from the target are better matched. Thereby, the light receiving processing unit 22 can detect a stable target in a state in which the best S / N ratio is ensured with respect to the target, and in distance measurement in the subsequent stage based on the target detection result, Good accuracy can be maintained (ST246).

  In parallel with the control operation of the polarization direction of the polarizing plate (# 1) 12 based on the target S / N ratio, the distance measurement analysis unit 23 performs target distance measurement. That is, the distance to the detected target is calculated based on the light emission timing signal from the light emission timing control unit 21 and the target detection timing signal notified from the light reception processing unit 22. The target detection timing signal notified from the light receiving processing unit 22 used in this distance measurement is the target detection timing signal detected by the light receiving processing unit 22 under a good S / N ratio by the operation steps of ST245 and ST246. Since the detection timing is less uncertain and more accurate, the distance measurement result also has good accuracy. The calculated distance measurement result is output to a subsequent device or the like (ST247).

  Thereafter, until the end of the operation is instructed, the target is irradiated with linearly polarized laser light (ST22), and the target is continuously irradiated with the laser light even when the target is moved. While controlling the irradiation direction (ST23), the operation of continuously acquiring the distance from the target (ST24) is repeated (ST25).

  As described above, in the laser radar device 1 according to the present embodiment, the polarizing plate (# 1) 12 and the polarizing plate (# 2) are provided immediately before the reflected light receiver 14 and the light receiving path of the imaging unit 17, respectively. The polarizing plate driving unit (# 1) 13 and the polarizing plate driving unit (# 2) 16 are arranged corresponding to the respective polarizing plates. At the same time, the reflected light receiver 14 and the imaging unit 17 receive reflected light with respect to the irradiated linearly polarized laser light through the polarizing plates. The target is detected by the light receiving processing unit 22 and the image processing unit 25 from the reflected light received through the polarizing plate, and the target S / N ratio at the time of detection is optimized, that is, the polarizing plate. The polarizing plate driving unit (# 1) 13 and the polarizing plate driving unit (# 2) 16 cause the polarizing plate (# 1) 12 and the polarizing plate (#) to match the polarization direction of the reflected light. # 2) Each of 15 is rotated.

  As a result, the light reception processing unit 22 and the image processing unit 25 can perform stable target detection in a favorable environment in which the target S / N in the reflected light is sufficiently secured. Also, since the level of background light, etc., whose polarization direction differs from that of reflected light is greatly reduced by passing through the polarizing plate, the level of reflected light and background light is particularly high when detecting targets at long distances. Even when a target is detected while the difference is small, the level of reflected light from the target is not lowered, the level of other background light is lowered, and the S / N ratio at the time of target detection is secured. Therefore, reliable target detection can be performed.

  Therefore, based on the result of such stable target detection, it is possible to measure the target with good accuracy while reliably directing the irradiation direction of the laser light in the target direction.

  FIG. 3 is a block diagram showing a configuration of a second example of the laser radar apparatus according to the present embodiment. About this 2nd Example, the part same as each part of the 1st Example shown in FIGS. 1-2 is shown with the same code | symbol or a name, The detailed description is abbreviate | omitted. The difference between the second embodiment and the first embodiment is that, in the first embodiment, two polarizing plates and their polarization directions are associated with the reflected light receiver 14 and the imaging unit 17, respectively. The reflected light receiver 14 and the imaging unit 17 receive the reflected light through the corresponding polarizing plates, and the polarization direction of each polarizing plate in the subsequent stage. In the second embodiment, a common polarizing plate and a polarizing plate drive control unit are provided for the reflected light receiver 14 and the image pickup unit 17. The reflected light receiver 14 and the imaging unit 17 receive reflected light through the common polarizing plate and perform various processes at the subsequent stage. Hereinafter, the difference will be mainly described with reference to the above-described FIGS. 1 to 2, the block diagram of FIG. 3, and the flowchart of FIG. 4.

