JPH04140606A - Shape measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the shape at real time in a simple constitution by extracting a voltage value of a sawtooth wave synchronized with a horizontal synchronous signal at the detecting timing of a luminance peak included in a video signal. CONSTITUTION:A measuring light casting device 30 scans while casting light every minute angle theta sequentially. The measuring light from the device 30 is reflected at the surface of an object Q to be measured, and reaches a TV camera 25 which is a photodetecting device. A video signal output from the camera 32 is input to a distance information analyzing device 34, based on which distance data Z related to the surface form of the object Q is analyzed. A measuring controller 36 controls the whole of this apparatus, supplying angular data theta related to the casting of the measuring light to the device 30. Moreover, the controller 36 feeds a parameter necessary for the analysis of the distance data to the device 34. Upon receipt of the analyzed distance data Z from the device 34, the controller 36 sends the data to a display device 38.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a shape measuring device that optically measures the shape of an object to be measured in a non-contact manner.

[Prior art] A non-contact method that irradiates measurement light onto a measurement target, receives the reflected measurement light reflected by the measurement target using, for example, a video camera, and measures the shape of the measurement target based on the received light information. 2. Description of the Related Art Shape measuring devices are known, and their applications are expected in various fields.

FIG. 5 shows the principle of the shape measurement described above.

In the figure, measurement light 100 emitted from a light source 10 at a predetermined angle θ is reflected on the surface of an object Q to be measured.
The light reaches the light receiving point 12. Here, the light source 10 and the light receiving point 12
The distance between the two is l, and in the figure, an XYZ orthogonal coordinate system is set with the direction of l as the X-axis direction. Note that in the figure, a slit light is shown as the measurement light 100.

In an actual shape measuring device, for example, a television camera is used as a light receiving device. The imaging surface of this television camera is schematically indicated by 14 in the figure.

Therefore, as understood from the composition shown in the figure, the imaging surface 14
The light receiving position of the measurement light at depends on the irradiation angle θ of the measurement light 100 and the surface shape of the object Q (distance 2 in the Z-axis direction). Note that the light receiving position (X coordinate) on the imaging surface 14
is indicated by an X.

Regarding such shape measurement principles, for example, Japanese Patent Application Laid-Open No. 62
It is explained in detail in Publication No. 228106, and the conclusion is that the distance 2 related to the shape of the object Q is the first distance shown below.
It is expressed by the formula.

z=f-J/(x+f-tanθ)-(Equation 1) Therefore, by scanning the measurement light 100, that is, by irradiating it while sequentially varying θ, three-dimensional shape information of a predetermined range regarding the object Q is obtained. Is possible.

[Problems to be Solved by the Invention] In conventional shape measuring devices, generally, a captured image is temporarily stored in an image memory inside a computer, and the stored image information is sequentially read out from this image memory to determine the brightness level. The distance information 2 was obtained by analyzing the light receiving position from the difference between the two and substituting the analyzed light receiving position X into the first equation.

Therefore, such software-based shape analysis takes a very long time, and therefore there is a problem in that it is impossible to measure a moving object.

On the other hand, the shape measuring device proposed in the above-mentioned Japanese Patent Application Laid-Open No. 62-228106 was said to be capable of real-time shape measurement, but it had the problem of complicating the device and increasing production costs. Ta.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a shape measuring device with a simple configuration that can perform shape measurement in real time.

[Means for Solving the Problems] In order to achieve the above object, the present invention irradiates measurement light onto a measurement object, receives the reflected measurement light from the measurement object with a television camera, and uses a television camera to detect the measurement light based on the received light information. In a shape measuring device that measures the shape of a measurement target, a sawtooth wave generating means for generating a sawtooth wave synchronized with a horizontal synchronizing signal of a video signal output from the television camera; The apparatus is characterized by comprising a brightness peak detection means for detecting a brightness peak indicating reception of the reflected measurement light, and a light reception position sampling means for extracting the voltage value of the sawtooth wave at the timing when the brightness peak is detected. .

Further, the present invention is characterized in that an analog calculation circuit is provided between the sawtooth wave generating means and the light receiving position sampling means for performing predetermined measurement calculations on the sawtooth wave.

[Operation] According to the above configuration, when a brightness peak included in a video signal is detected, the voltage value of the sawtooth wave is sampled at the detection timing, so the sampled voltage value is based on the reflected measurement light in the horizontal period. This indicates the light receiving position (x).

In other words, along with the output of the video signal from the TV camera and the camera, the receiving position (x
) can be obtained continuously.

Therefore, the light receiving position (x) can be calculated in real time as a sawtooth wave voltage value without any software determining the light receiving position.
It becomes possible to extract the distance information (z) and further analyze the distance information (z).

Furthermore, by providing an analog calculation circuit between the sawtooth wave generating means and the light receiving position sampling means, the sawtooth wave is processed into an analog information format that is easy to perform calculation and analysis later, before being sampled by the light receiving position sampling means. It is possible.

Therefore, for example, by applying an adder or a divider as an analog calculation circuit, it is possible to convert a sawtooth wave into a wave that includes shape information, and furthermore, by sampling the wave with the light reception position sampling means, it is possible to directly obtain distance information. (2) can be obtained.

