JP2001183461A - Distance-measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To verify condition changes of a measured range after the completion of the measurement. SOLUTION: This distance-measuring device includes a scanning means for changing a measurement direction and measures distances to measured objects in a plurality of measurement directions. The distance-measuring device comprises a monitor image pickup means for picking up a measured region as a range to be scanned, and a controller for controlling the monitor image pickup means to perform plural times of image pickups during a scan period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a distance measuring device for obtaining distance information to an object.

[0002]

2. Description of the Related Art Active or passive ranging is performed. For example, by measuring a so-called time of flight (TOF) from transmission of a light pulse to reception of a pulse reflected back from an object, a known light propagation speed is applied to obtain a distance between objects. be able to. As an application example of this distance measuring method to three-dimensional input, the present applicant has proposed a distance measuring device configured to scan an object by changing the projection direction with a deflecting mirror (Japanese Patent Application No. 11-748).
No. 37). By providing the scanning mechanism, measurement in multiple directions can be performed more quickly than in the case where the distance measurement is repeated by changing the position or orientation of the distance measurement device itself. If the deflecting mirror is intermittently driven at a constant angle so as to perform two-dimensional scanning, the distance measuring device can be used as a three-dimensional input device.

On the other hand, various types of three-dimensional input devices are provided with a function of performing color photographing of an object at the start or end of scanning of the object. The captured color image is used as identification information that allows a user of the three-dimensional data to know what the object is at a glance, texture for mapping to the three-dimensional model, reference information for correcting the three-dimensional model, and the like. You.

[0004]

As the number of measurement points (the number of measurement directions) increases, the time required for scanning increases. If transmission / reception is performed a plurality of times (for example, 10 to 100 times) per point in order to increase the measurement accuracy, the scanning is further lengthened. It takes about several minutes depending on the specifications. For this reason, if a moving object enters the measurement area during the scanning period or the whole or a part of the measured object moves, the measurement results of some measurement points may become abnormal data. The movement of the object does not affect the measurement as long as the position is off the scanning position that changes every moment even in the measurement area. Also, when the distance measuring device itself moves during the scanning period, a normal measurement result cannot be obtained.

Conventionally, since the change in the measurement situation is not converted into data, there is a problem that the user cannot verify whether the measured value at each point is correct at the stage of using the measured data. . Even though I thought that the measured value was abnormal, I could not tell whether it was a true measured value or an abnormal value that needed to be corrected. Further, even if the operator notices the movement of the object at the measurement stage, it is not possible to determine whether the movement of the object has affected the measurement result and determine whether the measurement is necessary again.

It is an object of the present invention to enable a situation change in a measurement area to be verified after measurement is completed.

[0007]

According to the present invention, moving image information is obtained by repeating imaging of a measurement area in parallel with measurement. By associating the moving image information with the measurement data, the user of the measurement data can verify whether or not a situation has changed during the measurement. Further, by displaying the moving image information, the measurement operator can check the measurement status. Verification and confirmation of the situation change can be performed by monochrome imaging, but it is preferable to perform color imaging so that the imaging data can be used for mapping.

According to a first aspect of the present invention, there is provided a distance measuring apparatus having scanning means for changing a measuring direction, and measuring a distance to an object to be measured in each of a plurality of measuring directions. And a controller that controls the monitor imaging unit so as to perform imaging a plurality of times during a scanning period.

In the distance measuring apparatus according to the second aspect of the present invention,
The monitor imaging unit performs imaging in a cycle of a full motion video. In the distance measuring apparatus according to the third aspect of the present invention, the monitor imaging unit periodically performs imaging once every main scanning.

According to a fourth aspect of the present invention, there is provided a distance measuring apparatus, wherein a memory for storing a plurality of frames of captured images obtained by the monitor imaging means, and a display means for reproducing the stored plurality of frames of captured images in the order of capturing. And

According to a fifth aspect of the present invention, there is provided a distance measuring apparatus for storing a plurality of frames of captured images obtained by the monitor image capturing means, and subdividing a scanning period from the stored plurality of frames of captured images. The image processing apparatus includes an image processing unit that extracts a partial image indicating a state of the measurement area in the period for each period and combines the extracted plurality of partial images, and a display unit that displays the combined image.