  As illustrated in FIG. 3, the laser radar device 2 includes a light transmitting / receiving unit 10 a, a control unit 20 a, and a driving unit 30. The light transmitting / receiving unit 10a emits and irradiates linearly polarized laser light at a predetermined timing, receives the reflected light through a polarizing plate having a variable polarization direction, converts the reflected light into an electric signal, and transmits the electric signal to the control unit 20a. Further, the driving unit 30 drives the laser beam so that the light transmission / reception direction is directed to the target direction.

  The control unit 20a controls the laser light emission timing of the light transmitting / receiving unit 10a, and based on the reflected light signal (electric signal) received from the light transmitting / receiving unit 10a and received through the polarizing plate, the laser light to the target The drive unit 30 is controlled so that the irradiation is continued, and the distance from the target is continuously acquired while the light transmitting / receiving unit 10a is directed in the target direction. Further, the polarization direction of the polarizing plate provided in the light transmitting / receiving unit 10a is controlled. Based on the control from the control unit 20a, the drive unit 30 drives the light transmitting / receiving unit 10a around two axes of the azimuth angle direction and the elevation angle direction, and directs the direction of light transmission / reception in a target direction.

  Next, the configuration of the light transmitting / receiving unit 10a and the control unit 20a will be described in detail. First, the light transmitting / receiving unit 10 a includes a laser light emitting unit 11, a reflected light receiver 14, an imaging unit 17, a polarizing plate 18, and a polarizing plate driving unit 19. Since the laser light emitting unit 11, the reflected light receiver 14, and the imaging unit 17 are the same as those in the first embodiment, description thereof is omitted.

  The polarizing plate 18 is provided in common immediately before the light receiving path of the reflected light receiver 14 and the light receiving path of the image pickup device 17 and includes reflected light and background light with respect to the laser light emitted from the laser light emitting unit 11. The light having a predetermined polarization direction is transmitted from the transmitted light. The polarizing plate driving unit 19 rotates the polarizing plate 18 and variably sets the polarization direction by a driving signal from a polarizing plate driving signal generation unit 28 in the control unit 20a described later.

  Next, the control unit 20a includes a light emission timing control unit 21, a light reception processing unit 22, a distance measurement analysis unit 23, an image processing unit 25, a drive signal generation unit 27, and a polarizing plate drive signal generation unit 28. The light emission timing control unit 21, the light reception processing unit 22, the distance measurement analysis unit 23, the image processing unit 25, and the drive signal generation unit 27 are the same as those in the first embodiment, and thus description thereof is omitted.

  The polarizing plate drive signal generation unit 28 sets the polarization direction of the polarizing plate 18 based on the light reception level of the reflected light when the light receiving processing unit 22 and the image processing unit 25 detect the target from the reflected light. A drive signal is generated and sent to the polarizing plate driver 19. In the present embodiment, the S / N ratio of the target acquired at the time of target detection is received from both the light receiving processing unit 22 and the image processing unit 25, and for example, the S / N calculated by further weighting them. The polarization direction of the polarizing plate 18 is set so that the ratio is the best. Since both the light receiving processing unit 22 and the image processing unit 25 detect the target based on the reflected light transmitted through the same polarizing plate 18, at the time of target detection with respect to the change in the polarization direction of the polarizing plate 18. When there is no significant difference between the two in the target S / N ratio, the drive signal can be generated using the S / N ratio acquired in either one.

  Next, the operation of the laser radar device 2 of the present embodiment configured as described above will be described with reference to the flowcharts of FIGS. 1 to 3 and FIG. In the following description, the same situation as in the first embodiment, that is, while controlling the irradiation direction with the movement of the target so that the moving target is continuously irradiated with the laser beam, The scene where the distance is continuously acquired is taken up, and the operation similar to that of the first embodiment will be briefly described. FIG. 4 is a flowchart for explaining the operation of the laser radar device 2.

