JP2008241273A - Laser radar device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser radar device and its control method capable of enhancing spatial resolution of a measuring object existing at a long distance or capable of enhancing spatial resolution of a specific object more than conventional resolution even at a short distance, while minimizing an increase in a load of a numerical arithmetic operation and an increase in required measuring time. <P>SOLUTION: This laser radar device has a laser oscillator 12, a light projector 14, a light receiver 16, a distance computing element 18 and a controller 20. A scanning pitch of a laser beam (a projection laser beam 2) scanning toward a measuring area, is changed based on distance data 9 provided by the distance computing element 18. An angle pitch of the projection laser beam 2 spatially scanning toward a predetermined measuring area, is changed by a change in the scanning pitch of the projection laser beam 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser radar apparatus that increases the spatial resolution of a measurement object at a long distance or increases the spatial resolution of a specific object even at a short distance, and a control method thereof.

A laser radar device is a device that projects a laser beam onto a measurement object, receives reflected light, and detects the distance to the object, the shape of the object, and the like from the time difference between the light projection and the light reception.
The laser radar device projects a pulsed laser beam at a constant cycle or projects a laser beam modulated at a fixed cycle, and receives and reflects the reflected light from the measurement object and transmits and receives the time difference And calculating means for calculating the distance from. By combining an optical one-dimensional or two-dimensional scanning mechanism such as a fine MEMS mirror, a polygon scanner, or a galvano scanner with a laser projector, two-dimensional or three-dimensional measurement of a measurement object is possible.

Conventional laser radar devices are disclosed in Patent Documents 1 to 3, for example.
Patent Document 1 aims at a laser radar device that can precisely measure the degree of depolarization by a scatterer, is easy to adjust and calculate, and is less likely to cause errors.

  This device is a laser radar device 50 that remotely measures the physical properties of a minute scatterer in the atmosphere, and as shown in FIG. 4, a laser device 54 that emits a laser beam 51 to the scatterer 52, and a scatterer 52. Is provided with a detection device 55 for detecting the Mie scattered light 53 and a calculation device 56 for calculating the degree of depolarization of the scatterer 52, and the light detector of the detection device 55 is parallel to the orthogonal plane of the polarization plane of the laser light 51. The intensity of the Mie scattered light is sometimes measured, and the arithmetic unit 56 calculates the degree of depolarization from the output ratio between the orthogonal time and the parallel time.

  Patent document 2 aims at optimizing the performance of a wide-angle laser radar device according to driving conditions, environmental conditions, and the like, and a wide-angle laser radar device with high safety.

  As shown in FIG. 5, this apparatus receives the reflected light, which is obtained by changing the pulsed laser light transmitted from the light transmitting unit 61 on the reflector, by the light receiving unit 63 including a plurality of light receiving elements 62, and transmits the pulsed laser light. When the distance / direction detector 64 measures the time difference from when the reflected light is received and the distance and direction from the position of the light receiving element that receives the reflected light to the reflector, the state of the vehicle or the state outside the vehicle is determined. Based on the output of the detecting means 65 to be detected, the combination of the plurality of light receiving elements is controlled by the light receiving element combination control means 66 and 67, and the outputs of the combined light receiving elements are added by the adding means 68, and this added output This measures the distance and direction to the reflector.

  Patent Document 3 is an apparatus that acquires three-dimensional image information of a measurement object by irradiating the measurement object with laser light and receiving reflected light from the measurement object, and uses a method that is different from a conventional system. It aims at acquiring a three-dimensional image at high speed using it.

  As shown in FIG. 6, the three-dimensional image acquisition apparatus includes a laser light emitting unit 70 that time-modulates the light intensity of laser light in accordance with a modulation signal having a predetermined frequency and irradiates the measurement object, and reflects the measurement object. Photoelectric converter 71 that receives the converted laser light and converts it into an electrical signal, and photoelectrically converts the reflected light of the laser light from the measurement object by controlling the reflective surface of the micromirror to a predetermined direction and turning it on. 3 of the measurement object using the micromirror array spatial modulation element 73 guided to the light receiving surface of the detector 72, the phase shift information with respect to the modulation signal and the position information of the ON micromirror in the received electrical signal of the laser beam. A data processing unit for obtaining dimension position information.

Japanese Patent No. 3567949, “Laser Radar Device” JP-A-7-191148, “Wide-angle laser radar device” Japanese Patent Application Laid-Open No. 2005-351851, “3D Image Information Acquisition Device”

In the above-described conventional laser radar device, there is a problem that the spatial resolution in the horizontal and vertical directions becomes coarser as the distance to the measurement object increases.
In order to solve this problem, if the spatial resolution in the distance is set finely by shortening the laser projection period, the number of measurement points per unit time increases. (For example, CPU) load increases.
Further, if the spatial resolution is set finely by reducing the scanner speed, there is a problem that the time required for measurement becomes long.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to increase the spatial resolution of a measurement object at a long distance while minimizing an increase in numerical calculation load and an increase in required measurement time, or even at a short distance. It is an object of the present invention to provide a laser radar device and a control method therefor that can increase the spatial resolution of a specific object more than ever.

