JPH0656296B2 - Shape measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-contact optical measurement system for measuring the shape of a measurement target.

[Prior Art] A non-contact type that irradiates a measurement light to a measurement target, receives reflected measurement light reflected by the measurement target with a video camera, and measures the shape of the measurement target based on the received light information. Shape measuring devices are known, and their applications are expected in various fields.

FIG. 5 shows the principle of the above-mentioned shape measurement.

In the figure, the measurement light 100 emitted from the light source 10 at a predetermined angle θ is reflected on the surface of the object Q to be measured,
The light receiving point 12 is reached. Here, the light source 10 and the light receiving point 12
Is 1 and in the figure, an XYZ orthogonal coordinate system is set with the direction of 1 as the X-axis direction. In the figure, 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 image pickup surface of this television camera is schematically shown by 14 in the drawing.

Therefore, as can be understood from the composition shown in the drawing, the imaging surface 14
The light receiving position of the measurement light in 1 depends on the irradiation angle θ of the measurement light 100 and the surface shape of the object Q (distance z in the Z-axis direction). The light receiving position (X coordinate) on the imaging surface 14
Is indicated by x.

For such a shape measuring principle, for example, Japanese Patent Laid-Open No. 62-62
No. 228106, the distance z relating to the shape of the object Q is firstly described below.
It is represented by a formula.

z = f · l / (x + f · tan θ) (Formula 1) Therefore, the measurement light 100 is scanned, that is, irradiation is performed while sequentially changing θ, thereby obtaining three-dimensional shape information of the object Q in a predetermined range. It is possible.

[Problems to be Solved by the Invention] In a conventional shape measuring apparatus, generally, a captured image is temporarily stored in an image memory inside a computer, and the stored image information is sequentially read from the image memory to obtain a brightness level. The distance information x was obtained by analyzing the light receiving position from the difference of ## EQU1 ## and substituting the analyzed light receiving position x in the first expression.

Therefore, such software-like shape analysis takes a very long time, and therefore, there is a problem that a moving object cannot be measured.

On the other hand, in the shape measuring device proposed in Japanese Patent Laid-Open No. 62-228106, it has been possible to realize shape measurement in real time, but there is a problem that the device becomes complicated and the production cost increases. It was

The present invention has been made in view of the above conventional problems, and an object thereof is to provide a shape measuring device having a simple configuration capable of performing shape measurement in real time.

[Means for Solving the Problems] In order to achieve the above object, the present invention irradiates a measuring object with measuring light, receives reflected measuring light from the measuring object with a television camera, and based on the received light information. In a shape measuring device for measuring the shape of a measuring object, 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, and a video signal output from the video camera It has a brightness peak detecting means for detecting a brightness peak indicating reception of the reflected measurement light, and a light receiving position sampling means for extracting a voltage value of the sawtooth wave at a timing when the brightness peak is detected. .

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

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

In other words, along with the output of the video signal from the TV camera,
Receiving position (x) of reflected measurement light included in the video signal
Can be continuously obtained.

Therefore, the light receiving position (x) is obtained in real time as a sawtooth voltage value without obtaining the light receiving position by software.
Can be extracted, and the distance information (z) can be further analyzed.

Further, by providing an analog operation circuit between the sawtooth wave generating means and the light receiving position sampling means, the sawtooth wave is processed into an analog information form that can be easily operated and analyzed 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 arithmetic circuit, the sawtooth wave can be converted into a wave containing shape information, and further, the light receiving position sampling means samples the sawtooth wave to directly obtain the distance information. It is possible to obtain (z).

[Embodiment] A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of the shape measuring apparatus 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 described with reference to FIG.

In FIG. 2, (I) shows a video signal output from the video camera. The waveform shown here is a signal waveform within the position horizontal period, and the luminance peak 20 generated by receiving the reflected measurement light reflected by the measurement target is shown.

FIG. 2 (II) shows a sawtooth wave synchronized with the horizontal synchronizing signal of the video signal. The sawtooth wave is generated in order to find the position of the brightness peak, as will be described later.

