JPH03505123A - distance measuring device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] distance measuring device field of invention The present invention relates to an optical radar device, and more specifically, the present invention relates to an optical radar device using a scanning mechanism. Instead of obtaining distance data point by point, the distance data points are obtained in parallel, that is, at the same time. The present invention relates to a device that uses The present invention allows robots to obtain “images” of their surroundings. It is particularly useful in robotics where it is necessary to

The invention therefore has general applicability only over short distances.

Description of prior art Prior disclosures related to pulsed illuminators, gated receiver view devices, Equally equalizes the strength of the target seen at distance and eliminates the effects of backscattered illumination. These are the most relevant. This is in the disclosure contained in the following document: It is treated as such.

Chernoeh, U.S. Pat. No. 3,305.633, An apparatus for enhancing the contrast of an image of a range target is disclosed.

Bamburg et al., U.S. Patent No. 3.899.250, The delay between the force pulse and receiver activation is controlled in subsequent pulse cycles. , make known corrections to distance sensitivity.

Fr@neh U.S. Pat. No. 4,226.529 teaches Adjustable time gauge to view target images at different distances. The view device is shown to be strengthened by the start operation.

Conttnt et al., U.S. Pat. No. 4,603,250, An image intensifier is used as a receiver, the photocathode of which is gated, and the micro A view device that adjusts the receiver gain by changing the channel plate voltage Disclosed.

This is due to poor focus control for gain-controlled video intensifiers. to solve various problems associated with Its gain is controlled solely by the voltage on the photocathode.

Details of the operation of the gated video intensifier are also disclosed.

The approach to the problem of obtaining a representation of distance data using pulsed illumination is as follows. Including things.

Klsider U.S. Pat. No. 4.066.124 provides pulsed illumination. technology and a combination of nine CCD sensors lined up in a row at a fixed distance Detects linear obstacles that can be

No. 3,463°588 to Msyerand et al. A pulsed illuminator that scans a scene vertically (along the direction of light propagation) The location is listed. The time delay between the output pulse and the receiver start pulse is The object at a distance corresponding to the time delay is seen as a result of the time delay. The device only detects. Then, for a given delay and therefore distance, The body can only be seen at that distance.

Endo US Patent! CB 2,139.036 A has a sight In order to detect the back reflection of the emitted laser light pulse, the sight is focused on the An optical radar for vehicles using a photodiode play is disclosed. Ru. Each diode is activated, allowing light to pass from the light source to the reflective object and to the light diode. The time required to return to the ord is measured. The reflection time is the The time, and therefore distance, taken by light to reach the object in the scene that is being focused It is therefore an object of the present invention to at least reduce the aforementioned problems of prior art devices. The object of the present invention is to obtain an improved optical radar distance measuring device.

Accordingly, one broad aspect of the invention is to provide rapid switching to illuminate a scene. a light source capable of generating an image, and receiving an image reflected from said scene and supplying an output to a control means. an image generator capable of switching at high speed, the light source and the image generator; are connected to pulses for triggering the light source and the image generator, respectively. pulsing means for supplying an image from the image generator; storage means for storing information and controls for sequencing the operation of said light source; logic and a logic circuit that processes the data and generates distance information related to the scene. The present invention provides an optical radar distance information measuring device including:

The control logic operates a switching device, the switching device causing the pulsing means to ) triggered to cause the light source to be continuously on or off. It is preferable to be able to switch to

Preferably, the light source is a laser diode array.

Preferably, the storage means is a video frame storage device.

Another broad aspect of the invention is (1) Illuminating the scene with continuous light from a light source and then reflecting the first video image. The process of storing data and illuminating the scene with pulse-shaped light that can be switched quickly from the light source. and storing the second video data reflected from the display. (3) Divide the second video data by the first video data to obtain the distance information of the scene. a process of obtaining associated distance information video data; and provides a method for obtaining distance information related to a scene.

This method stores the third image data reflected from the scene when there is no light from the light source. In order to remove the influence of background illumination, the first The method further includes the step of subtracting the third video data from the video data and the second video data. It is preferable to

In order to enable a better understanding of the invention, reference will now be made to the accompanying drawings to illustrate the specific details. An example will be described.

Figure 1 is a simplified block diagram of the devices that make up the device. Figure 2 shows the time profile of the reflected light pulse and the sensitivity of the image sensor in the device shown in Figure 1. , Figures 3 and 4 are respective plane views of the experimental apparatus used to illustrate the apparatus. Figure 5 shows the distance from the device when looking at the device in Figures 3 and 4. Show the video, Figure 6 shows the distance contours for the horizontal section of Figure 5; Figure 7 is a detailed block diagram of the device shown in Figure 1, and Figure 8 is a detailed block diagram of the device's hardware. Timing diagram showing timing details, Figure 9 shows the approximate output of the laser diode array and the sensitivity of the image intensifier, respectively. It is a graph.