A distance measuring apparatus according to a sixth aspect of the present invention has a memory for storing a plurality of frames of captured images obtained by the monitor imaging means, and determines whether or not there is an image change between frames in the plurality of frames of captured images. Is detected, and if there is no image change, the captured image of any one frame is recorded in association with the measurement data.

According to a seventh aspect of the present invention, there is provided a distance measuring apparatus which projects light to scan an object and receives light reflected by the object to reach the object in each of a plurality of measurement directions. Measure the distance.

[0014]

FIG. 1 is a block diagram of a three-dimensional input device according to the present invention. In the figure, solid arrows indicate the flow of data, and broken arrows indicate the flow of control signals.

The three-dimensional input device 1 includes an optical system 10 for transmitting and receiving pulsed light, a scanning mechanism 30, an optical system 40 for monitor photographing, various electric circuit elements, and an input means 70 for specifying an operation. Equipped to perform distance measurement by TOF method. The optical system 10 includes a laser light source (semiconductor laser) 1
1, a light projecting lens 12 for defining a spread angle of a light beam, a reflecting prism 13 for setting an optical path, a light receiving lens 14, and a photodetector (photodiode) 15. The laser light source 11 emits pulsed light having a pulse width of about 100 ns in response to power supply from the light emitting driver 21. The pulse light enters the scanning mechanism 30 through the light projecting lens 12 and the reflecting prism 13 in order, and
Reflects at and goes to the outside. Reflecting outside and deflection mirror 3
The pulse light returning to 1 is condensed by the light receiving lens 14 and enters the photodetector 15. The photodetector 15 outputs a photoelectric conversion signal S15 having an amplitude corresponding to the amount of received light.

The photoelectric conversion signal S15 is supplied to a signal processing circuit 22.
After being appropriately amplified by the A / D converter 23, it is sampled and quantized by the A / D converter 23 at a constant period. The received light data obtained by the sampling is sequentially written into the waveform memory 24. The waveform memory 24 can store waveforms for a time corresponding to the maximum measurable distance. The CPU 61 is responsible for specifying the light receiving time based on the light receiving data and calculating the flight time (light propagation time) from the transmission time to the light receiving time.
In specifying the light receiving point, the peak of the pulse is obtained by the center of gravity calculation. Thereby, the resolution can be improved as compared with the case where the local maximum value of the data is regarded as a peak. The transmission time is specified by starting waveform storage in synchronization with the light emission control. A timing controller 62 is provided for the control. The timing controller 62 controls the light emission driver 21, the A / D converter 23, and the waveform memory 24. However, the peak may be detected by monitoring the actual light emission amount.

In the calculation of the flight time, the measurement accuracy can be improved by repeating the transmission and reception of the pulsed light to increase the number of measurements per direction. The CPU 61
Referring to the measurement accuracy map stored in the internal memory, the timing controller 62 and the scanner controller 63 issue an instruction corresponding to the accuracy set for each measurement point.
To calculate the flight time based on the obtained predetermined number of received light data. Then, distance data DL corresponding to the inter-object distance is calculated from the flight time and the known light propagation speed (3 × 10 ⁸ m / s), and written to the output memory 25. The distance data DL is appropriately transferred to an external device (for example, a computer) connected via the connector 27. At this time, moving image information described later or a monitor image synthesized based on the moving image information is added to the distance data DL. Output memory 25
A data transfer controller 65 is provided for accessing an image memory described later. The device configuration related to output to the outside is not limited to the example. For example, the received light data may be output from the three-dimensional input device 1, and the distance data DL may be obtained by an external computer. The output of the three-dimensional input device 1 can be used as the photoelectric conversion signal S15. Further, there is a modification in which an external device controls the light emitting driver 21 and the like.