Therefore, in order to detect the brightness peak, a predetermined threshold value Vth is set as shown in (I), and the sawtooth voltage value is extracted at the timing when the brightness peak is detected. By doing so, as shown in (III), it is possible to obtain the light receiving position x of the reflected measurement light in the position horizontal period from the extracted voltage value.

Then, in order to obtain the distance information z from the obtained light receiving position x, the above-described calculation of the first expression is performed as follows.

That is, for the voltage value x shown in (III), (IV)
As shown in (1), if f · tan θ is added using an adder, and then f · l is divided by the addition result as shown in (V), the above-mentioned first expression can be realized, and the division result It is possible to obtain the distance information z as a voltage value from.

Here, the above-mentioned f · tan θ and f · l 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, it is possible to quickly and easily obtain the distance information z by extracting the sawtooth voltage value at the luminance peak detection timing and processing the voltage value in an analog manner.

FIG. 1 shows a preferred embodiment of the shape measuring apparatus 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.
The scanning is performed sequentially for each minute angle Δθ.

The measurement light emitted from the measurement light irradiation device 30 is reflected by the surface of the object Q that is the measurement target, and reaches the television camera 32 that is the light receiving device. Specifically, an image sensor (for example, CCD) provided inside after being focused by a lens system
An image of the measurement light reflection portion of the object Q is formed at.

The distance information analysis device 34 inputs the output video signal from the television camera 32 and analyzes the distance information z related to the surface shape of the object Q based on the signal. The distance information analysis device 34 will be described later in detail with reference to FIG.

The measurement controller 36 controls the entire device, and specifically supplies the measurement light irradiation device 30 with angle information θ relating to the measurement light irradiation, and the distance information analysis device 34. Is supplied with necessary parameters f · l, f · tan θ, Zm related to the distance information analysis.

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

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

Next, the distance information analysis device 34 will be described with reference to FIG.

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

The trigger circuit 40 detects the above-mentioned luminance peak included in the video signal 110, and the video signal 1
10 is compared with a predetermined threshold value Vth, and when a luminance peak is detected, a detection pulse is generated.

Then, the generated detection pulse is input to the waveform shaping circuit 42, where the pulse width is changed (0.5 μs → 2.0 μs) for later sampling.

On the other hand, the horizontal synchronizing signal 112 separated from the video signal 110 is inputted to the sawtooth wave generating circuit 44. Here, the horizontal synchronizing signal 112 may be supplied from another terminal of the television camera 32, or the measurement controller 3
6 may be supplied.

Here, the sawtooth wave generation circuit 44 outputs the horizontal synchronization signal 112.
The sawtooth wave V (t) having the same cycle as that of the scanning signal is generated in synchronization with.

The generated sawtooth wave V (t) is applied to the sampling circuit 5 described later.
2 is input to the sampling unit 52 via the analog operation unit 46 in the present embodiment.

The analog operation unit 46 is composed of an adder 48 and a divider 50.

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

Further, the divider 50 outputs the f · l signal 116 sent from the measurement controller 36 to the V output from the adder 48.
It is divided by (t) + f · tan θ signal. In the divider, an abnormal operation may occur when the denominator becomes 0V, so it is set to about 1V when there is no signal.

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

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

The sampling circuit 52 samples the voltage value of the sawtooth wave calculated in accordance with the brightness peak detection pulse output from the trigger circuit 40. The sampling circuit is composed of, for example, an analog switch or the like.

Therefore, the light receiving position x is determined by the sampling circuit 52, and the distance signal z is obtained.

Although the analog operation unit 46 is provided between the sawtooth wave generation circuit 44 and the sampling circuit 52 in the present embodiment, a similar distance signal z can be obtained even if it is provided in the next stage of the sampling circuit 52. Is.