In order to retrieve distance information about the scene, when only the light source is that of the present invention requires two modes of operation so that two images can be obtained.

Operating mode l Referring to FIG. 1, control hardware 1 selects switch 2 to turn on high speed light source 3. It is made to be turned on and off by a pulse generator 4. pulse generator 4 also drives a circuit (not shown in FIG. 1) that controls the sensitivity of the image sensor 5. conduct. The resulting images are stored in the control hardware.

Reference number 6 represents a video monitor.

In this mode, select switch 2 so that the light source is on continuously. . The resulting image obtained from the image sensor is stored again in the control hardware 1. It will be done.

process 11 is an image detected from mode 1.

Let mode 2 be the image detected from mode 2.

1 represents an image that depends on the surface selectivity of objects in the scene. Image brightness is calculated using the inverse square method Because of the law, it depends on the distance to the object. The image is created by the weight of reflected light pulses from the scene. The “on” time of the video sensor also depends on the gating effect caused by the tatami, and the distance Depends on.

Equation 2 is obtained when the light source is continuously on. Technique 2 is the reflectance of objects in the scene. It depends on the situation. The brightness of an image depends on the distance to the object due to the inverse square law. .

Let R be the range image and K be a constant calibration coefficient, then R = 11/12 The distance can be found by forming the quotient of the corresponding parts of 11 and 2, so that be done.

This process removes the effects of surface reflectance and inverse square optical loss. the only remaining influence is the convolution of the pulsed light with the gated video sensor. This is due to the

The idealized time contour raJ of the reflected light pulse and the sensitivity rbJ of the video sensor "b" is shown in FIG. The two convolutions are shown as "C" Ru. Each contour is a plot of relative size versus time.

The convolution value is the start of the reflected pulse at the receiver and the activation of the video sensor. Depends on the delay between the start of. This delay causes the light to move from the pulsed light source to objects in the scene. This is because of the time it takes for one round at 1 to advance to the image sensor 5 and return to the image sensor 5. Therefore, the distance For any pixel in the distance, the shape of the convolution function and the overall calibration coefficient K are Once you know, you can directly find the distance from the distance measuring device to any point in the image from R. Can be done.

The calibration factor is applied globally to all points in the image and includes a distance of a scene of known dimensions. X on getting a remote image? ) can be found. This only needs to be done once .

Advanced operating modes above to facilitate operation in non-ideal environments This means that the control hardware can acquire a third "background" video for inclusion during processing. It is an extension of the air. This footage was shot with a light source so that the effects of background lighting were recorded. Obtained in the off state.

With I3 as a background image, The process is modified so that R=K (1113)/(I2-I3). this is , removes background effects from 11 and 12, which cause errors in the distance values.

With reference to FIGS. 3 and 4, the experiments used to illustrate the apparatus are 150 +Have 6 test cards A released. Those cards cross the direction of the light source It is also shifted in the direction. Figure 5 shows the distance image obtained using the device, and Figure 6 shows the distance image obtained using the device. 5 shows the contours of the distances to various cards in the horizontal section of the image of FIG. 5;

Reference is now made to the more detailed block diagram shown in FIG. Pulse generator 1 1 is a timed trigger signal that drives the gate of the video intensifier 9. Supply to the intensifier driver 12. The bus/l/base generator is a laser diode array. It also triggers the drive circuit 17 associated with A. The laser diode used is It is a loop LTO15MF type. The light from the laser diode array is a sight (see diagram). ).

Light reflected from the sight is filtered to reduce the influence of light from external light sources. 7 into the image generator. The main lens 8 captures the light emitted from the door by Varo. ) 5772, focused onto the image intensifier 9. The video intensifier is NECTI 2 It produces an output observed by the television camera 10 which is 2C. TV camera 1° The output of is connected to frame store 14 and synchronous processor 13. device controller 15 operates the diode array 17 in pulsed mode (position a) and continuous mode (position b). ), and an electronic switch that allows operation in fully turned off (position C). Select the mode of switch 16. The controller 15 controls the three laser diode arrays. Three frame records in the frame store 14 correspond to the images obtained in the operating mode. Also select one of the storage buffers.

The three outputs from frame store 14 are processed by digital logic circuit 18. generates data representing distance information about the scene. This is digital-analog The converter 19 converts it into an analog signal. of the digital-to-analog converter The output is combined by circuit 20 with video synchronization information from synchronization processor 13. Ru. The resulting information is displayed on the video monitor 21.

The video intensifier 9 has a drive that changes from QV to -60V and back to QV at 30n5ec. It has a dynamic voltage. -850v is supplied to the microchannel plate (MCP (from McP in), the fluorescent screen acceleration voltage is 5KV (from screen to McP in). to MCP out).

The receiving lens optical device 8 includes a manually adjusted focusing lens and an aperture controlled by a galvanometer. It consists of a department. The filter is Kodak Wratten. ) The filter is φ87.