In the three-dimensional input device 1, the deflecting mirror 31 is intermittently driven to sequentially change the projection direction by a predetermined angle in the vertical and horizontal directions, and scan the object. Each projection direction corresponds to a sampling point (measurement point) in a three-dimensional input. During the distance measurement in one projection direction, the driving of the deflecting mirror 31 is temporarily stopped, and the projection direction is maintained.

The optical system 40 includes a variable magnification lens 41, an infrared cut filter 42, and a two-dimensional imaging device (C
CD sensor, CMOS sensor, etc.) 43,
Imaging is performed with a scanable measurement area (virtual plane) as a field of view. The lens 41 is arranged such that its optical axis is parallel to the projection direction when projecting the pulsed light in front of itself, and the principal point and the starting point of the projection are located in the same plane orthogonal to the optical axis, It is controlled by the lens controller 64.
The output of the imaging device 43 is quantized by the A / D converter 52 after passing through the signal processing circuit 51, and
3 and the moving object monitor image memory 57.

The contents stored in the monitor image memory 53 are updated for each frame. The latest frame read from the monitor image memory 53 is converted into an image signal by the D / A converter 54 and displayed on the monitor 55. On the other hand, the moving body monitor image memory 57 stores all frames captured during the scanning period. The time-series frames (moving image information) stored in the moving object monitor image memory 57 are sent to the D / A converter 54 via the image synthesizing circuit 58. The image synthesizing circuit 58 outputs a later-described synthesized image SG based on the time-series frames when the synthesized image display is designated. When the moving image display is designated, the image synthesizing circuit 58 enters a through state and outputs a plurality of frames as they are.

By looking at the monitor display, the user can confirm the measurement area before the start of the measurement, and can verify the presence or absence of a status change during or after the measurement.

FIG. 2 is a perspective view showing the configuration of the scanning mechanism. The scanning mechanism 30 includes a deflecting mirror 31, a motor 32 for vertical deflection, a mirror box 33, and a motor 3 for horizontal deflection.
4 and a fixed frame 35. In the vertical deflection, the mirror box 33 is fixed,
The deflection mirror 31 in the mirror box 33 rotates. The horizontal deflection is performed by rotating the mirror box 33 together with the mirror box 33. Holes large enough to allow transmission light and reception light to pass therethrough are provided in the bottom portions of the mirror box 33 and the fixed frame 35.

In the illustrated mirror arrangement state, the pulse light P1 incident on the deflection mirror 31 from the reflection prism 13
Is deflected in a direction corresponding to the angular position of the deflecting mirror 31, and travels toward an external object Q. The pulse light P1 that has reached the object Q is reflected on the object surface. As long as the object surface is not specular, its reflection will be diffuse. Therefore, at least a part of the reflected pulse light P <b> 2 goes to the three-dimensional input device 1 even if the incidence on the object surface is not normal incidence. The pulse light P2 returned to the three-dimensional input device 1 is deflected by the deflecting mirror 31, and enters the photodetector 15 via the light receiving lens.

FIG. 3 is a schematic diagram of a scanning mode. FIG.
If the main scanning is of the reciprocating type as shown in FIG. 9A, the object can be scanned efficiently. In the case where the mirror position is shifted due to the rotation direction of the deflecting mirror, if the main scanning is one-way as shown in FIG. 3B, the variation in the measurement position can be reduced.

FIG. 4 is an explanatory view of a modification of the image pickup optical path.
When the optical axis of the monitor image is set parallel to the projection direction when projecting directly in front, the point on the monitor image and the measurement point where the pulse light is actually projected are only the distance between the optical axes as shown in FIG. Shift. Usually, this deviation is not substantially a problem. However, if it is desired to minimize the deviation, FIG.
An optical system 40b having a configuration in which the optical axis of distance measurement and the optical axis of imaging using the half mirror 45 as shown in FIG. The half mirror 45 is arranged so that the optical path length p between the half mirror 45 and the projection start point is equal to the optical path length q between the main point of the lens 41.