[Examples] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the overall configuration of a shape measuring device according to the present invention. Further, FIG. 2 shows the principle of shape measurement according to the present invention.

First, the principle of shape measurement will be explained using FIG.

In FIG. 2, (I) shows a video signal output from a video camera. The waveform shown here is a signal waveform within the positional horizontal period, and shows a brightness peak 20 caused by the reception of the reflected measurement light reflected by the measurement target.

FIG. 2(n) shows a silver wave synchronized with the horizontal synchronization signal of the video signal. This silver wave is generated in order to find the position of the luminance peak, as will be described later.

Therefore, in order to detect the brightness peak, as shown in (1), a predetermined threshold value vth is set, and the voltage value of the silver wave is extracted at the timing when the brightness peak is detected. By this, as shown in (III),
From the extracted voltage value, it is possible to determine the light reception position X of the reflected measurement light in the position horizontal period.

Then, in order to obtain distance information 2 from the determined light receiving position X, the above-mentioned first equation is calculated as follows.

That is, for the voltage value X shown in (■), (IV)
As shown in , add f'tanθ using an adder,
Furthermore, as shown in (V), by dividing f-1 by the addition result, the first equation described above can be realized, and it is possible to obtain distance information 2 as a voltage value from the division result.

Here, the above-mentioned f-tan θ and f-J are supplied as voltage values from a predetermined controller, and the above addition and division are performed in an analog manner.

Therefore, as described above, by extracting the voltage value of the silver wave at the detection timing of the brightness peak and processing the voltage value in an analog manner, it is possible to quickly and easily obtain the distance information 2.

FIG. 1 shows a preferred embodiment of a shape measuring device according to the present invention to which the shape measuring principle explained in FIG. 2 is applied.

The measurement light irradiation device 30 irradiates measurement light such as spot light or slit light, and the irradiation is
Scanning is performed sequentially at every minute angle Δθ.

The measurement light emitted from the measurement light irradiation device 30 is reflected on the surface of the object Q to be measured, and reaches the television camera 32, which is a light receiving device. Specifically, after being focused by a lens system, an image sensor (such as a CCD) installed inside
An image of the part of the object Q that reflects the measurement light is formed.

The distance information analysis device 34 receives the output video signal from the television camera 32 and analyzes distance information 2 related to the surface shape of the object Q based on the signal. This distance information analysis device 34 will be explained in detail later using FIG. 2.

The measurement controller 36 controls the entire device, and specifically supplies angle information θ related to measurement light irradiation to the measurement light irradiation device 30, and also supplies angle information θ related to measurement light irradiation to the measurement light irradiation device 30. Necessary parameters related to distance information analysis for f・J! , f-tanθ, supplying Zm and tail.

The measurement controller 36 also receives the distance information 2 analyzed from the distance information analysis device 34 and sends it to the display device 38.

Here, although not shown, the measurement controller 36
, a predetermined control signal is supplied to the measurement light irradiation device 30, the television camera 32, and the distance information analysis device 34, and the entire device is synchronized.

Next, the distance information analysis device 34 will be explained using FIG. 3.

In the figure, a video signal 110 supplied from a television camera 32 is input to a trigger circuit 40.

This trigger circuit 40 detects the above-mentioned luminance peak contained in the video signal 110, and
10 and a predetermined threshold value Vth, and when a brightness peak is detected, detection 1<rus has occurred.

The generated detection pulse is then input to the waveform shaping circuit 42, where the pulse width is changed (from 0.5 .mu.s to 2.0 .mu.s) for later sampling.

On the other hand, a horizontal synchronizing signal 112 separated from the video signal 110 is input to a silver wave generation circuit 44. Here, this horizontal synchronization signal 112 may be supplied from another terminal of the television camera 32 or the measurement controller 3
It may be supplied from 6.

Here, the silver wave generation circuit 44 generates the horizontal synchronization signal 112.
A sawtooth wave V (t) having the same period as the scanning signal is generated in synchronization with the scanning signal.

The generated sawtooth wave V (t) is input to a sampling circuit 52, which will be described later, and in this embodiment, it is input to the sampling circuit 52 via an analog calculation section 46.

This analog calculation section 46 is composed of an adder 48 and a divider 50.

This adder 48 adds the f''tan θ signal 114 sent from the measurement controller 36 to the sawtooth wave.

Further, the divider 50 converts the f-1 signal 116 sent from the measurement controller 36 into the V output from the adder 48.
(t) Divided by the 10f-tanθ signal. In addition,
Since abnormal operation may occur in the divider if the denominator becomes 0■, it is set to approximately 1■ when there is no signal.

That is, addition and division using the denominator shown in the first equation are executed.

The output signal of the divider 50, ie, the calculated sawtooth wave, is input to a sampling circuit 52.

This sampling circuit 52 samples the voltage value of the calculated sawtooth wave according to the brightness peak detection pulse outputted from the trigger circuit 40. Note that this sampling circuit is composed of, for example, an analog switch.

Therefore, the light receiving position X is determined by this sampling circuit 52, and the distance signal 2 is determined.