However, the detection pulse generated by the trigger circuit 40 still contains a large amount of high frequency components even if the pulse width is changed by the waveform shaping circuit 42, and if sampling is performed using such a pulse, the response in the adder and the divider is increased. May not follow. Therefore, by providing the adder 48 and the divider 50 between the sawtooth wave generation circuit 42 and the sampling circuit 52 as in the present embodiment, it is possible to stably obtain the distance signal z.

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

As described above, according to such a 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 z. Here, since the device is composed of an analog circuit, there is an advantage that the distance information can be obtained extremely quickly.

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

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

In FIG. 4, the branched video signal 110 is input to the sync separation circuit 60. This sync separation circuit 60
Is for extracting a horizontal synchronizing signal from a video signal. Then, the output is input to the combining circuit 62 described later.

On the other hand, the distance signal z obtained by the distance information analysis device is sent to one input terminal of the subtractor 64. The maximum distance signal z _m indicating the maximum distance sent from the measurement controller 36 is input to the other input terminal of the subtractor 64. That is, when a distance signal is directly sent to the display device 38 for display, it is official to express the shape by shading according to the unevenness of the object (that is, the distance z). The distance signal z and the maximum distance signal z _m are compared to obtain the difference between them.

Then, the output of the subtractor 64 is input to the level adjusting circuit 66. The level adjusting circuit 66 is used in the display device 3.
The signal level is adjusted to the level of the video signal to be sent to S8.

Then, the output signal of the level adjustment circuit 66 and the synchronization signal output from the synchronization separation circuit 60 are input to the synthesis circuit 62, both are synthesized, and the video signal D including the distance information.
z is formed.

Therefore, by providing this video signal conversion unit, it is possible to perform drawing directly on the display device 38 without performing image formation by the measurement controller 36, and more rapid image display is realized.

According to experiments conducted by the present inventors regarding the apparatus of this embodiment, the distance measurement accuracy is about 1% at a distance of about 30 cm to the object, and it has been proved that sufficient accuracy can be obtained. Therefore, it can be said that there is no problem in analog processing.

As described above, according to the apparatus of the present embodiment, it is possible to perform shape measurement extremely quickly and to perform more rapid display, which is suitable for shape measurement of a moving object, etc. It has an advantage that the optimum shape measurement can be performed while monitoring.

[Effects of the Invention] As described above, according to the shape measuring apparatus of the present invention, the sawtooth voltage value synchronized with the horizontal synchronizing signal of the synchronizing signal is extracted at the detection timing of the luminance peak included in the video signal. Therefore, it is possible to extremely easily detect the light receiving position of the reflected measurement light and quickly obtain the distance information.

Further, by providing an analog arithmetic circuit between the sawtooth wave generating means and the light receiving position sampling means, it is possible to stabilize the operation of, for example, an adder or a divider related to the shape measurement calculation and perform the measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of a 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 is a specific configuration of a distance information analyzing 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 ... Measuring light irradiation device 32 ... TV camera 34 ... Distance information analysis device. 36 ... Measurement controller 38 ... Display device 40 ... Trigger circuit 44 ... Sawtooth wave generation circuit 46 ... Analog operation unit 48 ... Adder 50 ... Divider 52 ... Sampling circuit

Claims (2)

[Claims] 1. A shape measuring device for irradiating a measuring object with measuring light, receiving reflected measuring light from the measuring object with a television camera, and measuring the shape of the measuring object based on the received light information. Sawtooth wave generation means for generating a sawtooth wave in synchronization with a horizontal synchronizing signal of an output video signal, and brightness peak detection for detecting a brightness peak indicating reception of the reflected measurement light in the video signal output from the video camera A shape measuring apparatus comprising: a light receiving position sampling unit configured to extract a voltage value of the sawtooth wave at a timing when the brightness peak is detected. 2. The shape measuring device according to claim 1, wherein an analog operation circuit for performing a predetermined measurement operation on the generated sawtooth wave is provided between the sawtooth wave generating means and the light receiving position sampling means. The shape measuring device is characterized in that an already calculated sawtooth wave is input to the light receiving position sampling means.