According to the present invention, a laser oscillator that oscillates or modulates laser light at a predetermined period;
A projector that projects light while spatially scanning the laser beam toward a predetermined measurement area;
A light receiver for receiving the laser light reflected by the measurement region;
A distance calculator that calculates distance data from the time difference between the emitted and received laser light;
A controller for controlling the laser oscillator, projector, and distance calculator;
There is provided a laser radar device characterized in that the controller changes the scanning pitch of the laser beam scanned toward the measurement region based on the distance data obtained by the distance calculator.

  According to a preferred embodiment of the present invention, the projector is an optical scanner device that reflects laser light and scans one-dimensionally or two-dimensionally toward a predetermined measurement region.

According to the present invention, a laser oscillator that oscillates or modulates laser light at a predetermined period;
A projector that projects light while spatially scanning the laser beam toward a predetermined measurement area;
A light receiver for receiving the laser light reflected by the measurement region;
A method for controlling a laser radar apparatus comprising a distance calculator for calculating distance data from a time difference between laser light emitted and received,
There is provided a control method for a laser radar apparatus, characterized in that the scanning pitch of laser light scanned toward the measurement region is changed based on distance data obtained by a distance calculator.

  According to a preferred embodiment of the present invention, the scanning pitch is changed by changing the oscillation period of the laser beam or changing the angular pitch of the projector.

In addition, according to a preset pattern, the scanning pitch is made dense in the distant measurement area, and the scanning pitch is made coarse in the near measurement area, so that the spatial resolution in the horizontal direction and / or vertical direction at the position of the measurement object is obtained. Homogenize.
Alternatively, based on the distance data obtained by the distance calculator, the scan pitch is made dense in the distant measurement area, and the scan pitch is made coarse in the near measurement area. Alternatively, the spatial resolution in the vertical direction is made uniform.

  Further, when the presence of a new object is detected in a predetermined measurement area, the scanning pitch is made dense only in the existence area of the object, and only the periphery of the detected object is measured with higher spatial resolution.

  According to the above-described apparatus and method of the present invention, since the scanning pitch of the laser beam scanned toward the measurement region is changed based on the distance data obtained by the distance calculator, it is limited to a desired range in the predetermined measurement region. By increasing the spatial resolution by increasing the scanning pitch, it is possible to minimize the increase in numerical computation load and the increase in measurement time, and to solve the problem that the spatial resolution decreases at a distance.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an overall configuration diagram of a laser radar apparatus according to the present invention. As shown in this figure, the laser radar device 10 of the present invention includes a laser oscillator 12, a projector 14, a light receiver 16, a distance calculator 18, and a controller 20.

  The laser oscillator 12 oscillates or modulates the laser beam 1 at a predetermined period. The laser beam 1 is preferably a pulsed laser beam, but may be a modulated laser beam. The laser oscillator 12 can freely control the oscillation timing and pulse period of pulsed laser light or the modulation period and phase of continuous laser light by a control signal 5a from the controller 20.

The projector 14 projects the laser beam 1 from the laser oscillator 12 while spatially scanning toward a predetermined measurement region. Hereinafter, the projected laser beam is referred to as “projected laser beam”.
In this example, the projector 14 is an optical scanner device that reflects the laser beam 1 and can scan the projection laser beam 2 one-dimensionally or two-dimensionally toward a predetermined measurement region. As the optical scanner device, a fine MEMS mirror, a polygon scanner, a galvano scanner, or the like can be used.
The scanning speed of the optical scanner device can be changed in real time by the speed command 6 from the controller 20. Further, the angle information 7 of the optical scanner device is notified to the controller 20.

  The light receiver 16 receives laser light reflected in the measurement region (hereinafter referred to as “received laser light”). The light reception timing 8 of the light reception laser beam 3 is notified to the distance calculator 18.

The distance calculator 18 obtains the time difference between the laser light projected and received (projected laser light 2 and received laser light 3) from the control signal 5b from the controller 20 and the light reception timing 8, and calculates the distance data 9 therefrom. To do. The calculated distance data 9 is notified to the controller 20.
When the operation speed of the optical scanner is changed, not only a distance measurement method using a pulse laser but also a distance measurement using a phase difference method using a modulation laser is possible.

The controller 20 controls the laser oscillator 12, the projector 14, and the distance calculator 18, and laser light (projected laser beam 2) that scans toward the measurement region based on the distance data 9 obtained by the distance calculator 18. ) Is changed and output as control signals 5a and 5b and a speed command 6.
Further, the controller 20 generates angular distance information from the scan angle 7 of the optical scanner and the distance data 9 received from the distance calculator 18 and is not shown as measurement data 11 (two-dimensional data or three-dimensional data). Output to an output device (display device, storage device, control device, etc.).

  In the control method of the present invention, based on the distance data 9 obtained by the distance calculator 18 described above, the projected laser beam 2 is changed by changing the oscillation period or modulation period of the laser beam 1 or changing the angular pitch of the projector 14. The scanning pitch of is changed. By changing the scanning pitch of the projection laser beam 2, the angular pitch of the projection laser beam 2 scanned spatially toward a predetermined measurement area is changed.