  After the start of the apparatus operation, initial setting is performed for each part in the apparatus. This initial setting includes setting of the polarization direction of the polarizing plate 18 (ST41). Next, on the basis of the light emission timing signal from the light emission timing control unit 21, linearly polarized laser light is emitted in the target direction from the laser light emitting unit 11 of the light transmitting / receiving unit 10a (ST42), and the reflected light is applied to the polarizing plate. 18, and is received by each of the imaging unit 17 and the reflected light receiver 14 (ST43). As in the first embodiment, the operation for controlling the irradiation direction and the operation for distance measurement are executed in parallel.

  That is, as an operation for controlling the irradiation direction, the position in the target image is specified by the image processing unit 25 from the image of the reflected light received by the imaging unit 17 and notified to the drive signal generation unit 27. At the same time, the target S / N ratio is acquired and sent to the polarizing plate drive signal generator 28 (ST232 to ST234).

  On the other hand, as an operation for distance measurement, a target is detected in the light reception processing unit 22 from the reflected wave received by the reflected light receiver 14, and the target detection timing in the reflected wave signal is detected by the distance measurement analysis unit. 23, the target S / N ratio is acquired and sent to the polarizing plate drive signal generator 28 (ST242 to ST244).

  Next, in the polarizing plate drive signal generation unit 28, based on the target S / N ratio received from the image processing unit 25 and the target S / N ratio received from the light receiving processing unit 22, those values are converted into polarizing plates. It is determined whether or not it is the best in consideration of the 18 polarization directions (ST44). If it is determined that it is not the best (N in ST44), a driving signal is sent from the polarizing plate driving signal generation unit 28 to the polarizing plate driving unit 19, and the polarization direction of the polarizing plate 18 and the reflected light from the target. The polarizing plate 18 is rotated by the polarizing plate driving unit 19 so that the polarization direction of the polarizing plate is better matched. As a result, both the light receiving processing unit 22 and the image processing unit 25 can perform reliable target detection in a state where the best S / N ratio is secured with respect to the target (ST45).

  In the determination in the operation step of ST44 and the subsequent generation of the polarizing plate driving signal, in this embodiment, the target S / N ratio is received from both the light receiving processing unit 22 and the image processing unit 25, and For example, the polarizing plate 18 is rotated so that the average value thereof, the value calculated by weighting each of the values, and the like are the best, and this is used by using the target S / N ratio from either one. It may be configured.

  In addition, the target detection is performed under a better S / N ratio by the control operation of the polarization direction of the polarizing plate 18, and the more reliable target detection results are used. The drive signal generation unit 27 generates a drive signal for directing the light transmitting / receiving unit 10a in the target direction and sends the drive signal to the drive unit 30. The distance measurement analysis processing unit 23 performs target distance measurement. Is called. After that, until the end of the operation is instructed, the target is irradiated with linearly polarized laser light, and the reflected light is received through the polarizing plate, and the polarization direction of the polarizing plate is variably set to achieve the best. While receiving the reflected wave from the target at the S / N ratio, the control of the irradiation direction with respect to the moving target and the target ranging operation steps are repeated (ST46).

  As described above, in the laser radar device 2 of the present embodiment, the common reflected light receiver 14 and the imaging unit 17 are provided with one polarizing plate and a polarizing plate drive control unit, and the reflected light receiver 14 and Both of the imaging units 17 receive reflected light through the polarizing plate provided in common. Then, the light receiving processing unit 22 and the image processing unit 25 detect the target from the received reflected light, and the target S / N ratio at the time of detection is optimized, that is, the polarization direction of the polarizing plate. The polarizing plate 18 is rotated by the polarizing plate drive signal generation unit 28 and the polarizing plate drive unit 19 so that the polarization direction of the reflected light matches the polarization direction.

  As a result, as in the first embodiment, the S / N ratio at the time of target detection can be ensured and reliable target detection can be performed, while the direction of laser light irradiation is reliably directed in the target direction. The target can be measured with good accuracy. In the second embodiment, the reflected light receiver 14 and the imaging unit 17 receive the reflected light using a common polarizing plate, for example, both are disposed close to each other. In the case where there is no significant difference in the polarization direction of the reflected light received at, the polarizing plate and the mechanism for changing the polarization direction can be configured more simply than in the first embodiment, The entire device can be reduced in size and weight.

  Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1, 2, Laser radar apparatus 10, 10a Transmission / reception part 11 Laser light emission part 12,15,18 Polarizing plate 13,16,19 Polarizing plate drive part 14 Reflected light receiver 17 Imaging part 20, 20a Control part 21 Light emission timing control part 22 Light receiving processing unit 23 Distance analysis units 24, 26, 28 Polarizing plate driving signal generating unit 25 Image processing unit 27 Driving signal generating unit 30 Driving unit

Claims (6)

A laser radar device that irradiates a laser beam toward a target and continuously acquires the distance from the target while controlling the irradiation direction based on the reflected light,
A laser beam generator for generating and irradiating linearly polarized laser beam;
A first polarizing plate that transmits light of a predetermined polarization direction;
A first polarizing plate drive control unit that rotates the first polarizing plate to change the polarization direction;
A reflected light of the laser beam is received through the first polarizing plate, a target is detected from the reflected light, and a distance measurement processing unit that acquires a distance from the target;
A second polarizing plate that transmits light in a predetermined polarization direction;
A second polarizing plate drive control unit that rotates the second polarizing plate to change the polarization direction;
An image obtained by imaging the field of view within a predetermined range with respect to the irradiation direction of the laser light generator through the second polarizing plate is acquired, and the target is detected from the reflected light of the laser light imaged in the image, and this An irradiation direction control unit that controls the irradiation direction of the laser light emitted from the laser light generation unit, based on position information in the target image;
The first polarizing plate drive control unit rotates the first polarizing plate based on the received light level of the reflected light from the target in the distance measurement processing unit to change the polarization direction, and the second polarizing plate driving control unit The polarizing plate drive control unit of the laser radar device rotates the second polarizing plate based on the received light level of the reflected light from the target in the irradiation direction control unit to vary the polarization direction. .   The first polarizing plate drive control unit and the second polarizing plate drive control unit are both based on the target S / N ratio (signal-to-noise ratio) in the reflected light received respectively. 2. The laser radar device according to claim 1, wherein the polarization direction is varied by rotating the corresponding first polarizing plate or second polarizing plate. 3.   3. The laser radar device according to claim 1, wherein the laser beam generation unit generates the linearly polarized laser beam in a pulse shape. 4. A laser radar device that irradiates a laser beam toward a target and continuously acquires the distance from the target while controlling the irradiation direction based on the reflected light,
A laser beam generator for generating and irradiating linearly polarized laser beam;
A polarizing plate that transmits light of a predetermined polarization direction;
A polarizing plate drive control unit that rotates the polarizing plate to change the polarization direction;
A reflected light of the laser beam is received through the polarizing plate, a target is detected from the reflected light, and a distance measurement processing unit that acquires a distance from the target;
An image obtained by imaging through the polarizing plate within a predetermined field of view with respect to the irradiation direction of the laser light generation unit is acquired, and the target is detected from the reflected light of the laser light imaged in the image, and the image of the target An irradiation direction control unit that controls the irradiation direction of the laser light emitted from the laser light generation unit, based on the position information in the inside,
The polarizing plate drive control unit is based on one or both of a light reception level of reflected light from the target in the distance measurement processing unit and a light reception level of reflected light from the target in the irradiation direction control unit. A laser radar device characterized in that a polarizing plate is rotated to change a polarization direction thereof.   The polarizing plate drive control unit includes the target S / N ratio (signal-to-noise ratio) in the reflected light received by the distance measurement processing unit, and the target in the reflected light received by the irradiation direction control unit. 5. The laser radar device according to claim 4, wherein the polarization direction is varied by rotating the polarizing plate based on one or both of the S / N ratio (signal to noise ratio).   The laser radar device according to claim 4, wherein the laser light generation unit generates the linearly polarized laser light in a pulse shape.

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