FIG. 5 is a conceptual diagram of monitor imaging according to the present invention. The scanning start time Ts, the scanning time Tm, Tn,
The outputs (frames) of the imaging device 43 at a plurality of times including the scanning end time Te are stored in the moving object monitor image memory 57.
, Moving image information MG composed of time-series frames indicating a change in the state of the measurement area during the scanning period is obtained. In the figure, the scanned area in each frame is indicated by a dotted line. The arrow at the tip of the dotted line indicates the scanning position at the time of imaging. In the example of FIG. 5, a total of two vehicles cross the measurement area during the scanning period.

Since recording a moving image directly requires a large-capacity memory, moving image compression (MPEG) may be performed before recording. The imaging cycle is not limited to full motion (30 frames / second),
Appropriate values such as one second and the main scanning period can be selected.

FIG. 6 is an explanatory diagram of monitor image composition. In the example of FIG. 6, the monitor image SG of one frame is reconstructed based on the moving image information MG obtained by N times of imaging in each main scan (each deflection cycle in the sub-scanning direction). From each of a total of N frames F _i (i = 0, 1, 2,..., N−2, N−1), a partial image f _i corresponding to a measurement area for one line at the sub-scanning position at the time of imaging is cut out. , N partial images f _i are arranged and synthesized in the order of imaging. Although the monitor image SG obtained in this manner may include many unnatural portions in appearance, the real scene (situation change) related to the distance data DL is reproduced in a condensed form.

Here, it has been described that the image is taken every time one line moves in the sub-scanning direction. However, the image may be taken every few lines in consideration of conditions such as measurement speed. In addition, the timing of each image capturing includes a start time, an end time, and a main scan of one line.
Alternatively, it may be at any point during the scanning.

In the above, imaging (strictly speaking, taking in the output of an imaging device) is performed using the movement in the sub-scanning direction during the measurement operation as a reference timing, so that the region extraction at the time of synthesis is simplified. However, it is not necessary to synchronize the imaging timing with the main scan or the sub-scan. When imaging is asynchronous with scanning, the following series of operations is set. CPU 61
Commands the data transfer controller 65 to capture a one-shot image by the moving body monitor image memory 57, and at the same time, stores data indicating the current measurement point (the position of the main scanning and sub-scanning of the mirror) in the moving body monitor image memory. Send to 57. The moving body monitor image memory 57 records the measurement point data together with the imaging data. When creating the monitor image SG, a necessary partial image is extracted from each frame with reference to the measurement point data and synthesized.

FIG. 7 is a diagram showing a screen displayed by the monitor. In the example, the monitor is of a touch panel type. When the scanning is completed, a measurement result confirmation screen Q1 is displayed. The measurement result confirmation screen Q1 is composed of a total of four operation keys 91, 92, 93, 94 and an image display area 95. The user designates the monitor image (synthesized image) SG or the moving image information MG as a display target by the operations 91 and 92. The image is displayed in the image display area 95 in response to the designation. The user checks the measurement status by looking at the display, and inputs the determination result of the appropriateness of the measurement using the operation keys 93 and 94.

FIG. 8 is a flowchart showing an outline of the measuring operation. The CPU 61 arranges the deflecting mirror 31 at the scanning start position in response to the input of the start signal from the input means 70 (# 1, # 2). Each time one line is scanned, the measurement area is imaged, and the image data and the measurement data are recorded in association with each other (# 3 to # 6). When the scanning of the predetermined number of lines is completed, a measurement result confirmation process for displaying the screen Q1 is performed (# 7). When an OK operation indicating that the measurement situation is approved is performed, the measurement operation is terminated, and when a cancel operation is performed, a measurement start instruction is waited for again (# 8). In this embodiment, in step # 5, the imaging data is recorded for each measurement, but may be recorded once for a plurality of measurements. Preferably, recording is performed for each sub-scan operation as described above.

FIG. 9 is a flowchart of a measurement result confirmation subroutine. When the operation key 91 is turned on on the measurement result confirmation screen Q1, a necessary partial image f is extracted from each of the plurality of frames F to reconstruct one frame, and the obtained monitor image (synthesized image) SG is displayed. It is displayed (# 71 to # 73). When the operation key 92 is turned on, the moving image information MG is reproduced, and in parallel with this, the moving object detection for comparing the frames is performed (# 74). When the detection of the moving object is detected, a warning display notifying the user of the detection is performed (# 75). When the operation key 93 or the operation key 94 is turned on, the process returns to the main flow.