FIG. 2 is a first embodiment of the control method of the present invention. In this figure, (A) shows a conventional example, and (B) shows the present invention. In this figure, 10 is a device of the present invention, and 10 'is a conventional device.
In the conventional example shown in FIG. 2A, when the monitoring object 22 (predetermined measurement region) such as a fence or a wall extends from a short distance to a long distance, the angular pitch of the projection laser beam 2 is constant, so The spatial resolution becomes higher than necessary, but the spatial resolution at long distance (indicated by a double arrow) becomes too low.
On the other hand, as shown in FIG. 2B, in the method of the present invention, the angle pitch of the projected laser beam 2 is set based on either the distance data 9 obtained by the distance calculator 18 or a preset pattern. By changing, the scanning pitch is made dense in the distant measurement area, and the scanning pitch is made coarse in the near measurement area. This makes it possible to equalize the horizontal and / or vertical spatial resolution (indicated by double arrows) at the position of the measurement object, minimizing the increase in numerical computation load and measurement time. However, a uniform spatial resolution can be obtained regardless of the distance.

FIG. 3 is a diagram showing a second embodiment of the control method of the present invention.
In this example, when the presence of a new object 23 is detected in a predetermined measurement region, the scanning pitch is made dense only in the region where the object 23 exists, and only the periphery of the detected object is measured with higher spatial resolution.
By this method, it is possible to realize precise measurement of the detected object 23 while minimizing the increase in the numerical calculation load and the required measurement time.

  As described above, according to the apparatus and method of the present invention, based on the distance data 9 obtained by the distance calculator 18, the scanning pitch of the laser beam (projected laser beam 2) that scans toward the measurement region is changed. Therefore, by increasing the spatial resolution by narrowing the scanning pitch only within the desired range within a given measurement area, the increase in numerical computation load and increase in measurement time can be minimized, and the spatial resolution can be increased at a distance. The problem of lowering can be solved.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

1 is an overall configuration diagram of a laser radar device according to the present invention. It is 1st Embodiment figure of the control method of this invention. It is 2nd Embodiment figure of the control method of this invention. 2 is a schematic diagram of a “laser radar device” in Patent Document 1. FIG. 10 is a schematic diagram of a “wide-angle laser radar device” in Patent Document 2. FIG. 10 is a schematic diagram of a “three-dimensional image information acquisition device” in Patent Document 3. FIG.

Explanation of symbols

1 laser beam, 2 projecting laser beam, 3 receiving laser beam,
5a, 5b control signal, 6 speed command, 7 angle information,
8 Light reception timing, 9 Distance data,
10 Laser radar device, 11 Measurement data,
12 laser oscillator, 14 projector, 16 light receiver,
18 distance calculator, 20 controller,
22 monitored objects, 23 objects

Claims (7)

A laser oscillator that oscillates or modulates laser light at a predetermined period;
A projector that projects light while spatially scanning the laser beam toward a predetermined measurement area;
A light receiver for receiving the laser light reflected by the measurement region;
A distance calculator that calculates distance data from the time difference between the emitted and received laser light;
A controller for controlling the laser oscillator, projector, and distance calculator;
A laser radar apparatus, wherein a controller changes a scanning pitch of laser light scanned toward a measurement region based on distance data obtained by a distance calculator.   2. The laser radar device according to claim 1, wherein the projector is an optical scanner device that reflects laser light and scans one-dimensionally or two-dimensionally toward a predetermined measurement region. A laser oscillator that oscillates or modulates laser light at a predetermined period;
A projector that projects light while spatially scanning the laser beam toward a predetermined measurement area;
A light receiver for receiving the laser light reflected by the measurement region;
A method for controlling a laser radar apparatus comprising a distance calculator for calculating distance data from a time difference between laser light emitted and received,
A method for controlling a laser radar apparatus, comprising: changing a scanning pitch of laser light scanned toward the measurement region based on distance data obtained by a distance calculator.   4. The method of controlling a laser radar device according to claim 3, wherein the scanning pitch is changed by changing an oscillation period of laser light or changing an angular pitch of a projector.   According to a preset pattern, the scanning pitch is made dense in the remote measurement area, and the scanning pitch is made coarse in the near measurement area, so that the horizontal and / or vertical spatial resolution at the position of the measurement object is uniform. The method of controlling a laser radar apparatus according to claim 3, wherein:   Based on the distance data obtained by the distance calculator, the scan pitch is made dense in the distant measurement area, and the scan pitch is made coarse in the near measurement area, so that the horizontal and / or vertical in the position of the measurement object is obtained. 4. The method of controlling a laser radar device according to claim 3, wherein the spatial resolution of the direction is made uniform.   The present invention is characterized in that when the presence of a new object is detected in a predetermined measurement area, the scanning pitch is made dense only in the existence area of the object, and only the periphery of the detected object is measured with higher spatial resolution. 4. A method for controlling a laser radar device according to item 3.

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