In this embodiment, the analog calculation section 46 is provided between the silver wave generation circuit 44 and the sampling circuit 52, but it is also possible to obtain a similar distance signal 2 even if it is provided at the next stage of the sampling circuit 52. be.

However, even if the pulse width is changed by the waveform shaping circuit 42, the detection pulse generated by the trigger circuit 40 still contains many high frequency components, and when sampling with such a pulse, the response in the adder and divider will be may not be able to follow. Therefore, by providing the adder 48 and the divider 50 between the silver wave generation circuit 42 and the sampling circuit 52 as in this embodiment, it is possible to stably obtain the distance signal 2.

Note that when a microcomputer or the like is used as the measurement controller 36, the signals 114 and 116 are obtained by converting digital signals from the computer into analog signals using a D/A converter.

As described above, according to the distance information analysis device 34, it is possible to specify the light receiving position at the detection timing included in the video signal 110 and obtain the distance information 2. Here, since the device is constructed of analog circuits, it has the advantage of being able to obtain distance information extremely quickly.

Next, the video signal converter shown in FIG. 4 will be explained.

By sending the distance signal 2 shown in FIG. 3 to the measurement controller 36, it is possible to process the image in the measurement controller 36 and display it on the display device 38. It is preferable to provide a video signal converter as described below.

In FIG. 4, a branched video signal 110 is input to a sync separation circuit 60. This synchronous separation circuit 60
extracts a horizontal synchronization signal from a video signal. The output is input to a synthesis circuit 62, which will be described later.

On the other hand, the distance signal 2 obtained by the distance information analysis device is sent to one input terminal of the subtracter 64. Further, a maximum distance signal 2 indicating the maximum distance sent from the measurement controller 36 is input to the other input terminal of the subtracter 64. That is, when displaying by directly sending a distance signal to the display device 38, it is preferable to express the shape of the object with shading according to its unevenness (i.e., distance 2), and to express the shading, the distance is Signal 2 and maximum distance signal 2 are compared and the difference between them is determined.

The output of the subtracter 64 is input to a level adjustment circuit 66. This level adjustment circuit 66 is connected to the display device 3.
The signal level is adjusted to the level of the video signal sent to the video signal.

The output signal of the level adjustment circuit 66 and the synchronization signal output from the synchronization separation circuit 60 are input to a synthesis circuit 62, where they are synthesized and a video signal D containing distance information is generated.
z is formed.

Therefore, by providing this video signal converter, it is possible to directly draw on the display device 38 without forming an image using the measurement controller 36, thereby achieving even faster image display.

Regarding the device of this embodiment, according to experiments conducted by the present inventors, the distance measurement accuracy is approximately 1% at a distance of about 30 cm from the object, and it has been demonstrated that sufficient accuracy can be obtained. Therefore, it can be said that there is no problem with analog processing.

As described above, according to the device of this embodiment, it is possible to perform shape measurement extremely quickly and display it even more quickly, so it is suitable for measuring the shape of a moving object, etc. It has the advantage of being able to perform optimal shape measurement while monitoring the

[Effects of the Invention] As explained above, according to the shape measuring device according to the present invention, the voltage value of the silver wave synchronized with the horizontal synchronization signal of the synchronization signal is extracted at the detection timing of the brightness peak included in the video signal. Therefore, the receiving position of the reflected measurement light can be detected extremely easily, and distance information can be quickly obtained.

Furthermore, by providing an analog calculation circuit between the sawtooth wave generation means and the light receiving position sampling means, it is possible to perform measurements while stabilizing the operations of, for example, adders and dividers related to shape measurement calculations.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of the shape measuring device according to the present invention, Fig. 2 is a principle explanatory diagram showing the shape measuring principle according to the present invention, and Fig. 3 shows the specific configuration of the distance information analysis device. FIG. 4 is a block diagram showing the configuration of the video signal converter, and FIG. 5 is a principle explanatory diagram showing the principle of non-contact shape measurement. 30 ... Measurement light irradiation device 32 ... Television camera 34 ... Distance information analysis device 36 ... Measurement controller 38 ... Display device 40 ... Trigger circuit 44 ... Sawtooth wave generation circuit analog calculation Part adder divider sampling circuit

Claims (2)

[Claims] (1) In a shape measuring device that irradiates measurement light onto a measurement target, receives reflected measurement light from the measurement target with a television camera, and measures the shape of the measurement target based on this received light information, the shape of the measurement target is output from the television camera. a sawtooth wave generating means for generating a sawtooth wave synchronized with a horizontal synchronization signal of a video signal output from the video camera; and a brightness peak detecting means for detecting a brightness peak indicating reception of the reflected measurement light in the video signal output from the video camera. A shape measuring device comprising: a light receiving position sample means for extracting the voltage value of the sawtooth wave at the timing when the brightness peak is detected. (2) In the shape measuring device according to claim (1), between the sawtooth wave generating means and the light receiving position sampling means,
A shape measuring device characterized in that an analog calculation circuit is provided for performing a predetermined measurement calculation on the generated sawtooth wave, and the already calculated sawtooth wave is input to the light receiving position sampling means.