FIG. 8 shows relevant timing details of the device's hardware. timing belief Items (23), (24), and (25) operate the sound switch and turn on the room storage device. 14 illustrates selection signals for governing frame buffer storage selection within device 14; those The selection signal is an odd number of the interlaced video signal 22 from the television camera 10. Shown in relation to fields and even fields. control signal is asserted The time is the "active" time and is indicated by the reference numeral 26. During activity, signal 23 selects the pulse mode of the laser array. When signal 24 is active, it selects the continuous mode of the laser array and the active signal 25 selects the background mode. during which time the laser array is idle. No selection is active. At times (time interval 21), the laser array is also idle.

The active time for the selection signal is 2 video field times or 20m5 in length. It is ec. The interlaced video signal is represented by the low state of signal 22. The footage is captured during O's odd field.

Reference numeral 27 represents the recovery time between modes. This causes the phosphor in the image intensifier to , is allowed to return to the neutral state before the next selection. Recovery time is also 2f It is idle time. Their timing values depend on the persistent characteristics of the video generator. It will be adjusted.

Figure 8 shows how to drive the laser diode and drive the image intensifier during pulse mode. It also shows the timing of the waveforms. The length of the driving pulse 28 is 30n See. It is. The off time can be varied between 30nSecO and 100! l　 See, it's long. The image intensifier 9 has the same pulse duration and duplex as the laser array. It has a party cycle. The delay time 32 is + or −15 nS*e. I can do EIIM. The reason is the delay and long circuit between the laser array and the image intensifier. This is to compensate for displacement in the hand direction. The delay is set once after the device is created. and no further adjustments will be made unless recalibration is requested.

FIG. 9 shows an approximate graph of the laser light output 33 and the image intensifier 34. Drive circuit response Due to the limited response time, they deviate from the ideal square wave.

The effect of those imperfections on the final distance indication is easily calibrated out of the device.

In the preferred embodiment, the complete range image is obtained after three image sampling operations. In contrast, conventional devices repeatedly direct the longitudinal force along the direction of light propagation. Obtaining distance information by sampling and scanning the scene (Meieran) It will be appreciated that the present invention differs from the prior art, as described by Meyerand et al. cormorant.

As a result of the reduced number of samples, a distance representation of the scene is obtained much more quickly.

The images obtained from the three sources, the pulsed illuminator and the gated image generator, are A table of distance data about the sights seen, combined with special... bring about reality. This device uses exactly three images, one from each mode. to obtain a complete distance view of the image being viewed.

Simplified aspects of behavior that still produce results that are totally acceptable , the process of measuring the background image can be eliminated, and the background light level can be immediately determined. This process can be eliminated when the level is low.

Within the gist and scope of the great invention! Further, since the modification can be easily performed by a pedestrian, the present invention is not limited to the above-mentioned example. It should be understood that the invention is not limited to the particular embodiments described.

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Claims (1)

[Claims] 1. A light source that can be switched rapidly to illuminate the scene and a light source that can be switched rapidly to illuminate the scene. A high-speed switching device that receives the projected image and supplies the output to the control means. an image generating device connected to the light source and the image generating device, the light source and the image generating device; pulsing means for respectively supplying pulses for triggering the bioreactor; The control means includes a storage means for storing video information from the video generation device; control logic for sequencing the operation of the light source and processing data for the scene; and a logic circuit that generates distance information related to the optical radar distance measuring device. 2. The optical radar distance measuring device according to claim 1, wherein the control logic is a switching device. and the switching device is triggered by the pulsing means to switch the light source on. A light that can be turned on continuously or switched off. Radar distance measuring device. 3. The optical radar distance measuring device according to claim 1, wherein the light source is a laser diode door. This is an optical radar distance measuring device. 4. 2. The optical radar distance measuring device according to claim 1, wherein the storage means stores video frames. Optical radar distance measuring device that is a storage device. 5. (1) Illuminating a scene with continuous light from a light source and then reflecting a first video image. (2) the process of storing the data and (2) displaying the scene using pulse-shaped light that can be switched rapidly from the light source. illuminating and storing second image data reflected therefrom; (3) Divide the second video data by the first video data to obtain information related to the distance information of the scene. a process of obtaining distance information video data; and how to obtain distance information related to sights. 6. The method according to claim 5, wherein (4) reflecting from a scene when there is no light from a light source; The third video data is stored, and before step (3), the first video data and the second video data are stored. The method includes another step of subtracting third video data from the video data of. 7. The method according to claim 5, wherein the optical laser according to any one of claims 1 to 3 is used. A method using a distance measuring device. 8. The method according to claim 6, wherein the optical laser according to any one of claims 1 to 3 is used. A method using a distance measuring device. 9. An optical radar distance measuring device as substantially described above with reference to the accompanying drawings. 10. How to obtain distance information related to the scene roughly described above with reference to the attached drawings .