In the above-described embodiment, the configuration in which the distance is measured based on the time from the projection of the pulse light to the reception of the pulse light has been described.
The measuring method is not limited to this. A sensor that emits beam spot light and can detect the light receiving position (for example, PSD, C
The present invention can also be applied to a device that performs distance measurement based on a triangulation method using a CD or a CMOS sensor. The present invention is not limited to a so-called active method having a light projecting system, and can be applied to a passive distance measurement such as a stereo method.

[0035]

According to the first to seventh aspects of the present invention,
Changes in the situation of the measurement area can be verified after the measurement is completed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a three-dimensional input device according to the present invention.

FIG. 2 is a perspective view illustrating a configuration of a scanning mechanism.

FIG. 3 is a schematic diagram of a scanning mode.

FIG. 4 is an explanatory diagram of a modified example of an imaging optical path.

FIG. 5 is a conceptual diagram of monitor imaging according to the present invention.

FIG. 6 is an explanatory diagram of monitor image synthesis.

FIG. 7 is a diagram showing a screen displayed by a monitor.

FIG. 8 is a flowchart illustrating an outline of a measurement operation.

FIG. 9 is a flowchart of a measurement result confirmation subroutine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Three-dimensional input device (distance measuring device) 30 Scanning mechanism (scanning means) 40 Optical system (monitor imaging means) 61 CPU (controller) 55 Display 57 Moving object monitor image memory (memory) 58 Synthesis circuit (image processing means)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumiya Yagi 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Takashi Kondo Azuchi, Chuo-ku, Osaka-shi, Osaka 2-3-1, Machi-cho, Osaka International Building Minolta Co., Ltd. F-term (reference) 2F065 AA06 AA07 FF04 FF09 FF12 FF33 GG06 HH04 JJ03 JJ18 LL05 LL13 LL26 LL46 LL62 MM16 NN08 QQ03 QQ13 QQ23 DAQ13 QQ12 DA09 BA09 EA05 FA03 FA07 FA21 FA35 FA45 5J084 AA05 AD01 BA04 BA11 BA35 BB02 BB11 BB28 CA03 CA31 CA61 CA65 CA70 EA04

Claims (7)

[Claims] 1. A distance measuring device having a scanning means for changing a measuring direction and measuring a distance to an object to be measured in each of a plurality of measuring directions, wherein an image of a measuring region which is a scanning target range is taken. A distance measuring apparatus comprising: a monitor imaging unit; and a controller that controls the monitor imaging unit so as to perform imaging a plurality of times during a scanning period. 2. The distance measuring apparatus according to claim 1, wherein said monitor image pickup means performs image pickup at a cycle of a full motion video. 3. The distance measuring apparatus according to claim 1, wherein said monitor image pickup means performs image pickup periodically at a rate of once for each main scan. 4. The apparatus according to claim 1, further comprising a memory for storing a plurality of frames of captured images obtained by said monitor imaging unit, and a display unit for reproducing the stored plurality of frames of captured images in the order of capturing. Distance measuring device. 5. A memory for storing a plurality of frames of captured images obtained by said monitor image capturing means, and a measurement area for each period obtained by subdividing a scanning period from the stored plurality of frames of captured images. 2. The image processing apparatus according to claim 1, further comprising: an image processing unit that extracts a partial image indicating a situation and combines the plurality of extracted partial images; and a display unit that displays the combined image.
The distance measuring device as described. 6. A memory for storing captured images of a plurality of frames obtained by said monitor image capturing means, detecting presence / absence of an image change between frames for the captured images of a plurality of frames, and detecting no image change. 2. The distance measuring apparatus according to claim 1, wherein a captured image of any one of the frames is recorded in association with measurement data. 7. The distance to the object in each of a plurality of measurement directions is measured by projecting light and scanning the object while receiving light reflected by the object. Distance measuring device.